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The mkiv Supra Owners Club

What could cause slack in the proppeler shaft?


Guest Damien89

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It's normal to have slack.

 

Eh?

 

There should be no detectable "slack" in the prop shaft. It's two big hunks of metal that connect the gearbox output shaft to the crown gear on the axle with a tiny amount of damping in the middle.

 

What do you mean by slack exactly? Which diff does it have installed?

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Damien,

 

"Slack" in the prop shaft suggests to me that the rear universal joint has gone........there is a UJ at the rear of the prop shaft and there will also be UJ's at each half-shaft.

 

Hold prop shaft with one hand, and hold Diff nose drive with other(the bolted flange at the diff at which the prop shaft UJ is bolted to the diff) if you can turn one even slightly without the other moving, then the UJ is gone.

 

They are about £10 each and will require the prop shaft off to fit..........best get a garage to do it if you are not sure how........it should not take more than one hour for this at a garage.

 

Rgds

George

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There isn't a U/J at the back of the prop, it's a rubber doughnut. The front and middle joints are U/J,s, but as they are staked in they aren't a DIY job to change, far from it, and the prop needs re balancing after. The main trouble with MKIV props seems to be the sliding joint splines wearing, IMO.

 

Nor do diffs have "thrust bearings"....

;)

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Nor do diffs have "thrust bearings"....

 

I stand corrected, or am I just using the wrong term?

 

It was explained to me that there are parts akin to shims in the diff that hold it all tightly together, and that when they wear, you can get a clunk when the slack is taken up in the driveline?

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Welllll, there are shims, but they see no moving parts, and never wear. they preload the side bearings, which rarely wear, the thing that usually causes excess backlash (and diffs always, and should, have some), is the actual crown wheel and pinion teeth wearing, either to old age, excess torque, excess shock loadings, or poor lubrication.

 

I see most diff assembly "failures" on UK cars where the oil cooler pipes corrode and the thing runs low on, or out of oil. That, and asking a CWP to take double its design torque, don't do them any favours.

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What do you mean by slack exactly? Which diff does it have installed?

 

 

he may mean that when you are underneath the car and you grab the propshaft you can rotate it back and forth 5-10 degrees or so................i 'think' this type of slack is normal?

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I see most diff assembly "failures" on UK cars where the oil cooler pipes corrode and the thing runs low on, or out of oil. That, and asking a CWP to take double its design torque, don't do them any favours.

 

This is interesting, my diff seems to have more of a 'clonk' on hard acceleration from cruising than when I first got the car. It may just be that I notice it more know as am more in tune with the noises it makes. It is a UK car however, and one of the first things I had to do on it was replace the corroded and very leaky diff cooler (or at least, I have bypassed it for the time being as I don't do speeds anywhere near high enough to warrant it being there).

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Guest Damien89
he may mean that when you are underneath the car and you grab the propshaft you can rotate it back and forth 5-10 degrees or so................i 'think' this type of slack is normal?

 

Thats exactly what he has!!

Is that normal or have the uj or the rubber doughnut that are worn?

By the way he has a torsen diff.

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Thats exactly what he has!!

Is that normal or have the uj or the rubber doughnut that are worn?

By the way he has a torsen diff.

 

 

like i say i 'think' its normal............if someone in the know doesn't confirm i'll get round to checking my current car........my old uk spec definitely had this type of slack though.......

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Apologies for dodgy info in my post...........meant in good faith, but never having been under my Supra, I was assuming it had a standard prop-shaft set-up with UJ's.

 

As my ole daddy used to say, never assume or your liable to sound like the first three letters of the word!

 

Much appreciate the other posts.......I will need to have a good look under mine and just have a look at the condition of the drive doughnuts and check the diff oil level.

 

Rgds

George

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