Catorce

Slate, very interesting data indeed. What car were you putting 1400 pound fronts on?

As an aside, I spend the morning at Joseph Fan's shop looking at his 928 race car. I am not sure many people have the kind of experience Joe and Mark Anderson have racing 928s, and he thought 1000# fronts would be excellent for my car. In fact, his car (POC Champion in class) has 1000 or 1100 pound springs right now....as fronts.

slate blue

Thanks,

I need to get back to work so just a bit more info regarding these springing rates and where you should fit into them. Please have a look at this link;

http://www.optimumg.com/docs/Springs...Tech_Tip_1.pdf

This is what the engineer was banging on about. I'm sure given your CNC experience your maths will be up to working out your frequencies. I did a bit of CNC btw and really needed to brush up in the maths area, as you know when they teach it is in the very basic nuts and bolts of programming not using the software to spit out the programming.

So you should come out in the 1.5 to 2.0 Hz range, see what you come up with regarding that and that will confirm your choice.

Also I saw a bit of discussion regarding the suspension bushes. I know you could well make your own but please check out the bushes I am using. They are made in the U.K and are used in various race series. They make a street and a race version for the 928 and while I haven't fitted mine as yet they look very nice in deed. They have nice grooving in them for lubrication and the street versions come with a life time warranty so I would say they have confidence in their product. Also the pound is at record lows against your dollar as such they are cheap. The race series is the black series.

https://rennlist.com/forums/928-foru...-bushings.html

https://www.powerflex.co.uk/road-series/why-pu

https://www.powerflex.co.uk/black-series/about-us

As to the project cars, you can read a bit about them here. There is also a 7 speed transmission thread you may be interested in.

https://rennlist.com/forums/928-foru...er-thread.html

Catorce

Yep - had that issue on the Camaro when setting that car up. Factory bushings on that car are similar to factory Porsche bushings - a metal ferrule bonded to the rubber bushing that can preload enough to bind and upset the alignment if the bushing bolts aren't totally loosened prior to the car being set down.

In my experience bushings like that are for ride comfort, and have no place on a sporting car much less a race car. Correct, solid bushes don't have that issue. Also, performance bushes like those that DON'T have a bonded ferrule don't need to be settled like that.

Good point!

Catorce

Slate,

Good info, thanks for posting.

As to the bushings, I checked those out but I don't think polyurethane will cut it on a race car. It's just on the ragged edge on my heavily autocrossed Camaro -still too much play and softness for my liking. I am thinking 90 durometer solid delrin or something along those lines.

I won't know until I take the suspension apart and see what they all look like and what the factory was thinking.

Randy V

Many of us have upgraded to the solid delrin bushings on the steering rack. Sold by a couple vendors here.

Catorce

For that application I'm going solid aluminum....

Cheburator

Or you can do it properly and get uniball/rose-joints/spherical bearings all round. I can supply a kit for every single bush on the car.

Also, you will notice that the front suspension is kind of limited in terms of the amount of negative camber that you can dial in. You will need at least -2.5deg (-2deg 30mins) to make modern rubber work. Two ways you can solve the problem - fit lower arms from a S4 and upper arms from an early car, but you still have to rose-joint the pivot points, or you get custom A-arms.

Same story on the rear - you are limited to maximum camber of about -2deg. You will need adjustable banana links to dial more negative camber. With tyres this big at the back and the expected output from Carl's engine - forget about the Weissach axle actually working for you. You will have to pin the axle and reinforce the spring blades.

Braking - the 928, especially with ABS is very biased to the front. Empirical evidence from our last race - front brake temperature 320C - rears - 130C. The rears can be made to work a lot harder and relieve the workload of the front tyres. Think about a good bias valve if no ABS is installed. If ABS installed - fit a 964 bias valve freely available from your local Porsche dealer

Hope this helps,

Alex

Catorce

Cheb,

The rear suspension is already all heim joints and was set up correctly for this application. I have not yet closely inspected the front, but I suspect the same minus heim joints. Camber will not be a problem with this car (either too much or too little).

The Weissach axle isn't functional on this car either....

Will post suspension pics very soon.

Catorce

So today I had some more time to work on Panzerwagen. First order of the day was to remove the transaxle since I am having it rebuilt. For those that don't know me, I never just get a car "running". I rebuild EVERYTHING or at least check out what I have to make sure its in good shape.

On that note, I am sending out the G28.55 to be rebuilt. It's leaking oil, and I have zero history on this unit, so it goes in for the full treatment. I'll also probably have them throw a cooler on there and a spray bar or whatever they think is best for this applications. I don't do transmissions....I have them done.

So I dropped the *** end of the car, torque tube and all, because all of it needs to be looked at.

Some preliminary observations:

- Rear calipers are missing. No big deal.

- CV joints look like **** and the grease looks nasty. Also, the axle shafts are rusted. My guess is the missing CV boot clamps allowed water into the boots. These will be replaced.

- Really hate the way the cage was installed over the shock towers. I know WHY they did it this way, because they wanted to connect the shock towers with the cage. In doing so, however, they blocked the top of the shock towers where the damping is adjusted. Fine if you have remote reservoir shocks (I don't). I'll have to use the remote adjusters and drill an access hole. The damping needs to be adjusted!

- Delring bushings and heim joints look good, but each one needs to be inspected and cleaned up.

Overall, not too bad.

Oh, and a big THANK YOU Jackstands, for your support!

James Bailey

Those slide on American wheel spacers being none hub centric are dangerous as it puts too much load on the studs.... watched a 914 have a rear wheel pass the car when the stock studs worked loose it had 911 5 studs.

Mark Anderson

Good call Jim,
On my 928 I turned down factory hub centric spacers to get the desired width

Catorce

Agreed, total ****, going straight in the garbage can as soon as I measure them for reference.

1. I would never use two spacers on the same hub
2. Not hub centric.....

Good eyes Jim!

Catorce

Oh, and for those keeping track, the actual spring rates on the Devore car are:

FRONT: 0800.250.1000

REAR: 1000.250.500

I had mistakenly mentioned they were 1000 pounders in all four corners, but that's because I was looking at the rear part numbers at an odd angle. With the suspension removed from the car, it's obvious.

For those wondering, the way to read Eibach springs is as follows:

overall length, diameter, and pounds per inch.

So mine are 2.5" dia springs, 8" long in the front, 10" in the rear, 500 pounds in the back, 1000 pounds in the front.

So that clears that up!

Catorce

So I cracked open the diff cover and top plate on this trans, and at least TO ME, it looks as if it has been rebuilt and never run. In fact, I have never seen a trans that has had basically zero wear on any of the gear teeth or diff teeth.

Opinions????

Rob Edwards

That ring gear has seen plenty of use, though it looks fine. Mainshaft gears look fine from here. What's the model # stamped on the rear lower rib of the case?