Wheel Spacers

Jamie Summers · Sep 19, 2005

Chaps,
My C2, having undergone some fairly drastic surgery at 911 Bodyshop (long story - but will emerge more RS-like !) is about to go across the road to Jaz for a new corner balance and set up. I can't help but notice that every genuine 964RS that I see seems to fill its wheel arches better than a C2 running RS geometry. I seem to remember reading somewhere that the RS runs 21mm spacers on the rear with its 9" Cups and rolled arch lips - am I imagining this ? I couldn't find any reference in Adrian Streather's book or anywhere else. I assume the fronts have no spacer, just relying on the 7.5" fronts to fill the arch. For RS geomtery to work best presumably it is a good idea to use the same track width etc, so any info / confirmation / denial would b appreciated.

Thanks in advance,

Jamie

Laurence Gibbs · Sep 19, 2005

The spacers are'nt a standard fit but many people run them to improve handling and looks. Porsche apparently approve the use of 17mm spacers on the rear. Any spacer bigger than 6mm will require longer studs.

Tony · Sep 19, 2005

Jamie,
Laurence is right, but if you can get hold of a copy of Adrian Palmer notes when he was register secretary the topic is covered in detail - (fronts included).

Tony

Laurence Gibbs · Sep 19, 2005

i have that somewhere. If i find it i'll scan it and post it up.

Jamie Summers · Sep 20, 2005

Thanks Laurence, that would be kind. The 17mm rear spacer does ring a bell, I believe that was a general Porsche approval on all 964s not just RS. Can't say I've seen 17mm spacers available anywhere - just seems to be 15mm, 18mm, 21mm. No doubt Porsche themselves can provide 17mm at a price !!!

Jamie

Laurence Gibbs · Sep 21, 2005

please find scan of article here

Laurence Gibbs · Sep 21, 2005

for those who started reading the nurburgring bit here is page two

Jamie Summers · Sep 21, 2005

Thanks, great stuff - looks like I might go for the 21mm and 7mm set up, will look nice !

Keith Calder · Sep 21, 2005

ive tried 5 sets of wheels and 3 different spacers now...im on 20mm rears but the tyres do rub the arch under body roll and are causing a lot of stone chips on the front of the arch so i would say 15 /18mm would be plenty unless you roll the arch as the rs. 3mm fronts would be plenty if you dont want to extend the studs. if you dont believe me try a 5mm and use an open ended race nut so you can see the thread, (or use one off the rear spacer kit) you will be shocked how little is holding on the wheel. type 911 sell all you need link here -

http://www.type-911.co.uk/images/general/tip4.jpg

http://www.type-911.co.uk/ac_wheel.htm

Ian964 · Dec 13, 2009

Basically you're right. Assuming the rims are the same width, the outside of the new wheels will stick out 8mm further than the originals. Therefore you need a spacer 8mm less than your current one to achieve the same outside face position i.e. a 14mm spacer.

Tony · Dec 13, 2009

Hugh,
I assume the wheels are Mille Miglia, I used to run these with an 18mm spacer with no problem (with P Zero C's which shows how long ago it was).

Tony

Steve Brookes · Dec 13, 2009

Personally I'm not a fan of using any spacers (adds to unsprung mass and all that). However, I can see why you would like to keep using them because you've already got longer studs fitted. Porscheshop sells a good range of spacers:

http://www.porscheshop.co.uk/acatalog/wheel_spacers_shims_for_porsche.html

The bigger spacers tend to be the bolt on type so that you don't have to fit longer studs to the hub. However, you should be able to tap out the studs that are fitted to the spacers (since you won't need them).

Coincedently when I bought my car, complete with the MM wheels, it had 15mm spacers fitted on the rear (bolt on type) but the tyres didn't clear the arch. I guess because the arches aren't rolled on a C2. So I took them off and ended up selling them to Jason [

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Hacki · Dec 14, 2009

ORIGINAL: h_____

So I've tried to fit Steve's wheels this weekend.....the fronts are fine, but the rears arent right. So the original cup 1s are ET 55, and these are 47, (so 8mm difference. And I have a 22mm spacer on the rear, so I think this means I need about 16mm of spacer on the rear to make these fit the same. Is that right?

From that point of view, which is technically correct, it should be a 14 mm spacer, as Ian says.

To start some calculating: The Cup car has 68 mm ET with a 21 mm spacer, but with a 9,5" rim.
And it really fills the (rolled) arches, that´s as far as you can go. That again means, as mentioned above, a 13 or 14 mm spacer will be fine for 9" ET 47. (Tyre size 255/40 x 17)

Rgds,

Hacki

Hacki · Dec 14, 2009

ORIGINAL: Steve Brookes

Coincedently when I bought my car, complete with the MM wheels, it had 15mm spacers fitted on the rear (bolt on type) but the tyres didn't clear the arch. I guess because the arches aren't rolled on a C2. So I took them off and ended up selling them to Jason []

You are right. 15 mm spacer and ET 47 means a about 1 or 2 mm wider track compared to what is possible with rolled arches. So no way with standard C2 arches.

Rgds,

Hacki

h_____ · Dec 14, 2009

OK, thanks guys. Apart from my shocking Maths, I'll see what I can buy. Looks like most places (thanks for the link Steve) sell 15mm. I might have to go back and make 100% sure that the spacers are 22mm, as that seems an odd size too.

Hacki yes they are 9s on the rear. Tony, as Steve says they are the MM style replicas Suprised you got away with 18mm spacers, not sure if the R888s are less rounded, but it didnt look like much over 16mm would fit. I'm keen to get a set that bolt on, as they look like they create less stress on the wheel studs.

Steve, I'm not worried about unsprung weight really, if I was I should have put the mags on!! Having driven the car on track now, there is a good couple of seconds a lap in me, I recon another sec in the suspension, 1/2sec a lap in the brakes (maybe more), before I start worring about tenths lost in unsprung weight. [

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jason · Dec 14, 2009

I bought 9mm spacers off Porscheshop.

They were not flat and true and screwed up the handling on my car big time - took us ages to work out it was the spacers, thinking it was wheels, tyres, suspension etc.

When i told them all they offered was a discount on my 'next' purchase.

Threw them away and won't be using Porscheshop again.

Just my experience....

Dave Wilkinson · Dec 14, 2009

This whole "spacer" subject is full of nightmares - largely because there are so many different styles of both spacer AND wheel. My own situation is a little different to most since I have the wide body conversion and, hence, a need for spacers on the large side of huge to make the car look right.

The spacers which DON'T have the built in studs are more correctly called "shims" and they can come with or without the hub-centric ridge. With it, they locate correctly centred on the hub but without out they can very easily locate off-centre and cause much of the vibration problem that Jason described.

Even the spacers WITH the studs are not without their problems. Depending on what style of wheel you have you need to be careful with ensuring that there is sufficient clearance in the back face of the wheel to accommodate the protruding stud from the hub. I was forced to fit 23mm spacers on the front hub of my car because the 18mm units left too much stud protruding for the BBS LM 099 wheels to accommodate.

Things are never simple are they???

Regards

Dave

h_____ · Dec 14, 2009

ORIGINAL: Hacki

ORIGINAL: Steve Brookes

Coincedently when I bought my car, complete with the MM wheels, it had 15mm spacers fitted on the rear (bolt on type) but the tyres didn't clear the arch. I guess because the arches aren't rolled on a C2. So I took them off and ended up selling them to Jason []

Click to expand...

You are right. 15 mm spacer and ET 47 means a about 1 or 2 mm wider track compared to what is possible with rolled arches. So no way with standard C2 arches.

Rgds,

Hacki

So judging by the lack of spacers around 14mm. Do people think that a 15mm spacer with ET47 on a 9x17 wheel with R888s of 255/40/17 will fit?

or do I need need to check the camber on the rear too? Or should I be looking at a smaller spacer?

I'm not keen to spend a 100 quid on a spacer just to find that it doesnt fit, equally I dont want the wheels too far inboard.

Tony, you seem to have run these with 18mm spacer, but it just seems too big, were they 9" wheels?

Steve Brookes · Dec 14, 2009

ORIGINAL: Dave Wilkinson

The spacers which DON'T have the built in studs are more correctly called "shims" and they can come with or without the hub-centric ridge. With it, they locate correctly centred on the hub but without out they can very easily locate off-centre and cause much of the vibration problem that Jason described.

I've got some of the hub-centric shims that I bought from Porscheshop. OK, they're only 3 mm but they have proved to be excellent quality. Although, as said, I'm not a fan of spacers I needed to put these on to stop my toyo R888s that are on standard 9 x 55 wheels rubbing the oil line in the rear arch (it is flattened btw). I never had this problem when using the 9 x 47 MM wheels.

As Hacki said, you should be OK with 15 mm spacers because although the tyres snagged the outside arch of my C2 (when using the 47 offset wheels with 15 mm spacers), yours will have rolled arches and probably more neg camber.

While on the subject of spacers, do people find that using them to widen the track is a real improvement in handling? I would have thought if Porsche thought that the 64RS needed a wider of track, they would have given it one in the first place?

rs phil · Dec 14, 2009

while on this subject,my rear archs are rolled but very badly thought they were done afterwards when car was fitted with 18s speedlines with 15mm spacers

checked a few 964 rs when mine was at manthey and 2 had same as mine where they didnt feel as if they were fully done while two other were completly flat and felt perfect...any views on this?