Unstable at speed !

[BenG]

Hi guys.

Having a nightmare with the car lately. When im travelling 60+ MPH the car feels like its not planted and changing lanes on the M-way or dualcarrage way is becoming very scary. When traveling at speed and steering lightly (ie changing lanes) everything feels loose and the car seems to develop more roll and it feels like its going to spit me off the road sometimes (But probably being abit paranoid). If i corner hard everything is normal its just when steering lightly at 60+MPH. There is no feel = scary

So far ive had the following checked:

Tyre Pressures, condition, Wear. There is about 4 weeks left on them TBH.
Tracking
4 Wheel Alignment (camber, toe, etc)
Checked Dampers for leaks. The front ones are still solid also! Both set on 20 clicks.
Checked for play in steering department.
Checked bottom ball joints
All wishbone mounts are fine.

One of the front dampers is second hand and not sure how many miles its covered. I think maybe if both the dampers were put on a dyno they would not match up and could be causing the problem im having. this is Just one of the many possibilities. The problem has only developed during the last 6 weeks tho.

The next stage is to have the steering rack checked out for wear etc, new tyres, balancing, and then get the dampers re-built.

If anyone has any advice or help, or better still if someone has had the same problem, help is appreciated!

Over and out...

 

[BenG]

Had a good look at the tyres yesterday and noticed the outside half of the front tyres are worn quite a bit more than the inside of the tyres. there is about 0.5 to 1.0mm difference, :shock: I put this down to 'spirited' driving and having lower tyre pressures.

Maybe this would this explain why im getting less feel on the straights ! ?

 

[George K]

Ben

Uneven tyre wear could be the answer - most likely if well worn.

other ideas - is the steering wheel straight, if not could mean that the track rods are not equal length, which will give different bump steer on each side.

did the four wheel alignment include the thrust angle?

Tired rear dampers will make the car feel very unstable, as though the back is swinging in the breeze. It happended in my mini days actually quite terrifying - koni saved the day!

 

[BenG]

The steering wheel is perfectly straight, it pulls in a straight line and braking is stable.

4 wheel alignment included: Camber, Toe, Caster.

Going to get some new tyres next and see if anything changes.
If not im going to be very suspicious of the dampers and have to go down the expensive route of replacing/servicing them.

 

[g40steve]

See my sticky thread, viewtopic.php?f=2&t=5975

Someones just had them done, very good price.

 

[Luke335]

As George said, don't assume the problem is on the front suspension.
I think everyone's outside tyre edges wear out more, especially on the left (roundabouts). If it's just on the edge then I wouldn't think this is enough to cause the problem your describing, but if it's half way across then it would be the first thing to sort.

Road camber? One of my regular routes involves a road on which my car just won't track in a straight line. It's fine everywhere else.

Steering rack bushes?

 

[George K]

Luke have you tried the V70A yet - at my last event a 172 Cup arrived with them on, was instantly super competitive and couldn't understand why the rest of us were whingeing about the slippery conditions- through the Esses he said he just steered it, no fuss or drama!

 

[BenG]

Cheers for the input guys.

TBH ive got a good feeling its the tyres , at least I hope it is anyways. [-o<
Ive also noticed that it feels more unstable once the tyres have heated up !? :?

The problem has only developed in the last 6 weeks or so and ive driven the same roads many of times and the car used to feel like it was on rails. Confidence is decreasing rapidly !

Damper Rebuild/service was on the to do list anyways. So if it does come down to that im not fussed.

Ill post an update once i get new tryes fitted/balanced, There bordering legal at the min .

 

[Cue]

try going to -2.0 camber on the front - you won't be wearing the outside of the tyres then (unless you have a flat )

 

[George K]

Cue - for 2.00 negative I would recommend 10' - 15' toe-out. Your thoughts?

 

[hoolio]

Cue - for 2.00 negative I would recommend 10' - 15' toe-out. Your thoughts?

I found mine was much more sure footed and less affected by tram lines with the -2 degrees of camber and 10' toe out combination.

 

[Cue]

I'd like to try one running toe out at around 15' and compare it to mine, is it correct that where RWD cars tend to toe out under braking, fwd tend to toe in?

 

[BenG]

Update ...

New tyres fitted today. I know ive not given the chance to bed in but this handling situation has got worse in the past few days. Everything has gone soft and no feel. developed lots of roll and adjusting the dampers changes nothing, Is it possible both dampers have failed ! it certainly feels like.

Next step is to get them serviced/rebuilt.. go from there me thinks.

 

[Cue]

if you can push the front end down then yes, it's the dampers.

 

[BenG]

if you can push the front end down then yes, it's the dampers.

No, both still feel solid. cars becoming undriveable.
when driving 50+ I can move the wheel back and forth slightly and nothing happens, the faster I go the more i can move it if that makes sense.

 

[shiftspark]

Is there any strange noises or clunking? maybe something on the suspension/steering is coming loose?

 

[BenG]

No strange noises.

Could be something worn within the steering rack possibly. gonna get that checked out next weekend hopefully.
Feels like its getting worse each day !

 

[George K]

Ben G - have you tried the push down test on the rear? Other options could include a worn ball joint or suspension bush.

Cue toe out/in under braking depends entirely on whether there is positive or negative scrub radius. modern FWD cars generally have negative scrub radius, hence need a bit of toe out. Quite a lot of RWD cars have also gone this route for beter braking stability on splt mu surfaces. Neg scrub radius tends to counter-act torque steer, but does reduce steering feel - a much complained of modern trait.

 

[Ajr]

When my car felt very strange to drive and had all new suspension all round, it was the steering rack, not a clio but still.
That particular car ate 3 steering racks in 4 years of track days and hard road/rallying.

 

[BenG]

George - Ive tried the push down test on the rear. they are alot softer than the rear, you can physically push the rear end down slightly and the rebound is slow, I think this is normal. They have always dont that anyways and ive had no problems.