Bill Verburg

While 3614 is the highest # The list of US 993s that were prohibited from using 18s has only 57 non mostly consecutive entrys, the lowest is 99Xss 32 2697 next is 991SS 32 2698, 99 8SS 32 2701, 99 7SS 32 2706, 99 9SS 32 2707, 99 2SS 32 2712, ...


There were also 177 RoW listed

There were changes to the front hubs that are non congruent to the allowing of 18s

There were other suspension changes as well which I have previously posted also non congruent w/ the banned cars

nothingbutgt3

​​​​​​​So basically it is strictly necessary to bring the car to Germany and homologate it as a one off and then bring it back to Italy, because Porsche is not collablratimg at all with the private customer helping through it, I mean, providing the correct circumstances to both customer and public automotive office to get the car coherently upgraded for the 18"... only the TÜV does it.

IainM

Thanks TJ,
That's very thought provoking. I had been thinking about how much extra lateral force 18" wheels could produce and what impact that could have. For my steering rack bushing failure it seems plausible. The reality is that you'd never put 18's on the front and 17's on the rear so maybe you're onto something. I need to ponder that for a while.

I will comment that I have replaced all my rear links with new (updated) stock parts and even went to the RS part for the kinematic link. I never did like the way the steering radius changed as lateral force increased. With my new suspension linkages and a really good alignment, the car is very well behaved in corners. Maybe I was experiencing what Porsche was worried about.
Seems like a very logical explanation - can anyone confirm?

IainM

TUV and California DMV must be related to some perverse sadistic cult that takes pleasure in creating laws devoid of common sense. Their end goals are noble: ultimate safety on the autobahn and a clean environment; but the execution leaves a lot to be desired.
But we are very smart and usually can find ways to meet their regulations and still achieve the driving pleasure we desire (strive for)

IainM

Were there a changes to any of the rear suspension linkages around April 1995?

SC2993

This is a Porsche Technical Bulletin dated Sept. 13, 1994 that addresses changes to suspension components. My car is 1 of 4 that were pulled from the production line, my car was built in Jan. 1994 and sold as a 1995 model. It states "Four vehicles within the above VIN range were equipped with components that were subsequently instituted as Production Version 2. This was done to provide comparison vehicles for production: They are:

994SS320203
993SS320225 (my car)
998SS320270
991SS320272

There were (3) Production Versions in suspension components, the first in Dec. 1993 and the second in Jan. 1994 and the third in Feb. 1994

I have included the TSB for all to review.

nothingbutgt3

I would like to understand, see and compare the parts that were different, i. e. the second version parts that could accept the 18" wheels, compared to the older ones that cannot.
Is there also a different body, I mean shaped different or less resistant?

The 993 I stripped to the bare zync plated metal doesn't exhibit any visible difference with the 'silver 96, but maybe there are some dofferences in the steel used.

​​​​​​​the chassis and suspebsion parts are foing to be all changed, so in this regards, honologating at a public office that would like to understand and work, there should be any problem, being the car compliant to the 96 - configuration.

cobalt

I find it interesting that Porsche has made these claims and yet my 94 turbo and the RoW 92 turbo S along with the 964 3.8RS/RSR all came with 18" very heavy speedline wheels and essentially no changes to the front suspension. They did not install the reinforcement brace and there is nothing structurally different about the tub. So what gives?

I tracked many 964's for well over 20k miles running 18" wheels no brace although upgraded suspension and had not one issue and no excessive wear and tear to my bearings or anything for that matter. So what gives why can my turbo run 18's and my C2 or 95 993's can't? I don't believe there is an answer that won't require Porsche's legal team to answer. Meanwhile I run all my 964's with 18" wheels and never had any issues.

I did install the rothsport brace on MY C2 recently and it does tighten up the steering a bit but I got cheap on my track car and made one out of aluminum angle 1" x 1" it is far stronger than the factory or rothsport part and cost less than $10 to make.

PS: I will add that the turbo does receive a different front strut that has a 14mm and 12mm bolt vs the stock C2 which had 2 12mm bolts. Although on my track cars I did use struts with the 12 and 14mm bolts.

JPS

I've had 3 993s. Been at some of the best shops around. All 3 just put in the brace and tracked it too.

IainM

Thanks JK,
Kinda fits but there's #'s 320478 thru 323614 that are all production version 3 but are still prohibited from running 18's.

Bill Verburg

All 993 use the 12/14mm bolts for the strut to wheel carrier connection

cobalt

So then I see no reason why Porsche says you can't use 18's other than the lawyers have some say in it. If it was fine for the 964 RS/RSR and turbo 3.6 why shouldn't it be the same for all 993's? The tubs are essentially the same up front. The suspension components also at least on the front end. Is there anything anyone can think of that would make the rear suspension of the 993 susceptible to issues?

TJ993

Geometry change to c arms and possibly bushings as per post 15. 95 should update c arms to 96
tj

Bill Verburg

My guess is that TUV got involved somehow. The TSB which describes the 18" upgrade only makes mention of the addition of the rack brace

nothingbutgt3

You mean the front A-arms? What's the difference between - 95 and 96-?