TonyC Posted October 19, 2012 Report Share Posted October 19, 2012 The TR6 diff mounts as we know are compromised through the original design, but having upgraded to polybush mounts in an effort to solve a 'rear end clunk' I notice that even now there is still possibility for diff movement. Consider the rear mounts - the issue is the amount of clearance between the chassis stud (OD 0.5580") and the sleeve (ID 0.6335) which fits over the stud and carries the assembled polybushes and mounting plate. This clearance of 75 thou (1.9 mmm) - known in engineering terms as a 'horses collar fit', must surely give rise to 'noise and movement' when 150 bhp is delivered to the diff. Question: has anyone out there either shimmed the stud or better still replaced the sleeve with reduced internal diameter - say 0.560 - 0.565 and if so with what results? TonyC Quote Link to post Share on other sites
AlanT Posted October 20, 2012 Report Share Posted October 20, 2012 Do you know for sure that you don't have a crack through the metal bracket that holds the rubbers. Two out of four of mine were broken. But its really hard to see with the diff in. Al. Quote Link to post Share on other sites
TonyC Posted October 21, 2012 Author Report Share Posted October 21, 2012 Hi Al, yes diff mounts are solid and no signs of cracking / corrosion, and have been reinforced. The poly bush upgrade has made a huge difference but still there is a slight clunk on initial reverse after forward motion and initial forward motion after reversing. Clearly some movement somewhere and that massive clearance between stud and sleeve is a sensible suspect. Thanks, tony Quote Link to post Share on other sites
smizgals Posted October 22, 2012 Report Share Posted October 22, 2012 (edited) Hi Al, yes diff mounts are solid and no signs of cracking / corrosion, and have been reinforced. The poly bush upgrade has made a huge difference but still there is a slight clunk on initial reverse after forward motion and initial forward motion after reversing. Clearly some movement somewhere and that massive clearance between stud and sleeve is a sensible suspect. Thanks, tony Tony, I had exactly the same after polybush upgrade and failed to find the cause for a long time. On a suggestion here checked the front ones to find that they had different heights. Stan Edited October 22, 2012 by smizgals Quote Link to post Share on other sites
Damson6 Posted October 22, 2012 Report Share Posted October 22, 2012 (edited) Have you got the wrong bushes as it seems a large tolerance! Did you use copper slip or thick grease when assembling bushes? If the diff mounts are good usual reason for clunks are the drive shafts or U/J's (including propshaft). Also how much backlash has the diff got? If these are fine one other thing it may be is a slack brake adjuster to backplate. Check by putting on handbrake and then rocking wheel. Cheers Derek Edited October 22, 2012 by Damson6 Quote Link to post Share on other sites
jerrytr5 Posted October 23, 2012 Report Share Posted October 23, 2012 Or it could be the front diff plate starting to fracture..... Jerry Quote Link to post Share on other sites
BlueTR3A-5EKT Posted October 29, 2012 Report Share Posted October 29, 2012 (edited) Or it could be the front diff plate starting to fracture..... Jerry I'd second that... Or the 4 bolts that hold it to the axle case not tight enough - some one changed the nose seal and forgot to re-tighten the bolts after removing the washers to get the seal through. - Trade trick is to peen the edge of the washers to allow the seal past...... Peter W Edited October 29, 2012 by BlueTR3A-5EKT Quote Link to post Share on other sites
TonyC Posted November 12, 2012 Author Report Share Posted November 12, 2012 Thanks to all for input advice and experiences. I have now made a couple of new sleeves to replace existing from the poly bush kit. Clearance between stud and sleeve is now circa 4 thou. The overall length of the sleeve was also reduced by around 30 thou to allow some compression of poly bushes on final installation. I am now confident that there is no diff movement outside that afforded by the poly bushes themselves. Sleeve to stud assembly included liberal use of silicone grease. Unfortunately the modified sleeves were made from mild steel so will be subject to corrosion so stainless versions are planned over the winter. It will be interesting to examine the mod again after some use. If anyone wants the relevant dimensions of the existing and modified parts send me an email and I will be happy to send you the drawings. TonyC Quote Link to post Share on other sites
roulli Posted November 12, 2012 Report Share Posted November 12, 2012 Hi Toni, Have you tried allready if the the "clonks" are gone, now after you have shimmed the mounts? Regards Patrick Quote Link to post Share on other sites
Martti Ojanen Posted November 19, 2012 Report Share Posted November 19, 2012 For your infromation: www.tr-nord.de sells "Drehmoment-Stütze" alias Torque Arm to restrict diff movement. See http://www.tr-nord.de/portal/alias__Rainbow/lang__de/tabID__64/DesktopDefault.aspx! This is Babel Fish translation: "Torque arm for TR 4A - 6 order. No. KA 105spt The motor force affects the recording points through the differential the diff.-bridges. Here it comes to cracks and fractures. To strengthen this area, we have a Torque arm is manufactured. It is attached under the front right diff.-holder, the counterpart is attached to body frame and welded at the 4 corners." I myself have this part and plan to install it this winter. Martti Quote Link to post Share on other sites
stuart Posted November 19, 2012 Report Share Posted November 19, 2012 That would work but if the diff mounts are properly re-enforced in the first place then you shouldnt need it. Stuart. Quote Link to post Share on other sites
RogerH Posted November 19, 2012 Report Share Posted November 19, 2012 I think it is brilliant in that these cars are 40/50 years old and people put the effort in to invent/design/construct new gadgets/solutions/things to improve them. Long may it last. Roger Quote Link to post Share on other sites
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