[Mk2] [Generic] bumpsteer gremlins - now sorted

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Hi all, thoughts on bumpsteer culprit please?

Just moved from std rev2 staggered size 15" soft walled tyres on aftermarket alloys offset 40 front 35 rear to 16" wheels offset 35 front 32 rear fitted with Yoko AD08R 205/45 fr 225/45 rear.

Immediately experienced quite severe bumpsteer and also knocking from rear - could these symptoms be connected?

Whilst wheel offsets are likely to be a contributing factor I'm guessing the main cause is lower ball joints after reading quite a lot on bumpsteer and tramlining on this forum.

So, whilst it would seem obvious to change front lower ball joints, could it actually be the rear joints that are knocking / causing the problem?

Any ideas welcome starting with balljoints please

[Marf]

AD08R certainly have stiff sidewalls, so any geometry or wear issue may be affected further or become obvious due to less softness in your overall setup

When was the last time you had a geo? What's your suspension setup?

[Donato]

Have you lowered your car by any amount?

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Thanks both for the input

Yes I'm pleased the stiff tyre walls have highlighted issues with suspension

4 years since car was four wheel laser aligned; it was running a @ 25mm lowered setup at the time. Interesting to note there were no issues with bumpsteer at that time.

Ohlins shocks were blown so I swapped to standard rev2 shocks and springs all round.

There was no geo realignment, however all tyres wore evenly and the car felt balanced.

Another recent change of shocks is now half done, black billies and standard turbo springs swapped onto rear, just about to swap black billies onto front - no doubt different shocks front to rear contributes to a degree to the problem as I suspect the std shocks up front to be way past their best.

Now I do have Apex 30mm lowering springs which I'm in two minds about fitting at this stage since I know they can contribute to bumpsteer, however I am bearing in mind that wasn't an issue on the original lowered setup.

One other thing, at last mot had an advisory re small amount of play in one of rear wheel bearings

Since I'm fitting the front black billies asap fitting new front lower ball joints can't hurt, will also check track rod end condition

Any other thoughts welcomed

[Marf]

Sounds like a back to basics job. Get all the suspension checked for play and have the geometry verified and adjusted as needed. Do the wheel bearing too.Might be cheaper to get a known good hub swapped on.

There is some play in the stock turbo bilstein suspension in terms of camber adjustment, if you've been swapping shocks after a geo 4 years back it definitely wants checking

And yeah, different shocks front to rear wont be helping.

On those tyre sizes with stock suspension and a good geo, it should feel fecking fantastic

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That's reassuring !

I'll get on with the overhaul right away

Thanks for the advice great support on this forum

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I'm embarrassed

when I recently had the new tyres fitted I asked the tyre fitters to inflate to certain pressures, which they hadn't bothered to do

horrified when I checked pressures today ( tyres were warm )

rears weren't so bad at 35 psi each side

however the fronts were 34 offside / 18 nearside !!! serves me right for not checking pressures myself right after they'd been fitted

since the AD08s have a stiff sidewall and I want to keep a degree of comfort I've dropped from the standard pressures slightly to 26 psi front / 29 psi rear - too low or ok ?? opinions please ?

Anyway .. NO MORE BUMPSTEER or pulling to left and right ( when I think about it now it pulled to the left more, should've been obvious what the problem was )

car feels really great and the grip of the Yokos is so reassuring , went out for a drive to horseshoe pass Llangollen today and loved it !

I'm still hearing a few knocks coming from back so I'll be fitting new rear lower balljoints and if knocks persist I'll check droplinks and topmounts .

Even though I made a really stupid mistake by not checking the basics I'd rather be honest about it so it will help someone else on here encountering similar problems

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update .

When I drove more bumpy rural roads it turned out tyre pressures weren't the total cure I hoped for but correcting them obviously helped.

Just fitted new front lower balljoints and front billies, apex 30mm lowering springs - some improvement now

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Issue now completely sorted.

Had a four wheel alignment (Dinos settings ) on a hunter machine, local guy just opened up shop . Charged me £55 which I thought reasonable and would recommend

Car transformed, much less nervous on steering, feels stable and neutral through twisties. Couldn't be happier, now I can really start to exploit the yokos