Pelican Parts Forums - random notes on 964/993 suspension

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- Porsche 964 & 993 Technical Forum (http://forums.pelicanparts.com/porsche-964-993-technical-forum/)

- - random notes on 964/993 suspension (http://forums.pelicanparts.com/porsche-964-993-technical-forum/693615-random-notes-964-993-suspension.html)

Hey all - since I used this and a few others threads to gather some great information for my suspension refresh, I wanted to share what I measured on my 94 964.

Changing the longitudinals alone creates a 16mm increase, per side. I know I've read 12.5 and a few other things. I know there are different long part numbers for 964, so maybe they aren't all the same - but in my case, I used a plumb bob and it was reasonably accurate.

The other thing to understand is that the 993 uprights, both RS and non-RS move the ball joint location, resulting in the hub of the wheel moving INBOARD by 8mm per side. so when you combine a 993 upright and a 993 long on a 964, it actually moves each wheel outboard by 8mm per side (16mm - 8mm).

This is also the reason that when swapping in 993 uprights only, people have trouble getting enough camber; the entire upright and strut assembly is pulled inboard by 8mm.

So you have the choice of 993 uprights and then maybe wheel spacer and add adjustable camber plates/maybe trim the towers a hair... or you can do 993 longs with 993 uprights for a total increase of 8mm per side...and this is pretty tight for most cars. 18x8 ET50 (popular) cars are already pretty close and I don't see this an easy move. Oleg, at the time had 7inch wheels so he might have had all the room in the world.

I'm going to modify a pair of 964 longs to see if I can get exactly in the right spot.

I know you have looked into this deeply but I am still not sure. I have two C2's one has 993 uprights the other 964. Both cars use 18 X 8 Et 52 wheels up front and 225 tires. I have nearly identical track alignments on both cars and have no issue with obtaining the camber I need. Both front tracks appear to be the same. When I measured the longs albeit not as i would have liked I found that the axis for the A arm was changed and that it isn't a straight forward outward or inward change but pushed the caster forward using the 993 longs on another car I did. That was a wide body. Both C2's use upper mono ball plates. I have no actual measurements but visually I can see no difference and both cars align without issue.

For some reason I can't post pics today but both show to sit nearly identically. I will try to measure but too busy for this right now. I will report back when I get a chance.

Quote:

Originally Posted by Cobalt (Post 12476331)

I was having trouble with the site too - seems better now.

I get it - and I'm sure there could be some other variables, too. The one undeniable thing is - where the balljoint goes in the 993 upright is different than the 964..and this is relative to the face of the upright (4 bolt face). So no matter what, using a 993 upright on a 964 (and keeping 964 longs) pulls the wheel in 8mm (or close to that). Put 964 and 993 uprights face down on a table with no hubs and you will see what I mean. Strut mounts, drop links line up perfectly between the two...the balljoint location, not at all.
Of course, different wheels, spacers, camber plates, ride height, rolling fenders...all affect how you experience this but with everything being equal, the front track width is reduced by about 16mm total by changing nothing but the uprights to 993.

The fellow over on Rennlist that did the measuring is Jeff33702, it's the most complete and I believe accurate comparison of the mixture of various 964 and 993 parts that i have seen

A summery

Quote:

Add 993 long to 964 while STILL using the 964 uprights (No one is doing this on their cars, this is just for reference) pushes the face of the upright bearing surface out by abou 16mm. That's the long by itself.

Using 964 long with a 993 upright pulls the face of the upright towards the car (reduces track) by 8mm. This is what most people are doing and seems maybe adding a 5mm spacer AND then a slight struggle with the camber.

Using a 993 long with a 993 upright pushes the upright bearing face out by 8mm...because the 993 long is +16mm and the 993 upright is -8mm.

The moral of the story is - when using 993 uprights on a 964, you will reduce the track -8mm per side. If you move to 993 longs with the same 993 uprights, you will increase the track +8mm per side.

993 uprights on a 964

Quote:

Originally Posted by Bill Verburg (Post 12478924)

The fellow over on Rennlist that did the measuring is Jeff33702, it's the most complete and I believe accurate comparison of the mixture of various 964 and 993 parts that i have seen

A summery

993 uprights on a 964

I actually had the 964 uprights on my wide body using 993 longs and later converted it to the 993 RS uprights. Whatever change if any appears to be negligible on a WB IMO.

I think the poster here might be someone you know. ;)

Quote:

Originally Posted by Bill Verburg (Post 12478924)

Hey Bill, yes, tha'ts me, Jeff :) I have a different name here vs Rennlist.

I only posted here because I've enjoyed the benefit of knowledge in this thread (and others) so thought I'd just add my notes.

I've since completed a set of modified longs for testing and re-measured. I now have exactly the same track as a stock 964, but using 993 uprights only.

http://forums.pelicanparts.com/uploa...1749653085.jpg

You can see the offset slightly here - there has been additional metal added to reinforce the inside of the front and rear holes.

the thing that helps the driver the most is scrub radius

a stock early 911 w/ 7ET23.3 has a +52.3 mm s/r this imparts a tremendous amount of feel and feedback to the steering wheel

w/ ABS brakes you need o to - s/r

a stock 964 w/ ET55 has s/r of 0, and feels numb

a stock 993 w/ 7 ET55 has a s/r of -10 and feels better but not as good as a 911

anything that can increase neg s/r will make the car feel better and be more fun too drive