my cossy

can someone tell me what it could be ive put 2 new tyres on the rear and the old back ones on the front (these have done 9k ) with loads of tread and when i get to 60-80 mph the steering wheel shakes now i know what most of you will say check for balancing but ive done that 3 times and she is fine could it be the discs or something like that it even shakes when i brake around that speed ,what else could it be
cheers

ryn004

You said you haev balanced the wheels, did you also check wheel alignment?

Turbotits

iTrader: (2)

try putting the new tyres on the front to see if this gets rid of the problem.if it does then youve either got an oval tyre or rim or they havent been balanced properly.If it doesnt then start looking deeper
Or are you having the balancing checked at the same place every time?It could well be that there machine has not been calibraited for months or even years,If the machine is out your never gonna get then balanced right

wacky.banana

My Cossy,

Once you have tried Turbotits idea let us know the results. If the fronts are ok with the new tyres then you definitely have a problem with either an oval rim or a dodgy tyre.

I had this problem once and it turned out that the offending tyre had been spliced in 2 places from new, ie had been made from two separate rolls and had 2 hotspots plus a 3rd hotspot not related to the other 2.

The tyre was eventually balanced out but it took a combination of static and dynamic balancing plus the help of a tyre engineer from the manufacturer concerned to get it right!

Good luck.

WB

wacky.banana

Oh one more thing; are you using spacers between the wheels and the hubs? If yes ditch them immediately as these will be the prime cause of wobble between 60 & 80mph.

Cheers

WB

Elmer Fudpucker

Aren't you supposed to have the best tyres on the front anyway?

my cossy

ive got the 2 new tyres on the front and ill let you know the out come on swapping the wheels over ive got the pff-7 18s on
cheers for all the info lads ill keep ya posted

davedipster

Indeed, best tyres with more tread should always go on the front no matter what car you have.

simo

I think that you might be wrong here chap. A lot of tyre depots / people advise best tyres on the rear so that the car is more stable under hard breaking & helping to stop the rear breaking away.

Simon

Apple

Also check if the balancing was single or twin plane - single tries to average out all the vibration with one balance mass and is always a compromise. Quite a few had an issue with vibration at indicated 80mph (73mph true speed.) I had my wheels twin plane balanced and it sorted out the problem... AFAIR twin-plane considers radial and axial unbalance so you iron out vibration "out of round" and also side-to-side wobble.

This assumes it is reasonably possible to balance the wheel and tyre and they aren't a mile out to start with...

Are PFF7s a strong wheel or has it been dinged?

davedipster

I am wrong m8, got mixed up.
The best tyres should always go on the back. As you have less control over the back wheels of any car.
If the front looses grip, this can be corrected by steering inputs and power/brake inputs. So yes ‘best tyres on the back’ is what I should have said.

Elmer Fudpucker

I don't agree with that

The majority of your braking is done on the front wheels,plus I prefer to steer my car using those some front wheels

my cossy

swapped wheels around (front to back and so on ) and it is fine they said rear tyres wear at a different angle to the front so its fine now lads
cheers

Scoobedoo

can warped discs cause wheel vibe?

Gear Head

iTrader: (2)

Only under braking.

Scoobedoo

i feel a vibration through the steering wheel and seat when i hard accelerate sometimes. I was wondering if it was related to the type of road surface or balancing. Had new tyres fitted but still does it.