Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length

[TheBoy]

Dunlop SP9000s.  Always been happy with those on my MV6.

However, after a stink of aggressive driving before Christmas, they seem to have lost a lot of the grip.  Also, seems to tramline quite badly now, and the car is easily unsettled with even small bumps, including cateyes.

Could I have damaged the tyres?  Or more likely whacked the tracking/geometry?  When I changed the track rod end, I had to get it retracked, asked them only to adjust the side I'd touched (so as not to disturb WIMs settings), but they said they had to adjust both sides.

 

[JamesV6CDX]

I would double check everything for excess play - and assuming there isn't any, get back to WIM for a checkup?

[2woody]

tyres do go "off", but not in your situation.

they react poorly to UV light exposure and they age, both resulting in a hardening of the rubber.

if you've put a lot more work into the tyres all of a sudden, you will remove a layer of relatively hard rubber, exposing fresh "soft" rubber underneath. This results in more grip, not less.

I'd consider all of the factors at play here :-

the age of the tyre
the pressures you're running at
ambient temperature
road surface condition
car changes ( load, tracking, camber, etc. )

and see if you can identify anything else that's changed.

it's actually surprising how much a little change can affect the feel of a car. I've recently installed a switch to relieve the steering of its speed-sensitivity - the result is a car that now handles much much better, which can only be due to increased steering effort and feedback. I've actually quite surprised myself how much of a difference this has made.

[Seth]

I would double check everything for excess play - and assuming there isn't any, get back to WIM for a checkup?

Exactly J, but you speak about the road surface conditions.
They have a lot to do with handling characteristics. The M4 is a nightmare surface-wise, and local roads are pot-holed everywhere. I don't reckon on your tyres being at fault, it's more likely to be the road surface.

[Kevin Wood]

What he said.  ^

It sounds more likely that it's a suspension geometry issue. Did they give you a report after adjusting it? Might be wroth a check of all the bushes in case something's moving.

I'm assuming, unless they are complete muppets, that they only adjusted the toe. It should be obvious to anyone who understands what they are doing that only the side where the track rod has been changed needs adjustment...   Then again, they probably have a procedure they work to, and lack the understanding to do anything else.

I guess if the toe were incorrectly set it could cause a bit of tramlining, especially if the wheels are toeing out under some conditions. It won't hugely affect the level of grip nor the "in-corner" performance unless it's vastly out though.

I find tyres get more prone to tramlining as they wear. Could it just be that you've taken a couple of mm out in a reasonably short period and are feeling the effects?

Is the wear even? Any serious feathering of the tread edges?

Kevin

[Kevin Wood]

I would double check everything for excess play - and assuming there isn't any, get back to WIM for a checkup?

Exactly J, but you speak about the road surface conditions.
They have a lot to do with handling characteristics. The M4 is a nightmare surface-wise, and local roads are pot-holed everywhere. I don't reckon on your tyres being at fault, it's more likely to be the road surface.

Very true. The roads have deteriorated quite a bit since before Christmas due to pot holes and the fact that so much grit has been used, which tends to wear ruts in the tarmac.

Plus, I find salted roads, even when dry, have much reduced grip and, of course, lower temperatures mean the tyres need to be worked more before they warm up and provide their best grip. Dropping the pressure a little in this weather might help.

Kevin

[feeutfo]

yes tyres go off, but i've only experienced this with very soft trackday rubber. Its the heat cycles that kills them, hence tyre warmers to keep the temp constant between races or sessions.

 I suppose its could follow that road tyres would do the same if experienceing extreme cold, near 0° air temp and road temp., to extreme heat and smoking then back down to almost freezing on cold tarmac. I would imagine they would feel crap after that.

You canged front shocks and springs at Newent, depending how long suspension takes to settle in it may well have differant settings now, esp after a good work out...? my top mounts where creaking or cracking in the turets for a while after changing shocks, and springs may take a while to settle down maybe?

[TheBoy]

The tyres were all new last summer, still retain a good 7mm I'd say.

I have a small amount of play in both front wheel bearings, particularly NSF, only its not wheelbearing at fault. Awaiting parts, and re-WIMing afterwards.

Wonder if I have screwed the geometry (last done week after Newent), would explain why they had to adjust both track rods.  Then, if they screwed it, that would fit in as well. No report, they used a crappy 4 wheel laser tool, and obviously didn't really know how to use it, just 'its got to point to same number both sides, mate'

[Kevin Wood]

Sounds like they have just braced the steering wheel straight ahead and adjusted both sides. I still maintain that unless they got it miles out (enough for it to be toeing out, or toeing in by a lot) it wouldn't have made much difference if that's all they were adjusting.

New suspension components relaxing after a bit of use is a possible, though. :-/

Kevin

[TheBoy]

Sounds like they have just braced the steering wheel straight ahead and adjusted both sides. I still maintain that unless they got it miles out (enough for it to be toeing out, or toeing in by a lot) it wouldn't have made much difference if that's all they were adjusting.

New suspension components relaxing after a bit of use is a possible, though. :-/

Kevin

Maybe I should pop it over, let you have a spin, see what you think?

As it happens, I'll be passing your place this weekend anyway, if you're about   

[Kevin Wood]

As it happens, I'll be passing your place this weekend anyway, if you're about

Nope. I'm going out. Keys to the garage under the mat.

Kevin

[Kevin Wood]

Looking at the weather forecast I have an idea what  the limiting factor with grip might be, though. :-/

Keivn

[feeutfo]

As it happens, I'll be passing your place this weekend anyway, if you're about

Nope. I'm going out. Keys to the garage under the mat.

Kevin

  better take the westy with you then.

[Martin_1962]

The caravan tyres are deformed and starting to crack - not moved since 2008

Just blown £90 on a new pair

[TheBoy]

The caravan tyres are deformed and starting to crack - not moved since 2008

Just blown £90 on a new pair

I could have saved you money. I would have provided a gallon of petrol, and a box of swan vestas. Everyone's a winner