Judder when reversing on full lock

[Anonymous]

I have recently had an accident in my 54 MR2, somebody drove into the side of me.  The car has been repaired by a Toyota dealership.  When I reverse on full lock the car now judders.  The judder seems to be coming from the front of the car.  The dealership claim that this is a characteristic of MR2's.  Is this true???  If it is, what can be done to rectify it???  It certainly didn't do it from new.

[edward.carter]

yep this has happened to a number of people, was covered not too long ago in quite some detail, have a search.

[roger]

IIRC its the outside of the tyre having to travel further than the inside - it grips and grips then suddenly releases as it tries to catch up with the inside. Well thats the scenario anyway.

With a 54 plate I assume your tear wear is minimal, so it is a possibility.

[Anonymous]

the dealership have now agreed to replace something on top of the spring strut or something like that.  sorry, I don't know anything about cars, infact I have only opened the engine bay once and that was because I pulled the wrong lever when I went to fill up with petrol!

[spit]

the dealership have now agreed to replace something on top of the spring strut or something like that.  sorry, I don't know anything about cars, infact I have only opened the engine bay once and that was because I pulled the wrong lever when I went to fill up with petrol!

s:lol: :lol: s:lol:  

There's debate whether the judder is a strut thing or a worn tyre thing (or combination). Good news that your dealership have agreed to sort it though.

[Liz]

Interesting article on the boxster club about this, the Porkers do the same, there is a scientific reason for it, something to do with the tyre surface on the road surface and lack of adhesion and then the tyre jumps and makes it seem like its juddering.... will find the link and post it.

[Anonymous]

will find the link and post it.

Absolutely shameless plugging of another owners club forum!!   s:wink: :wink: s:wink:

[Liz]

will find the link and post it.

Absolutely shameless plugging of another owners club forum!!   s:wink: :wink: s:wink:

I call it trying to be helpful!   s:wink: :wink: s:wink:   to save you having to look at a Boxster forum I have copied the info....Rogers post above is correct as you can see!

It's a function of steering geometry and the resulting angle the inside wheel tyre makes to the road on full lock. The inside wheel doesn't ever make a circle of a radius perfectly matched to that of the outside wheel and because the outside one grips better (it is more upright and has bigger grip patch) the inside will "jump" on some surfaces to relieve the mismatch. Whether it jumps or whether the tyres deflect to absorb the mismatch depends on surface, dry/wet/frozen etc.) and friction. It's the "jump" as the tyre hops slightly across the road that makes the noise.

The thread also mentions something called the Ackerman angle which is the difference in slip angles.

Another link ACKERMAN ANGLE

[aaronjb]

You could just search on this very forum for 'Ackerman Angle', as I seem to recall GSB posting a very technical and in-depth explanation right here only a few weeks ago  s;) s;)  (Or a couple of months.. time is compressing, must be an age thing)

[Tem]

You could just search on this very forum for 'Ackerman Angle', as I seem to recall GSB posting a very technical and in-depth explanation right here only a few weeks ago  s;) s;)  (Or a couple of months.. time is compressing, must be an age thing)

 m http://www.mr2roc.org/phpBB2/viewtopic.php?t=2088 m

[Liz]

I will go in a corner and shut up then  s:oops: :oops: s:oops:

[aaronjb]

I will go in a corner and shut up then  s:oops: :oops: s:oops:

 s:oops: :oops: s:oops:  I didn't mean you had to do that, Liz  s:) s:)

Unless you're going to come and sit in my corner   s:twisted: :twisted: s:twisted:  

I mean.. um.. anyway, yes, back on topic..

[heathstimpson]

I never experienced this previously but over the last three days it jumps/judders badly on a reverse left turn. It may be my tyres are wearing a bit but I'll probably get Mr T take a look before the warrenty ends in six weeks time  s:wink: :wink: s:wink:

[Anonymous]

heathstimpson, that sounds exactly like my problem.  Apparently it's a characteristic!

[kanujunkie]

how fast are you guys going to cause this, i cant go more than a snails pace backwards because of the clutch, so this becomes an of interest item to me

[Anonymous]

i'm going very slowly like 5mph.  It happenes when I reverse out of my parking space in the morning.  My space is quite tight up against a wall so you can imagine the speed I would be going.

[Anonymous]

I have the exact same problem when I reverse out my space in the morning, thought I had developed a fault.

[spit]

how fast are you guys going to cause this, i cant go more than a snails pace backwards because of the clutch, so this becomes an of interest item to me

Stu, yes its a slow speed thing. Its just returned on my '2 in reverse. (I had it on full lock in 1st gear aswell three years ago, but those tyres were really stuffed).

As you can see, I'm treating it as tyre wear (my front F1s are up to 45,000 miles now - still legal  s:shock: :shock: s:shock:  ), but as I mentioned above there are some in our membership who have regarded it as a strut problem and cured it their way. Either way, its some sort of geometry thing, and all hail Liz for giving it a name.  s:wink: :wink: s:wink:

[kanujunkie]

and all hail Liz for giving it a name.  s:wink: :wink: s:wink:

[waynes world mode]

were not worthy, were not worthy

[/waynes world]

[Anonymous]

Its a completely natural 2 thing for it to do. Mine has done it for ages on my old Bridgies. They had worn down pretty badly and there was more "smooth" tyre on the road than wasn't. Changed to Toyo's and it went away completely! Now, winter is here and the slippery, greasy roads, the tyres are worn down again and its back, with vengeance. And this time I am not worried. Its just "grip, NO GRIP, grip, NO GRIP, grip, NO GRIP" ad nauseum at slow speeds in reverse. I really wouldn't worry about it.

[Anonymous]

I have had it on both 2's that i have had in the last few months.  Certainly notice it more when its colder or slippery when reversing out of my space in the morning.

[Liz]

Either way, its some sort of geometry thing, and all hail Liz for giving it a name.  s:wink: :wink: s:wink:

Can't take credit for that - Grant was there first if you look at the link which Tem posted, to be honest I hadn't seen that thread, I just borrowed the quote from Boxa.net who are all far superior to me!!

[heathstimpson]

how fast are you guys going to cause this, i cant go more than a snails pace backwards because of the clutch, so this becomes an of interest item to me

Very slow in my case too. Just strange how I have never had this before but the last week it is really bad. The temperatures in my area have not gone above freezing and the last two days its stayed around -3  s:? :? s:?  When the car has been driven and warmed up it goes away so i suspect its a combo of the front tyres having 22K on them now and being extremely cold  s:wink: :wink: s:wink:  Will be buying a new set of Toyos in the very near future so will see if it disappears  s8) s8)

[Anonymous]

Mine does this on full lock going forwards, too - it feels really awful!

The car's only got 2300 miles on it - should I get Mr T to look at it, or is it really perfectly normal?

I've never known anything like it on any other car in 35 years of driving.

[aaronjb]

The car's only got 2300 miles on it - should I get Mr T to look at it, or is it really perfectly normal?

If it's the 'clonk.... clonk' noise as you drive forward & backward (rather than the 'grindgrind' as you actually turn the steering wheel) then yep, perfectly normal (depending on tyres, some peoples don't do it, some do)

I've never known anything like it on any other car in 35 years of driving.

It's down to a combination of the front steering geometry (quite aggressively set) and having very very little weight over the front wheels (due to lack of an engine, mainly  s:) s:) )