My new BBS wheels won't fit without a fight...

[jimmyslr]

My very shiny BBS race wheels, the new aluminium ones, arrived last week. I thought I'd slot them on today; a job of 10 minutes...oh no it isn't. Someone must have been here before so all advice gratefully received. The story is:

- The car is wearing standard 17" mags and runs 7mm and 17mm spacers on the front and rear respectively. The inside of the BBS rims (where it seats against the hub) are flat, as opposed to scalloped like the mags. This means it fouls the nuts which retain the rear spacers. I have removed the rear spacer but the upper inside shoulder of the tyre now seems very close to the bodywork (ie the inside of the wheen arch). This is probably exacerbated by the camber I'm running. Either way, it looks too tight and some spacer seems necessary. My options seem to be put a small spacer on (ie something that doesn't have its own studs / need retaining or to fit longer studs and get a wider spacer (again avoiding the need for retaining nuts that will foul the seating of the rim)

- The new front wheels pass very close to the brake caliper extremitites. The near point on the rim is the bolt heads that join the split rim together. With no spacer these pass within 1mm of the bleed nipple dust covers. This seems too close so the 7mm spacer is back on. which helps the cause and gives 5mm of clearance between rim and caliper. Does this sound enough?

- What is recommended in terms of threads engaged on a wheel nut? If I am using spacers and shortening the available stud length I wonder how far I can go

I am new to this game and was surprised the BBS rims didn't slot straight on and didn't seem to work absent spacers. Has anyone been through all this for me before? Also, I am off to the Ring in less that 2 weeks and had just had my new rims fitted with Dunlop SSRs for that purpose. There isn't much time to get the car anywhere to have someone do new, longer rear studs for instance, so simple suggestions best!

 

[tim court]

Try www.type-911.co.uk

Find out what the standard stud length is then just add the thickness of your spacers.

Reducing the thread 'bite' is not a very good idea....

 

[RSR]

Agree with Slider. I think you are worrying about nothing.

Firstly: The people who sell the shims (without bolts/nuts) and spacers (with bolts/nuts) know what is safe for your Porsche. Hence why the 17mm are spacers and the 7mm are shims. So for your wheels if you do feel like you want to run something then put 7mm shims all round or in the short term put the 7mm shims on the back and nothing on the front. As you suggest only other alternative is to replace the studs in the actual hub for longer ones so you can then run the 17mm spacers like shims. This will need access to a hydraulic press to get the studs out your 17mm spacers (making them shims) and then also to replace the studs in the hubs. This will be a lot of hassle.

Secondly: BBS should have supplied you the correct off sets for your car, though I do appreciate the amount of camber you are running on your one.

Try running it with just the 7mm on the front and go for a hot lap of your local area. Everything should be fine.

 

[tim court]

Hmmmm......

Porsche supplied the Mk1 GT3 with 5mm spacers/shims and 5mm longer bolts.

You can buy 5mm spacers without the longer bolts true enough - so why then do Porsche feel the need to supply longer bolts?? 7mm is a fair bit of thread IMHO.

 

[RSR]

I know what you're saying Tim and i'm not sure regards the later cars with bolts instead of nuts.

However on the air cooled cars if you use the open ended steel nut instead of the closed end ally nuts its clear to see that even with 7mm shims the nut does still go completely on with some of the stud protruding. I thought so long as the whole nut is threaded on it doesn't really matter how much dead unused stud is left.

Jimmy you could use the steel nuts that were holding the 17mm spacers on to bolt on the rear wheels with the 7mm shim and have a check yourself. If in doubt please check with your local friendly Porsche workshop as all this is just my opinion. I don't want a litigation case when you hang it on the armco after atempting the fox hole flat. []

 

[tim court]

ORIGINAL: RSR

I know what you're saying Tim and i'm not sure regards the later cars with bolts instead of nuts.

However on the air cooled cars if you use the open ended steel nut instead of the closed end ally nuts its clear to see that even with 7mm shims the nut does still go completely on with some of the stud protruding. I thought so long as the whole nut is threaded on it doesn't really matter how much dead unused stud is left.

Jimmy you could use the steel nuts that were holding the 17mm spacers on to bolt on the rear wheels with the 7mm shim and have a check yourself. If in doubt please check with your local friendly Porsche workshop as all this is just my opinion. I don't want a litigation case when you hang it on the armco after atempting the fox hole flat. []

100% agreed.... Good engineering practice to have a minimum of a couple of thread turns past yer nuts.

 

[jimmyslr]

Thanks chaps. I was a bit frustrated with the BBS wheels as I thought so long as offsets were correct they would just slip on. I think the inner profile of the wheel is different (the mag seems more dished in the spokes whereas the BBS is flatter with a more prominent outside shoulder - if you see what I mean) and it is that that is giving the front issue.

The plan of attack is to leave the 7mm shims on the front as this ensures some clearance of the brake calipers vs no clearance with no shim. On the back I will take off the 17mm spacer with offending nuts and overcome the inside top edge of the tyre issue by fitting another 7 mm shim instead (I think the issue here is camber related). The open ended nuts from the existing rear spacer seem a good plan.

As I push for that sub-8 minute lap let's hope it all hangs together[]

 

[pressing]

The last time your car was there it was laping just under 8 minutes. Just to give you something to aim for! Full lap not bridge to gantry BTW.

 

[jimmyslr]

Seems a bit optimistic! I hear Russell was top driver, but Walter Rohrl (sp?) would struggle with that surely.

 

[pressing]

Not optimistic, better power to weight ratio than GT3 which does sub 8 minutes, also track geometry and sticky Corsas, and RG has driven in excess of 1000 laps.

 

[jimmyslr]

This is really not helpful as now I will feel a complete failure[]

 

[pressing]

Are you going out to the 'ring with RMA? Sure he will give you a ride round in his GT2 this time. 200bhp more than the 964 mind!!

 

[jimmyslr]

Yep, Ring with RMA. I was there last year in my Caterham and I think RP there too with his (now my) car. That was the year with ice on day 2 and snow on day 3/way home! I met the GT2 at Silverstone a month or so back, but will try to cadge that ride to see those 8 minute times

 

[pressing]

Sub 8 minutes in the GT2 Jimmy! See you there.