SeanF Posted May 9, 2019 Report Share Posted May 9, 2019 Evening All. I have knock (possibly better described as a clunk) from the drivetrain when I lift the clutch and the wheels start to move. I can also hear it at low speeds when releasing the clutch after changing gears 2 - 4. Cannot hear it at high speed. The car drives beautifully apart from this. Could this be the problem? The play seems to be only in the nearside diff yoke and I cannot detect any play in either side shaft splines or UJ's which are all new. Can anyone tell me what the problem might be here and what the fix might involve? The diff has not been rebuilt, but CTM replaced the seals and bearings about 5 years ago after which it sat in my garage during my re-build. Many thanks, Sean Quote Link to post Share on other sites
RogerH Posted May 9, 2019 Report Share Posted May 9, 2019 Hi Sean, Assuming the splines and UJ's are OK on the drive shafts then it could be excess backlash on the diff crown wheel. I have a similar knock. Roger Quote Link to post Share on other sites
Nigel Triumph Posted May 9, 2019 Report Share Posted May 9, 2019 The most common transmission knock from an IRS TR is from worn universal joints, usually in rear half shafts, sometimes in the prop shaft. Next most common clunk is worn splines in the half shafts. Nigel Quote Link to post Share on other sites
Waldi Posted May 9, 2019 Report Share Posted May 9, 2019 Sean, If you press the UJ’s and splines full with grease and still hear the clonk you can eliminate those I think. Based on the movie (very good) it sounds like the diff. Waldi Quote Link to post Share on other sites
rcreweread Posted May 9, 2019 Report Share Posted May 9, 2019 Sean - if you decide you want to go down the route of a replacement diff , I have a couple of newly refurbished 3.45 diffs sitting on a shelf, which are surplus to my requirements - have sent you a PM with full details cheers Rich Quote Link to post Share on other sites
SeanF Posted May 9, 2019 Author Report Share Posted May 9, 2019 Thank you all for your input so far. I'm pretty sure it is not the UJ's as these are all new and greased (including the propshaft). I can find no manual play in the splines on the shafts. I have had them off again to check. When I rock the inner part of the drive shaft only, the play and noise (audible in the video) is still there and as I say above appears to be only in the passenger side of the diff. 3 hours ago, RogerH said: Assuming the splines and UJ's are OK on the drive shafts then it could be excess backlash on the diff crown wheel. I have a similar knock. 1 hour ago, Waldi said: Based on the movie (very good) it sounds like the diff Roger, if its excess backlash, is this something that can be lived with, or is damage being done by ignoring it? What is the fix? Thanks again. Sean Quote Link to post Share on other sites
John McCormack Posted May 10, 2019 Report Share Posted May 10, 2019 (edited) Diff back lash. A bit worse than usual but I wouldn't be spending a lot of money or time fixing it yet. These cars are not perfect, trying to make everything perfect will cause a lot of heartache and financial pain. Edited May 10, 2019 by John McCormack Quote Link to post Share on other sites
RogerH Posted May 10, 2019 Report Share Posted May 10, 2019 Hi Sean, as you know it is there then try and drive around it. I shall live with mine through the summer and think about a 4th rebuild in the autumn. On start up lift the clutch slowly to engage drive. Changing gear shouldn't be a problem. Slowing down can cause backlash so I dip the clutch. As mentioned by GT6M (Markus) even a rebuild may not solve it. Roger Quote Link to post Share on other sites
John McCormack Posted May 10, 2019 Report Share Posted May 10, 2019 23 minutes ago, RogerH said: Hi Sean, as you know it is there then try and drive around it. I shall live with mine through the summer and think about a 4th rebuild in the autumn. On start up lift the clutch slowly to engage drive. Changing gear shouldn't be a problem. Slowing down can cause backlash so I dip the clutch. As mentioned by GT6M (Markus) even a rebuild may not solve it. Roger +1. Smooth driving almost eliminates the noise and you can still give it a gut full of throttle when in gear. Quote Link to post Share on other sites
DRD Posted May 10, 2019 Report Share Posted May 10, 2019 10 hours ago, John McCormack said: Diff back lash. A bit worse than usual but I wouldn't be spending a lot of money or time fixing it yet. These cars are not perfect, trying to make everything perfect will cause a lot of heartache and financial pain. I agree with John, they all do this to a lesser or greater degree and its probably very difficult/expensive to eliminate entirely. Daz Quote Link to post Share on other sites
SeanF Posted May 10, 2019 Author Report Share Posted May 10, 2019 Thanks All, What a great form this is! HAGWE Sean Quote Link to post Share on other sites
SeanF Posted June 15, 2020 Author Report Share Posted June 15, 2020 Afternoon all. I am following up on this post from last year where I described my "Knock". See video in first post above. I still have the knock and if anything it is getting worse. On Saturday I allowed the car to freewheel downhill with the engine off and noticed that I could hear a knocking noise just from the revolution of the wheels. Today I jacked the back up to investigate and isolated it to the rear wheels. Definitely coming from the diff. I would welcome everyone's opinion on whether this is something that needs attention soon or if it still something that I can "drive around" Is this a major fix or is a reconditioned diff a better option? You can hear it in the video link below. Many thanks, Sean Quote Link to post Share on other sites
Robert Price Posted June 15, 2020 Report Share Posted June 15, 2020 Had exactly the same on my last 6. Jack up the rear on axle stands and hold the prop shaft with some gripping gloves and turn each way and see what you hear, then do the same on the drive shafts, you may find its is a UJ, or worn splines on the shaft or prop. I found the rear wheel could be turned three quarters of an inch each way without moving the diff. The whole lot was replaced which I obtained from Prop Tech. it is just a case of elimination, good luck. Rob Quote Link to post Share on other sites
RogerH Posted June 15, 2020 Report Share Posted June 15, 2020 Hi Sean, that is a bu66er indeed. Isolate each drive shaft ;- somehow lock the output from the diff so that both UJ's and the wheel can be wobbled back and forthwith nothing from the diff at all. Any noises then you have found it. If the drive shafts are good then it must be coming from the Diff. if you need to take it off and get it sorted these people were high;y recommended 2 years ago in doing a TR6 http://www.testransmissions.co.uk/tes-transmissions-contact-us-2008.html Roger Quote Link to post Share on other sites
SeanF Posted June 15, 2020 Author Report Share Posted June 15, 2020 4 hours ago, RogerH said: Hi Sean, that is a bu66er indeed. Isolate each drive shaft ;- somehow lock the output from the diff so that both UJ's and the wheel can be wobbled back and forthwith nothing from the diff at all. Any noises then you have found it. If the drive shafts are good then it must be coming from the Diff. if you need to take it off and get it sorted these people were high;y recommended 2 years ago in doing a TR6 http://www.testransmissions.co.uk/tes-transmissions-contact-us-2008.html Roger Thanks Roger, Any suggestions on ways to "somehow lock the output from the diff so that both UJ's and the wheel can be wobbled back and forthwith nothing from the diff at all."? I'm sure you've done it before Cheers, Sean Quote Link to post Share on other sites
RogerH Posted June 15, 2020 Report Share Posted June 15, 2020 Hi Seran, never done this but I'm sure it is do'able. Very large Mole grip or G clamp holding onto the output flange and another clamp hoilding that against something solid. Report back on the lash up engineered design you conceive. Roger Quote Link to post Share on other sites
Gene Levy Posted June 16, 2020 Report Share Posted June 16, 2020 Mine had loose wire wheel adapters. Quote Link to post Share on other sites
SeanF Posted June 16, 2020 Author Report Share Posted June 16, 2020 15 hours ago, RogerH said: Report back on the lash up engineered design you conceive. Roger Roger and all, I managed to engineer a diff immobilisation tool using the very latest nano-technology. See the photo below. The resulting immobilisation is, I would say, 99% rather than 100%, but...... With the diff immobilised, my offside wheel has zero play. There is some play in my near side wheel as captured in the video linked here. This is very little compared to the movement and noise I have with the diff unleashed as can be seen in my two earlier videos above. What do you all think on whether my problem is diff or driveshaft or both? Many thanks, Sean Quote Link to post Share on other sites
RogerH Posted June 16, 2020 Report Share Posted June 16, 2020 As your subtle immobiliser has removed all the play then the becomes the prime suspect. If you can quickly remove it and tie up with a local diff builder then go that way. Otherwise wait for the autumn/Winter and get it sorted then. Mine has a clonk when taking up drive and I can live with that. Your knocking noise is a worry. Roger Quote Link to post Share on other sites
Mark69 Posted June 16, 2020 Report Share Posted June 16, 2020 Sean, what happens if you unleash the offside diff, leaving the near side. Quote Link to post Share on other sites
SeanF Posted June 16, 2020 Author Report Share Posted June 16, 2020 2 hours ago, Mark69 said: Sean, what happens if you unleash the offside diff, leaving the near side. Mark, Thank you for suggesting this. With the offside output shaft released and the nearside one still immobilised, I clearly hear the knocking noise when I spin the offside wheel (ie with the nearside wheel not moving). I think this strongly suggests that the knock is in the diff because 1. The nearside which has some minor play in the driveshaft is not moving 2. I know the offside driveshaft has zero play therefore the knocking noise cannot be from driveshaft play so must be from the diff. QED Thank you all for your help. Sean Quote Link to post Share on other sites
John McCormack Posted June 17, 2020 Report Share Posted June 17, 2020 13 hours ago, SeanF said: Mark, Thank you for suggesting this. With the offside output shaft released and the nearside one still immobilised, I clearly hear the knocking noise when I spin the offside wheel (ie with the nearside wheel not moving). I think this strongly suggests that the knock is in the diff because 1. The nearside which has some minor play in the driveshaft is not moving 2. I know the offside driveshaft has zero play therefore the knocking noise cannot be from driveshaft play so must be from the diff. QED Thank you all for your help. Sean This might indicate the bearing in the diff is at fault. Is there any grinding noise from the diff near the axle when you spin the wheel? Diff backlash shouldn't give a knocking when it is rotating, only on take up and back off. Quote Link to post Share on other sites
ntc Posted June 17, 2020 Report Share Posted June 17, 2020 Sounds like you may have a broken tooth on the crown wheel Quote Link to post Share on other sites
Mike C Posted June 17, 2020 Report Share Posted June 17, 2020 54 minutes ago, ntc said: Sounds like you may have a broken tooth on the crown wheel Might be a good idea to have a look at the diff oil for metallic particles. Quote Link to post Share on other sites
John McCormack Posted June 17, 2020 Report Share Posted June 17, 2020 1 hour ago, ntc said: Sounds like you may have a broken tooth on the crown wheel Yep, that too! Quote Link to post Share on other sites
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