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jd74914
Hello all.

I figured I’d throw up a progress thread for my car’s second rebuild. For those who don’t know me my name is James and I’ve been a 914 addict since age 13 (now 26) and used to hang around here a bunch more. It seems like a good start to this thread would be some background information. Its first build took place when I was in high school (age 13) and ended as a freshman in college. When I originally purchased the car it didn’t run and had some pretty serious external rust problems. I rebuilt the motor, fixed tons of electrical issues, replaced all of the rotten metal with new (all hand-formed since I didn’t have the money to pay for reproduction pieces), and repainted. Everything was done in my garage with the exception of turning/balancing the flywheel and I learned how to MIG weld and paint from my dad, some books, and through a lot of practice.

After reassembly, it was my daily driver for 3.5 years during my undergrad degree. I pretty much drove it hard and put it away wet for the entirety of these years and it never saw a garage. Something about getting a mechanical engineering degree, dating a few girls, working throughout the year as a design engineering intern, and finding FSAE cars really limited the amount of time I spend on my own car. By the end of my undergrad degree there were some pretty rough spots, mostly in terms of the suspension/brakes and a pesky ignition switch (replaced 3 or 4 times and it kept failing), which pushed me to taking it off the road and fixing everything correctly. I thought it might take about a year-that was 3.5 years ago! wacko.gif

Just like after the first rebuild, life got in the way and the car sat as I went through a master’s degree, worked full time, continued to play with FSAE cars, and starting working on friend’s real racecars. Now I’ve finally finished my MS (and know way too much about fluid dynamics and heat transfer laugh.gif ), am applying to schools for a Ph.D., still haven’t stopped [advising] FSAE design, and really want to drive her! The play was to start and finish rebuilding the suspension last summer (I saw Chris Foley-Racer Chris in the grocery store one day and told him this), but I got carried away and a bit behind. This thread is to chronicle the build back to the road.

We’ll start with a few pictures from when it was originally completed in 2006/7 (well, it's missing the plates and still has the original windshield but...).

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jd74914
***** Hijack Start *****
Since it’s been my main non-academic/vocational distraction for the last 7 years, a few OT FSAE pictures are probably warranted. For those who don’t know, FSAE is a college competition in which teams design and build a formula-style racecar for international competition. The cars are new every year, and the teams cycle members about every 3-4 years since they are academically-linked. I personally think it is the best learning experience for future engineers. And now for the sale’s plug: If anyone is interested in donating funds, components, or machining/RPing time, the guys would love to talk to you.

2013 UCONN FSAE Quick Spec. Notes

Suspension
10" wheels, 18.5x7.5" tires
Cast magnesium uprights
75 and 85 mm deep groove ball bearings
Custom "hindle" - Integrated hub, spindle, wheel center(6061-T6) with 4340 RC50 tripod inserts
Symmetric hindle design (same for all 4 corners)
LSA suspension, push-rod actuated dampers, front ARB
100% Ackermann
30 deg max steering angle
Kaz Tech/Cane Creek double-adjustable dampers


Brakes
Wilwood PS-1
Titon rear-pivot masters
Remote-mount bias adjust

Drivetrain
Semi-custom salisbury differential (built using BMW E30 LSD clutches and ramps)
Cast magnesium case, aluminum end caps
15.9# overall weight (including mounting pillow blocks, bearings, sprocket, stub axles, etc.)
Custom 4340 tripod stub axles
3 speed transmission, max speed 77.9 mph @ 12 krpm (which has problems eating gears...now drive 2nd and driven 2nd and 6th are cryo'd and shot-peened)

Chassis
4130, TIG welded, normalized
1800 ft-lb/degree twist
65# base frame weight, 70# fully loaded (not incl. stressed panels)
CFRP stressed floor, firewall, rear bulkhead
435# assembled weight goal (haven't weighed yet)

Engine/Controls
2001-2003 GSX-R600 motor
13:1 compression
Est. 85 hp @ 9.5 krpm, 45 ft-lb @ 8 krpm
Eq. length 4-2-1 headers tuned for 2nd resonant freq. @ 7.5 krpm, 18 ga mild steel, ceramic coated
Ti Akropovic muffler
Intake tuned for 2nd resonant freq. @ 8.5 krpm, 40% glass-filled nylon SLS
28mm SLS throttle body
Performance Electronics PE-3 ECU
Texense shift cut (programmed ignition cut in ECU for clutchless shifting)
Manual shifter/hand clutch

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jd74914
And a few shop pics just because...There is a nice Stuska dyno, manual lathe, and pretty OK design room with computers as well (always looking for more CFD/FEA machines laugh.gif ).

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***** Hijack over - Back to normal programming *****
EdwardBlume
Good luck with your build(s)....
r_towle
Good to see you back at it again, now stop getting distracted and get her going again.

You may want to research the option of a push button starter switch like some race cars use, along with the reliable power function of the ignition switch.

Rich
jd74914
Thanks Rich and Rob...I'm definitely trying to get her going...albeit somewhat slowly as I'm pretty easily distracted. laugh.gif

My initial plan (May 2013) was to replace the stock EFI with a MegaSquirt3. When I was actually driving the car, I had been having problems with intermittent failures and random broken wires. Figuring that these problems were mostly related to the 40 year old wires, the easiest solution seemed like remaking the FI harness. After thinking about it a little more, it seemed like a waste to remake an entire wire harness and still be handicapped by an antiquated controller. I’ve had experience building harnesses and tuning with a few aftermarket engine management systems [Performance Electronics PE1 and PE3, Adaptronic e420c, MicroSquirt] through FSAE and some other modified car builds so I picked the MS3 mostly for the cost and fact that I haven’t had the opportunity to play with any newer MS stuff.

The first step in any harness build is measuring out the harness end locations, so I pulled the motor to measure wire lengths, add cam/crank position sensors, reseal the oil cooler, and repaint the tin. As I was doing this I noticed some rust on “jacking” donuts and rear right trailing arm mounts so out they came. While in there I started poking at the frame rails and noticed some rot so out they came as well.

The first few pictures show some of the damage and then the quick suspension jig made to keep everything aligned after cutting. The door jams are also braced with angle welded from the upper seat belt bolt mounts to lower door jambs.

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jd74914
Off came the fender for easy cutting into the longs. That's only a little rust, right? laugh.gif

Note the old patch (80's perhaps) on the bottom left part of the image.

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A view from the back (read: I hate jack posts).

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Don't you love thresholds covering old rusty thresholds? dry.gif

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jd74914
Once the cutting started, I had a really hard time stopping...

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jd74914
A few more pictures of the suspension console and long. deconstruction.

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I'm on the quest to get everything up-to-date so more to come tomorrow.
Cairo94507
Terrific story and glad to see you are working towards your Ph.D - single biggest factor in being able to continue playing with our cars. I love seeing these cars go under the knife to repair their rusting bones. Best wishes and have fun restoring your lifetime friend.
jd74914
QUOTE(Cairo94507 @ Dec 26 2013, 10:17 AM) *

Terrific story and glad to see you are working towards your Ph.D - single biggest factor in being able to continue playing with our cars. I love seeing these cars go under the knife to repair their rusting bones. Best wishes and have fun restoring your lifetime friend.


Thanks! smile.gif

The last pictures ended with about 60% of the right long pulled off and a whole bunch more metal cut out. Since the car was dimensionally-unstable at this point, the immediate need was to fix most of the structure. The next pictures show the first portion of the inner long fix.

You'll notice that I'm not remaking the metal in exactly the same fashion as it was removed, it's actually about 12mm taller than the original cross-section and will have extra stiffening plates installed on the top and bottom faces. This modification increases stiffness more than an Engman kit (I'm tired now, but I'll write in the moment of inertial calculations later) without adding much additional weight (it's stiffness-to-weight efficiency is actually much better than Engman's and slightly better than the factory). It also has the added benefit of being essentially free since I'm making all of the pieces from sheet anyways. The oddly placed channel is for this buildup. When I get to posting the math details I'll also post a sketch of the new metal so everyone who wants can see how I'm adding it.

The inner fender well repair panel needed to have a slightly odd end finish to match the frame rail end, but I think it came out pretty nicely.

The rest of the pictures show some additional metal replacement at the engine mounts and hot air inlet duct section. Chances are these heater ducts will not come back in as originally intended and will instead become wire chase-ways for the ECU. The duct cutout in the new metal at duct inlet is funny looking (weird non-oval shape) since it has yet cut to the exact opening. The hell hole bottom wasn't too bad, but while in there seemed like a prudent replacement.

That's all for now...so enjoy some pictures. smile.gif

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ChrisFoley
Wow, a little bit of project creep there. Better now than later though.
Looks like a good time to install a raised suspension pickup kit while you're at it. smile.gif

We have a chassis here which needs much of the same repair work.
Ed's busy bolting it down to our Slutty bench right now.
r_towle
When the heck did you do that? Last week?

And Chris, I must have missed the slutty bench last time I was there, it's on my must see list how.
jd74914
QUOTE(Racer Chris @ Dec 27 2013, 08:59 AM) *

Wow, a little bit of project creep there. Better now than later though.
Looks like a good time to install a raised suspension pickup kit while you're at it. smile.gif


Yes, just a little scope creep. I figured it'd be nice to build what I [think I] want the first time around. I just raised the front spindles and have been thinking about the rear. laugh.gif

QUOTE

Ed's busy bolting it down to our Slutty bench right now.

lol-2.gif

QUOTE(r_towle @ Dec 27 2013, 07:38 PM) *

When the heck did you do that? Last week?


Hahaha A few weeks ago...I'm trying to get everything up to date now.

--------------------------

As a change of pace I raised my front spindles 18mm (slightly under the fit limit of a 15 inch wheel). Since I started with tapered Boge struts, raising required a little sectioning rather than a simple weld cut, press, and new weld. I sectioned a length from the strut top, cut the strut bottom, and then TIG'd the spool in. Note that the sectioned piece needed to be tacked and then shaved length-wise to fit the strut bottom's smaller dimensions. Unfortunately, I didn't take pictures of the process, only the "final" product.

Note that I'm going to put a RSR-style double shear tie rod mount onto the strut, machine a tapered bolt to fit the existing tie rod end, and a few spacers to play with the bumpsteer.

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*The strut housings are straight despite ho they might look in pictures. smile.gif
saigon71
Looking good...especially the jig to insure the suspension console is in the right spot.

In my experience, project creep just happens with these cars.

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jd74914
A late thanks Bob! smile.gif

I was going through my camera and found some pictures of the next steps of this project (only a year after the last post haha).

In the past year I've jet-set all over the place for work, lost my job due to company bankruptcy, signed up for full time doctoral research in laser diagnostics, started an engineering consulting gig, had the opportunity to play with LeMans-grade engine control hardware (see Life Racing F88) and way too much more so my 914 progress has been super slooooooooooooooooooow. blink.gif smile.gif Hopefully life will let me get a little more done this year! laugh.gif

The first pictures show fixes to the general inner fender structure where the metal was either soft or had been poorly replaced the first time around.

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jd74914
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ChrisFoley
QUOTE(jd74914 @ Dec 29 2014, 04:09 PM) *

...
, lost my job due to company bankruptcy,
...

How convenient for the new company to run out of money so quickly. Previous owner seemed to make it work for the long term.
I wondered how you made out when that happened but figured you would land on your feet either way.
r_towle
is the car originally green, orange, or yellow?
jd74914
Over the course of last winter, I couldn't stop thinking about lowering the rear of the car. Unfortunately, I wasn't comfortable dropping the roll center super low just by cranking down on a set of threaded spring perches without making any kinematic changes. I actually drew up both the front and rear suspension in a kinematic software I have access to and looked into modifying the pivot points, etc. Through this modeling I decided to raise the rear trailing arm mounts (just as a note changing from trailing arm to multi-link suspension was considered, but in the end I decided to stay semi-trailing arm since an suspension genre switch is really easier in a full custom car).

Additionally the car needed new bushings. As this project was moving more into the realm of questionably street-able I decided to try something different and switch to spherical bearings in the rear pivots. I'm still a little worried about how they are going to work, but my rationale was that in the worst case I would just throw away my modified arms and cut the inner pivot out of the car for replacement with something a different. The cost to change is pretty low so I'm not too worried; the most disappointing part would be throwing away the machining necessary to make the new "pivot shafts."

Just for size reference, the sphericals have a 3/4" bore. I went with this size because it most closely matched the size of the existing pivots. I don't remember the exact numbers, by the factor of safety for the spherical (radially-loaded) is something like 8 if the car experiences a 3g bump, 2g brake, and 2g lateral load all at the same time with the entire weight of the car on a rear wheel. laugh.gif

Anyways, the next pictures show a little suspension modeling (no real kinematics unless some really wants to see plots) and then the trailing arm inserts. They were machined as such because I did not want a stress concentration for the bolt at the trailing arm/spherical interface. As designed, the bolt shank goes through the spherical and into a flat in the trailing arm and the the threaded portion starts. The tube everything is combined in gets pressed into the trailing arms and the edges welded. I don't have pictures of the part but it all went pretty smoothly.

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jd74914
QUOTE(Racer Chris @ Dec 29 2014, 04:15 PM) *

QUOTE(jd74914 @ Dec 29 2014, 04:09 PM) *

...
, lost my job due to company bankruptcy,
...

How convenient for the new company to run out of money so quickly. Previous owner seemed to make it work for the long term.
I wondered how you made out when that happened but figured you would land on your feet either way.


Yup, there was definitely some funny business there. It's not owned by a Korean company who seems to be in it more for the long run which is good since, while expensive, the product does work well.

QUOTE(r_towle @ Dec 29 2014, 04:23 PM) *

is the car originally green, orange, or yellow?


Hahahaha Original color is orange. I thought I wanted a green car so the innards are green and then after seeing it I decided I actually wanted a yellow car. It's slowly getting back to more yellow. Once it's finished this time around everything should be yellow.
jd74914
The trailing arm mounts were moved up by about 1.8 inches and completely remade. When I took out the old outer mounts 4/6 bolts snapped so remaking them was altogether easier than drilling out the bolts and retapping. At the same time I remade the longitudinal structure.

The longs themselves were redesigned and made taller with slightly different metal thicknesses/layering. This was done to increase the vertical moment of inertial and improve the car's bending stiffness in this area. From a design perspective, the new geometry (more or less 0.5" taller with some strategically sized metal thicknesses) results in a 246% bending stiffness improvement over stock with a stiffness/weight efficiency (in terms of moment of inertia/cross-sectional area) of 4.927e3 mm^4/mm^2 vs the stock efficiency of 4.042e3 mm^4/mm^2. Overall weight increase is about 27 pounds. For reference the Engman kit (best as I can tell since I haven't held one) weights 18 pounds and increases stiffness by 168% assuming an OEM long to start with.

You'll note that it will still be double layered with the corrugated inner. The insulated heater tube was removed and a solid tube put in its place. This might get used as a wire tray later. Anywhere there are butted seams there is also a backer lap joint.

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jd74914
And just for fun some new stuff...

The trigger wheel is from Mario at The Dub Shop and I do need some tender springs. smile.gif

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jd74914
Then chuckc here had a great deal on some phonedials and the suspension to go with them so I just had to go 5-lug. Now the next trick will be raising the spindles on the Bilstein struts and selling the 4-lug raised spindle struts.

That's all I've got! Hopefully the next update will be in far less than a year! laugh.gif

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Phoenix914
QUOTE(jd74914 @ Dec 29 2014, 05:14 PM) *


That's all I've got! Hopefully the next update will be in far less than a year! laugh.gif]


I certainly hope so. This is just getting good!
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jd74914
QUOTE(Phoenix914 @ Dec 29 2014, 05:36 PM) *

I certainly hope so. This is just getting good!
popcorn[1].gif


I'll try!

Quick exploded view of the new trailing arm inner features so they might make more sense (couldn't find the models yesterday night).

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Chris Pincetich
Curious about that trailing arm inner and your strategy for the end bolts. Are they torqued down super tight? Did you keep them "loose" and use locktite on the threads?

The reason I ask I my set-up, and it's propensity to get loose. I have an aftermarket roller bearing trailing arm pivot and it is secured on both ends by bolts like yours. They get a little loose, so I just re-tighten them....but soon will get in there to re-grease and rehab and likely coat the threads w some sort of locktite.

Great work and impressive math beerchug.gif
jd74914
QUOTE(Chris Pincetich @ Dec 30 2014, 04:35 PM) *

Curious about that trailing arm inner and your strategy for the end bolts. Are they torqued down super tight? Did you keep them "loose" and use locktite on the threads?

The reason I ask I my set-up, and it's propensity to get loose. I have an aftermarket roller bearing trailing arm pivot and it is secured on both ends by bolts like yours. They get a little loose, so I just re-tighten them....but soon will get in there to re-grease and rehab and likely coat the threads w some sort of locktite.


I'm planning on torquing them down normally and possibly using just a little loctite tape on the threads (and lot of anti-seize on the shank). I'd be a little afraid of using too much loctite because any corrosion also adds to the locking effect and it would be a shame to have to drill out big bolts.

One of the reasons I didn't like the needle bearing kits is that I couldn't see any way for them to allow misalignment on the inside ear. When you bolt the outer side to the piece that lets you adjust toe the bearing lines up nicely and won't cause any loosening if there is a little bit of bind. The ear is fixed however, and at least the kits I've seen didn't seem to have anything in there to allow for misalignment. I might be wrong, but I've always figured that the misalignment where wouldn't allow the bolts to stay tight or promote even thrust bearing wear. In my setup, the bolting point in the ear can pivot as it's a spherical bearing, so you're always bolting exactly perpendicular to the bearing if that makes sense.

I could be totally wrong, so take that with a grain of salt, but that was my rationale for going this way and not building with needle bearings. If this doesn't work I've been thinking I'll put a needle nearing setup together with misalignment washers to allow bolting perfectly normal to the thrust surface.
FourBlades

Awesome job rebuilding the long! first.gif

Lets see more soon.

John
Mueller
Great progress.....

Have you considered using misalignment washers on the bolts?
Misalignment washers

If you want to play with and experiment with a needle bearing for cheap, pay shipping and I'll send you an old unused Nadella bearing that was left over from when I used to make the kits.

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yeahmag
Andy and I talked about this a bit. The problem is the misalignment washers are really quite thick. Would need to rengineer the kit to accommodate them.
Jeff Hail
The inner ear will bend/deflect a little bit when adjusting toe. Trust me.

I like those pivot shafts!
jeff
This setup should eliminate the bind when adjusting rear toe...Click to view attachment
jd74914
QUOTE(FourBlades @ Dec 31 2014, 12:45 PM) *

Awesome job rebuilding the long!


Thanks!

QUOTE(Mueller @ Dec 31 2014, 02:39 PM) *

If you want to play with and experiment with a needle bearing for cheap, pay shipping and I'll send you an old unused Nadella bearing that was left over from when I used to make the kits.


That would be awesome! PM sent! smile.gif

QUOTE(yeahmag @ Dec 31 2014, 04:25 PM) *

Andy and I talked about this a bit. The problem is the misalignment washers are really quite thick. Would need to rengineer the kit to accommodate them.


Looking at it there really isn't much room in there unless you grind off part of the control arm not a bid deal, or recess the shafts into the arm.

I went this way mostly for cost since everything is new anyways. Even good spherical bearings are pretty cheap compared to the Nadella rollers.

QUOTE(Jeff Hail @ Dec 31 2014, 07:58 PM) *

The inner ear will bend/deflect a little bit when adjusting toe. Trust me.

I like those pivot shafts!



Interesting...I wish I had looked more closely when pulling everything off. Thanks Jeff! I'm hoping I can pull this off with a level of quality near your car's!

QUOTE(jeff @ Dec 31 2014, 11:52 PM) *

This setup should eliminate the bind when adjusting rear toe...


Yep, mine is quite similar to that on the frame side. used bearing cups from UB Machine because I didn't really feel like machining customs ones. The main difference between that setup and mine is that I didn't weld threaded bushings straight into the trailing arm and instead pressed in an assembly to ensure co-linearity.
jd74914
A few more pieces. I seam welded the trailing arm mounts and then machined 1.75" holes in them for my spherical bearing housings. I screwed up on the first one by not machining an insert to help it hold shape with all of the heat and warped it a bit which required a little honing. After making that mistake I turned an aluminum piece to pull heat out of the housing which seemed to work well. We'll see how the slightly out-of-round housing works out. The bearing pressed in OK, but I think I might make another one since we don't have a shortage of suspension mounts. laugh.gif

Unfortunately the final product picture is blurry, but I think you can get the idea. I just found the last picture and thought it was cool so I added it. It's of the bottom of the gas tank in a '58 John Deere 420C bulldozer which I clearanced to fit a taller battery for Father's Day.

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jd74914
Forgot to add this in the last post...

Those trailing arm brackets are really tough stuff. I'm guessing they are made of 41xx series steel since I tried cutting one pretty slowly with a hole saw and wasted the hole saw even using lots of oil. Mild steel parts don't tend to do that. A carbide cutter on the mill worked much better. laugh.gif For anyone thinking of seam welding them they also weld really nicely (definitely cold rolled)!
veekry9
I missed this thread last year as I was off on other pursuits and have just now discovered this build.
We were/are using the sls technique to create lost foam patterns for small production runs of exotic metal castings.
The FormulaSAE racer is a jewel,well done. The pertinent specification of interest to me was the torsional stiffness of the chassis.
Now the arduous journey begins,the sheetmetal repair of the 914 and the skilled application of lightweight reinforcement.

Q
The longs themselves were redesigned and made taller with slightly different metal thicknesses/layering. This was done to increase the vertical moment of inertial and improve the car's bending stiffness in this area. From a design perspective, the new geometry (more or less 0.5" taller with some strategically sized metal thicknesses) results in a 246% bending stiffness improvement over stock with a stiffness/weight efficiency (in terms of moment of inertia/cross-sectional area) of 4.927e3 mm^4/mm^2 vs the stock efficiency of 4.042e3 mm^4/mm^2. Overall weight increase is about 27 pounds. For reference the Engman kit (best as I can tell since I haven't held one) weights 18 pounds and increases stiffness by 168% assuming an OEM long to start with.
You'll note that it will still be double layered with the corrugated inner. The insulated heater tube was removed and a solid tube put in its place. This might get used as a wire tray later. Anywhere there are butted seams there is also a backer lap joint.
Q

Yeah,this is what I like,the deepening of the cross section of the longs,the use of corrugated rather than flat sheetmetal panels.
That you are placing them internally is brilliant and never occurred to me,looking from the outside of my pristine longs.
I'm going to use that idea as it's a great solution to the flexi flyer characteristics of the floorpan.
A stiff perimeter monocoque ala 904,not outside the box,inside.Terrific.

Some of this may be of interest to you as no doubt you're proficient in the use of cae software.
https://www.rhino3d.com/
http://www.cimsystem.com/
http://www.mastercam.com/en-us/
http://www.caelinux.com/CMS/


jd74914
Finally did a little more work this weekend after a long hiatus with a lot of work, an almost move to KY, and a bunch of other people's projects in between.

I've been spoiled by working on cars that don't require welding or painting upside down and decided to build a rotisserie to reduce the amount of overhead welding on all of the suspension mounts. This time around the whole bottom will be stripped, repainted, and undercoated which will also be nicer to do on a side. My goal is to make a quick and dirty one to not take much time away from the overall car build so I'm modifying 2 cheap engine stands to do the job. They don't have pivot bearings so hopefully the car won't be too hard to turn, but I guess I'll cross that bridge in a few weeks when loading it on.

To try and avoid having the longest car build ever I'm trying to spend at least half a weekend day per week working just to make a little progress. laugh.gif

--------

First step was to cut apart the vertical leg, add about a foot of metal. This results in a pivot-to-bottom brace height of 38", giving about 3" of safety factor from the widest point of the car to brace. The pivot also needed to be made parallel to the bracing as the engine stand was tilted non-parallel. Next was to repeat the modifications on the second engine stand leg. After a whole bunch of hack fixture and a bit of welding the second stand was done too. Note that (2) pieces of 1.375" square x 0.1875 wall steel were used since I didn't have any of the correct 1.5x3x0.100" box beam. It should be plenty strong enough for a light car though.

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Next week's goal is to get metal to make the arms to attach to the bumper mounts, some cross bracing, and connect the 2 stands under the car. smile.gif
jd74914
October 2016 Update:

Not much got done this month due to school commitments. I did get time to clean off the car and start organizing parts. Yesterday I also got the intake manifold assembly off of the LGT motor, removed the TGVs and started removing all of their parts in preparation for gutting them. I'm going to be removing the throttling valves and welding up the throttle shaft ports in the coming weeks. Pictures coming soon.

This picture is stolen off the web, but essentially the end goal of the TGV delete.

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Additionally, I started designing the mounts and arms for the new sway bar. It's a NASCAR bar from HRP. Before deciding on the final arm length, I wanted to check the effective installed motion ratio to understand at what point further adjustment is useless. Some initial basic calculations indicate that an 8" arm length is enough, but the actual travel math is relatively complicated since the control and bar arms move in different planes. To solve this I added the bar into my suspension kinematics model, but unfortunately the effective motion ratio is a bit harder to pull out than I thought it would be. Results TBD. smile.gif

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jd74914
I picked up a gearbox off Craigslist this week. It's out of a 2012 WRX and has ~30k miles (the car was wrecked). It bench shifts smoothly and is super clean so I'm hoping that it isn't messed up inside, but I guess we'll see when the center diff comes out.

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I've got feelers out now for a broken central diff in the local area so I don't have to ruin this one making a locker if it's in good shape. Good ones seem to go for $200-350 on NASIOC so selling this one would go pretty far in offset the overall transmission cost. Anyone here have a broken diff they'd be willing to let go for cheap? laugh.gif biggrin.gif

The 2008-2014 WRX transmissions seem to be pretty stout units. Some threads on the Subie forums show their gear widths are greater than the early WRX transmissions and the case castings seem to be a little beefier too. Unfortunately, around here at least they are a bit more expensive than the older push-clutch Legacy, Impreza, etc. stuff. Right out of the box the gear ratios appear pretty well matched, though even with the 3.900 front diff first gear seems a little bit low. Ideal 1st gear is from an STi RA but those gears/main-shafts are super rare and priced accordingly.

The plot below shows tractice force, or the actual power put through the tires into the ground, vs. vehicle speed for the 08-14 WRX transmission. It assumes a perfectly stock '05 Legacy GT power output (shown in the second plot). In terms of pure acceleration and drive efficiency, you want this curve to have a parabolic shape. The parabolic shape means that power to the ground is constant and at its maximum. As mentioned before, 1st is a little bit low, but it's going to stay that way forever probably. laugh.gif The easiest way to make the in-gear traction numbers fit the overall traction parabola better is to shift the engine powerband up slightly and increase torque in the 4100-4600 rpm range. With some AVCS and boost tuning this shouldn't be too difficult. sunglasses.gif

One other thing to note is the red "max tractive force" line. This line is the most force the tires can handle and still retain traction. It's a pretty simplistic calculation just using CG, wheelbase, and an assumed single tire coefficient of friction which then calculates dynamic driving wheel weight and from that max sustainable tractive force. The number isn't correct since I'm just guessing CG, weight, etc. The tire friction coefficient is pretty questionable since I've never seen one for street tires (only slicks) and the fact that it's not taking into rotation speed or any lateral forces added by the suspension kinematics. It is useful to basically know first gear and the start of second are really just for burnouts! laugh.gif

The spreadsheet used for these calculations is attached is anyone wants to play with it. No guarantees on accuracy, though I believe everything is correct. The format was borrowed from something posted a long time ago on Pelican Parts by B. Smith (IIRC, unfortunately I never wrote down the source), but has been modified extensively. You can add different gear ratios in, I just only put in some common stuff. Check out the last page for some Subaru transmission information if you want to play around with different gears not listed in the list or personalize it to your transmission.

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Stock dyno plot (not mine, just from a local eddy current dyno)
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jd74914
Ok, I guess the spreadsheet add doesn't work for .xlsm

It's attached in a .zip format so anyone who wants to try it will have to unzip it before using.
914forme
QUOTE(jd74914 @ Oct 31 2016, 07:37 PM) *

Additionally, I started designing the mounts and arms for the new sway bar. It's a NASCAR bar from HRP. Before deciding on the final arm length, I wanted to check the effective installed motion ratio to understand at what point further adjustment is useless. Some initial basic calculations indicate that an 8" arm length is enough, but the actual travel math is relatively complicated since the control and bar arms move in different planes. To solve this I added the bar into my suspension kinematics model, but unfortunately the effective motion ratio is a bit harder to pull out than I thought it would be. Results TBD. smile.gif



really love what your doing but over complicating it a bit. The distance front the bar center to the center above the A-Arm is your ideal location since th pivots move in multiple plains. Then you are "stuck" with the number of degrees the amounts will allow your bars to travel with out binding over the range of the suspension. two points in a cad drawing will not tell you that, real world will. This of course is based on the factory U tab on the arms, and a double sheer tab up top running a set of rod ends for the drop links. If you are using a spherical bearing on the arm, or a different high angle mount, then your movement can be greater.

Looking forward to seeing your solution to the Nascar bar mounts. I know I gave lots of thought to mine before I said WTF.gif and just did it! Best solution confused24.gif I do know they do not bind with bar rotation.
jd74914
I got a sweet set of single adjustable JRZ shocks for the rear from Stephen (914forme). smile.gif

They take 2.25" springs-my old shocks took 2.5" so I'll need to get some new springs. The rod-end spring perches are pretty nice in that they fit to the eyelet. The trailing arm attachment bolt is a pretty nice piece as well. These should work well with the raised "stock" shock console I'm planning.

Notes for later: Perch thread dimension is said to be M52x1.5. That is incorrect because the major diameter of the threads is ~2.1565 vs 2.046" (51.97 mm) it should be for that thread.

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This morning I turned down some 6061 spring spacers so I can run a zero-weight helper spring and avoid having the main spring come off the perches when the car gets jacked up. The smaller lip is for the helper spring and larger for the main coil. These are going into the pile for anodizing now.

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jd74914
Also pulled the intake wiring harness off. With all of the zip ties and hard to get to connectors, it was a bit of a pain. I didn't take a picture, but this car doesn't have a MAF installed (thought all of these did...need to do some more reading there), but did have the associated connector and a pretty slick sealing blank on the loom.

It contains most everything (engine-wise) besides the camshaft phasing controls (AVCS), crank position sensor, and coil driver wires. I was expecting the harness to be perfect given it came off a motor only 11 years old laugh.gif, but it had some issues. It looks like someone has been into it before and cut/spliced some wires. Its a little strange since they didn't make any changes; perhaps they were trying to do some troubleshooting and didn't have the correct probes.

Next step is to identify all of the connectors and reverse engineer the harness to start building a new one. The plan is to build a separate intake and engine block harnesses with firewall bulkhead connectors for fast engine removal. We'll see how that works out!

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My cheap NASCAR expansion tank arrived. Buying a used tank was cheaper than buying the nice almost-but-not-quite hemispherical tube caps, so I went for it. It'll go nicely with the NASCAR bar. laugh.gif I'm pretty stoked to weld on some mounts, loose the lower wiggins fitting, and go to town with it.

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914forme
QUOTE(jd74914 @ Dec 20 2016, 11:46 AM) *

I got a sweet set of single adjustable JRZ shocks for the rear from Stephen (914forme). smile.gif

This morning I turned down some 6061 spring spacers so I can run a zero-weight helper spring and avoid having the main spring come off the perches when the car gets jacked up. The smaller lip is for the helper spring and larger for the main coil. These are going into the pile for anodizing now.

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Nice job on the spacers.

jd74914
QUOTE(914forme @ Dec 20 2016, 01:24 PM) *

Nice job on the spacers.


Thanks! Spending lunch turning spacers to save $50 for other stuff seemed worth it. smile.gif
jd74914
Next up are some TGV deletes. I really just started going through these so I could reduce the I/O on my ECU, not so much for any huge power gains. A bunch of companies sell nice milled versions for not too much money considering the machining complexity (IAG ~$300), but I'm way to cheap to buy them so I decided to do them myself. A lot of people just remove the butterfly valves like in the first pictures below, but given the difficultly to remove it seemed worth it to tally delete the crossbars and smooth the lip the butterfly sits on when closed.

Note: theoretically, the engine probably won't run as well at low revs (especially while cold) with these deleted. When closed they basically reduce the size of the runner dramatically to increase the velocity of flow hitting the injection stream. The increase in velocity would result in increased droplet entrainment, or better mixing. The fuel jet is essentially a jet in crossflow so increasing crossflow (runner) velocity decreases the momentum ratio of the injector stream and should cause it to bend over and not hit the back wall as hard.

To delete you basically just:
1) Remove the TGV assemblies-easiest if you first remove the fuel rail
2) Remove the butterflies. Easiest way is to drill out the peened back side of the screws and then use an impact screwdriver on the front. Otherwise you can also just drill out the screws all together.
3) Remove all of the hardware (actuator, position sensor, etc.)
4) Tap out the shaft
5) Use a hacksaw to cut the "cross brace" as close to the inside surface as possible
6) Pick up your favorite die grinder and flame burr and go to town on the remaining brace. While you're at it you might as well smooth the butterfly plate lip. It's easiest if you mount in a vice and then use some beeswax, cutting oil, or machine coolant on your burr so it doesn't gum up.
7) Weld up the shaft holes.
8) Grind welds down smooth and go over whole interior with sanding wheel.
9) Clean up whole TGV body and reinstall (or whatever)

I'm only up to step 6 so far-didn't have time to borrow the TIG during lunch today. Hopefully I'll get there next week. smile.gif

Disassembled on the bench (4):
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Shot of the cross brace inside before cutting and comparison after cutting (5).
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You can see the little lip mentioned in (6) on the opposite side of the TGV interior as the cross brace.
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Mounted in the vice after some grinding (6).
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jd74914
Another view of the material taken out with slightly better lighting.

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The last step is to weld up the shaft holes and do a bit of sanding to remove any small gouges left from the die grinder. The shafts do ride on plastic bushing which are pretty easy to grind out with the grinder (I couldn't get them out by hand, not sure if that's typical or not). I'm probably going to blast these too to try and get rid of some of the oxidation and then paint or something to keep them nice.

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jd74914
QUOTE(914forme @ Nov 13 2016, 07:21 PM) *

really love what your doing but over complicating it a bit. The distance front the bar center to the center above the A-Arm is your ideal location since th pivots move in multiple plains. Then you are "stuck" with the number of degrees the amounts will allow your bars to travel with out binding over the range of the suspension. two points in a cad drawing will not tell you that, real world will. This of course is based on the factory U tab on the arms, and a double sheer tab up top running a set of rod ends for the drop links. If you are using a spherical bearing on the arm, or a different high angle mount, then your movement can be greater.

Looking forward to seeing your solution to the Nascar bar mounts. I know I gave lots of thought to mine before I said WTF.gif and just did it! Best solution confused24.gif I do know they do not bind with bar rotation.


I'm planning on running a high misalignment rod end on the arm-side to gain a bit more travel. That said, as angle increases the force applied to the arm increases tremendously, so buckling can become a concern. I still haven't gotten a change to measure everything yet so we'll see. smile.gif

The mounts will look similar to OEM mounts. I wanted to keep the mounting geometry the same so I'd be easy to align and let me use the stiffening plates from MADDOG. The big difference is that instead of the OEM bushing, I'm going to use a Frelon-lined flanged sleeve bearing. These are self-lubricating and are supposed to last well in dirty environments but that's something driving will need to validate. The bar certainly spins well in them! laugh.gif

The CAD views are below (drew it up to check some clearances before making chips and buying fasteners). I'm going to machine first thing next week when my metal comes in (6061-T6). They are a bit beefy, but I really didn't want to risk HCF cracking after a few years of use and exposure to sand/salt. The gap you see between the bushing mount and backing plate is ~0.110 to account for inner fender and stiffener thickness.

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914forme
Nice design

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