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The mkiv Supra Owners Club

knocking/slipping from front


Daston
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Hey guys when my wheels are on full lock it feels like they are twitching accross the road like slipping a bit or knocking kind a hard to describe but the steering wheel twitches and it makes a slight scrape/knock sound. Anyone had this? Could it be tracking or bushes?

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bit of a obvious one but have you checked the insides of your tyres? as on mine due to camber settings the insides wear alot quicker than rest of tyres and when theyre on the way out they usually slip on cornerning

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This is quite common, apart from checking your tyre's for uneven wear, the most likely cause is the subframe bolts not being up to torque. Checking the subframe bolt torque is part of a regular service but is very often missed.

 

If the bolts are loose it causes the entire subframe to move which causes a knocking from the entire front end and vauge suspension/steering feel.

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I get this but only when it's cold out. I reckon it's just fat tyres that are stone cold and on full lock (especially when reversing) they just slip (or drag) a little. Never happens once they are warm or during the summer.

 

I'm also thinking that wet tarmac may play a part.

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I get this but only when it's cold out. I reckon it's just fat tyres that are stone cold and on full lock (especially when reversing) they just slip (or drag) a little. Never happens once they are warm or during the summer.

 

I'm also thinking that wet tarmac may play a part.

 

From the supra's I've driven hard most have a tendancy for some understeer in the wet when entering hard corners, resulting in the front skipping a little. However Daston says it's happening on full lock, so presumably when at very low speed (i.e. parking). This is a classic sign of a loose front subframe.

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If it's only when your on full lock, i take it this is low speed manuvoring, i'd be inclined to think it's down to the effects of the power steering system pressure relief.

 

Purhaps the cold is having an effect on the viscosity of system fluid and making the symptoms seem worse, road/floor surface can produce unusual characteristics like this such as a twitching through the steering when manuovering on lock al 'la 3 point turn.

 

If it is that it's nothing to worry bout, get your subframe bolts checked for tightness anyhoo, i used to get a slight clonk from mine just manuvoring/braking forwards and backward in a straight line at low speeds, which was cured by torquing up the subfarme bolts.

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..but what if one's sub-frame is okay as mine is?

 

I reckon it's cold, hard tyres sliding on damp/wet surfaces on full lock at low speeds.

 

I bet it won't happen in the summer.

 

Well if the sebframe is checked, he can rule it out. Just recommending the most likely cause here :rolleyes:

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Chris Wilson posted about this years ago. It occurs most when reversing, as the two front wheels do not track together correctly at full lock. WIth soft warm tyres in summer they have enough "give" in them to flex and "absorb" the difference until you straighten out. However in winter, the tyre can only flex so much, then it skips a little bit across the tarmac to catch up, and that's the knock you feel and hear.

It's nothing to worry about, it's all part of Toyotas design.

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It's because of the induced camber on lock from having a fairly high amount of castor angle as stock. Wider wheels exacerbate it, especially ones with low profile tyres and none stock offsets. The steering lock when manoeuvring unloads large percentage of the tyre width, and it skips rather than transfer load to the ground. Even a stock car will do this, to a certain extent, especially on loose surfaces like gravel. The wider the tyre, and the lower the sidewall profile, the worse this phenomenon will be.

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