BenB
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| posted on 16/5/08 at 08:29 AM |
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Calling all handling experts :)
My brother came over last night with his toe-in gauge and an inclinometer and we had a little look at the tracking on the Locopan. The main symptom
was twitchy handling at speed.
Turns out I had -1.2deg camber on the nearside, -4.5deg on the offside and about 5 degrees of toe-in
Which generally would be considered to be excessive toe-in and excessive camber on the offside.
Trouble is as a rule of thumb isn't it a lack of camber and toe-in that normally causes twitchiness not an excess.... Confused 
My worry is that it could be a ride height issue. I've got quite a bit of pre-load on the front shocks to give sufficient sump clearance.
I'm worried the air coming under the car could be lifting the nose. Obviously not having a boat anchor in the nose it might lift easily.....
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mookaloid
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| posted on 16/5/08 at 08:37 AM |
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The thing with this is that there is no real right or wrong for any particular car - it's just what ever settings work best.
However, the large amount of camber on one side and large amount of toe in are probably not good...
I would start at a degree or so neg camber and straight ahead or maybe 1 deg toe in to see how that goes and experiment after that.
Cheers
mark
"That thing you're thinking - it wont be that."
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BenB
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| posted on 16/5/08 at 08:42 AM |
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That's what I'm planning on... It'll be interesting to see how it changes the handling... Just got to wait for my transit upper
swivel nuts to come back from being turned down on the lathe.
At the moment I've got a whole zero threads(!) from the top swivel coming through the nylock bit of the securing nut and after having the bottom
swivel nut come off at speed I'm keen for the same not to happen on the top nut.... A turned down nut (so that some threads actually engage with
the nylon bit) and liberal amounts of threadlock should do it though...
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jambojeef
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| posted on 16/5/08 at 08:58 AM |
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In my experience it'll be the toe-in thats contributing to the twitchiness.
In my little note book of settings Ive been playing with (I know I know) the car felt much better with slight toe out on the front.
I was having similar problems fighting the car at speed over typically UK broken roads but it was transformed within 2 turns of the track rod.
I have to say, all I was trying to do was dial out the twitchiness, it may have affected the maximum grip available when cornering. Oh for a little
test track on the roof of the house FIAT style!
Geoff
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gingerprince
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| posted on 16/5/08 at 09:22 AM |
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quote:
Originally posted by BenB
My worry is that it could be a ride height issue. I've got quite a bit of pre-load on the front shocks to give sufficient sump clearance.
I'm worried the air coming under the car could be lifting the nose. Obviously not having a boat anchor in the nose it might lift easily.....
Don't think the ride height itself is that important, but the difference front to rear is. Certainly in the MK you want about 20mm lower at the
front. I'd assume a similar configuration for any chassis but could be wrong.
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BenB
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| posted on 16/5/08 at 09:27 AM |
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Yup. I think I've got about 30mm front-rear!!!!!
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mad4x4
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| posted on 16/5/08 at 11:25 AM |
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IMHO - may not be correct
Rear Camber can have a lot to do with how tiwitchy a car is,
In EXTREMES - (best to describe)
If you have a lot of POS rear camber the vehicle will be tale happy as tires slide as only the inner edge is on the road
if you have lot negitave camber the vehicle Vehicle will bit in on the out egde of the tire and grip to much (i.e. dig on the outter edge)
If you have no Camber similar but less dramatic is that the inner edge lifts as the car goes into the corner giving a mider effect of negiative camer.
Ideally you want some positive camber (top inmost) just enough so that in a hard corner the complete tire is squarely on the ground
Hope this makes sense - Try at you own risk
Scot's do it better in Kilts.
MK INDY's Don't Self Centre Regardless of MK Setting !
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Bob C
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| posted on 16/5/08 at 12:03 PM |
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mad4x4 - I think you have pos/neg camber back to front - positive camber is when the tops of the tyres are further apart than the bottoms!
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David Jenkins
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| posted on 16/5/08 at 12:37 PM |
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If it was my car, I'd start by setting everything straight and even before trying an experiments! My book car has the front wheels at 1 degree
negative camber, 0 toe-in (i.e. straight ahead). Originally it was fractionally toe-out and very unpleasant to drive - it would follow lorry ruts on
main roads, twitch over white lines, etc. This is pretty much what Stanniforth says in his book - toe-in gives very good straight-ahead stability but
poor turn-in, while toe-out gives excellent turn-in but very twitchy going straight ahead. He recommends that you choose which way to go according to
what you want from the car.
I chose the middle way for road use - 0 degrees gives acceptable stability in a straight line, with decent turn-in. It's now totally predictable
on typical British roads.
Goodness knows what having different settings on each side will do to your handling! 
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blakep82
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| posted on 16/5/08 at 01:27 PM |
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i'm no expert at all, but i'd have thought with 5 degrees of toe in, you've got the left wheel trying to go right, and the right
wheel trying to go left... they're both battling each other, and surely that could cause twitching too? if nothing else, it'll be wearing
tyre quicker than it needs too anyway
________________________
IVA manual link http://www.businesslink.gov.uk/bdotg/action/detail?type=RESOURCES&itemId=1081997083
don't write OT on a new thread title, you're creating the topic, everything you write is very much ON topic!
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BenB
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| posted on 16/5/08 at 01:36 PM |
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Well I agree- it'll turn in very easily surely because one wheel is already pointing in that direction!!!
Tyre wear isn't a major problem as they're 7 years old Yoko a539s that are well past their best rubber-wise but still loads of tread
left....
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iank
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| posted on 16/5/08 at 01:54 PM |
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quote:
Originally posted by BenB
Tyre wear isn't a major problem as they're 7 years old Yoko a539s that are well past their best rubber-wise but still loads of tread
left....
Of course 'concrete' tyres won't help your handling in the slightest either. Best get some decent rubber on as well while
you're sorting the handling.
--
Never argue with an idiot. They drag you down to their level, then beat you with experience.
Anonymous
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adithorp
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| posted on 16/5/08 at 02:54 PM |
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5' toe in is massive! Basically your front tyre are going in different directions.
I'd get the camber equal and the toe-in to somewhere between 0 and 1' and work from there.
adrian
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MikeRJ
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| posted on 16/5/08 at 03:10 PM |
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Have you checked for bump steer as well? That makes a car horrible to drive.
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Ivan
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| posted on 16/5/08 at 04:37 PM |
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I agree with others that 5 deg toe is way excessive - what's happening is that as one wheel unloads in bump the other wheel turns the car making
it very unstable feeling.
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David Jenkins
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| posted on 16/5/08 at 05:21 PM |
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Somewhere around 0.5 would be better! I still suggest 0 degrees as a starting point though.
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Volvorsport
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| posted on 16/5/08 at 05:23 PM |
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can you adjust the rear toe in ?
as commented before , 5 degrees toe in is quite a lot , start with parallel .
www.dbsmotorsport.co.uk
getting dirty under a bus
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roadrunner
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| posted on 16/5/08 at 06:11 PM |
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My car used to be really twitchy in a straight line on bumpy roads, i found that the car was too high on the dampers, the suspension was bottoming out
, when i got it lowered it made a massive difference.
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NS Dev
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| posted on 16/5/08 at 09:17 PM |
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If your stuart taylor has the same chassis as mine then its "not a bad" starting point.
Mine handles fine at any speed that I care to drive it at.
Things to watch are the usual, it needs soft springs and soft damper setup if its not to skip over bumps. Hard sprung cars of the sort of weight of
these are terribly twitchy as they are constantly losing grip at each corner.
As others have said, 5 deg toe is far too much, but shouldnt specifically cause twitchiness.
Poor tyres can, a new set will probably work wonders, again, get the softest sidewalls that you can, most tyres are designed for heavier cars and are
too tough in the sidewall, again leading to skittishness and lack of grip.
A048 yoko's are nice and compliant.
Retro RWD is the way forward...........automotive fabrication, car restoration, sheetmetal work, engine conversion
retro car restoration and tuning
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