Peter Vernon Posted August 7, 2008 Report Share Posted August 7, 2008 Having run the gauntlet this year my TR6 car failed the MOT for the first time in twelve years, not a bad run but the ball joint along with a new windscreen wiper will be on the car tonight and normal service will be resumed. An advisory note was issued by the tester indicating a knock from the rear of the car on braking, no play in rear suspension etc. I noticed this knock last year on take-up after reversing or reversing after moving forward. I thought it was diff backlash so had the diff rebuilt to go with the new driveshafts and new chassis. However it is still evident and as the MOT Boy Scout has noticed it and in an effort to foil him in the future I want it fixed. I am not one for giving the MOT man any excuse to fail the car in the future. One thing though, what the heck is causing the knock? Propshaft UJ's spring to mind but before I remove the exhaust etc to get at the propshaft has anyone any other ideas? Just for info the chassis is completely rebuilt, driveshafts are the GKN type with only one UJ per side, all UJ's on the driveshafts are newish. Any help appreciated. Quote Link to post Share on other sites
88V8 Posted August 7, 2008 Report Share Posted August 7, 2008 I noticed this knock last year on take-up after reversing or reversing after moving forward.One thing though, what the heck is causing the knock? Propshaft UJ's spring to mind but before I remove the exhaust etc to get at the propshaft has anyone any other ideas? I think you have to take the diff out to get at the propshaft, and if the ujs were going I'd expect to notice it in engine-speed vibration before it reached the clonk stage. So it's a knock not a click - not the driveshaft click. Chassis rebuilt so not the diff mountings. I suppose the bolts holding the driveshaft flanges onto the diff are tight? What wheels do you have? If wires, could be loose on the splines. Ivor Quote Link to post Share on other sites
stuart Posted August 7, 2008 Report Share Posted August 7, 2008 Or the splined hub adaptor nuts working loose. Stuart Quote Link to post Share on other sites
Kiwifrog Posted August 7, 2008 Report Share Posted August 7, 2008 Or the splined hub adaptor nuts working loose.Stuart Or the splines themselves being worn, had this problem on a TR4A I had a few years ago Alan Quote Link to post Share on other sites
88V8 Posted August 8, 2008 Report Share Posted August 8, 2008 Or the splines themselves being worn, had this problem on a TR4A I had a few years ago Yes and I had this on an MGC. On the back, due to the constant torque reversal, the hub splines wear and so do the wheel centre splines, in the end even if they're done up tight you still get the clonk. If the front wheels have always been on the front, and the backs always on the back, you may be able to confirm this by swapping them. If the clonk is gone or less, you'll know that's the cause. Having done that, I would then put the fronts back on the front, because by leaving them on the worn back hubs you'll soon knacker the fronts as well. The good news is that there's no rush to replace the wheels and hubs as I don't think they represent any sort of risk, and they're already scrap. Perhaps you could get the spokes and rims rebuilt onto new centres, have heard mixed report of this... Of course if you don't have wires, we're all heading off on a wild goose chase... Ivor Quote Link to post Share on other sites
Les Pettitt Posted August 8, 2008 Report Share Posted August 8, 2008 Hi Peter, I put up with a knock for 18 years. I had the diff rebuilt and replaced all the uj's but still it knocked. By the merest chance the son of my company mechanic noticed the cause of the problem as it was being reversed off a ramp. The diff was hitting the chassis because the metal insert in one of the diff mounting rubbers had become detached from the rubber allowing the diff to move up and down. I am embarrassed to say that I removed and replaced the diff and didn't think to check the integrity of the mounting bushes. Worth a check if you haven't replaced them recently. Regards Les Quote Link to post Share on other sites
TR6 Poor Posted August 10, 2008 Report Share Posted August 10, 2008 Put the handbrake on just so it drags a little, and drive forward and backwards, I bet you don't hear the clunk. Could this mean it is in the backing plates where the wheel cylinder goes thru the backing plate? Let me know please what your results are. Cheers Quote Link to post Share on other sites
Peter Vernon Posted August 10, 2008 Author Report Share Posted August 10, 2008 Put the handbrake on just so it drags a little, and drive forward and backwards, I bet you don't hear the clunk. Could this mean it is in the backing plates where the wheel cylinder goes thru the backing plate? Let me know please what your results are. Cheers As soon as it stops raining and I have put the fuel pump on I will try it and let you know. Wretched Bosch pump from well known supplier, (like a growth in your lawn) put a kit together with a pump that was not man enough (5 bar/ 70psi and flow rate too low) and mine is giving up the ghost making a grinding noise, I am changing it before it goes all together. Peter Quote Link to post Share on other sites
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