Wheel spacers

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Alan W
Joined: Thu 20 Jun, 2013 11:56
Posts: 668

  Z3 roadster 2.8
Location: Bexley, Kent UK

Wheel spacers

Post by Alan W » Mon 09 Nov, 2015 19:30

I really like the style 64 wheels on my car but being a face-lift model the wheels don't quite fill out the rear arches enough for my liking so l was thinking along the lines of a series of 20mm or 25mm hubsentric spacers, the ones that bolt on to the rear drum before you put the wheel on. I'd be interested to hear of other owners experiences with these and whether there are any downsides to fitting them?
1999 facelit Z3 Roadster 2.8 Auto in Cosmos Black aka 'Gloria'
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Mugs
Joined: Wed 07 Aug, 2013 02:26
Posts: 341

  Z3 roadster 1.9

Re: Wheel spacers

Post by Mugs » Mon 09 Nov, 2015 19:54

i have a pre-face 1.9 with a wide arch conversion using 5 series rear style 32s (with spigot rings) and 20mm heliocentric spacers to fill out the arches. i've had them on for 18 months and have had no problems at all. i went for steel spacers as i didn't trust alloy ones.

ralft01
Joined: Mon 02 Jun, 2014 09:00
Posts: 37

  Z3 roadster 2.8

Re: Wheel spacers

Post by ralft01 » Fri 13 Nov, 2015 10:46

There are quite a few posts about wheel spacers on the forum, which I suggest you search and read before you decide, particularly with regard to bolt-on or through-bolt spacers.
I have 25mm spacers on the rear and 15mm on the front. Absolutely no problem, in fact you won't notice a lot of difference while driving, if any at all.
My only advice; get a decent set, there are some cheap and nasties available.
Also, steel versus aluminium! My only concern with aluminium is the longer term electrolytic reaction, which may cause corrosion. Having said that, most of the 'decent' sets are aluminium.

Alan W
Joined: Thu 20 Jun, 2013 11:56
Posts: 668

  Z3 roadster 2.8
Location: Bexley, Kent UK

Re: Wheel spacers

Post by Alan W » Fri 13 Nov, 2015 17:08

Thanks ralft01
1999 facelit Z3 Roadster 2.8 Auto in Cosmos Black aka 'Gloria'
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Mugs
Joined: Wed 07 Aug, 2013 02:26
Posts: 341

  Z3 roadster 1.9

Re: Wheel spacers

Post by Mugs » Fri 13 Nov, 2015 20:45

my friend is in the GTR forum and he showed me a photo of a GTR R35 with a high end alloy spacer that had literally broken apart hence my not trusting the alloy. the ones i found are stainless hubcentric and are bolt on the hub type (which is the recognised correct engineering method)

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c_w
Joined: Thu 19 Aug, 2004 17:50
Posts: 4032

  M roadster S50

Re: Wheel spacers

Post by c_w » Sun 15 Nov, 2015 11:47

Mugs wrote:my friend is in the GTR forum and he showed me a photo of a GTR R35 with a high end alloy spacer that had literally broken apart hence my not trusting the alloy. the ones i found are stainless hubcentric and are bolt on the hub type (which is the recognised correct engineering method)
I'm not so sure about that as with the bolt-on type you really are now trusting the integrity of the wheel spacer to hold your wheel on. With the bolt through type you are merely clamping it between the wheel and the hub, not hanging your wheel off the spacer.

Maybe coincidence, but here is a failure of this bolt on type failure, I would not fit this type to my car personally;

http://www.gtr.co.uk/forum/167822-warni ... acers.html
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I wouldn't worry too much about the material if you understand the principal of how the wheel is fitted the car; there's nothing wrong with alloy spacers as long as they fit right. I wouldn't go beyond 15mm though, I run 10 or 12mm on mine, which are clamped between the hub and wheel with longer bolts. This means the wheels is bolted on the same way as stock. The spacer doesn't really take any unusual loading as the correct hubcentric centering plus bolt torque should mean it can't ever break unless the wheel bolts came loose or it was incorrect fitment in the first place.

gookah
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Joined: Thu 07 Aug, 2008 10:51
Posts: 2727

  Z3 roadster 2.8

Re: Wheel spacers

Post by gookah » Sun 15 Nov, 2015 21:36

I have just bought some of the 'bolt to the hub' type.
The trouble with the alloy version, as in the photo, and as Mugs rightly pointed out, is that because the holes for the hub bolts are opened up, counterbored and countersunk, it will leave very little metal (of a weak type) to hold all the forces a wheel can impose.
The ones I have bought are steel ones, so at least they are as strong as the hub material itself.
Having said that, I have never had a problem using standard alloy spacers and longer bolts, however I am more reassured by the steel "bolt to the hub' style, as you don't have the longer bolts levering rotational forces from a greater distance to where they actually fasten,
Think of it this way, what would happen if you bolted your wheel onto a 1 metre wide spacer, 5 x 1 metre long bolts screwing 12mm into your hub threads, then try and do a fast start and see how easy it is to rip out those threads out. that is what worries me about standard spacers with longer bolts.
The hub centric part takes the weight of the wheel/car, but has no bearing on the rotational forces generated.
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c_w
Joined: Thu 19 Aug, 2004 17:50
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  M roadster S50

Re: Wheel spacers

Post by c_w » Mon 16 Nov, 2015 20:47

You example is leverage. So using your example with bolt-on spacers; you'd bolt the spacer to the hub (down some massive boreholes :D ), and then bolt the wheel at the end with normal length bolts. The end result is the same thing really, the wheel spacer bolts will be under a lot of stress and this time you've added two joint points, one of which is likely to be less strong than the original wheelhub.

There is some debate with how much load the centre spigot takes; I've always understood that it's main job is to centre the wheel. Some cars (very rare I would admit) don't use them at all. You can also use plastic spigot rings to centre wheels, which maybe gives an indicator of loading. I'd always argue bolt torque holds the wheel on, but the forces ares actually through the hubface. Rotational forces are negligible in the context of holding a wheel on a car.

As I say I wouldn't use much more than 15mm, otherwise may as well just get better suited offset wheels. But the bolt through are safer "IMO".

gookah
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Joined: Thu 07 Aug, 2008 10:51
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  Z3 roadster 2.8

Re: Wheel spacers

Post by gookah » Tue 17 Nov, 2015 00:18

I disagree,
In the example I quoted I believe the rotational forces would cause the longer bolts to deflect more than short ones.

Think of it another way, loosen every bolt slightly and see the rotational deflection in the long bolts versus doing the same with the short bolts,
I bet by turning the wheel hard enough I could rip the threads out easier with the long bolts than I could do with the bolt on version.
I am not talking about shear forces on the csa of the bolt itself, I am talking levering the threads out.
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Z3 1.9 Sport Progress Journal (Wifey's)

I have an element of 'M-styling' on my car, If that's a good enough reason for the manufacturers to adorn a 320 with the M badge, then its certainly a good enough reason for me..

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Southernboy
Joined: Thu 07 Oct, 2010 13:39
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  Z3 roadster 3.0i
Location: Johannesburg

Re: Wheel spacers

Post by Southernboy » Tue 17 Nov, 2015 12:12

In the real world, all spacers are less safe than a wheel bolted to a hub. Other than the actual wheel to hub issue, there is also the issue of extending the effective length of the axle by using a spacer. This places more leverage on the suspension arms, springs and shocks as well as changing the angle of the drive axles to the diff. The most sensible solution is to fit a wheel which will provide a better fit in the wheel arch and at least eliminate the doubling up of mating surfaces at the hub by using a spacer.
"Normal is overrated"
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Dino D
Joined: Fri 10 Feb, 2012 16:59
Posts: 376

  Z3 roadster 2.8

Re: Wheel spacers

Post by Dino D » Wed 18 Nov, 2015 20:51

In the US they use stud conversions a lot more than here, especially when using spacers.

So far I just bought 4 studs to test how I get on with them (2in each rear wheel). Ive found they help me place the wheels easily along with 12mm spacers. I'd like to get round to doing all of them with a quality set. Then there are lovely extended wheel nuts to (normal ones will do though) which pushes the cost up so need to get saving...

Does anybody know what method Porsche used on the spacers it supplied with certain RS models?

I'm pretty certain I've read of racing teams using spacers too but would assume they use studs for easier tyre changes.

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