Handling problem, intermitent veering!

dcod · June 2, 2011, 14:29

Hi,

In the last week, twice I have come up to a (different) roundabout and the car would suddenly want to veer to the right for a split second s:scared: :scared: s:scared: . Today, I was driving slow round a flat righthand corner and the car suddenly felt like it wanted to veer left for a split second! s:crazyeyes: :crazyeyes: s:crazyeyes:

Anybody had this or can think what may cause it? Brakes/ABS/Power Steering ...

Dave

markiii · June 2, 2011, 14:43

start with teh obvious

what tyres are you running?

Anonymous · June 2, 2011, 14:52

probably tracking the road. normally happens when the front tyres are starting to wear low.

dcod · June 2, 2011, 15:05

Bridgestones on the front and embarrassingly different cheapish on the back .. (times were hard a few years ago s:oops: :oops: s:oops: ). Yes, they are all getting fairly low but more importantly they are pretty old (rubber hardening?).

I have had dodgy handling with tyres before but this felt far scarier than normal. Maybe I just havn't got to this level of 'dodgyness' before.

Do Bridgestones get this bad when fairly low?

Anonymous · June 2, 2011, 15:22

most brands do as far as i know. guess its down to more grip as the tyre wears low. when replacing try and get all tyres the same,

markiii · June 2, 2011, 15:31

mixed rubber, and most of it old and wearing

i'd fix that first then look elsewhere its the most likely culprit.

mr2 is incredibly sensitive to tyres

dcod · June 2, 2011, 15:37

Will do, was hoping to wait a little while and get wheels and tyres, can't afford wheels as well at the mo.

I think I'll go and me a set of Toyo T1Rs, they seem to be all the rage and quite affordable.

Thanks for everyones replies. s:D

s:D

Dyn-Evo · June 2, 2011, 15:39

Have you checked whether one of your brake calipers is seizing / seized..?

Mine was like this a few weeks back: I had refurbed all my calipers last summer, so it didn't cross my mind they could be faulty...any of them..! s:D

s:D

However, car failed the MOT last month and the NSR was seized. I refurbed it last week, using a new piston, grease and seals, and the car is TOTALLY different now... s8)

s8)

I very much suspect that some of the handling "problems" people have reported here over time wil have been due to this, rather than the much-maligned, but mis-understood mis-matched tyre makes /stagger.....?

Its very hard to accurately diagnose stuff like this in the real world, as you also get side-winds, tramlines, etc, which cloud things considerably.

After dismantling an EHPS pump, I do believe it is possible that this MAY have some profound effect on handling on our cars..? Perhaps its effect varies randomly at various speeds, giving the impression that the steering is "wandering"....? (Yes, I DID have the correct stagger tyres when I experienced this! s:wink: :wink: s:wink: )
This is just a theory currently, but time will shed more light on this...... s:wink: :wink: s:wink:

One final thing which may be worth noting:
I can report that with the 100mm space-saver tyre on the NSR, and a 225/45/16 on the OSR, the car felt remarkably stable at 60mph...
..in fact, FAR more so than when I had 225's both sides but with the binding caliper.......

..for what its worth!

dcod · June 2, 2011, 15:55

Hi Dyn-Evo,

Brake binding was a thought with me but I've had a veering right AND left ... unless both are binding!

Can binding be diagnosed without the brakes currently bound? ... if you see what I mean. Or do have the calipers refurbished and hope it's cured it?

I hate intermitent problems, had a Porsche 911 SC (1979) once that kept failing to start. Everytime the car was transported off to a garage, the car started ok after getting there! Grrrr! Found out eventually that it was an engine cut-off switch that activates upon the car being upside down! The switch is also engaged when the ignition is off. It was sticking s:twisted: :twisted: s:twisted:

Thanks,

Dave

markiii · June 2, 2011, 16:04

misunderstood tyre effects?

really?

some peoples stupidity knows no bounds if they think mismatched tyres aren't a problem

calaerial · June 2, 2011, 21:01

Have to say that i have today felt the benefit of fixing tyre mis-matches.

My car had a fairly significant pull to the left since i got it, feared it might be chassis bend since it was a cat D write off in 2003 (Non-recorded for some reason, but admitted by the seller). It was running 185/55/15s all round, with 3 different tread patterns (NSF - Goodyear Eagle NCT, OSF - Pirelli P6000, Both rears - Hankook K105 Ventus Prime)

Today the fronts reached the legal limit, or more accurately they reached the legal limit a few weeks ago, i reached the limit of my nerve and more importantly, pay day.

Put some Lassa Impetus on both fronts, and even with a different pattern front to back, and an incorrect stagger the car handles 100% better now, its cured that nasty understeer and completely fixed the pull to the left. Drives straight and true now.

As for your veering without experiencing the pull its different to understand exactly how bad we're talking, but if we assume for a moment its not tyres i'd say bushes would be my next suspect, maybe allowing too much play when the weight shifts. My brothers 320d had worn bushes on the back and you could see the back end shifting about something eeerie when he put the hammer down.

dcod · June 3, 2011, 08:40

Ok, so it happened again last night. This time I was doing 2mph and it felt like I was driving through a deep puddle or the left front caliper came on. Each time it happens I'd say it last for about 1 second then everythings back to normal.

Can't be tyres at that speed. ABS? Can ABS apply the brakes or can it only de-apply the brakes.

s:? :? s:?

Dave

calaerial · June 3, 2011, 08:47

I cant imagine it being tyres at anything like 10MPH or less.

I'm fairly confident the ABS system on the MR2 isnt sophisticated enough to be able to apply the brakes, that would be more of a job for EBD or something of the sort, applying braking pressure to whichever wheel has traction, could malfunction i guess. But either way the 2 doesnt have it. What really confuses me is that its doing it in both directions, a seized caliper would do it in one direction - constantly or intermittantly.

I'm out of ideas i'm afraid.

markiii · June 3, 2011, 09:01

don't see why tyres cant affect at low speed?

your right the abs can't apply the brakes

dcod · June 3, 2011, 09:15

I'm glad you can both see my confusion!

Hopfully taking my car to my local garage today. I'll see what they say.

I've read the MR2 has BA (Brake Assist) on the SMT, I guess it should have it on the manual aswell.

Anonymous · June 3, 2011, 09:22

dont think we have any form of traction control except an lsd which is mechanical.

SteveJ · June 3, 2011, 09:30

Nope - no BA on the SMT. Facecelift SMT cars did get VSC which used the ABS pump to apply the brakes on individual wheels to stop the car going too sideways. Made for great safe fun on roundabouts (until I discovered the technique for overcoming it!)

dcod · June 3, 2011, 09:54

No BA on SMT? Not according to this.

"In addition, the MR2 Roadster SMT incorporates the innovative features of Vehicle
Stability Control (VSC), Traction Control (TRC) and Brake Assist (BA), which
automatically aid the driver to control the effects of wheel spin, correct any understeer
or oversteer and supplement braking force if required."

m http://www.toyota.co.uk/bv/1024-heritag ... _Aug03.pdf m

calaerial · June 3, 2011, 09:56

Quote from: "markiii"don't see why tyres cant affect at low speed?

your right the abs can't apply the brakes

Generally i would bow to your greater experience and perhaps you are right but my early learning center understanding of physics says that tyre slip occurs when the inertia placed upon the contact area in any direction is greater than the resistance the tyre generates against the tarmac at any given moment, for this problem to be tyre related it would have to be either uneven sizes causing a difference in rotational speed (ruled out), a massive difference in the rolling resistance of the tyres on one side (n/a because the problem would be constant, not intermittent) or some sort of loss of traction, probably on one wheel, causing a directional change.

But i cant believe that any modern tyre, even a bald one from an old bus generates so little resistance as to be overcome by the force of a lightweight car like the MR2 travelling at 10MPH on plain tarmac, even if wet.

Plus any directional change caused in this way would effectively be a diversion of kinetic energy from forward acceleration, at 10MPH i dont understand where the energy required to cause such a "veer" would come from. Not through a tyre slip anyway.

Alternatively, and i say this in all seriousness, i could be talking out of my rear...

markiii · June 3, 2011, 10:02

Quote from: "dcod"No BA on SMT? Not according to this.

"In addition, the MR2 Roadster SMT incorporates the innovative features of Vehicle
Stability Control (VSC), Traction Control (TRC) and Brake Assist (BA), which
automatically aid the driver to control the effects of wheel spin, correct any understeer
or oversteer and supplement braking force if required."

m http://www.toyota.co.uk/bv/1024-heritag ... _Aug03.pdf m

as steve said only post facelift

mr-ed_smt · June 3, 2011, 10:03

Quote from: "dcod"No BA on SMT? Not according to this.

"In addition, the MR2 Roadster SMT incorporates the innovative features of Vehicle
Stability Control (VSC), Traction Control (TRC) and Brake Assist (BA), which
automatically aid the driver to control the effects of wheel spin, correct any understeer
or oversteer and supplement braking force if required."

m http://www.toyota.co.uk/bv/1024-heritag ... _Aug03.pdf m

I've done 45k miles in my '53 SMT over that last 2 years, it that REALLY surprises me! it certainty doesn't drive like it has BA.

Edit: I think I may be confusing BA with EBD however s:? :? s:? ?

dcod · June 3, 2011, 10:11

Quote from: "markiii"as steve said only post facelift

Steve said no BA, facelift got VSC.

What's important is that I don't have BA. I just can't think what is causing this.

markiii · June 3, 2011, 10:15

Quote from: "dcod"
Quote from: "markiii"as steve said only post facelift

Steve said no BA, facelift got VSC.

What's important is that I don't have BA. I just can't think what is causing this.

he said post facelift have vsc which uses the abs pump, sounds like BA to me?

calaerial · June 3, 2011, 10:19

If you've got BA that would certainly be a likely culprit.

In fact as Hugh Laurie once said, its "As guilty as a puppy sitting next to a pile of poo"

Dyn-Evo · June 3, 2011, 12:08

ABS / BA / traction control are all basically reliant on the ABS sensors.....

Perhaps you have one (or more?) generating some sporadic info...not enough of a fault to throw a code on the dash, but enough to make the ECU respond unfavourably to the signal....maybe..?

Having said that, though, that would indicate a (possibly fatal) major design flaw on Toyota's part, if the system CAN perform this way, making the car dangerous to drive without a code being generated and a CEL being thrown..... s:? :? s:?

I must say, my similar experiences over the last 2 years, running many different tyre makes, staggers and under different road conditions, seem to indicate that there are things going on that CANNOT be related to tyres (especially stagger), due to the low running speeds (on occasions), and the fact the car is running dead straight on a dead straight road in zero wind conditions.....?

I reckon either the active BA or the PAS systems MAY be throwing a spanner in the works for us, somewhere.....?

Tyres seem to get the blame for virtually everything on this forum?? s:roll: :roll: s:roll:

Rarely a mention of driver error, driving too fast into a corner...or maybe even an ongoing mechanical problem with our cars that we're not actually aware of yet........?