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The mkiv Supra Owners Club

wider than stock tyres - different power steering fluid ?


AJI
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When running on wider than stock front tyres is there any general concensus that says you should run a thinner/thicker or upgraded power steering fluid ?

 

I've noticed on both my Supra and my GTfour that after a fast few laps on the track that my power steering fluid seems to be getting quite hot and is slightly spilling out of the reservoir.

 

 

If so, what grade of steering fluid is reccommended?

 

Cheers.

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I didn't think that power steering fluid/transmission fluid came in "grades" as such.

 

I'm sure you can get oils of differing quality though.

 

If its getting that hot, maybe you should think about putting a small cooler inline to reduce the temps.

 

TBH, CW is far more qualified to answer this question than me though ;)

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Bobbeh - yeah that may also be something to do with the problem ;)

 

 

Well I think I'm going to change it to be on the safe side.

I'm guessing this fluid is like all the others in that it absorbes water and become less effective with water content.... similar to how brake fluid absorbes water and fades when it gets hot.

 

It may be the proposed water content that is expanding with the heat causing it to expand and over flow ??

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Yes Bob I did, I started out like AJI, local track days with power steering fluid popping out. I was guessing I was drifting to hard or I had lost a top seal or something?

HOW WRONG I WAS!! That error of diagnosis almost cost me my life. Coming off the ring into the pit the rack started to stick, and five minutes later I managed to get it parked. Cost me a pump and a rack.

Reason - PAS fluid gets old, absorbs moisture and generally wears out. IF I had changed it I would have been fine. However the supra system doesn't hold that much PAS fluid. So I fitted a cooler, and next time I want to get a larger reservoir as well.

 

This is a very serious track issue, you could easy loose your car and your life with this problem. 10 yr old power steering is done, trust me its done, you just dont want to wait until it shows you that its done. Personally I wouldnt go near a track again without changing the fliud, once a year.

 

AJI I told you twice last year to change the PAS fluid before going to the ring, as its the most demanding track in the world on PAS, listen young man.........have I advised you badly yet? lol.

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ha ha yeah your right Ernie !

 

For some reason I was thinking you were on trackday tyres which would explain the extra loading on your power steering pump.

I therefore assumed normal road tyres although on a 22km circuit would be fine.

 

But advise is now understood and I will be changing my steering fluid before the next visit.

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I dont think you'd have problems fast road driving even at the ring, but shuffling the steering wheel all over the place as if you're drifting probably makes the problem a lot worse than it is.

 

I'm sure Toyota would have tested the system to last longer than 8/9 mins of hard driving, so with decent PAS fluid you should be ok. Adding extras like Chief says should only help matters especially if you know you're going to be driving the car hard its only a good thing to aid durability.

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