Unstable at speed !

[Cue]

the rear is a lot softer than the front, which should be rock solid - no give under human pressure.

sounds more like a steering issue than a suspension issue.

George, still not got my head fully around scrub radius, the principle is fine but 2 + 2 = 5 at the mo lol....

 

[BenG]

Cars getting looked at on Tuesday. Hope the problem is identified easily enough.

 

[shiftspark]

Cars getting looked at on Tuesday. Hope the problem is identified easily enough.

Theres a few threads on cs about cars with vague handling faults might be worth a look.

Let us know how you get on , hopefully it will be a minor issue that may have been over looked.

Good luck

 

[George K]

Cue; scrub radius is the distance at ground level between the projection of the strut from the top mount, through the bottom ball joint onto the ground (the pivot point) and the centre of the tyre. In the case of negative scrub radius the pivot point is outbaord of the tyre centre, so under braking the wheels want ot toe-in. This is the more stable option as braking forces are much higher than those for acceleration.

 

[Cue]

i now get it - wheels running vertically parallel to the damper/strut = positive scrub.

Wheels running at say a positive camber against an angle of say 30 deg. to the strut/damper = negative scrub. as the line falls outside that of the line of wheel (when looking horizontally from the front or rear).... :-k

 

[George K]

Cue - spot on - it actually happens with much less extreme angles than you mention. Audi started it in the early '70s andh ave suffered from numb steering ever since! Minis were always postive scrub, hence the superb steering. The strut damper angle is in fact KPI (normally 9 -13 degrees).

 

[Cue]

yeh that was just an example, i can them assume that the closer to zero you get, then the best of both worlds you'll be getting - i.e stability v steering feel. Although major influencing factors will be the rack, suspension traits, even wheel base width and length...

 

[Luke335]

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!

George, I took them to the Nurburgring and they were fantastic thanks. Positive steering, loads of grip and progressive too. I was really surprised. On a hairpin close to the 'ring I turned in extra hard to see what would happen and it felt like it was going to tip over. The front just turned and the inside rear just launched into the air and back down with a bump. After that I thought they were going to be a nightmare, but on the track they were great. They did get a bit hot though, and I think they need less pressure for prolonged use. A guy there said he ran 19psi on an old 5 series track car. Some of the tread has obviously got too hot and is coming away, but they're still not warn out yet.

I'm sure if I had used the PE2's they would have been shot by the end of the day and it would have been much less fun (I did try and get hold of some Hankook's as my PE2's needed replacing all round but I failed). As I was driving with a Z4M coupe and a 911 C4S I needed all the help I could get too! I'm really considering Mark Fish's suspension mods now though as the Trophy rolled so much....Still not tried the tyres in the wet though, thanks for the tip.


Ben,
Sorry to hijack the thread, let us know how you get on. I had a similar problem to this on a Saxo vtr (12,000 miles)but I'm afraid I never solved it! Something happened under braking and I thought I had a puncture it drove so badly. Unfortunately it stayed like that. I hope you have more success.

 

[George K]

Luke - really glad you enjoyed the V70A - they are great in the wet, but can not handle standing water.

 

[BenG]

Had my car looked at today and could find nothing wrong. He took it for a test drive and said there was nothing wrong with the steering rack. We both had a good poke about underneath, checked out anti roll bar mounts, springs, dampers, ball joints, you name it...
He said to get the dampers services and maybe change the rear ones also. Then go from there..
Its funny because ive got the dampers set at 26 clicks and going over speed bumps feels alot softer than normal, but yet still solid when I do the push down test. also when heavy cornering everything feels pretty normal but under light cornering thats when it all feels soft and no feel.
Im in the process of getting my bike on the road again so I can have transport while the dampers are being worked on. Hopefully new/serviced dampers all around will be fitted by x mas.

No worries on hijacking the thread by the way. some good info being posted

 

[shiftspark]

Ben
Is there anyone with a Trophy near you as you could do a comparison with theirs?

May help you solve this.

 

[BenG]

No where near as far as I know . Id love to do a comparison, I thought about this a while back.

Its only now and again I see a Cliosport of any kind in my area let alone a Trophy

 

[Cue]

if you fancy a trip back down to west yorkshire i'd help you with the comparison but with solid top mounts mine will feel alot firmer anyway...

 

[BenG]

Cue. It would definitely be worth a trip down, however, like you say with solid top mounts fitted yours would feel alot firmer anyways and even if you were to drive mine, mine would feel alot softer in comparison.
Im going to service the dampers as it was on the to-do list anyways, but, if this does not solve the problem I would appreciate coming down for visit.
Much appreciated. 8)

 

[Cue]

just give me a shout.

 

[SirSimon]

As Cue. However, if you fancy a trip to Scotland! I'll be more than happy to help.

Si

 

[shiftspark]

Cue. It would definitely be worth a trip down, however, like you say with solid top mounts fitted yours would feel alot firmer anyways and even if you were to drive mine, mine would feel alot softer in comparison.
Im going to service the dampers as it was on the to-do list anyways, but, if this does not solve the problem I would appreciate coming down for visit.
Much appreciated. 8)

Yep can help out if you need a visit

 

[BenG]

Thanks for all the support guys. Very good of you all to offer.
Ill keep this in mind if the new dampers dont solve the problem. Thinking of ordering some solid top mounts and fitting them at the same time. Be worth doin if the damper are being refitted.

It will be 6 weeks now until I can send them off ! Ill keep you all posted with the progress...

 

[Ajr]

Any news? My car has been doing something similar on and off.

The tracking had been out since i got it, but it drove great on wet or dry roads. Gradually the wishbone balljoints went so i fitted new wishbones & got the tracking done, it felt very different, and great in the dry for all of two days. I checked all of the bits i'd changed, none of it had come loose at all, and i fitted new bolts to be safer than sorry, and it was the same.

When i have the problem the car wanders a lot, it's usually ok at balanced throttle on straight flat roads, but any sort of bumps, dips or cambers, or if i brake it is all over the place! Accelerating calms it a little usually but doesn't change the lack of grip & snappy handling in the wet & strange feeling through steering. earlier on i accelerated in 2nd to about 4k, when i went to change gear the car swerved at least a foot across the road on a straight flat bit of road, i get the icy understeery feel on damp surfaces at low speeds, which leads into snap oversteer/4 wheel slide depending on how i react, and no it's not icy! I've also got a slight whur/whine noise so i'm starting to suspect the wheel bearing. I have visually inspected everything front and rear a good few times, need to give things a physical test for plan and smoothness of operation soon though i guess.

 

[BenG]

Hi Mate. Still got nothing sorted yet, Im going to be getting front dampers serviced this month hopefully if I can get them booked in.

I still get quite a bit of grip but the handling does seem to be off, the lack of feel puts me on edge all the time so ive cut down on the spirited driving.
There are so many speedbumps where a live I wouldnt be suprised if the internals of my dampers were shot..

Reading your post it does sound like you may have a problem with Dampers though, may be worth getting them looked at ?