Uber 911

Does anyone have a clue as to why I need to keep balancing my Cup 2 wheels and Continental tyres? I've had the car 6 months and its on its 7th all round balance - When done its fine they just go off after 2-3 weeks?

Chris

RSGulp

Is it fronts or rears you're having trouble with?

Uber 911

rich964rs, both ends - however the rears go off a little less.

chris

demonfish

i presume your not losing weights?

the only other thing i can think of is wheels coming slightly loose? then they whip em off, re balance, re tighten and problem goes away?

dfinnegan

Is the tire slipping around the wheel? Maybe try marking the tire and wheel.

parsecnc4

Using any spacers on your wheels? I cannot imagine all 4 wheels having the same out-of-balance issue.

springer3

Contis are pretty good tires, but any tire can have belt de-laminations that shift around and change the balance. How old are the tires? How fast have you driven on them? Any history of running under-inflated? Tires can be damaged if run fast to too little air pressure.

Inspect the lug nuts and the mating sphrerical depressions in the rim. If all looks good, it may simply be time for some new rubber.

Uber 911

Thanks to all for your input, answers as follows;

How old are the tires? = About 6 months old
How fast have you driven on them? = On a peri track(airfeild) about 120mph
Using any spacers on your wheels? No, but I notice the fronts catch the inner arch
i presume your not losing weights? = There are no witness marks of them falling off.

Note: Fronts go out between 5-10 gram. Rears last time were out by 30-35 grams

RSGulp

If you said just rears I was going to suggest the tyres are not seated properly and you may be spinning the rims inside the tyres. The front's losing balance too has me puzzled as much as you.

As Demonfish mentioned, are your wheels becoming slightly loose after driving for a while? Are the wheel nuts being torqued correctly when refitted? How much painted surface is there between the whell and the hub (there should be minimal).

Has the tyre company has their machine calibrated lately? It might be a problem at their end?

Uber 911

hi Richrs, wheel nuts torqued to 130nm and checked pretty regularly. FYI - the car does about 350 miles a week on motorways. New discs on the front, however the balance problem was there prior to fitment.

I've used three different tyre balance companies to eliminate calibration problems.

Your point "How much painted surface is there between the whell and the hub (there should be minimal)." is interesting. I'll clean off any paint where the wheel meets the hub and try that.

RSGulp

Now we know your wheel nuts are consistently at 130Nm I'm not sure paint on the mating surfaces is the problem. Still wracking my brains to think what might cause your wheels to go out of balance though - unless a kid in your street has started collecting wheel weights?

Just out of interest, where was your avatar photo taken? Looks an interesting place to visit.

RSGulp

Can you get the wheels, and tyres checked for 'roundness' on their outer diameter?

I'm thinking the company balances the wheel and they feel fine, then you drive the car 350 miles per week on the motorway. Maybe something is causing the 'dynamic' of the wheel/tyre to change. Perhaps if the tyres are flat-spotted (from sitting for a long length of time in previous ownership) the balancing initially takes out any difference in feel, but then as you drive the tyre is still wearing unevenly because it's essentially 'bouncing' along the tarmac?

Okay, I admit I kinda clutching at all possible straws here...

Do you have locking nuts fitted which are much heavier than the other lightweight wheel nuts?

Uber 911

Hi Richrs, I do have locking nut fitted and 'clutching at the same straw' asked Unit 11 in Warrington their opinion of the red dot stud and weighting - "makes no difference" came the answer. I do think the next route is your point of roundness, I'll have them checked.

The avatar was taken at; Donington Park Grand Prix Collection(Derby). Apparently the largest collection of F1 cars in the world +150. About 20 years of McLaren F1, about 12 years of Williams F1, 60-70's F1, CART, a £3m recreation of a Bugatti Royale, Lotus 4wd F1(yes they tried it)

Great day out when its raining!

Uber 911

Well guys its now down to weekly visits, the fronts run out by 15-20 grams at about 300 miles and they are 'round' tyres.

I've also changed front and rear discs to get rid of bad vibration under heavy braking and 'hunting' under very slow braking. £600+ later and the problem's exactly the same, although the rear off side hub is very slightly out according to a micrometer that was put on it.

Any ideas to solve these two problems before I bail on this car and go back to reliable Italian pedigree?

Rocket Rob

This may be a stretch but have you checked your wheel bearings? A loose wheel bearing will feel like an out of balance tire.