Max Energy

Michael,
That is a cool car and a real piece of Porsche Racing History.
Is that one of yours? What Block is that Cast Iron?
Max

MAGK944

It is an awesome build. I'm curious to know why they would go to the trouble of producing a fiberglass us spec rear bumper when they had a lighter row rear bumper in the stock room. Class rules?

951and944S

924

T

951and944S

Anyone up for dropped spindles...?

T

Cloud9...68

That's a beautiful summary of the situation - thanks very much. My feeling is that this is a worthy endeavor for folks who are very far up the curve in terms of their driving skill and experience. I think I need to focus on my driving for awhile until I get to that level - to be honest, I couldn't even tell you if my car is front- or back-end limited in terms of grip. It feels pretty well balanced to me, and the instructors at the track have said the same thing. The most glaring issue with my car (other than the loose nut behind the wheel) is the fact that the suspension and brakes are so capable that the tires aren't keeping up, and this is the primary car-related item I'm currently working on addressing.

Dave W.

Good observation! My guess is that they did this to keep the control arm level to maintain anti-dive braking geometry. When the caster block is higher than the front control arm pivot it has less brake dive. I wouldn't want to raise the front inner pivot point on the control arm without compensating for the added brake dive somehow.

Dave W.

The main mod I see in the rear suspension in terms of roll center geometry, is the inner pivot appears to be raised slightly with a plate. Is it really that simple? Can we just move the inner pivot up slightly to reduce roll?

333pg333

I did look at replacing the stock spindles with some custom ones down here. Not cheap but advantageous on many levels. One, you can design all these improvements into a one piece billet design. Two, you can utilise a much larger bearing than the stock ones which are pretty small compared to a lot of other cars. Especially with a lot of downforce cars exerting higher levels of Gs into these parts than they were ever designed for. We have decided to just change the front bearings after every meet. Lastly, these parts are old. I doubt many of us are crack testing their spindles?

FrenchToast

The 924 2.0s used cast iron.

Front is the same way. Either dictated by rules or not, likely to maintain the US appearance as the car was designed for SCCA.

michaelmount123

No, not many left, for sure. This one was never run. It's now with Freisinger in Germany.

The rear has no torsion bars; coil-overs only.

Yes, the caster blocks encase solid spherical bearings and mounted on the inside of the frame rails. Caster was fixed, and camber was adjusted at the strut mount with an eccentric. I did run a 933 with a 944 engine with the raised steering. It's a manual rack, of course.

It was a 924 2L (Audi) engine. Yes, I owned that car at one time. I negotiated the purchase of 3 of them and all the remaining factory 933 spares for a client years ago. It all came from Vasek Polak's amazing shop/collection. I ended up with the car in the photo.

Yep, US configuration since the car was developed for SCCA D/Production to showcase the 924 here in the States. Porsche threw a ton of DM at this project. Holbert was also involved.

Yes, the rear control arm is raised. The height is also adjustable with shims (look closely). This way rear camber can be quickly adjusted without affecting the toe. Less obvious is the reinforcement of the rear arms.

It was mine years ago. It seems that Friesinger has (almost) all of the original configuration cars and he now controls the value. Apparently BIG money now. I never measured the motion ratios, but did pay attention to the front roll center and realized I was running my car too low (I had another 933 with a 944 engine). On these 933 cars, Porsche had the suspension geometry figured out.

michaelmount123

Oh, did anyone notice the Titanium progressive springs?

Droops83

In that case, I'd leave well enough alone and learn to drive the snot out of it as-is. You can always come back and do this mod later, and by then you may have found out if I broke anything.

Cloud9...68

I agree. However, I also think that if and when I level my front control arms, and thereby raise the roll center, I should do the same at the rear, and this is a much harder task than the mods to the front suspension discussed in this thread. The guy who made and sold several modified torsion tube carriers with the raised trailing arm mounting points says he isn't planning to make any more after the parts he has on hand to make a few more are gone, and Kokeln hasn't made theirs for years.

topley

I just received mine from Bruce a couple of weeks ago. It is the "extra beefy" design and though I am by no means any kind of engineer it certainly does seem like a strong unit. I am slowly assembling all the pieces to upgrade from the 85.5 suspension parts to late ABS parts. I will wait to do the entire rear in one go when I am ready to add ABS and everything. That won't be for a while so that won't stop me from upgrading just the front end earlier. I just don't like the angle of the control arm pin with the stock arm as low as I have the car.

Cloud9...68

I will be anxious to hear how your car turns out. Getting the roll axis correct on these cars after lowering them makes all kinds of sense - I just hope either Bruce or someone else will be available to continue making the modified torsion bar carriers to enable matching the rear to the front.