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Wheel Spin-loss Of Traction


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#1 mattw13

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Posted 22 February 2010 - 06:17 PM

I realise it is very difficult to diagnose without seeing/hearing/ feeling but.....

The car seems to be lossing traction mainly from the passenger side. I have changed the tyres and the dampers(2nd hand dampers off my other mini)-The old ones were completely shot! The CV joint seems ok and so does the wheel bearings, track rod end and the ball joints. The lower arm moves freely and I have just changed the tie bar. The car drives true and straight but it really does feel like the tyre is not being pushed down and so loosing traction.

Should the lower arm be under pressure from the rubber spring when the car is at rest?

Any suggestions?

Cheers Matt

#2 Wil_h

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Posted 22 February 2010 - 06:39 PM

Have you fitted hi-los? if so it's quite easy to set them up so all the weight is across one diagonal of the car. The result is one of the front and one of the rear wheels will be 'light' In extreem case it will be possible to lift the car up on the 'light' wheels.

This will of course result in wheelspin on just one front wheel all the time. The best way to fix it is by having the corner weights set, but getting all the hi-los the same length side to side is a good first step.

#3 mattw13

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Posted 22 February 2010 - 06:54 PM

I have not fitted Hi-Lo's and the car is still running the original cones- This is is all I have left to try. I really do need to know if the car at rest should be placing the rubber cones under stress?

Cheers

Matt

#4 mattw13

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Posted 22 February 2010 - 08:20 PM

Sorry but this is a bump- I really need to know the answer to my question above before tommorrow. Cheeers

Matt

#5 tadleysimon

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Posted 22 February 2010 - 08:51 PM

when the car is just sitting there there will be a little stress on the cones yes as they have to support the weight of the car.

#6 mattw13

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Posted 22 February 2010 - 10:05 PM

Ok so I think it is probabley linked to the cones, maybe the knuckle joints, as the car appears to be sitting with the weight through the dampers. I can lift the knuckle joint up while the car is stationary with the weight through the wheels.

Has anyone ever heard of cones sagging soo much that they are completley innaffective?

I will try and remove them tommorrow and see if it makes a difference.

Does anyone have any small hands they can lend me?!! I found trying to remove the upper arm pin the most frustrating job so far!!Any tricks?

Cheers Matt

#7 icklemini

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Posted 22 February 2010 - 10:37 PM

Sure the bump stops are fitted?

if the rubber springs were so bad, then at least the weight of the car would be on the bump stop... this would press onto the top arm... 'pushing' down the hub to the bottom arm...

Top arm not siezed??

Edited by icklemini, 22 February 2010 - 10:41 PM.


#8 tadleysimon

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Posted 22 February 2010 - 11:07 PM

gets some pictures up mate because something sounds wrong.

of the cones are really squashed its possible you could have a little stack in the knuckle join when the car is jacked up but if its on 4 wheels they shouldnt move at all as the weight of the car should be on the cones,trumpes, top arms ect

#9 The_Mistro

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Posted 22 February 2010 - 11:13 PM

mine did this when i fitted new shocks, myt old ones were shot to pieces, and the new ones made it sit a good inch higher, i think because of this it had altered the castor angle or something!

#10 mattw13

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Posted 23 February 2010 - 02:31 AM

I will have a look at the bump stops and try and take some pictures as I go tommorrow. For now I think I will rob the top arms, cones,bump stops and Hi-Los from my other mini just so that this one can be used. I have also got a new set of KYB gas adjust dampers that I will try as they have a lot more resistance than the gmax ones that I have put on there for now. I am determined to get this sorted so that I can get on and use this mini how it should be.

Cheers for all the quick replies

Matt

#11 Wil_h

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Posted 23 February 2010 - 07:50 AM

mine did this when i fitted new shocks, myt old ones were shot to pieces, and the new ones made it sit a good inch higher, i think because of this it had altered the castor angle or something!


It won't have affected the caster, that's impossible. What is most likely is that the ne shocks you bought were gas pressurised, which effectively add to the spring rate.

Sound like a plan to change all the bits.

#12 GraemeC

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Posted 23 February 2010 - 09:52 AM

Shocks do not affect the ride height - even gas pressurised ones will not have enough force in them to alter the spring rate enough to give a perceivable change in ride height. It is more likely that in changing the shocks something has moved.
However - Wil, surely a change in ride height will affect caster slightly as the bottom arm will be pulled forward by the fixed length of the tie bar moving through an arc. Obviously camber will change too, and tracking.

As for the OPs problem. It is theoritcally possible that if the cone is so knackered that the car is sat on a bottomed out shock, especially if the shocks are standard length not lowered type. However it is unlikely.
I would expect something else is holding the corner up - either sat on bump stops or a seized top (or bottom) arm as mentioned. Does the car look low?

#13 icklemini

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Posted 23 February 2010 - 11:52 AM

Shocks do not affect the ride height - even gas pressurised ones will not have enough force in them to alter the spring rate enough to give a perceivable change in ride height


hmm - have seen it before with a mini fitted with 'gas-a-justs'.. they were quite strong and certainly did lift the car...

#14 GraemeC

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Posted 23 February 2010 - 11:56 AM

Interesting - thanks for setting me straight. They really must have some pressure in them!

#15 icklemini

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Posted 23 February 2010 - 12:06 PM

you couldnt squeeze them down at all easily once you tool the strap off that held them compressed... maybe it was a dodgy set, but it did certainly make the car 'sit up'...




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