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Play in the diff?

Discussion in 'Gearboxes and drivetrain' started by DAV8, Sep 10, 2017.

  1. DAV8

    DAV8 Member

    Hi All, Can anyone advise the best way to check the amount of play in the diff'? my car is a 1971 V8 auto, I have owned the car since 1975 and I am fairly certain that it is the original, it has covered approx 180,000 miles, my main reason for enquiring is:- the type 35 auto box sometimes will change down a bit rough giving the diff a bit of a thump, I suspect the box may need some attention before too long and perhaps the diff, I was thinking if I lift the rear of the car with the wheel clear of the ground and then hand turn the wheel to see how much play there is at that point? does this make sense? or I am happy to listen to any advise. Thanks in advance
  2. Willy Eckerslyke

    Willy Eckerslyke Well-Known Member

    In my experience (of a manual 4-cyl P6 so feel free to ignore me...), every time I think a problem is developing in the drive train it turns out to be a drive shaft universal joint. I might just be allergic to the things but I seem to be replacing at least one a year. The last one cleared up a clonk similar to what you describe, and even substantially reduced a judder that I was sure was coming from the clutch.
  3. harveyp6

    harveyp6 Well-Known Member

    With both wheels on the ground see how much you can turn the prop backwards and forwards. That should show how much play there is in the diff, and if there is play in any of the driveshaft UJs. If you move the prop at the gearbox flange you'll be able to see any play in the prop UJs as well. Check the diff bearer plate and mountings, and the pinion mounting as well.
  4. Richard Zahra

    Richard Zahra Member

    @harveyp6 - how much do you expect the propshaft to rotate with the wheels on the ground on a 4 cyl manual car? I've just come back from a trip to Sicily and noticed that if travelling at around 50 mph or more and releasing the accelerator, a vibration can be felt and heard. I did not have the opportunity to go above 60 mph and most of my driving was at 30 - 40 mph since I was participating in a Sicilian car club event around Ragusa. Here in Malta I rarely have the opportunity to go above 50 mph and when I do its for a split second and will have to brake to slow down. When cruising or accelerating she's a dream.
  5. DAV8

    DAV8 Member

    Hi All, Okay, I have checked the prop shaft as Harvey has described it and there is little or no play anywhere in either the shaft or the uj's, the diff bearer plate etc are all okay, with everything at working temperature (i.e. the gearbox oil is hot) the quality of the shifts is sometimes a bit rough especially the down shifts, the engagement into forward or reverse from neutral will give a bit of a clonk, oil level in the box okay (although this does leak quite a bit especially when it has been stood for a while, nothing unusual here) could the box need some attention?
    DAV8 Dave
  6. harveyp6

    harveyp6 Well-Known Member

    It sounds like the kickdown cable might need adjustment. The symptoms you describe are often the result of the pressures in the box being too high, so if you also have slightly late upshifts that would also indicate that the outer cable needs adjusting upwards in the bracket to reduce the line pressure. Do it a little at a time, roadtesting in between adjustments.
  7. DAV8

    DAV8 Member

    Thanks Harvey, I'll have a look at that, I have been out for a run today (lovely weather) and the changes all seemed okay except for the delays in the forward to reverse and vice versa, sounds a bit like "sods law"

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