ChrisW
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| posted on 31/5/12 at 09:30 AM |
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Suspension experts: twitchy at speed and scrubbed front tyres
This is related to my MR2. It's a mk2 rev2 running K-Sport coilover suspension. It's lower than stock but not much, and it runs on
17" wheels as opposed to the stock 15's, again not crazy (people put 18's and even 19's on these cars)
Since the new suspension it's always been a little twitchy at speed. I think that's the correct way of describing it. There's no
real problem, it's just it doesn't feel confident that it's firmly gripping the road above about 70-80. As it's a weekend toy
and lives on the B roads most of the time I've never bothered to investigate too far.
However, today I spotted that it's also scrubbed the inner edges of the front tyres. We're talking literally the inner inch or so, and
right down so that the canvas is just about visible on one. Clearly they've got to be changed, but I'd like to stop the same happening on
a brand new set! I'm guessing I've got too much negative camber from the lowered suspension which has caused this but the wheels
aren't visible leaning in like you see on these silly low cars.
Question 1: Is it likely that these two problems are inter-related?
Now, I have camber adjustable top mounts on the suspension the allow me to move the top of the strut outwards. They're in the stock positions
(ie centre of the strut tower) at the moment but it's fairly simple to move them to the outer position.
Question 2: Is this something I should be messing with myself or should I take it to someone with the proper kit and knowledge to do it properly?
Any advice from those that understand the complexities of suspension appreciated!
Chris
My gaff my rules
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coyoteboy
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| posted on 31/5/12 at 09:41 AM |
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Take it to a 4 wheel alignment place and get them to reset the geometry to something more sane. Lowering it may well have altered the front toe too so
it's now toeing out a bit at speed (i.e. with increased drag from the rolling res) - this will both scrub the tyres inner edge and cause it to
be twitchy as hell (had the same issue on my GT4). Did you get it 4 wheel aligned when the new sus went on? It's worth the £40 in reduced tyre
wear!
That said... they are fairly harsh on the inner edge when thrown around b roads a lot and if the 17s are wider than stock you could have camber issues
too which are less well dealt with than by 15s with deep flexy sidewalls.
[Edited on 31/5/12 by coyoteboy]
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phelpsa
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| posted on 31/5/12 at 09:42 AM |
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They could be related or could be independent. My advice would be to get the alignment checked out properly.
FWIW I run 1 degree overall toe in and 1 degree negative camber on the rear; parallel toe, 1.5 degrees negative camber and max castor on the front on
my MR2 (mk1) and its pretty much perfect.
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amalyos
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| posted on 31/5/12 at 09:54 AM |
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If it's twitchy at speed in a straight line, it sounds like your running Toe out. Suggest running a small amount of Toe In.
http://stevembuild.blogspot.com
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britishtrident
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| posted on 31/5/12 at 10:43 AM |
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Not enough toe-in -- especially on rear
Midies and rear engined cars are extra sensiitive to rear toe MGF & MG TF get very twitchy if the rear toe setting is wrong.
[I] “ What use our work, Bennet, if we cannot care for those we love? .”
― From BBC TV/Amazon's Ripper Street.
[/I]
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zilspeed
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| posted on 31/5/12 at 05:04 PM |
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Agree with the comments regarding toe settings.
Been there.
Not funny, and also explains the inner scrubbing.
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MikeRJ
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| posted on 31/5/12 at 06:40 PM |
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Note that at very high speed (well over 100mph) the early Mk2 MR2s feel very nervous indeed, irrespective of geometry. I never discovered how quick
mine would go as it felt terrifying. Toyota's fix for this on the later cars was to put a small wind deflector in front of the front wheels.
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HowardB
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| posted on 31/5/12 at 06:53 PM |
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quote:
Originally posted by MikeRJ
Note that at very high speed (well over 100mph) the early Mk2 MR2s feel very nervous indeed, irrespective of geometry. I never discovered how quick
mine would go as it felt terrifying. Toyota's fix for this on the later cars was to put a small wind deflector in front of the front wheels.
ratio between drag and lift, very interesting in fast cars,.. I have been reading Katz,.. 
Howard
Fisher Fury was 2000 Zetec - now a 1600 (it Lives again and goes zoom)
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theconrodkid
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| posted on 31/5/12 at 08:05 PM |
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deffo sounds like tracking,pity i sold my gauges some time ago
who cares who wins
pass the pork pies
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Nickp
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| posted on 31/5/12 at 08:19 PM |
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These are the settings we run on our MR2 V6 road/track car, handles a treat and's very predictable 
Suspension settings-
Front Toe 0deg
Rear Toe +0.3deg/3mm(IN)
Front Camber -2.0
Rear Camber -1.5
Front Caster 3.0
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ChrisW
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| posted on 1/6/12 at 08:56 AM |
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Thanks All
I've taken the plunge and booked it in at Northampton Motorsport next week for 4-wheel alignment and corner weight to set the spring platforms
up properly.
Hopefully that will fix it!
Chris
My gaff my rules
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steve m
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| posted on 1/6/12 at 10:45 AM |
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Chris
Are you taking Kermit to lemans again then?
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ChrisW
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| posted on 2/6/12 at 01:29 PM |
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Yes, that's the plan. Don't worry - the brake lines are all sorted this year!! 
Chris
My gaff my rules
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ChrisW
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| posted on 6/6/12 at 06:31 PM |
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Update to this: I took the MR2 over to Northampton Motorsport today.
Seems the tow was a mile out, towing out instead of in. It also needed more camber, so the top mounts were adjusted first. Doing that brought the
tow pretty much into spec anyway so it only needed a tweak after that.
Corner weights were pretty much spot on once the anti roll bar was adjusted for zero preload.
On the road the car feels much better, a lot more planted at speed and a lot more confident. All in all I'm very happy.
Northampton Motorsport are also highly recommended. They were happy to let me watch and ask stupid questions, and kept the tea coming all
afternoon!
Chris
My gaff my rules
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phelpsa
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| posted on 6/6/12 at 07:08 PM |
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quote:
Originally posted by ChrisW
Update to this: I took the MR2 over to Northampton Motorsport today.
Seems the tow was a mile out, towing out instead of in. It also needed more camber, so the top mounts were adjusted first. Doing that brought the
tow pretty much into spec anyway so it only needed a tweak after that.
Corner weights were pretty much spot on once the anti roll bar was adjusted for zero preload.
On the road the car feels much better, a lot more planted at speed and a lot more confident. All in all I'm very happy.
Northampton Motorsport are also highly recommended. They were happy to let me watch and ask stupid questions, and kept the tea coming all
afternoon!
Chris
Glad its all sorted Willing to share what you ended up with?
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