Help - Search - Members - Calendar
Full Version: Suspension upgrade
914World.com > The 914 Forums > The Paddock
Randal

Been thinking about what it would take to build in tubes or whatever to allow a complete Boxster suspension swap out on a 914.

It is likely a big project, but maybe not.

Anyone else been thinking about this? sawzall-smiley.gif
J P Stein
I have mulled it over. I've decided to sell the $hitbox instead.
Randal
QUOTE(J P Stein @ Jul 15 2009, 08:07 AM) *

I have mulled it over. I've decided to sell the $hitbox instead.


I'd be interested in hearing your thoughts on the project, i.e., other than the conclusion you reached...

BTW I have my motor back, ready to go back into 222. It's sitting in my garage on an engine stand.

I'd have it back in, except for a bit of a setback I RAN into.
grantsfo
I'd rather see the car run. rolleyes.gif

But yes Boxster suspension would be a huge improvement. If you get out to an event I'll let you take some runs in my car. You will be amazed at how much better Boxster suspension is over 914. I can do absolutely stupid stuf fand recover in the Boxster.

We do have some local people looking at Boxster suspension swaps. I'm just not aware of anyone executing yet.
grantsfo
QUOTE(J P Stein @ Jul 15 2009, 08:07 AM) *

I have mulled it over. I've decided to sell the $hitbox instead.

I'll have enough class to not say what JP said when I sold my car, but will ask a question. JP, You trading up to a Miata? happy11.gif
Randal
QUOTE(grantsfo @ Jul 15 2009, 09:57 AM) *

You will be amazed at how much better Boxster suspension is over 914. I can do absolutely stupid stuf fand recover in the Boxster.




Hardly, as I've had a reasonable amout of seat time in Spec Boxsters from the beginning of Spec Boxsters.

Like the first day we took out Bill's Spec Boxster at a GGR autox and did pretty well.



Randal
QUOTE(grantsfo @ Jul 15 2009, 10:10 AM) *

QUOTE(J P Stein @ Jul 15 2009, 08:07 AM) *

I have mulled it over. I've decided to sell the $hitbox instead.

I'll have enough class to not say what JP said when I sold my car, but will ask a question. JP, You trading up to a Miata? happy11.gif



Do me a favor Grant, please leave the "poking" to some other web site.

I'd personally like to hear JP's technical opions on the matter; IMHO the "poking" or joking or whatever you call it just eliminates the opportunity to get people discussing what I was trying to discover.
J P Stein
I didn't get much past the looking it over stage. The Boxster suspenders are still Mac strut which doesn't appear to be a huge advantage over the 914 set-up except.....
If a guy was able to adapt the Box ball joints to the 914 A arm, then use the upright & strut, you would get the advantage of reduced scrub radius with wide front wheels (larger back space wheels could then be fitted) There would be some modifying to the upper mount to attach it. Neither of these seem to be a show stopper.....but a fair amount of fab work.

I have never gotten a good look at the rear. It would seem (at a glance) to need a new subframe fabbed for attach points. It seems very superior to the stock 914 set-up.
That said, a custom double A arm set up may be no more difficult since a new subframe is needed no how.

I want to simplify my AX experience. I can't keep up with the shitbox. The preliminary plan would be to set up my Mr.2 Turbo to run B Stock against the RX8s. Tires & shocks is about all one can do....but a Miata is not out of the question.
john rogers
You could do what Ron Mistak did with his 914 and put a late model rear suspension under it. That is the GT-1 looking car and I heard the cost was close to astronomical including all the tube frame work. I would think it would be easy (relative) to cut away a Boxster body and save the bulkheads as necessary and then put all the outer panels of a 914 GT over it. The Boxster could be narrowed, shortened, etc as needed as long as reassembly was done correctly.

But once all that is done the question becomes where do you race it?
J P Stein
QUOTE(john rogers @ Jul 15 2009, 06:25 PM) *


But once all that is done the question becomes where do you race it?


The SCCA autocross Mod class......PCA, too.
These classes are among the few places that a hot rodder that likes turns can play.
Randal
QUOTE(john rogers @ Jul 15 2009, 06:25 PM) *

You could do what Ron Mistak did with his 914 and put a late model rear suspension under it. That is the GT-1 looking car and I heard the cost was close to astronomical including all the tube frame work. I would think it would be easy (relative) to cut away a Boxster body and save the bulkheads as necessary and then put all the outer panels of a 914 GT over it. The Boxster could be narrowed, shortened, etc as needed as long as reassembly was done correctly.

But once all that is done the question becomes where do you race it?



Your right, it is likely out of the question cost wise to duplicate, in tubes, the attachment points and use a 914 starting point.

On the other hand, just for fun, I've got to take a closer look at Bills Spec Boxster and figure out just how many "attachment points" would have to be fabricated.

With some of the 3D software out there the job might be something that could be documented, then built.
EdwardBlume
Randal, you know Jason Samson right? I think he was working on a similar result for the rear but for a different application..

BTW - if you'd like to put together a crew and install your engine, Cade and I are in...
Chris Hamilton
I'd like to do like Chevy did with the fiero. Take a modern FWD car frontend and put it in the rear, and just fix the tie rods to a solid mount.

Imagine a honda B16 frontend in the rear of a 914? Double wishbone suspension and 160hp from 1590cc @ 8200rpms, and limited slip diffs that cost $700! The whole rig would probably cost $1500 from a civic si.
Joe Ricard
89 Civic hatch has some really nice suspension. Good camber control and looked to be fairly simple to cut hunks off a Civic and weld them to a 914.

Then the brakes can be infinately upgraded.

However if I was going to start cutting stuff I would look at the 3rd gen RX-7
jimmybryan
QUOTE(Chris Hamilton @ Jul 16 2009, 02:50 PM) *

I'd like to do like Chevy did with the fiero. Take a modern FWD car frontend and put it in the rear, and just fix the tie rods to a solid mount.

Imagine a honda B16 frontend in the rear of a 914? Double wishbone suspension and 160hp from 1590cc @ 8200rpms, and limited slip diffs that cost $700! The whole rig would probably cost $1500 from a civic si.



Something like this, perhaps?........

http://www.kimini.com/
stewteral
QUOTE(J P Stein @ Jul 15 2009, 08:07 AM) *

I have mulled it over. I've decided to sell the $hitbox instead.



Hey Randal:

Tim is a 914World member and has an incredible tube-frame 914-V8 in which he has built his own 5-Link rear suspension.

In order to do the same, you would need to rebuild the whole back-end of the car with a tube sub-frame to accept a new design suspension.

So the question is: do you have the shop, tools, know-how and WILL to go all the way. Once you start, there would be NO going back as you would HAVE to remove all the original 914 suspension mounting points.

For a complete discussion, I'd suggest emailing Tim: byndbad914@yahoo.com

Best of luck,

Terry
naro914
If you really want to do a nice 914 suspension upgrade, consider ERP's 935 front suspension, camber boxes and Fox coil overs all around. They are amazing... I have them on Papa Smurf and the handling and steering input is wonderful. Like driving a whole new car. Fully adjustable, nimble, never fights back like torsion bars do. I want to put it on Huey too one of these days...

Pics:
Randal
QUOTE(naro914 @ Sep 14 2009, 08:07 PM) *

If you really want to do a nice 914 suspension upgrade, consider ERP's 935 front suspension, camber boxes and Fox coil overs all around. They are amazing... I have them on Papa Smurf and the handling and steering input is wonderful. Like driving a whole new car. Fully adjustable, nimble, never fights back like torsion bars do. I want to put it on Huey too one of these days...

Pics:



Amazing.

What kind of investment is that package?
Chris Hamilton
Bob, that suspension system on your car looks very nice. Those really look like fantastic pieces.

It is not however a modern suspension system like we are talking about here. I don't see anywhere in the car that the actual suspension geometry has been changed beyond what can be done with basic upgrades on a 914. The trailing arm shape and pivot points are still in the stock locations, and the front A-arms and struts appear to be basically the same geometry also.

The main thing that I'd like to change on my 914 is the curve described by the rear trailing arms as they move on their pivot, and your car doesn't seem to have addressed that point.
naro914
QUOTE(Chris Hamilton @ Sep 15 2009, 12:47 AM) *

Bob, that suspension system on your car looks very nice. Those really look like fantastic pieces.

It is not however a modern suspension system like we are talking about here. I don't see anywhere in the car that the actual suspension geometry has been changed beyond what can be done with basic upgrades on a 914. The trailing arm shape and pivot points are still in the stock locations, and the front A-arms and struts appear to be basically the same geometry also.

The main thing that I'd like to change on my 914 is the curve described by the rear trailing arms as they move on their pivot, and your car doesn't seem to have addressed that point.


Chris,
You are correct, in fact that only changes in the rear are putting the remote resevoir shocks instead of standard - and much stiffer springs. The big changes are in the front. the geometry can be changed pretty substantially in the front since all the components are very adjustable. We can dial in just about any camber, and any ride height we want, and it handles great. Plus with the coil over set up, we can now easily adjust spring rates too. I noted it above, but one thing I was really surprised with was the steering input changes. With the old system, I had a very hard time turning the wheel when pushing it in and around the garage - 11" wide slicks will do that. Now, I can reach in the window and turn the wheel with one hand, very easily. It almost feels like the car has power steering.

Little story: Nadine and I decided to put the suspension on. I told her the car would run better on the track. So we did. She never asked how much it all costs, until we were heading home after our first track weekend and she said "OK, I love the suspension, feels great. So....how much did it cost?" I said "well, uhh...." she interupted me and said " did it cost a months salary" I said "no, not at all", and she then said "Great, then it was worth it!"

Gotta love a girl that understands the value of money.... piratenanner.gif

Just curious, what do you hope to gain with the upgrade? Knowing the way a Boxster suspension is, I'm not sure I can see how it could fit?

Chris Hamilton
Bob, sounds like the front suspension you have is working very well for you.

What I hope to gain with the rear suspension upgrade is the ability to lower the car and run wide tires without getting a severe camber curve, and to fix whatever the heck else is going on back there when the trailing arms get into funky angles in a lowered car.

We've got guys in 996s out at our events running 335 R18s, and our 914s start to screw up when we've got 225s on them. Certainly we have people running wider wheels and tires in 914s, but they have to decide either to stiffen up the rear past where would be ideal to limit the suspension travel, or they end up running the tires on their corners.
naro914
gotcha.
just fyi, I run racing slicks on Papa Smurf, 11" front, 12" rear wheels. I run -1 degree camber front, and -1.3 degrees rear
SirAndy
QUOTE(Chris Hamilton @ Sep 15 2009, 10:06 AM) *

What I hope to gain with the rear suspension upgrade is the ability to lower the car and run wide tires without getting a severe camber curve, and to fix whatever the heck else is going on back there when the trailing arms get into funky angles in a lowered car.

Raise the rear suspension pickup. That way, you can lower the car while keeping the stock camber curve.
And custom springs & shocks will still give you the same amount of travel.

I think this would be by far the easiest way to get what you want.
shades.gif Andy
Chris Hamilton
QUOTE(naro914 @ Sep 15 2009, 11:49 AM) *

gotcha.
just fyi, I run racing slicks on Papa Smurf, 11" front, 12" rear wheels. I run -1 degree camber front, and -1.3 degrees rear



Yes, you can get perfectly fine static camber by playing with shims, but what is your camber when your car squats under accel, or when you are cornering at the limit in a broad corner? Those numbers are going to be drastically different than a 996 that starts with -1.3 degrees camber in the rear and 12" wheels.
SirAndy
QUOTE(Chris Hamilton @ Sep 15 2009, 06:23 PM) *

but what is your camber when your car squats under accel, or when you are cornering at the limit in a broad corner? Those numbers are going to be drastically different than a 996 that starts with -1.3 degrees camber in the rear and 12" wheels.

I don't think progressively more negative camber as you load your suspension is necessarily a bad thing ...
idea.gif Andy
naro914
how can you measure camber under load?

And I agree with Andy - even with newer cars, you can see the neg camber increase under load. I've seen a picture of a buddy with a race set up 993 on hard cornering and you can see the wheel 'buckle' under the load to major neg camber. Don't we want that?
Chris Hamilton
QUOTE(naro914 @ Sep 15 2009, 07:41 PM) *

how can you measure camber under load?



To measure camber under load you can measure how far you flex the suspension, and then apply that reading to your camber curve, which is going to be a function of wheel travel.
JazonJJordan
popcorn[1].gif ...(thanks guys!)...
naro914
QUOTE(Chris Hamilton @ Sep 15 2009, 10:52 PM) *

QUOTE(naro914 @ Sep 15 2009, 07:41 PM) *

how can you measure camber under load?



To measure camber under load you can measure how far you flex the suspension, and then apply that reading to your camber curve, which is going to be a function of wheel travel.


follow up question: how do you measure the flex in the suspension at a given load?
Chris Hamilton
QUOTE(naro914 @ Sep 15 2009, 08:36 PM) *

QUOTE(Chris Hamilton @ Sep 15 2009, 10:52 PM) *

QUOTE(naro914 @ Sep 15 2009, 07:41 PM) *

how can you measure camber under load?



To measure camber under load you can measure how far you flex the suspension, and then apply that reading to your camber curve, which is going to be a function of wheel travel.


follow up question: how do you measure the flex in the suspension at a given load?


You can use a travel sensor on the shock, that will tell you how far it gets compressed at the maximum point. These things are getting cheaper all the time, and allow you to datalog how your suspension works throughout the course of a lap, and compare runs when you make suspension changes.

If you don't want to invest in any kind of logging you could probably also do something with chalk or paint or tie wraps or something just to see how far your trailing arm moves.
turboman808
The suspension setup on my sosltice is pretty dam sweet. If I was to take drastic steps to get the car handling like I want I would looking into the sosltice suspension for sure. But that seems like a really diffucult way to solve the problem.

As far as making it a more modern suspension I installed some performance shocks on my brothers GTI 2-3 years ago and thought it looked like something designed 100 years ago. Front was similar to the 914 and rear looked like a metal girder.


I plan to go with the 930 style front arms and either fox racing or podium shocks all around. I have a feeling that would give you what you are looking for. It's just a matter of tweaking it perfect. Sadly thats probably beyond my skillset and will need to get Chris(tangerine racing) to get it tuned perfect.
ChrisFoley
QUOTE(Chris Hamilton @ Sep 14 2009, 11:47 PM) *

I don't see anywhere in the car that the actual suspension geometry has been changed beyond what can be done with basic upgrades on a 914. The trailing arm shape and pivot points are still in the stock locations, and the front A-arms and struts appear to be basically the same geometry also.

The 935 front end as Bob pictured has valuable geometry alterations in addition to the increased adjustability. Several manufacturers make similar products and they aren't all the same however.
The better ones, such as ERP and what I have from TRG on my race car, have the inboard lateral pivot moved inward and upward substantially.
This improves the angle of the arm on a lowered car and decreases the camber change through the range of motion.
The outboard spherical bearing is also raised in comparison to a stock ball joint, which allows a substantially raised spindle, thereby further improving the camber curve.

Using a threaded body RSR type strut allows 2 1/4" coilovers which saves 1/8" on tire clearance and improves scrub radius compared to the 2 1/2" coilovers required on stock struts.
Additional scrub radius improvements require re-cambered struts such as are on our white FP car.
Unfortunately the "935 type" (Kanna Motorsports headbang.gif ) suspension parts on the white car do not have all the geometry improvements of the ERP setup.
The Tangerine Racing Products camber box setup allows camber angles from negative 3* to 0* so DOT tires or slicks can be used effectively.

The front end isn't where the biggest grip issues lie on a 914 suspension however. Lowering a 914 exacerbates the shortcomings of the stock semi-trailing arm rear suspension arrangement.
The roll couple at the rear is quite high, potentially even above the cg when slicks are used with stock pickups because of the pivot shaft angle required to get a proper camber angle. The camber/toe curves are less than desireable as well.
A combination of raised pickups and de-cambered trailing arms is needed to solve these problems if retaining a stock-type suspension.
The Tangerine Racing FP car sits less than 3" off the ground at the jacking donuts and has the roll couple at about 8-9" off the ground, way below the cg.

All this is a lot of work but still quite a bit less than grafting parts from another car onto a 914 or building a subframe and multi link suspension from scratch. Eligibility for racing or AX classes below "Modified" is retained as well.
grantsfo
Thats a nice solution for front. But rear still needs some help. In my opinion rear suspension is biggest weak link with 914.
naro914
Chris,
wow, and I got it because it looked cool! smile.gif and 3" huh? Jeez...I just measured Papa Smurf and we're at 4". I thought we were low, now I feel like a Baja racer....

Seriously, yes, the ERP system only really addresses the front set up, there is still work to be done on the rear of a 914. What it HAS given me though it the ability to do much more adjustment with the shocks and spring settings, thereby being able to dial out a lot of the deficiencies of the stock rear components.
ChrisFoley
QUOTE(naro914 @ Sep 17 2009, 11:49 AM) *

and 3" huh? Jeez...I just measured Papa Smurf and we're at 4".

What is your tire diameter? My cantilever slicks are about 23" dia.
The inner end of my pivot shafts are 11.5" high, making the trailing arms perfectly flat at rest.
Britain Smith
Chris, can you send me the installation instructions for the rear suspension raised pick-up points...I want to determine how difficult it would be to do.

-Britain
naro914
tire diameter is about 23.5 +/-. Goodyear slicks on 12x16" rear, 11x16 front wheels. pic:
naro914
try the pic again...
Chris Hamilton
QUOTE(grantsfo @ Sep 17 2009, 09:36 AM) *
In my opinion rear suspension is biggest weak link with 914.


Precisely the point of this thread! Grant, now that you've been playing the boxster I'm sure you've felt this haven't you?


Chris,

I'd love to see pictures of a 914 with the trailing arm pivot raised!
andys
QUOTE(Racer Chris @ Sep 17 2009, 09:03 AM) *


The roll couple at the rear is quite high, potentially even above the cg when slicks are used with stock pickups because of the pivot shaft angle required to get a proper camber angle. The camber/toe curves are less than desireable as well.
A combination of raised pickups and de-cambered trailing arms is needed to solve these problems if retaining a stock-type suspension.
The Tangerine Racing FP car sits less than 3" off the ground at the jacking donuts and has the roll couple at about 8-9" off the ground, way below the cg.



Chris,

Can you explain why you de-camber the trailing arms? I'm taking de-cambering as removing that 1.5* of camber (or more?) built into the stock trailing arm. Do you then lower the inside ear of the pivot shaft (to lower the roll center?) thus angling the pivot shaft?

Thanks,

Andys
ChrisFoley
QUOTE(andys @ Sep 18 2009, 11:27 AM) *

Can you explain why you de-camber the trailing arms? I'm taking de-cambering as removing that 1.5* of camber (or more?) built into the stock trailing arm. Do you then lower the inside ear of the pivot shaft (to lower the roll center?) thus angling the pivot shaft?

Lowering the car increases negative camber. In order to reduce the excessive camber from lowering, shims are required to move the outer pivot downward. This raises the rear roll couple dramatically, and has a negative effect on toe/camber curves as well. By removing the camber that the factory built into the trailing arm I can return the pivot shaft to a good angle for roll couple as well as toe/camber control. I offer rebuilt/reinforced trailing arms with -0.75* or 0.0* of camber instead of the stock -1.5*.
With my setup the pivot shaft angle is almost the same as factory with no shims, about -1.0*.

QUOTE
I'd love to see pictures of a 914 with the trailing arm pivot raised!

Two different 914s with the trailing arm pivot raised 3".
The white car sits higher off the ground and has -0.75* trailing arms.
The tangerine car has 0.0* trailing arms. Both have about -0.7* camber at rest.

naro914
damn you...just when I thought I was getting close to being done spending money on my race car (at least as far as upgrades go) you go and make me start thinking of doing more stuff... headbang.gif

0396
QUOTE(naro914 @ Sep 14 2009, 08:07 PM) *

If you really want to do a nice 914 suspension upgrade, consider ERP's 935 front suspension, camber boxes and Fox coil overs all around. They are amazing... I have them on Papa Smurf and the handling and steering input is wonderful. Like driving a whole new car. Fully adjustable, nimble, never fights back like torsion bars do. I want to put it on Huey too one of these days...

Pics:



Very very cool!
This is a "lo-fi" version of our main content. To view the full version with more information, formatting and images, please click here.
Invision Power Board © 2001-2024 Invision Power Services, Inc.