cerbera wheels on wedge

[ultimaybe]

Hi all, couldn't find a definative answer to the question 'do Cerbera wheels fit a wedge?' so I bought some and did some work....
My car is a series 2 350i. The Cerb wheels have 245 45 16 rear and 225 50 16 fronts.


Issue 1:
Wedge PCD is 112, Cerb is 114.3

You'll need some PCD variance nuts. These just allow the collar of the nut to float and so seat correctly in the wheel and keep the force of the nut parallel to the wheel hub.


Issue 2:
The spigot size is different- this is a saftey issue. The spigot carries the weight of the car, NOT the wheel nuts!
Wedge is 63.4 and the cerb is ?? (see below).

You'll need spigot adaptors. Having access to a lathe and not being a fan of the plastic ones available I made my own.
I found that the cerb wheels already had a spigot ring in them. I removed this and was left with a 78mm by 6.5mm recess in the wheel for the new ring.
New spigot rings: Inner bore 63.5 (+.05 -0), outer bore 77.95 (+0 -.05), thickness 6.45mm (+0 -.05)

I also opted to include a 5mm shoulder on the rings to hold the wheel spacer on the rear wheels (see below).

Issue 3: (on my car, with my tyre combination)
The rear tyres are 245 45 16. These touched the rear tie bars.

You'll need wheel spacers. I used 5mm but this really doesn't leave enough clearance. I'd suggest 7mm, or reduce the tyre size to say, 225 50 16?



Issue 3b:

The rear wheel studs end up a bit short.

I suggest you remove the old wheel studs and fit some 10mm longer ones. I haven't done this yet but I assume they're just the press in type and can probably be changed without removing the hub.

The result:
There's no vibration, the steering doesn't feel any heavier (certainly not once you're moving).

Hope this is usefull to somebody out there.
I took some photos of the process so if people think it will be usefull I'll post them.

Andy

[rev-erend]

For issue 3 - the Steve Heath tie bars should solve that one.

[JR]

Hi, that's some work you've done there.

This topic has been discussed a few times but the search function on here is rubbish.

Issue 1: even with fancy nuts the force is not distributed evenly. I wouldn't fancy them if you enjoy spirited driving. (Being pedantic the Cerb PCD is 4.5")

Issue 2: the spigot does not carry the weight of the car - it's there to help centre the wheel. If the spiggot is carrying some weight then the wheel is not centred. Your wheel is held on by the friction developed by the tensin in the bolts. Yes, I know that this is a worrying concept the first time that you hear it.

Issue 3: Cerb ET 41, wedge ET 23.

[ultimaybe]

Thanks for the feedback- still a work in progress. I take your point about the nuts, but reason that the force is being taken correctly by the stud and nut so I'm confident that it's safe.

I forgot to actually note the ET of the Cerb wheels- I think the front and rear are different, as as far as I'm aware it's the fronts that have to be correct (has a lot to do with suspension/ steering geometry Vs center of tyre contact patch). Though pushing the rear wheels out from the intended position could put more stress on stuff like studs, nuts, etc.

I've noticed that now the suspension has settled (always takes a little drive to do this) the clearance to the tie bar is ok- though a full droop it's probably tight.

Will post more as we go. Remeber anyone reading this- take note of all the other posts, there could be some stuff I'm saying or doing that's just plain wrong!

[JR]

ultimaybe said:

Thanks for the feedback- still a work in progress. I take your point about the nuts, but reason that the force is being taken correctly by the stud and nut so I'm confident that it's safe.

I forgot to actually note the ET of the Cerb wheels- I think the front and rear are different, as as far as I'm aware it's the fronts that have to be correct (has a lot to do with suspension/ steering geometry Vs center of tyre contact patch). Though pushing the rear wheels out from the intended position could put more stress on stuff like studs, nuts, etc.

I've noticed that now the suspension has settled (always takes a little drive to do this) the clearance to the tie bar is ok- though a full droop it's probably tight.

Will post more as we go. Remeber anyone reading this- take note of all the other posts, there could be some stuff I'm saying or doing that's just plain wrong!

Para 1. It does introduce a moment on the stud though but it's the uneven force on the wheel that is usually the main problem.
Para 2. Sounds like you haven't got Cerb wheels but T car spiders - same PCDs but different ETs.

Have to go, bye.

[CarbonWedge]

Excellent post, well done for getting some useful figures, i couldn't measure accurately enough when I did mine! My cerb wheels are the same ET all round, and only just clear rear tie rods, I can confirm that the Steve Heath tie bars are a better option!

[ultimaybe]

ok, more info
All my wheels are 7 1/4J ET35. are they cerb wheels? Have I got 2 sets of fronts?

[JR]

ultimaybe said:

ok, more info
All my wheels are 7 1/4J ET35. are they cerb wheels? Have I got 2 sets of fronts?

No, they are not Cerb wheels. From another thread: 'I've measured a set of RL 17s off the car: the offset isn't stamped on the inside and all of the wheels have both the same rim width and the same offset.
They are 8J x 17 with a 41mm offset (calculated by measuring the overall width of the wheel, 9", and subtracting half of that from the distance from the outside of the rim to the hub face, 6 and 1/8th", giving 1 and 5/8", or 41mm.) The PCD is the traditional english 4.5" or 114.3mm. So with the wider rim you may well need spacers whatever the offset.'
http://www.pistonheads.com/gassing/topic.asp?h=0&a... on the Cerb

I've also never heard of a 7 1/4J wheel. Whatever they are they're not from a TVR AFAIK.

[pault0007]

Hi, don't want to be a kill joy but ive got 17 inch wheels on mine and it really F***s the ride up its so harsh that even with 25 psi in the tyres i can't live with it and im going back to a standard set up.

Just thought it might save you some pain.

[ultimaybe]

Mine's really smooth with these 16s on, I've started at 24psi and I'm running (afaik) standard shocks/springs. My guess is you're running very low profile 17s? Pehaps my sidewalls are just a bit more flexible?
I'll have to pop one off again to check the width. 7 1/4J did seem a little odd to me!

I've compared them to pictures of other cerb wheels and they look identical, so I'd be interested to see what people think they came off of... ?

[adam quantrill]

For those of you running 16" on the back - either Cerb wheels or 16" OZ's - I have just acquired a pair of Toyo Proxes at around £100 each, which is the best price I could find for decent branded tyres in this size, and they arrived pretty quickly, from Camskill.co.uk

[MarkS1966]

I had TSW 17" wheels with 235/45/ZR17 Fulda tyres on my 350 when I bought it.
They looked alright and totally filled the holes, however, it was almost undrivable, irrespective of tyre pressures, I tried low, medium and high and nothing made any difference, the car just "tram-lined" down the road, which was more than a little scary on a few occasions.
I thought I was being a "wuss" and not getting enough heat into the tyres, but nope, the wheels just weren't that great in the handling stakes.
The rears missed the tie bars by about 4 or 5mm only!
And the front rubbed on the chassis on full lock, not a lot, but enought to notice it in car parks and getting in and out of my garage.
I made the decision to return to the standard 15" lattices and the car handles a gazillion times better now.

I've put the wheels and tyres on f-bay if anyone is interested in them?

http://www.ebay.co.uk/itm/290751625650?ssPageName=...

Edited by MarkS1966 on Wednesday 1st August 21:28

[chapperssx]

adam quantrill said:

For those of you running 16" on the back - either Cerb wheels or 16" OZ's - I have just acquired a pair of Toyo Proxes at around £100 each, which is the best price I could find for decent branded tyres in this size, and they arrived pretty quickly, from Camskill.co.uk

Hi Adam
Did you at some point use Nexen on the rear of the SX ? If so were they ok ?

[adam quantrill]

Yes I ran Nexen N3000's I think they were on the back, and they were OK.

Then I followed some advice when getting fronts and got N2000's - these have far lower grip (although they might possibly last longer but that just prolongs the situation).

So - N3000's OK (but not as good as S-02's or T1R's), N2000's to be avoided on the wedge.

[chapperssx]

Cheers Adam i'll give these a go to see what their like...Seem ok for 70 quid..
Nexen 3000