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Topic: Still pulling ? (Read 1105 times) |
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mr._floppy
Junior Member
 
Posts: 100
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Still pulling ?
« on: Apr 28th, 2006, 12:43am » |
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Fitted new wishbones and bushes yet still drifts to the left. Brakes are fine as are the springs and shocks.
Had the front alignment checked on them state of the art sooper dooper computer things. Camber within tolerances, Castor angle slightly out, but equal on both sides so it shouldn't pull, toe-in adjusted to perfection, yet it still drifts to left on cambered roads. My poor right arm is sore with continually correcting the steering. @
Apart from misaligned rear wheels "pushing" it to the left ( of which there's no evidence ), I'm stumped. 
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Jonnycab
Senior Member
Former owner of 2.3 Ultima Facelift saloon
Posts: 3900
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Re: Still pulling ?
« Reply #1 on: Apr 28th, 2006, 3:18am » |
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There are only four other suggestions I can think of:-
The outside of the tyres are more worn than the inside
You are stuck in the lorry gulleys
The car has been involved in an accident at some point & the subframe is bent
The rear brake is binding or the bearing is dry
Sorry if this isn't much help.
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Highlander
Moderator
Expert
13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
Posts: 8244
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Re: Still pulling ?
« Reply #2 on: Apr 28th, 2006, 4:17pm » |
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tyres ok?
correct direction of rotation, pressures? same size? 
too big a difference in front treads might do it? 7mm on one and 2 on another?
rear inner wishbone bushes? allowing a "steering" effect?
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on Oct 17th, 2011, 12:35pm, Simmo wrote:I give up !  Too much for an old boy!  |
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mr._floppy
Junior Member
Posts: 100
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Re: Still pulling ?
« Reply #3 on: Apr 29th, 2006, 12:15am » |
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As I'm replacing the two front discs after being on the car only 6ooo miles ( the dreaded wobbly steering wheel when braking has returned ) I'll try swapping the two front tyres over, as one is almost done and the other almost new !
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mr._floppy
Junior Member
Posts: 100
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Re: Still pulling ?
« Reply #5 on: Apr 30th, 2006, 12:30am » |
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Swapping the two fronts has made an improvement, although I'm unsure if it's the difference in tyre tread ( which can only affect the N/S ride height by a couple of mm ) or a slightly biased alloy.
Mmmmm ( thinks !  ) Do you think the MOT tester will allow a 16" wheel on the N/S front and 15" for the others ?
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Kjetil S
Senior Member
2001 BMW 520iat
Posts: 1419
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Re: Still pulling ?
« Reply #6 on: Apr 30th, 2006, 1:58am » |
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Don't know about the UK laws and regulations, but I know it would be instant fail here in Norway. Probably not a good idea anyways. Up here it's illegal to use different tyre types (and therefore different wheel sizes) on the same axle, with good reason.
Edit: Will recalculate how much drag this would lead to tomorrow, when I'm more awake 
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http://uncyclopedia.org/wiki/Norway
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Bren
Full Member
I claim the 5th amendment officer
Posts: 241
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Re: Still pulling ?
« Reply #7 on: Apr 30th, 2006, 2:52am » |
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And the same applies in the good old U.K
Bren
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Kjetil S
Senior Member
2001 BMW 520iat
Posts: 1419
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Re: Still pulling ?
« Reply #8 on: Apr 30th, 2006, 1:52pm » |
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Okay, did some quick math now.. In 100km/h (approx 60mph) and with 195x65R15's, a tyre worn 5mm more than the other (on the same axle) would "lag behind" 44cm or 17 inches per second. This should give the same effect as trying to roll an empty glass bottle of coke in a straight line 
My calculations (someone will probably find a comma error or three):
New tyre
Height of rubber: 195*0,65*2mm = 253,5mm
Height of rim: 15"*2,54mm/in = 381mm
Total height: 634,5mm
Circumference: 2*Pi*(635,5mm/2) = 1993,34mm (Formula for circumference is 2Pi*r where r is half the diameter)
100km/h (62.5mph) = 27,78m/s (100/3,6)
converted to millimeters: 27777,78mm/s
wheel rotations per second: 27,78 / 1,993 = 13,94
worn tyre (-5mm)
Doing the same math as above, subtracting 10mm from the height, gives a circumference of 1961,92mm, 31,42mm less than the brand new one.
At 13,94 rotations per second, this makes a difference per second of (31,42*13,94) 437,99mm.
If anyone spots an error, please tell me
A little note: 5mm wear difference on a 195x65R15 is A LOT, so this is probably bit extreme, but still possible.
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Snoopy
Administrator
Very old.BAD tempered and missing friends.
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Re: Still pulling ?
« Reply #9 on: Apr 30th, 2006, 4:18pm » |
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there is an easy calculator on this site HERE for working out Rolling radii and stuff like that saves getting the calculaotr out and also give you some very useful info!
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Snoopy
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Re: Still pulling ?
« Reply #11 on: Apr 30th, 2006, 4:30pm » |
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In theory you are correct but in practice you probably would not notice the difference in the rtyre sizes as the on with theLARGER tytre will just rotate slower and therfore NOT travel as far......
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Highlander
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13 Scorpios, XR4x4, Suzuki SJ413 for off road :)
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Re: Still pulling ?
« Reply #12 on: Apr 30th, 2006, 5:35pm » |
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So is the pulling sorted now Mr Floppy?
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on Oct 17th, 2011, 12:35pm, Simmo wrote:| I give up ! Too much for an old boy! |
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Jonnycab
Senior Member
Former owner of 2.3 Ultima Facelift saloon
Posts: 3900
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Re: Still pulling ?
« Reply #13 on: Apr 30th, 2006, 10:54pm » |
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A little bit too technical for me....Einstein was a mathmatical genius, but I don't think he had the Scorpio in mind when he made his calculations.
A pulling to the left problem is probably a lot more simple, & nothing to do with simultaneous equations.
How long has it been pulling to the left Mr._Floppy?
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mr._floppy
Junior Member
Posts: 100
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Re: Still pulling ?
« Reply #14 on: May 1st, 2006, 12:49am » |
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It has always drifted left, the meatier tyre is now on the N/S and has counteracted the pull quite a bit. I've also adjusted the front alignment to a slight toe-out ( naughty, I know ) position which gives better straight ahead stability but slightly heavier steering.
However it's been a fruitful day, put new discs and pads on the front and rear and now the usually pathetic handbrake is back to full braking power and the wobbly steering has ( hopefully for good ) dissappeared.
Small tip: If you are trying to retract ( turning clockwise ) the rear caliper pistons and seem to be getting nowhere, try turning them anti-clockwise for a couple of turns then back to clockwise rotation.
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Jonnycab
Senior Member
Former owner of 2.3 Ultima Facelift saloon
Posts: 3900
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Re: Still pulling ?
« Reply #15 on: May 1st, 2006, 1:06am » |
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If it has always drifted to the left since you've had it, then could it be possible that the last owner had an accident, & even though it was repaired, the repairer failed to notice a distorted subframe?
Also, I assume you know this, but both front tyres should be the same size & so should both back tyres. The back tyres can be bigger than the front tyres for an MOT but not vice-versa.
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