wheel spacers

[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 (14!!! i.e. 22 - 8 =14!!) of spacer on the rear to make these fit the same.  Is that right?

The current studs on the rear are very long, too long for me to get a socket on the nuts without the spacer fitted.  With the spacer fitted the wheel protrude beyond the archs.

 

[Ian964]

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]

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]

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 []

 

[Hacki]

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]

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_____]

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. []

 

[jason]

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]

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_____]

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 []

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]

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]

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?

 

[Tony]

I'm 99% certain they were 18mm and with 17x9" MM wheels. Strictly speaking as Dave says they're shims. Bought 8 or 9 years ago they 21mm Porsche ones as recommended in one of Adrian Palmers original articles. However with them I couldn't fit the MM wheels so had them machined down. Still run them with the original 9" cup wheels so will measure them tomorrow to be sure. Am about to fit 17x9 Dymags with a 58 offset so that should be interesting! Tony

 

[Hacki]

ORIGINAL: Tony I'm 99% certain they were 18mm and with 17x9" MM wheels. Strictly speaking as Dave says they're shims. Bought 8 or 9 years ago they 21mm Porsche ones as recommended in one of Adrian Palmers original articles. However with them I couldn't fit the MM wheels so had them machined down. Still run them with the original 9" cup wheels so will measure them tomorrow to be sure. Am about to fit 17x9 Dymags with a 58 offset so that should be interesting! Tony

Tony, 21 mm was the original Cup spacer used with ET 68 and a 9,5" wheel. So no wonder MMs (ET 47, 9") don´t fit with 21 mm spacers. Will be interesting how big they are now after being machined down. What I mentioned in a post above means that there is a few mm space left, so the wheels will never touch the rolled arches. (Although I run little neg camber in the rear for road use from time to time) You can go a little closer (i. e. a little bigger spacer), but I doubt it makes sense. It also depends on how much neg camber you run. That makes a big difference, too. But then the inside clearance has to be checked properly. And, no two cars are exactly the same. If it works on one car only just, that doesn´t mean the wheels/spacer combination will fit on any other car. I personally prefer enough clearance to make sure the tyres don´t touch. Rgds, Hacki

 

[h_____]

Hacki, Thanks for the reply, I thought that was your post implied, was just looking for confirmation, before I shell out for 15mm spacers. Tony, thanks - it looks like we have an answer. I'm going to order some 15mm spacers before the end of the week.

 

[Dave Wilkinson]

It might be worth mentioning here that each additional degree of negative camber approximates to something like an additional 5mm of clearance between the top of the wheel and the wheel arch. The maths aren't THAT accurate, but it gives you an idea. Regards Dave

 

[Tony]

Spacers are definitely 18mm, car is running just under 21/2 degrees negative camber and 255/40 Rossos. Must stress this is with std mag wheels. Won't work with the Dymags, flange is too deep so if anybody has any hub centric shims of 6 - 9 mm I'm in the market! Tony

 

[h_____]

thanks Tony, standard Mags are ET 55 I think, so I can see how that would work. Dave, I had no idea that camber would make that much difference. Not to suggest that I would ever use camber to fix the wheel fitment of course.

 

[Tony]

Last word on the subject -you might find this useful. http://www.1010tires.com/wheeloffsetcalculator.asp Tony

 

[Melv]

ORIGINAL: h_____ thanks Tony, standard Mags are ET 55 I think, so I can see how that would work. Dave, I had no idea that camber would make that much difference. Not to suggest that I would ever use camber to fix the wheel fitment of course.

Not just camber, ride height too -think about it...... Couldn't be bothered to spell it out, but this site stresses the knock-on effect of altering camber/ride height etc....: http://www.aa1car.com/library/ride2h.htm