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Fitting 18" wheels on early C2 993

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charlesw
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charlesw PCGB Member
2020/03/04 19:07:34 (permalink)

Fitting 18" wheels on early C2 993

I am considering fitting 18" twist spoke wheels on my '94 C2.  I read in FAQs that some chassis numbers are "can't do it", some " you must fit a steering rack brace" and some "no problem, brace already fitted".  As the middle part of my chassis number is ....ZRS.... rather than ....ZSS.... I fear I drop into the first category?!  As this post was in 2010 I'm wondering if things have relaxed? I have seen a number of '94 cars with 18" wheels so wonder what may need to be done so I can do this if possible?  Thanks.
 
Charles

8 Replies

IndischRot
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Re: Fitting 18" wheels on early C2 993 2020/03/04 19:42:44 (permalink)
IMHO you're not missing much by staying with 17s. Lighter wheels/tyres = more nimble handling.
MoC2S
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Re: Fitting 18" wheels on early C2 993 2020/03/04 20:43:25 (permalink)
Hello Charles, Long time no speak !
 
Several issues here ..
Factory info is here .. https://www.porscheclubgb.com/forum/tm.aspx?m=174129 so the numbers begin up in the ZSS range
Before model year 1996 (T) only Coupe vehicles within the following vehicle identification
number ranges may be retrofitted with 18-inch wheels:
WP0 ZZZ 99 ZSS 31 2528 up to WP0 ZZZ 99 ZSS 31 7018 (rest of world)
The unsprung weight of each wheel tyre combination is different ; ie, hollow spoke 18s will be a lot lighter than solid spoke 18s - I'm sure I posted all the wheel weights here somewhere ..
Walter Rohrl got his fastest 993 lap on the nurburgring on the 18" combination .. there were no points awarded for 'forgiveness' or 'recoverability', if you get my drift !
 
i'm pretty sure it is around chassis changes introduced for the MY 95 introduction of the TT, but the above info should reflect your situation .. no real changes from previously spelt out here !
 
Cheers, Maurice

Maurice Piper
993 Register Secretary 2003-2020
993 Assistant Register Secretary 2001-2003
' Wild things are always faster'
from ' Two Dogs' by Philip Hodgins
charlesw
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Re: Fitting 18" wheels on early C2 993 2020/03/04 23:47:18 (permalink)
Hi Maurice, indeed, nice to hear from you!
 
I really do like the 18" look although I am aware of the compromises.  However, from what you say it looks as if I would have to buy a later car to get it!!  My chassis number at ZRS obviously comes before the permitted ranges of ZSS numbers.  Have you any idea what the limitation is with the early chassis?  Do you know of any way round this?
Thanks
Charles
PORKA
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Re: Fitting 18" wheels on early C2 993 2020/03/05 06:01:06 (permalink)
I fitted 18" Turbo twist wheels to my very early 1994 993 C2 way back in the day, don't have the car anymore or the VIN no, fitted ok and also fitted the rack brace as well which it did not have.
Drove very well, looked better than the 17" alloys and did a considerable mileage both in the UK and Europe in it
 
 
 
 
post edited by PORKA - 2020/03/05 06:02:52

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MoC2S
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Re: Fitting 18" wheels on early C2 993 2020/03/05 12:13:09 (permalink)
charlesw
Hi Maurice, indeed, nice to hear from you!
 Have you any idea what the limitation is with the early chassis?  Do you know of any way round this?
Thanks
Charles

 
Ah, the wonders of PET ! After some digging, part number changes in this area for MY95 include :
Wheel Carrier (Upright)
Front Wheel Hub
Wheel Bolt
and for MY96 the RHD rack was changed.
 
My febrile imagination leads me to think they might have strengthened these components .. .. A few years ago, we (Registers) instituted an arrangement for channeling tech info/requests into Porsche GB - I tried it without success but ..
 
You could always 'downgrade' to the RS setup : designed for 18s and reduced toe variance at lower ride heights as depicted here : http://www.carnewal.com/products/993/p93013/Bump-Steer-Conversion-Package
The bad news is it has just seen a price rise of 250% (!!) and you'd still have to change the hub setup, and I wouldn't want to guarantee that was it !
 
If we are thinking about G loads with your sedate style of driving ( ) Pirelli Trofeos are now approved for 17" & 18" fitments without restriction on MY, so things can't be too weak !
 
You might want to talk to somebody in the race prep field (Colin Belton springs to mind), but the stickier 17" tyre seems the more obvious route.
 
cheers, Maurice
 
 
 
 
 

Maurice Piper
993 Register Secretary 2003-2020
993 Assistant Register Secretary 2001-2003
' Wild things are always faster'
from ' Two Dogs' by Philip Hodgins
Mark Elder
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Re: Fitting 18" wheels on early C2 993 2020/03/05 20:59:09 (permalink)
FWIW I had a loan set of 18" turbo twists on my '96 coupe for a couple of weeks while its 17" cups where away for a refurb.  Handling noticeably more skittish so I was keen to get the 17s back on.  Unfortunately the tyres were also different, so not conclusive.

Mark Elder
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charlesw
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Re: Fitting 18" wheels on early C2 993 2020/03/13 18:28:30 (permalink)
Thanks for all your replies, guys.
 
As you know, ideas don't stay still!!  I'm now looking at a Bilstein/Eibach B12 Pro Kit set-up to go along with a change of wheels - nothing too extreme.  Has anyone made this change?  I've taken Maurice's advice and am talking to Colin Belton about the wheel situation.  I suspect I will be making a visit up to Warrington to find out exactly what is involved and how much?!  Given that a change to 18" may be possible I'm looking at either the turbo twist (hollow spoke if pos) or the MY02 5 spoke from the narrow body 996 and I believe, Boxster - 996.362.136.03 fronts and 996.362.140.03 rears.  I've seen these on a number of 993s and they look great.  I'm looking to buy used so was wondering where is the best place to advertise - wanted?
Many thanks
Charles
 
 
MoC2S
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Re: Fitting 18" wheels on early C2 993 2020/03/14 15:31:05 (permalink)
Well, there's a buy / sell section on here, PCGB web site and Porsche Post ..
 
I run Bilstein B8s / M033 springs pretty happily w/ my hollow spoke 18s at M033 height ..

Maurice Piper
993 Register Secretary 2003-2020
993 Assistant Register Secretary 2001-2003
' Wild things are always faster'
from ' Two Dogs' by Philip Hodgins
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