Harsh gearchange on 93 disco auto

Hi Ive a problem progressively getting worseon 3.9 v8 disco(133K) on zf autobox the gearchanges are getting far more noticable than they used to be. the 1-2 shift hesitates slightly and the top gear lockup lurches under low loads or slight overrun conditions. The change down from 4th at about 15-20 mph is very noisy there is a very noticable clank comes from the rear of the gearbox around the handbrake drum/ propshaft area. Kick down sometimes can sound quite harsh quite a large Thud when changing down .I have done all of the usual checks like suspension bushes ball joints etc and cannot find any problems there.There does seem to be excessive slack in the take up of the transmission on the rear prop I believe on 94 MY there is a donut fitted to the rear prop.I ought to add that the mainshaft lubrication was modded by landrover at 28k this involved the fitting of new oil flinger no modded gears. My questions are How much slack is acceptable in the rear prop takeup.If the donut was fitted to the prop to eliminate this is it retro fittable to an earlier model. How likely is it that the fault lies in the gearbox. I am sure there are numerous people out there who have experience of this fault happening to themselves,I welcome any feed back I can get. Tia Al

Reply to
alan
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Are you sure the prop UJs or splines aren't shot?Check the front too. Do you mean slack in the rear prop, or in the rear diff. If the latter, check the halfshafts too. There shouldn't be any play in the prop. But some play in the diff (not much!!) is acceptable. You'll prbably find its several different things alll adding up to create the overall problem. More likely to be props/halfshafts/diffs than the box. Another thing worth checking is the CV joints in the front axle if you can find any play there.

Andy

Reply to
Andy Warner

Ive just been underneath again the front and rear diff both have play in them probably about 10 deg rotation at the prop flange there is no play noticable on the props themselves, the rear diff is very noisy when taking up the slack tho` where the front isnt.Instead of a small metallic knock as on the front diff the rear one "rings" this seems to be the sound I get on change down Is this why the donut was fitted to later models or is there something in the diff that has worn and is causing this ringing .The oil has been regularly changed in both diffs and I have not noticed any metallic particles in the oil on either. Thanks Al

Reply to
alan

I wouldn't think the donut would solve the problem. 10 degrees doesn't sound too bad for diff play. It might be worth taking the rear prop off and locking the centre diff. If you go out for a drive and see the problem has gone then you know to investigate the rear diff further. Once the prop is off, it won't be a massive job to take the rear diff out and check the halfshafts too. There may be some damage to the pinion wheels or the drive flange. Shouldn't take more than 1/2 a day to pull it all apart and investigate. You'll be able to pick up a good 2nd hand diff for under £50 and you may as well fit new halfshafts if they're worn badly on the splines. Might be worth checking all the bushes too, as if badly worn all sorts of clunks can arise when taking up drive. Also check the A frame ball joint.

All the best Andy

Reply to
Andy Warner

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