steering mod for 17 inch wheels
Thread Starter
Instructor
Joined: Dec 2001
Posts: 176
Likes: 0
From: England
steering mod for 17 inch wheels
If I remember correctly cars before 1991 need a stering mod to stop the tyres rubbing on the arches. Does anyone have any more info on this? Part numbers? What is involved in fitting?
Thanks
Thanks
Thread Starter
Instructor
Joined: Dec 2001
Posts: 176
Likes: 0
From: England
Found out some info now:
According to Porsche TSB 49106 you need to fit part 964.347.325.02
I think this was standard on 92- cars but can not find any data to back this memory up <img src="confused.gif" border="0">
According to Porsche TSB 49106 you need to fit part 964.347.325.02
I think this was standard on 92- cars but can not find any data to back this memory up <img src="confused.gif" border="0">
Addict
Rennlist Member
Rennlist Member
Joined: Mar 2002
Posts: 3,606
Likes: 1
From: Highland Park, IL
Steve,
I recently mounted 7x17 and 9x17 wheels, both with 55mm offsets, on my 91 C4. Tires used were 205/50 and 255/40 which are standard Porsche spec.
There is only one problem with this modification. The widened front wheel will cause the tires to rub the inside of the car's body when turned at full lock. The common solution is to use a 1/4" wheel spacer which does not require you to replace your studs; however, it would have made more sense to buy front wheels with a smaller offset, 49mm perhaps, since that's effectively what the spacer does.
With the spacers on, I still get a tiny bit of rub when I lock fully to the left. This issue may be an alignment/centering problem, so I'd say a 49mm offset will get you most of the way there.
The Porsche part you mention is the steering stop, right? That's a bit more involved modification. Maybe someone on the BB can elaborate?
Good luck!
JB
I recently mounted 7x17 and 9x17 wheels, both with 55mm offsets, on my 91 C4. Tires used were 205/50 and 255/40 which are standard Porsche spec.
There is only one problem with this modification. The widened front wheel will cause the tires to rub the inside of the car's body when turned at full lock. The common solution is to use a 1/4" wheel spacer which does not require you to replace your studs; however, it would have made more sense to buy front wheels with a smaller offset, 49mm perhaps, since that's effectively what the spacer does.
With the spacers on, I still get a tiny bit of rub when I lock fully to the left. This issue may be an alignment/centering problem, so I'd say a 49mm offset will get you most of the way there.
The Porsche part you mention is the steering stop, right? That's a bit more involved modification. Maybe someone on the BB can elaborate?
Good luck!
JB
Racer
Joined: Jan 2002
Posts: 323
Likes: 0
From: Oxford, England
Joey
That is interesting as my RS has 7.5J fronts (still with 205/50 tyres) with a 55 offset
The track must be slightly wider on the RS as there are no spacers fitted and obviously there is no rubbing but the turning circle is horendous
I stand corrected!!!
That is interesting as my RS has 7.5J fronts (still with 205/50 tyres) with a 55 offset
The track must be slightly wider on the RS as there are no spacers fitted and obviously there is no rubbing but the turning circle is horendous
I stand corrected!!!
Trending Topics
Thread Starter
Instructor
Joined: Dec 2001
Posts: 176
Likes: 0
From: England
[quote]Originally posted by joey bagadonuts:
<strong>Steve,
I recently mounted 7x17 and 9x17 wheels, both with 55mm offsets, on my 91 C4. Tires used were 205/50 and 255/40 which are standard Porsche spec.
JB</strong><hr></blockquote>
The 55 front and rear offsets are correct as per Porsche specs. The spacer I mentioned fits on the ends of the steering rack to limit the ammount of lock available and hence stop the rubbing of the wheel on the arch. I can post a copy of the TSB if you want
<strong>Steve,
I recently mounted 7x17 and 9x17 wheels, both with 55mm offsets, on my 91 C4. Tires used were 205/50 and 255/40 which are standard Porsche spec.
JB</strong><hr></blockquote>
The 55 front and rear offsets are correct as per Porsche specs. The spacer I mentioned fits on the ends of the steering rack to limit the ammount of lock available and hence stop the rubbing of the wheel on the arch. I can post a copy of the TSB if you want
Rennlist Stories
The Best Porsche Posts for Porsche Enthusiasts
10 Porsche Colors That Have More Personality Than Most People
Verdad Gallardo
Guntherwerks' Final Speedster Creation Is the Ultimate Porsche Restomod
Verdad Gallardo
10 Reasons I Hate Going to the Porsche Dealership (& the 1 Reason I Stay)
Joe Kucinski
Porsche Shakes Up The Nürburgring Lap Record Table Once Again
Verdad Gallardo
6 Ways the Porsche 911 GT3 S/C Redefines Performance
Joe Kucinski
10 Wildest Homologation Specials Porsche Ever Sold
Verdad Gallardo
Super Rare RUF BTR III Comes Out of Hibernation, Looking For a New Home
Verdad Gallardo
10 Porsche Opinions That Can Start a Fight
Joe Kucinski
One-Off Porsche 911 S/T Takes Inspiration From Famous '70s Race Car
Verdad Gallardo
Addict
Rennlist Member
Rennlist Member
Joined: Jun 2001
Posts: 577
Likes: 3
From: Stuttgart FRG
Hello
If you mount larger wheels you have to cut the rear edge from the firward wheel arch clear.
Porsche has shown how and where in a service bulletin wich is given out by Porsche ( Call Mr. Wüst Q Porsche 0711 911 8260 ) when you mount the 17" Cup and have to do your paperwork at TÜV ( so the engeneers there can check the clearance.
UPs sorry forgot the US has other rules
Maybe usefull for the european listers.
Grüsse
If you mount larger wheels you have to cut the rear edge from the firward wheel arch clear.
Porsche has shown how and where in a service bulletin wich is given out by Porsche ( Call Mr. Wüst Q Porsche 0711 911 8260 ) when you mount the 17" Cup and have to do your paperwork at TÜV ( so the engeneers there can check the clearance.
UPs sorry forgot the US has other rules
Maybe usefull for the european listers.
Grüsse
Instructor
Joined: Mar 2002
Posts: 243
Likes: 0
From: geneva switzerland
[quote]Originally posted by Roland Kunz:
17" Cup and have to do your paperwork at TÜV (so the engeneers there can check the clearance.
UPs sorry forgot the US has other rules
Maybe usefull for the european listers.[/QB]<hr></blockquote>
You lucky boys in germany you got the TÜV, we in switzerland got the Cantonal Automobile Service. A bunch of idiots, following drastic swiss idiotic anti-all laws <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> . Everything is forbidden!! Fitting wheel spacers? Forbidden:nono, drilled brake discs (rotors)? Forbidden:nono, Stainless steel brake hoses? Forbidden:nono, better brake pads? Forbidden:nono, another steering wheel? Forbidden:nono, A cup pipe? Forbidden <img src="graemlins/nono.gif" border="0" alt="[nono]" /> . At least in Germany if a part ist TÜV approved you can do something
Hope things are a bit easier in the US and England.
Note: my car must be totally illegal!! Hierk Hierk Hierk, I feel like a modern Robin Hood ore should I feel like Wilhelm Tell??
Cheers to all Thomas
<img src="graemlins/wave.gif" border="0" alt="[byebye]" />
17" Cup and have to do your paperwork at TÜV (so the engeneers there can check the clearance.
UPs sorry forgot the US has other rules
Maybe usefull for the european listers.[/QB]<hr></blockquote>
You lucky boys in germany you got the TÜV, we in switzerland got the Cantonal Automobile Service. A bunch of idiots, following drastic swiss idiotic anti-all laws <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" /> . Everything is forbidden!! Fitting wheel spacers? Forbidden:nono, drilled brake discs (rotors)? Forbidden:nono, Stainless steel brake hoses? Forbidden:nono, better brake pads? Forbidden:nono, another steering wheel? Forbidden:nono, A cup pipe? Forbidden <img src="graemlins/nono.gif" border="0" alt="[nono]" /> . At least in Germany if a part ist TÜV approved you can do something
Hope things are a bit easier in the US and England.
Note: my car must be totally illegal!! Hierk Hierk Hierk, I feel like a modern Robin Hood ore should I feel like Wilhelm Tell??
Cheers to all Thomas
<img src="graemlins/wave.gif" border="0" alt="[byebye]" />
Addict
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Joined: May 2001
Posts: 8,027
Likes: 17
From: Parafield Gardens
Oh dear, I am away for a while and the old stories re-appear. George your RS is fitted with 10mm steering stops. pre 1992 964s were fitted with 6mm steering stops and these have to be replaced with 10mm versions if you install 17 inch wheels. The RS does not have power steering and this creates more room up front as compared to a 964 with power steering. The C4 has evenless room because of the front diff and drive axles.
The old "I never had a problem statement". Well I have some really nice photos of wheel rub caused by 17 inch wheels of 55mm offset especially on 1989 C4s. try driving a full lock going backwards. I bet you get some wheel rub. You might not hear it but pull off the wheel and check it out.
Thomas, I know how you feel. Our Kanotanl inspectors are paranoid about wheels and tyres. You can install 20mm or less wheel spacers in Appenzell without getting into trouble. They check a set of their own specs for wheel track.
Ciao,
Adrian
911C4
The old "I never had a problem statement". Well I have some really nice photos of wheel rub caused by 17 inch wheels of 55mm offset especially on 1989 C4s. try driving a full lock going backwards. I bet you get some wheel rub. You might not hear it but pull off the wheel and check it out.
Thomas, I know how you feel. Our Kanotanl inspectors are paranoid about wheels and tyres. You can install 20mm or less wheel spacers in Appenzell without getting into trouble. They check a set of their own specs for wheel track.
Ciao,
Adrian
911C4
Race Car
Joined: Jun 2001
Posts: 3,706
Likes: 10
From: Virginia Beach, Va.
I have plenty of photos that indicate my front 17" wheels were rubbing on my 1991 C2...just goto <a href="http://www.porsche964.co.uk" target="_blank">www.porsche964.co.uk</a> and you'll see evidence of rubbing. 
I have yet to update to the 10mm steering stops, but plan to. For now, and after the fact, I am using 3mm spacers up front which seem to cure the problem for now.
I am using the 996/Boxster "S" 17" Twist wheels, 17" x 7" (55mm backspacing) and the 8.5" (50mm backspacing). The fronts did rub from the get go, too bad I noticed it after a week or two of driving around! <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Now you think that's trouble? Today I am having my 245 and 275 series Hoosier track tires mounted on my 17" Cup IIs (7.5" and 9")...luckily I have LOTS of 6,5 and 3mm spacers available - and don't worry, I spent a good part of the weekend installing extended wheelstuds.
Now if that isn't asking for some rub marks...I dunno what is!
I have yet to update to the 10mm steering stops, but plan to. For now, and after the fact, I am using 3mm spacers up front which seem to cure the problem for now.
I am using the 996/Boxster "S" 17" Twist wheels, 17" x 7" (55mm backspacing) and the 8.5" (50mm backspacing). The fronts did rub from the get go, too bad I noticed it after a week or two of driving around! <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Now you think that's trouble? Today I am having my 245 and 275 series Hoosier track tires mounted on my 17" Cup IIs (7.5" and 9")...luckily I have LOTS of 6,5 and 3mm spacers available - and don't worry, I spent a good part of the weekend installing extended wheelstuds.
Now if that isn't asking for some rub marks...I dunno what is!
Addict
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Lead Rennlist
Technical Advisor
Rennlist
Lifetime Member
Joined: May 2001
Posts: 8,027
Likes: 17
From: Parafield Gardens
Dear Christer,
It is not correcting you. I followed exactly the advice given by, I had these wheels fitted to my 1990 C2 and they caused no problems. I purchased these wheels, installed them and damaged my C4. Nuf said on that. Every 964 is different, everyone has different expectations and needs and I try and approach each request of this nature as being the first one ever.
I am installing 225s up front this week. I have the 109mm steering stops and I am still installing 5mm spacers because I do some hard and heavy cornering. plus I need full lock to get into and out of my parking place.
Ciao,
Adrian
911C4
It is not correcting you. I followed exactly the advice given by, I had these wheels fitted to my 1990 C2 and they caused no problems. I purchased these wheels, installed them and damaged my C4. Nuf said on that. Every 964 is different, everyone has different expectations and needs and I try and approach each request of this nature as being the first one ever.
I am installing 225s up front this week. I have the 109mm steering stops and I am still installing 5mm spacers because I do some hard and heavy cornering. plus I need full lock to get into and out of my parking place.
Ciao,
Adrian
911C4