MARK Posted October 7, 2020 Report Share Posted October 7, 2020 I have a thrumming vibration coming from the rear of my TR6. It starts at about 65 mph but goes quiet on lifting off the throttle. The diff mounts have been replaced but the vibration remains. There does not seem to be any obvious UJ issues. I have heavy duty rear outer drive shafts fitted. Any thoughts as how to isolate the problem ? MARK Quote Link to post Share on other sites
Mick Forey Posted October 7, 2020 Report Share Posted October 7, 2020 Could be a bearing in the diff, I had a similar noise/vibration under load and a diff rebuild sorted it out. Have you checked the propshaft UJs? Mick Quote Link to post Share on other sites
JochemsTR Posted October 7, 2020 Report Share Posted October 7, 2020 Mark, has your propshaft been balanced? and check whether prophaft has a minimum of 15-20mm space to slide back and forth. Jochem Quote Link to post Share on other sites
DRD Posted October 7, 2020 Report Share Posted October 7, 2020 I had this, it was due to worn UJ's in the propshaft, ended up replacing it with a new one as the wear caused irreparable damage. Quote Link to post Share on other sites
Stagpowered Posted October 7, 2020 Report Share Posted October 7, 2020 I had this problem when I first had my TR which eventually knocked out one of the UJs . When I came to replace the UJ I realised the shaft had been assembled 1 spline out (prior to my ownership) so I re-assembled the shaft with the UJs aligned properly and the vibration disappeared and the UJs have lasted 70,000 miles since then. Neil Quote Link to post Share on other sites
Chilp3 Posted October 8, 2020 Report Share Posted October 8, 2020 Hi Mark, My 73 TR6 also has a vibration albeit at motorway speeds. It's more noticeable as you press on and then let the power off. However dipping the clutch suggests it's a balancing issue somewhere. The car is presently at TRGB and the next step will be for them to replace the prop-shaft and at the same time inspect the diff and bearings. The diff mounts have been recently strengthened with new standard bushes which will of course make everything more rigid. This may contribute to the vibration but hopefully it will be clearer when everything is off the car. I will post a further update in due course as potentially the findings from the team at TRGB might be helpful for you and your TR6. Best Regards, Peter Quote Link to post Share on other sites
Andy Moltu Posted October 8, 2020 Report Share Posted October 8, 2020 Check your universal joints. Things that were previously fine don't tend to go suddenly significantly out of balance but U/Js can and do wear out or seize. If in doubt replace. Whilst you have the shafts out feel the diff for bearing play or notchiness. Quote Link to post Share on other sites
alec Posted October 8, 2020 Report Share Posted October 8, 2020 I had this vibration problem at speeds approaching 70 the car is a 74 model & have owned for 34 years & as far as I can remember never had anything done to the rear wheel bearings / hub ect I had the opportunity to replace the hubs & drive shafts with the TRGB versions with CV joints although rather expensive the cured the vibration & make the car feel more positive in fast bends. Quote Link to post Share on other sites
MARK Posted October 8, 2020 Author Report Share Posted October 8, 2020 Looks like a careful check of transmission. I am going to check tyres and wheels first, then move onto driveshafts. Unless someone suggests something else. Thanks as ever for the words of wisdom and suggestions ! MARK Quote Link to post Share on other sites
stuart Posted October 8, 2020 Report Share Posted October 8, 2020 Bit of a long shot but have a look at the very rear of the diff and see what clearance there is to the front edge of the boot floor, I had one in here a few years ago that had similar noises and turned out the diff was just contacting and a little tweek with a tyre lever sorted it. Stuart. Quote Link to post Share on other sites
Chilp3 Posted November 2, 2020 Report Share Posted November 2, 2020 Hi Mark, Further to my earlier post regarding the vibration issue I am pleased to confirm that TRGB have now discovered the problem. Having changed the prop-shaft this made no discernible difference. The diff was then changed for a known sound unit previously rebuilt by Pete Cox. Following the test drive all traces of the previous vibration have now thankfully gone. We can only assume the problem was with a bearing or other diff related issue. We're now looking forward to collecting the car which has also now had the CV drive-shafts fitted. Hopefully the car should now be a lot smoother, we shall see. I hope that you successfully get your car sorted as this kind of problem can be hugely frustrating as well as ruining the driving experience of these great cars. Best Regards, Peter Quote Link to post Share on other sites
Robert Price Posted November 3, 2020 Report Share Posted November 3, 2020 The last TR6 I had also suffered the same symptoms, vibration under throttle, went away on overrun, it was the uj's on the propshaft. Took the prop off to Prop Tech and they fitted new GKN UJ's and balanced the prop. It would be my first check, it is easy to remove, good luck. Miss the tinkering during this lockdown, my Boxster is already well polished! Rob Quote Link to post Share on other sites
rcreweread Posted November 3, 2020 Report Share Posted November 3, 2020 Mark - if you find ultimately you may need to change your diff, I may be able to help out with a rebuilt one - have sent you a PM ( personal message - click on envelope icon in top RH corner of the forum page) Cheers Rich Quote Link to post Share on other sites
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