I see what you mean but just think how much better this car will be than stock. Or even those that only are able to reinforce the longs. I think I'll be all right.

So your not planning on gutting the chassis and putting this tube frame under it? Because that what it sounded like.

No I'm not gutting the entire chassis but I am removing quite a bit from the rear. It will not have the rear strut towers, transmission mounts, engine support, rear suspension attachment points, rear lower trunk sheet metal and engine sheet metal wrap around.

Well I've had to take a break to prepare for my son's wedding. I've taken little windows of time and worked on the chassis table thoug. It's almost complete just need to add the webs for the trusses and it's ready to mount the 996 on it first. I'm going to compile xyz coordinates for all of the suspension pick up points on the 996 and then transfer those coordinates onto the 914. That way I will keep the same suspension geometry that the factory had. I'll also be doing a twist test on the 996 and on the 914 pre-tube chassis and post tube-chassis. It will be interesting to note how much better the 914 chassis will be. I'll be taking all of the measurements with a laser plummet and a laser distance measure....stay tuned.

Sweet table! Very very nice! You work fast!

I've always wanted twist measurements; they should be really interesting. I've built solid "shocks" and twisted some formula cars. It's relatively easy to do and really neat to see how the results compare to FEA expectations. Unfortunately, our FEA was always a bit optimistic because it didn't include finite stiffnesses for all of the suspension joints.

It would be really interesting if you could twist it a few times after the tube frame with and without the engine, belly pan, etc. just to see how much incremental stiffness each piece adds.

Looks like your moving along well. I did a 914 with 993 suspension a long time ago with an LS6 and G50-52. I had the rotisserie and set up and a welding table For the suspension set up. With no room to store the stuff I got rid of it and now I have a new 914 project starting and was planning on making all the stuff again. As you know it is a huge investment and a lot of work. How about right after you get your chassis set up and of the table you do mine and recover some of the money you have in all this effort? I am just down the road in San Diego. Also here is another thread that you may have seen but its always good to see what others have going and see how they went about things.

http://www.914world.com/bbs2/index.php?sho...219539&st=0

Looking good so far and I will be following the progress. And here is a shot of my 914Click to view attachment

CSDIILIGAF hey that 914 you did with the 993 suspension looks killer. Let's talk about using my rotisserie and frame table. I'm thinking that I can just rent it out to you for an extended period of time. That way your cost will be a fraction of the cost to make and I get a little back for my investment. PM me and give me your contact information I'm sure I can learn from someone who's done it already. Glad to have you commenting.

JD74914 Instead of using the solid shock idea, which is a cool idea by the way, I was thinking of just setting the car up on 3 jack stands on the frame table, clamping them down and loading the wheel that doesn't have the jack stand under it. What do you think? Is there a better way? And yes I would like to test the twist under various conditions. We're just going to geek out and have fun with the numbers as well as the final product.

Does anyone have a good idea as to how to set up a jackstand with some form of a clamp to attach to bottom of longs? Taking all good suggestions. Bad ones will be ridiculed . Just kidding of course but yeah let me know how you'v e done it or saw someone else do it. BTW no Mo-Clamps those are North of $200 each.

I'm thinking of welding these to the end of a 2x2 post and using them instead of a jack stand. They are cheap and will do the job.

Weld a block of steel on one side, and tap for 2 3/8" bolts, add another on the others side and pinch the seem. Add knurling if you want between the jaws. Stands will need to be able to move as this design is not self centering.

Click to view attachment

Our weld C clamps to the to of the jack stands.

Or weld a set of nuts to steel plates, weld steel plates under the rockers, bolt them to the fixture and grind them off once done.

Put wooden blocks under the rockers, drill holes through the rockers , wooden blocks, and fixture, use all thread, bolt it down.

I am guessing this is to do twist testing.

I would weld three legs down, and not use jack stands, as you will have to strap the car down anyways

Use weldable trailer rings onto the logs, put what ever you want under it, ratchet it down with welded rings on your fixture.

Trailer rings can be found that are rated for 18,000 of force per ring, and cost about 12.50 per ring plus shipping. Then some big straps, or chain. Or just load binders.

Cast, thinking they will break at the bolt hole as you apply force diagonally to them.

914FORME I like your idea about the trailer rings. Yes that will be necessary to be able to hold the car down for the twist test. I'm going to hold down into concrete with a wedge anchor. I do believe that the clamps that I have are rated for 750lbs. I'm going to give them a shot and see what happens.

Well look at what came it today. The parts look to be first rate. Everything is USA made with the exception of a wand piece that is made in Germany. The company told me that they stand by their product and that if I'm not happy with the results that they will take it back. We will see. Supposedly they were able to do 1 sf per 1 min and 15 secs. Not bad at all.

Well chassis table is complete. I measured it with a survey grade level and it is straight to 1/64th or 15 thousands of an inch. Now I can start about with actually working on the 914 rather than building all of the infrastructure (Rotisserie, Chassis Table, Sand Blast Cabinet). I guess I could have done it on the concrete floor and then have a twisted frame. But I couldn't live with myself. Rather, I'm doing it this way though because I just can't do this not knowing if my work is straight. However I have 3 weddings to attend in the next 2 months so my weekends are going to be used up in nonsense cause you know where I would rather be.

The order of work will be as follows.

First load 996 and measure and do a twist test.

second wet sand blast 914 on rotisserie

repair rust and epoxy primer

fourth put 914 on chassis table and do baseline twist test then start building tube chassis

Wow. That's a sweet piece of work.

Thanks bud.

It all depends on what you want to get out of it.

The clamping jack stands sound like a good idea you're most concerned with seeing changes in chassis stiffness and comparing to your FEA model. It's certainly easier than making solid shocks and hub adapters to clamp to the table and would produce really interesting data. I would love to see how close the FEA comes to actual!

On the other hand, it doesn't give you a great feeling on the stiffness of the whole system. I like to think of the chassis as a huge bracket which holds the suspension together; basically something that connects the dots. The most important reason to have a stiff chassis (besides impact safety which is a whole other design arena) is to remove an additional "spring" from your suspension. A flexy chassis can make suspension tuning difficult since it is sometimes tough to tune around that unknown spring. I did hub connections for my twist tests because I wanted hub-to-hub stiffness to understand the whole system. There can be a shocking amount of compliance in suspension mounts and components which you will miss if just doing a pure chassis twist. I have read that OEMs spend millions of dollars making sure mounting compliance is minimizes which is something the normal person isn't able to do.

Since you're keeping the stock suspension measurements, perhaps making hub adapters which bolt to the table wouldn't be so bad since you could use them multiple times and on both chassis? Just thinking out loud. I really do like the clamping jack idea too, the above were jut things to think about.



Those should do the trick! They can hold a stupid amount on i-beams so I don't see why they wouldn't work on a flange.

Your table is awesome BTW! I'm super jealous!

JD74914 your responses are always so on the spot and I really do appreciate them. It is what makes these forums. With respect to the twist test incorporating the compliance in the bushings, tie rods, etc., I agree wholeheartedly. However, what I am trying to do is to get a chassis stiffness so that I know how to set up the springs. My current 996 suspension needs new bushings and ball joints, so checking it in this fashion will be counterproductive for my purposes. As you may already know, a rule of thumb is that if your suspension stiffness is more than 10% of the chassis stiffness, then a portion of the chassis will be flexing and absorbing the loads instead of it going into the springs and dampeners. This condition will give a horrible ride and will cause premature cracks in the chassis. I suspect that this happens quite often when people put a really stiff spring on a stock 914 chassis. As would be my case if I just used the springs off of a car that weighs 3274 lbs and placed them in a car that weighs 2100 lbs.

The chassis torsional stiffness that I will check will be:

1) The baseline existing 914;
2) The 914 with the longs stiffened;
3) The 914 with the steel roll cage;
4) The 996 in stock form (oh oh).

My intent is to help other teener's so that they can see if stiffening the longs truly works. And if so, how well? It will be very interesting to me and to others, I suspect.

I've been reading that a typical torsional stiffness for a sports car is somewhere between 10000 and 20000 ft-lbs/degree. Also, F1 cars are much higher than 20,000 ft-lbs/degree.

I hope to load the 996 on the chassis table this weekend. Them I'm off camping to Sequoia so I won't be updating for about one week.

BTW I really did like the way the chassis table turned out. It's nice to know that what you are basing everything off of is straight and true.

Well the 996 is up on the chassis table. I was surprised to find that it had a twist of 1" in the frame. Wow I wonder how this thing handled? I wonder how it got that twist? I don't see evidence of a major wreck?

Heat?

Could be...that's a lot of twist. Check that German engineering on the radiator setup . Every square inch used and you'd never know with the panels on.

76-914 That has to be it. The fire was centered at the left rear corner and that's where the twist is. And here I am asking the stupid questions to the obvious answer.

Chris H. Yes I love the way they did it. Interesting to note that they are set up to exhaust UNDER THE CAR. I figured out a way to use all three in my design. I want the front trunk to be completely useful.

Frames do some pretty weird things when highly heated, especially if they haven't been previously stress relieved. Moving that far is pretty shocking.



Glad my comments are helpful in some way.

The 10% rule is good, you figure it keeps your chassis an order of magnitude stiffer so the end effect of its flexing is second order on the overall system. That said, I wouldn't base spring setup off chassis stiffness. What people normally do is decide on a suspension stiffness (say 1 deg/g) and then back out the wheel rate then spring rate, and then make sure their chassis is a stiff enough spring to be ignored.

Ride and handling doesn't have to be poor with a flexy chassis; think about how well some superkarts perform. From what I've read, some of the current F1000 cars also use the chassis stiffness as a tuning knob as well. In a 914 with stiff springs the flexible chassis is definitely bad because of fatigue failures like you noted.



I'm very interested to see as well. In a rust-free car I'm not sure there is actually much benefit to long-stiffening with the Engman/Maddog doublers since the area moment of inertia increase is fairly low. On my car I made the longs deeper (well, on the side I'm finished with at least haha) to gain the h^3 advantage in bending stiffness.



I believe these numbers are a little low. We always shot for at least 1500-2000 ft-lbs/deg on our lightly spring formula cars. Just to provide a Porsche comparison, here is some stiffness information I saved from somewhere a few years ago:

Porsche 996 Turbo (early): 9,957 ft-lbs/deg or 13,500 Nm/deg
Porsche 959: 9,515 ft-lbs/deg or 12,900 Nm/deg
Porsche Carrera GT: 19,177 ft-lbs/deg or 26,000Nm/degree

The Lotus Esprit is known for being pretty flexy and is said to be about 4315 ft-lbs/deg.

Current F1 cars I believe are currently much stiffer, though some may also be using their chassis as sprung members; the modeling you can do with $100M+ is pretty crazy.

The numbers above might not be correct since I can't remember the source, but give a little perspective. It should be really interesting to see what your 996 looks like!

Just make sure you keep the suction tube on top of the wand and dont point it up.

Once I got water in the media suction tube it was a bitch to get clean.

And the Pressure ratings for the washer to use is minimum. Mine was adequate ate 3500 psi and 4 gpm

Bet the twist was from when the fire hose quenched the fire; the sudden temperature change probably sucked it in like you would use a torch and rag to suck in a body panel.

The mystery twist has been discovered. Note to self make sure all jack stands are set to the same height. Frame is straight. This is great news since I need to measure the suspension cradle points on the 996 to transfer them to the 914.

cwpeden Yes thanks for the heads up.

jd74914 i'm wondering how much benefit it would be to use the Engman and then add a strip of 1/8" flat stock on the top and bottom flange. That would add quite a bit more to the moment of inertia. The section modulus would be much better than the metal along the sides of the stiffener kit. I suspect that the Engman kit gives more rotational stiffness than bending stiffness though. We will see.

Well I finished measuring the 996 suspension cradle points. Here is how I did it.

First I laser plummet the bolt
Click to view attachment
Then I transfer that mark to the ground floor like this
Click to view attachment
Then I measure horizontally like this
Click to view attachment Click to view attachment
Then I measure vertically like this
Click to view attachment
I also measure all of the diagonals and there you have it. All of the measurements needed to transfer to the 914.

Next step is twist test on 996. I'm out for a week camping so that will have to wait.

Have fun. Looking forward to your next update!

OK back on it. I'm out one week and I can't even find my project on the boards. It was soemthing like 6 pages deep. Anyway, got back from Sequoia and got to twisting the frame on the 996. Here are pictures of my contraption

This is the digital dial indicator that I usedClick to view attachment

Here is how it triggers the dial indicator Click to view attachment

I added 100 lbs (2 -45's and a 10) at a distance of 11.375' This created 1137.5'-lbs of torque. Crazy deflection in the 2x2 but it was still only 50% stressed.Click to view attachment

The final number for the convertible 996C4 is......4,568'#/Degree. Seems to be pretty flexible.

Well this weekend member CSDILLIGAF and I will be making the nest for the suspension cradle. He's doing the same project so we'll work on the suspension and frame portions, and who knows what else? It's very helpful to have someone such as him working along side with me. According to my count this will be his 3rd successful Frankenstein transplant. He's the one that did a full 993 suspension on a tube chassis 914. From what I understand his 914 currently races in a very famous race and does very well. I love these 914's they are an incredible platform to work with.

Well here is the suspension nest or fixture as some call it. CSDilligaf came over and we hit it for 8 hours straight. Only stopped of for a carnitas burrito, with rice and beans and all the fixins. Couldn't have done it so fast without CSFilligaf. It was nice to bounce ideas off each other as we put this thing together. Thank you for the input, work and the sweet bushings that you machined. Really pleased with the way it's coming out. It is almost complete as we only need to add the strut tower locations and finish welding a couple of more beads and cross bracing. After this, I can start building the frame for the 914 with this suspension nest centered and elevated within the shell of the 914. Enjoy the pics.

Rudy, I really enjoyed myself working at your place. A little on the hot side and sweat my butt off but we sure hung in there. We got a lot of work done. Cant wait until the next stage of the build.

Subscribed and really enjoying this build....truthfully, I can read some of this but I sure as heck don't understand it...amazing work though and really interesting to see what someone (who clearly has an amazing background) can do with a car in their backyard...speechless actually and thanks for posting. Grant

NS914 Thank you for your kind words. This build would have been very difficult 20 years ago due to knowledge being bottled up in some guru's head and not being able to be shared with no more than those within physical proximity. However, now with the "information superhighway", all we have to do is to research online and fill in our void areas with the specialized knowledge of others. This truly is a great time to be doing projects such as this since one can pull from the collective knowledge of the online community. Trust me we all learn from each other.

Back to the project now. I'm tying in the strut towers today and will have pictures up later. After that....the suspension fixture will be complete. Next step will be to strip the 914 and epoxy primer. I'm using the epoxy primer from a company called SPI. Then pull the 996 of the chassis table and insert 914 onto suspension fixture. Then the fun will start. The rotisserie, the chassis table and suspension fixture was only preparation to work the on the 914.

The SPI epoxy is good stuff ! My project was sprayed in 2009 with it and has served me well. The project is still in the garage, waiting for me to finish the paint job -

Are you going to use their base and clears as well?

It will be awesome to see the 914 up on the table and start the whole process of joining the 996 suspension into a 914 chassis. I will make another trip up to help. Be sure to post about how the blasting of the 914 goes.

DAKOTAEWING yes I will be using all SPI material. From the research that I've made they seem to be the HOT TICKET.

CSDILLIGAF yep I'll call you when I get ready to place the 914 in THE NEST . That will be monumental.

Attached are pictures of how I located and tied the strut locations to THE NEST. Man we had to do alot of of the 996 frame to get these locations.

Here is the space age template for the strut towersClick to view attachment

Here is the space age marking of said templates Click to view attachment

This is what was used to cut Click to view attachment

Here it is in place Click to view attachment

Well the suspension nest is complete and the 996 can be pulled off and put away.

Very Cool Rudy! Looks great, You've come a long way so far. The fun part is about to begin.

Well the 996 is finally off the nest and no longer needed. Big milestone for me. I'm blasting the 914 this weekend and epoxy primering it.

Well I started to wet blast the 914 and I ran out of sand. I've already used 2000 LBS. I think that I can get away with another 5 bags but I'll just get 10 just in case. Sand is cheap. Here is the video

https://youtu.be/RZ0oQxO59Y8

Hi, what set up are you using for wet blasting? I think I bought a similar set up: http://www.globalindustrial.com/p/outdoor-...CFcFbhgod4vUAMA

but I am definitely not getting the same pressure you are. I'm using a Costco 2,600PSI pressure washer so its probably more like 2,000psi (maybe) and I was having a lot of trouble with clogged lines. If I kept blasting and had someone making sure the pick up tube was always in sand and the pick up hose flowing down to the nozzle then it was ok. The minute I stopped to looked at my progress the sand would clog though.

I'm using the Power Eagle set up. I blew by 2000 lbs of sand and no clog ever. I would dump 300 lbs (3 bags) of sand into a 35 gal trash container. Then I covered to keep the sand dry and clean of debris. I absolutely loved the performance. It wasn't cheap though. It cost $300. However, it did not clog once and I even turned it upside down. I am using a Dewalt 4200 PIS with 4 GPM. Sand is #30 silica sand.

Thanks for the info. Yeah I think my nozzle is basically the same. I think the bigger pressure washer is key though. I'll try renting a bigger one when I get going again. Your Build looks great! I'm going the V8 route as well.

WOW! that Baby sure does the job.

Yes I was very happy with the performance. It will probably take another 2 hours. For a total of 7 hours and 2500 lbs of sand. Let me tell you though it is the messiest job you will ever do. It's best to do in an open field or in an enclosure. Definitely not something to do in your shop or in your driveway. I'm on 2 1/2 acres with no neighbors so it worked out for me.