17" Cup Wheels on 90 C4?
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Burning Brakes
Joined: Aug 2002
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From: St. Louis
17" Cup Wheels on 90 C4?
I am considering buying a 1990 C4 Cab. The one I am looking at has the Design 90 wheels. I would like to add the 17"cup wheels if I buy the car. I think I remember reading somewhere that the 89-91 964's could only have 16" wheels...is that correct or can you put 17's on?
Thanks,
Mark
Thanks,
Mark
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From: Highland Park, IL
Yes, the 89-91 cars can run 17" wheels but it has more to do with the widths which typically go up from 6" to 7". The 92 and newer cars have a steering stop limiter which reduces the steering box travle to accommodate wider wheels otherwise the tire rubs the inside tire well. Common remedies are to install this limiter (964.347.325.02), use 1/4" spacers (get proper ones, not shims) or live with a slight rub at full lock. Actually, I installed a strut tower brace which eliminated the rubbing problem on my 91 C4. No one has confirmed similar results, but I swear by it.
The 7"x17" and 9"x17" wheels normally have offsets of 55mm. 993 Cup Wheels often come with 70mm rear wheels, so pay close attention to all the specs. If you can find a front with a 48mm offset, you won't need spacers and your problem will be solved--unless you put very wide tires on the car, i.e. >225mm treads.
It's nothing money and diligence won't solve.
The 7"x17" and 9"x17" wheels normally have offsets of 55mm. 993 Cup Wheels often come with 70mm rear wheels, so pay close attention to all the specs. If you can find a front with a 48mm offset, you won't need spacers and your problem will be solved--unless you put very wide tires on the car, i.e. >225mm treads.
It's nothing money and diligence won't solve.
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From: Parafield Gardens
Dear Mark,
1989 C4s, 1990/1991 C2s and C4s have 6mm steering stops. If you install 17 inch wheels with 205 tyres without doing anything you will get wheel rub. Normally at full lock. C4s are worse than C2s by the way. Due to a slighly different design up front.
To fix this problem you need to firstly carry out a slight body modification to remove part of bracket which can damage the 17 inch tyres and you will need to install a 3-5mm spcare up front or remove part of the steering system and replace the 6mm steering stops with the 1991 model year 10mm steering stops. Spacers is easier and cheaper. I can promise you that the tyres will find something to rub on if you do not do this basic work. As has already been suggested you must check the offsets. I recommend 50mm front and 55mm rear. It is quite common to find 55mm fronts as well.
Ciao,
Adrian
911C4
PS: For the record, 1989, 1990, 1991 Normally aspirated 964s were never offered with 17 inch wheels. Turbo were of course. If you wish to install 17 inch wheels then a Technical Service Bulletin to carry out modifications (ones shown above) is required. We were not supposed to install 9JX17 on the rears either. We all have but watch the oil line on the RH side.
1989 C4s, 1990/1991 C2s and C4s have 6mm steering stops. If you install 17 inch wheels with 205 tyres without doing anything you will get wheel rub. Normally at full lock. C4s are worse than C2s by the way. Due to a slighly different design up front.
To fix this problem you need to firstly carry out a slight body modification to remove part of bracket which can damage the 17 inch tyres and you will need to install a 3-5mm spcare up front or remove part of the steering system and replace the 6mm steering stops with the 1991 model year 10mm steering stops. Spacers is easier and cheaper. I can promise you that the tyres will find something to rub on if you do not do this basic work. As has already been suggested you must check the offsets. I recommend 50mm front and 55mm rear. It is quite common to find 55mm fronts as well.
Ciao,
Adrian
911C4
PS: For the record, 1989, 1990, 1991 Normally aspirated 964s were never offered with 17 inch wheels. Turbo were of course. If you wish to install 17 inch wheels then a Technical Service Bulletin to carry out modifications (ones shown above) is required. We were not supposed to install 9JX17 on the rears either. We all have but watch the oil line on the RH side.
Track Day
Joined: Jul 2002
Posts: 20
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From: Dublin, OH
Mark,
I am running Cup wheels on my 90 C4 Cab and have had no problems. Take a look at my web site to see what they would look like on your car.
<a href="http://members.rennlist.com/leav02/C4%20Cab.html" target="_blank">90 C4 Cab</a>
Doug
90 C4 Cab
Dublin, OH
I am running Cup wheels on my 90 C4 Cab and have had no problems. Take a look at my web site to see what they would look like on your car.
<a href="http://members.rennlist.com/leav02/C4%20Cab.html" target="_blank">90 C4 Cab</a>
Doug
90 C4 Cab
Dublin, OH
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Drifting
Joined: Sep 2001
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From: Milton, GA
I have run 17" wheels on my 1990C4 and I had it lowered and drive it hard on the track. The fronts are 205 or 225 tires, with 7" wide wheels (55mm offsets). I never did the work that Adrian always recommends and I can say for certain that wheel rub ocurred. At full lock there was some rub on the lower part of the inside fender liner - probably due to low speed parking-type maneuvers. This was mostly a cosmetic, low damage annoyance, that would concern many people (not me). On the other hand, probably due to a combination of the wheel/tire combo, lowering, hard driving on the track (full compression of suspension at high speed), etc, there was some dangerous rubbing at the top inside of each side, where the tires got ripped apart over time, on brackets that were previously concealed by the fender liners. The tires first wore through the liners, then got chewed up on the brackets.
I have some pictures here:
<a href="http://home.attbi.com/~jbalthasar/wheel_well.htm" target="_blank">http://home.attbi.com/~jbalthasar/wheel_well.htm</a>
I am installing a wide-body kit on my car and plan to have more clearance room on the inside of the wheel well. I will achieve this with conservative offsets for the custom wheels that I plan to order.
I do highly recommend the 17" wheels, as they performed much better for me, and they looked alot better. Obviously, Adrian's advice should be followed, wrt stops and spacers. Good Luck, and if anyone is interested in buying some wheels, I am selling 3 sets of my old wheels (17" twists)
<a href="http://home.attbi.com/~jbalthasar/wheels_fs.htm" target="_blank">http://home.attbi.com/~jbalthasar/wheels_fs.htm</a>
to fund one set of custom wheels!
I have some pictures here:
<a href="http://home.attbi.com/~jbalthasar/wheel_well.htm" target="_blank">http://home.attbi.com/~jbalthasar/wheel_well.htm</a>
I am installing a wide-body kit on my car and plan to have more clearance room on the inside of the wheel well. I will achieve this with conservative offsets for the custom wheels that I plan to order.
I do highly recommend the 17" wheels, as they performed much better for me, and they looked alot better. Obviously, Adrian's advice should be followed, wrt stops and spacers. Good Luck, and if anyone is interested in buying some wheels, I am selling 3 sets of my old wheels (17" twists)
<a href="http://home.attbi.com/~jbalthasar/wheels_fs.htm" target="_blank">http://home.attbi.com/~jbalthasar/wheels_fs.htm</a>
to fund one set of custom wheels!
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Instructor
Joined: Mar 2002
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From: La Spezia - City of Sun&Sea , Italy
I have 17" 993 wheels on my'90 C4. You can see them on PCaronline:
<a href="http://www.p-caronline.com/directory/ferry23" target="_blank">http://www.p-caronline.com/directory/ferry23</a>
<a href="http://www.p-caronline.com/directory/ferry23" target="_blank">http://www.p-caronline.com/directory/ferry23</a>
Race Car
Joined: Jun 2001
Posts: 3,706
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From: Virginia Beach, Va.
Mark, I have a lowered '91 with TWO sets of 17" wheels, one set is the 993 Cup II...the other set is the 17" 996/Boxster S "Twist" wheels.
The Cup II wheels are my track wheels, 7" front, 9" rear with 55mm offset all four.
I use 245mm track tires up front with RUB, even with 3mm spacers. Eventually I will install the correct steering stops and/or longer studs to facilitate a SAFE installation of 5-6mm spacers.
For the rear, with 275 series Hoosiers, they rub the insides of the fenderwells and the oil line. I use two 6mm "shims" (spacers) in there but have extended wheel studs.
Understand if you stay with a 225 or smaller tire on the front and 255 on the rear you'll be okay, but the fronts will always rub as Adrian says, at full lock.
So, get yourself a set of 3mm spacers and try your luck with a 205 series tire...you'll likely get away with NO rub. Any larger size tire on the front and there's NO way you'll get away without rubbing. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Joey B. what do you mean by "proper spacers, not shims"?? Bolt-on spacers begin at 15mm, anything below that will be a "shim" per say...I use them with no issue and my 964 goes through several times the stress than most.
As far as using spacers on the front wheels...I feel the need to remind people that anything more than 3mm is pretty much unsafe with factory aluminum lug nuts. If you don't believe me, put a 6mm on there and count the turns of your worn aluminum lug nut - you'll be shocked!
Do the right thing and don't use over 3mm worth -or- install longer wheelstuds...it's not that difficult.
Of course, the "cure all" is the "proper" steering stops.
The Cup II wheels are my track wheels, 7" front, 9" rear with 55mm offset all four.
I use 245mm track tires up front with RUB, even with 3mm spacers. Eventually I will install the correct steering stops and/or longer studs to facilitate a SAFE installation of 5-6mm spacers.
For the rear, with 275 series Hoosiers, they rub the insides of the fenderwells and the oil line. I use two 6mm "shims" (spacers) in there but have extended wheel studs.
Understand if you stay with a 225 or smaller tire on the front and 255 on the rear you'll be okay, but the fronts will always rub as Adrian says, at full lock.
So, get yourself a set of 3mm spacers and try your luck with a 205 series tire...you'll likely get away with NO rub. Any larger size tire on the front and there's NO way you'll get away without rubbing. <img src="graemlins/cussing.gif" border="0" alt="[grrrrrrr]" />
Joey B. what do you mean by "proper spacers, not shims"?? Bolt-on spacers begin at 15mm, anything below that will be a "shim" per say...I use them with no issue and my 964 goes through several times the stress than most.
As far as using spacers on the front wheels...I feel the need to remind people that anything more than 3mm is pretty much unsafe with factory aluminum lug nuts. If you don't believe me, put a 6mm on there and count the turns of your worn aluminum lug nut - you'll be shocked!
Do the right thing and don't use over 3mm worth -or- install longer wheelstuds...it's not that difficult.
Of course, the "cure all" is the "proper" steering stops.
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From: Highland Park, IL
[quote]Originally posted by Jeff Curtis:
<strong>Joey B. what do you mean by "proper spacers, not shims"??
As far as using spacers on the front wheels...I feel the need to remind people that anything more than 3mm is pretty much unsafe with factory aluminum lug nuts. If you don't believe me, put a 6mm on there and count the turns of your worn aluminum lug nut - you'll be shocked!</strong><hr></blockquote>
I think you clarified everything quite nicely. I'm also concerned about the 1/4" (6.4mm) spacers offered by various vendors which they claim can be used with stock lugs. Nice work, Jeff!
<strong>Joey B. what do you mean by "proper spacers, not shims"??
As far as using spacers on the front wheels...I feel the need to remind people that anything more than 3mm is pretty much unsafe with factory aluminum lug nuts. If you don't believe me, put a 6mm on there and count the turns of your worn aluminum lug nut - you'll be shocked!</strong><hr></blockquote>
I think you clarified everything quite nicely. I'm also concerned about the 1/4" (6.4mm) spacers offered by various vendors which they claim can be used with stock lugs. Nice work, Jeff!
Advanced
Joined: Nov 2001
Posts: 96
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From: Albuquerque, NM
[quote]I'm also concerned about the 1/4" (6.4mm) spacers offered by various vendors which they claim can be used with stock lugs. Jeff! <hr></blockquote>
FWIW, I ran H&R 6mm spacers (a bit under 1/4", I think) on a previous autocross car (Intera Type R), and they actually came with the longer studs.
I guess it would vary with the vendor.....as always, buyer beware.
BL
FWIW, I ran H&R 6mm spacers (a bit under 1/4", I think) on a previous autocross car (Intera Type R), and they actually came with the longer studs.
I guess it would vary with the vendor.....as always, buyer beware.
BL
Thread Starter
Burning Brakes
Joined: Aug 2002
Posts: 754
Likes: 14
From: St. Louis
Thanks for the responses everyone...It sounds like spacers are the quick cure for the rubbing.
Craig, I am looking at the one in the post. Do you know the car?
As for your wheels, I may be interested. I will let you know after I see the car this weekend.
thanks,
Mark
Craig, I am looking at the one in the post. Do you know the car?
As for your wheels, I may be interested. I will let you know after I see the car this weekend.
thanks,
Mark
Drifting
Joined: Jul 2001
Posts: 2,298
Likes: 78
From: St. Louis
Mark,
I haven't looked at the car, just remember the ad in the paper. Wife says that I can't have two p-cars so I need to sell my 944 Cab before getting super serious about a 911/964/993. I can't remember if this car has been at any club events though. If you need a PPI, try Kent at German Auto Specialists in Crestwood Industrial Park. But the $25500 asking price with 70k on the clock seems like a nice price point.
I haven't looked at the car, just remember the ad in the paper. Wife says that I can't have two p-cars so I need to sell my 944 Cab before getting super serious about a 911/964/993. I can't remember if this car has been at any club events though. If you need a PPI, try Kent at German Auto Specialists in Crestwood Industrial Park. But the $25500 asking price with 70k on the clock seems like a nice price point.