Ade - C4 91

Hi all,

I recently replaced the 16" wheels on my 91 C4 with 17" Speedline wheels from a 993 Targa.
Now I've noticed that there's some rubbing on the inside rear front against the oil pipe line.

The wheels are 17x9 55 offset with correct P approved Conti's, N1 255/40/17 tyres.

I understood that with this combination of model year (91), unmodified suspension, correct alignment and wheel offset (55) that the rear wheel shouldn’t encounter this problem.

Tried changing the Tyre pressure on the rear. was 36 now trying 42, with no improvement.

Ok. What should I do?
I'm considering a 5mm spacer to bring it out to a 50 offset, but will this just hit the wheel arches?

Thanks

Ade
91 C4 Amazon Green

Bill Gregory

Ade,

If you need a spacer, you might check around as you should be able to find a 3mm spacer, which may be enough to take care of the rubbing. I know you can get aluminum spacers as thin as 1/16", although they take some trimming around the edges to fit a Porsche hub.

Adrian

Dear Ade,
All the 964s are slightly different and this is why I always say when it comes to wheels and tyres "you have to check" "Measure and test". You can do two things. Flatten your oil pipe (common action amoung Cupcars, RS and RSA owners) but it must be done professionally. I think there is a specially flattened pipe available or install spacers. I would go with a 5mm spacer both sides. You will not hit the wheel arches unless you are "VERY" low. There is still quite a lot of room left in the wheel arch.
Ciao,
Adrian
911C4

Jeff Curtis

Ade, take it from me, I had the same problem when donning my 17" x 9" track wheels (55mm offset)...a set of 6mm (1/4") wheel spacers from Performance Products took care of it.

Keep in mind, I use steel lug nuts with my track wheels...I would not take away that many threads and expect to torque an aluminum lug nut to 95lbs!! So, you might look into getting extended lug bolts as well, Performance sells those too...I'm actually going to install a set so I have ALL threads of the steel lug nuts making contact.

I don't use the spacers with my street wheels, 17" x 8.5" (50mm offset)...so I my aluminum lug nuts are okay to use then.

Ade - C4 91

Thanks guys,

I'll get 5mm spacers asap.

Take care and have a great new year.

Ade.

MikeF

Where do you get steel lug nuts?

Jeff Curtis

Ade, I think you're more likely to run into a set of 6mm spacers (1/4") than 5mm, they will work perfectly. Maybe England has different "P-car" spacers available...I dunno. The ones I got from Performance were for Porsche and fit like a glove.

Mike, you can get steel lug nuts from NAPA and several other outlets, call Windward or EBS as well, the ones from NAPA look kinda goofy, my friend got a set from there...they had a flange on them as to screw "faux" black plastic lug nuts on or something?

Mine are just plain good 'ol steel lug nuts for Porsche with the correct "foot" to seat in the lug holes of Porsche wheels. If you would like a JPEG of a set, let me know by emailing me personally.

MikeF

Thanks Jeff,

Will call EBS tomorrow. Hope they're not as pricey as aluminum...any idea?

Jeff Curtis

Nope...VERY cheap, maybe $2 each?

Ade, I am currently in the hunt for a set of 3mm (1/8") spacers...if you find a set in your search...please let me know asap!

3mm spacers shouldn't cause a safety issue, even when using factory aluminum lug nuts, with 6mm, I would worry about not enough thread contact...although I have used 6mm spacers on the track with steel lug nuts...there's just enough thread contact to pass tech.

Ade - C4 91

Jeff,

I just purchased a set of 5mm spacers from www.design911.co.uk, quite pricey but everything is in the UK. They only sell 5mm and up. I don't recall seeing any 3mm anywhere.
BTW. The guy selling them said that there is ample thread to continue using alu. nuts with 5mm spacers for the road. Do you agree?

Ade


Good luck,

Ade

Jeff Curtis

ADE, 5mm will work better than 6mm, although not a big difference. Keep in mind when I use my 6mm spacers, I am using my steel, open-end lug nuts where I can see that the stud doesn't come all the way out when they are torqued down @100lbs. That's 6mm less thread contact on an aluminum lug nut, about 2mm less on the steel.

The PCA guideline for track safety says that you have to have at least the thickness of the stud in thread contact...meaning that if the studs were 5/8" (15mm) thick, you would have to have at least 5/8" (15mm)thread contact...that is how I justify using these spacers with steel lug nuts as they pass that standard, just barely.

I don't however think this is a good guideline to use with aluminum lug nuts, but I may be wrong. You would be putting the same amount of stress on the aluminum lug nuts as you would the steel - but I'm sure you know the tensile strength difference between steel and aluminum...not to mention that aluminum lug nut threads experience a considerable amount more wear than a steel one would with constant removal/reinstall.

To make a long story short, I would want as many threads in contact with an aluminum lug nut as possible. I'm sure you'll be okay...you'll just have 5mm less thread contact.

How much were the 5mm spacers??

Ade - C4 91

Hi

About 50GBP including tax for the pair. Think that's about 2x cost in the US.

Quite expensive considering I could make them up in 30 mins on a lathe and it about 3GBP material cost.



Ade