Wheel Wobble under braking.

[Mikeyplum]

I've always had a little wheel wobble under braking and put it down to the stty discs I bought when I couldn't really afford a decent set. That and I didn't scrape the hub face when I changed the discs.

I have recently repaced my 195/65/15 alloys with some 225/45/17 ones and have noticed and incread in wobble under braking.

Although I haven't had them balanced yet, I have been out for a drive and under normal driving I can't feel any vibrations through the wheel, so they seem pretty balanced.

Could it be the wheel change exagerating the wobble? Or is it more than likely the wheels aren't balanced properly, adding to the stty discs and improper fitment making them wobble in the first place?

Cheers
Mikey

[davepoth]

Increased unsprung mass outboard of the brakes would make more of a wobble if the discs were out of balance - it's a lever, and you're applying more mass to the far end of it.

[Wild Rumpus]

Wobble under braking is often caused by sticking brake callipers - I'd have them checked.

[Mikeyplum]

davepoth said:

Increased unsprung mass outboard of the brakes would make more of a wobble if the discs were out of balance - it's a lever, and you're applying more mass to the far end of it.

The rolling radius is the same, are you referring to the weight of said unsprung mass? (i.e same lever length, more weight on the end of it?)

[littleredrooster]

Wheel wobble under braking is commonly caused by knackered suspension bushes. Fitting wider wheels will exaggerate the wobble.

[lankybob]

Would the car be able to pass an MOT with shot bushes though?
My car gets it quite badly and it has just had a MOT

[davepoth]

Mikeyplum said:

The rolling radius is the same, are you referring to the weight of said unsprung mass? (i.e same lever length, more weight on the end of it?)

Yes, I am. That's why I said mass, the formula being f=ma.

[4key]

littleredrooster said:

Wheel wobble under braking is commonly caused by knackered suspension bushes. Fitting wider wheels will exaggerate the wobble.

^that.

Wobble at 60mph ish, Wheel balancing

Wobble on the pedal, Disks

Wobble under braking, Bushes

All in general obviously, just the normal causes

[Mikeyplum]

davepoth said:

Mikeyplum said:

The rolling radius is the same, are you referring to the weight of said unsprung mass? (i.e same lever length, more weight on the end of it?)

Yes, I am. That's why I said mass, the formula being f=ma.

Sorry, I'm a layman

Thanks though

[Mikeyplum]

4key said:

littleredrooster said:

Wheel wobble under braking is commonly caused by knackered suspension bushes. Fitting wider wheels will exaggerate the wobble.

^that.

Wobble at 60mph ish, Wheel balancing

Wobble on the pedal, Disks

Wobble under braking, Bushes

All in general obviously, just the normal causes

Hmmm... Ok thanks! I wouldn't have thought of that tbh!

[The Wookie]

Also, if you've changed the wheel offset that could have an effect on the amount of wheel wobble you experience

[Mikeyplum]

The Wookie said:

Also, if you've changed the wheel offset that could have an effect on the amount of wheel wobble you experience

It has changed, been widened from 38 to 32.

[rb5er]

Warped discs

[GreatGranny]

I get it under heavy braking and at the last MOT they said my discs (& pads) would need changing soon so I put it down to that.