p7rider Posted March 31, 2021 Report Share Posted March 31, 2021 Went to fit a trunnion kit on my rear suspension rebuild. I'd had the kit a few years but never checked it. When I fitted it the plastic bushes, they were loose in the hub. I measured them and they are 0.020" under size. So about 10 times the play of the old ones I removed. So today a turned a new set from a material called Acetal , this is made for bushings among other things. I have a nice push in fit in the hub but the sleeves were a bit too tight once the bushes were fitted. I had some old sleeves which are a smaller diameter and these went in , but with some play. So the sleeves are a nominal 9/16 diameter but mine were either .004" over or under size. Exactly 9/16 will be good. Also all of them are too short. I calculated the tube length to be 1.990". this then will be the same length as the hub plus to bush heads each 1/16" plus 0.010" for the seal shims. So before I go ahead I want to be sure that when tightened up the vertical link should clamp the spacer tube not the bushes? I found some interesting notes and drawings on another site which confirm my thoughts. Although they allowed some clearance , so their tube length was 1.995". Hopefully I've attached their excellent drawing. Spitfire Rear Trunnion Dimensional Analysis.pdf Link to comment Share on other sites More sharing options...
p7rider Posted March 31, 2021 Author Report Share Posted March 31, 2021 1 Link to comment Share on other sites More sharing options...
johny Posted March 31, 2021 Report Share Posted March 31, 2021 Yes essential the total thickness of the sleeve and two outer seal shields is slightly more than the width of the trunnion housing with bushes fitted. Must admit Im impressed with the tolerances youre working to! Link to comment Share on other sites More sharing options...
PeteH Posted April 1, 2021 Report Share Posted April 1, 2021 It`s (quite) a while since I did them on the 13/60, so bear with me. But I seem to recall having to "spread" the Wishbone very slightly to get the Sleeve into place?. I am assuming, (none of the manual`s/advises confirm), that the sleeve is "hardened up" and the bushes rotate on the sleeve, NOT (the sleeve) on the bolt? (which IMV would be pointless?). Pete Link to comment Share on other sites More sharing options...
p7rider Posted April 1, 2021 Author Report Share Posted April 1, 2021 Thanks for replies . Worked out tube length again . Dust shields are .020" thick . So tube length I've used is 1.980" Link to comment Share on other sites More sharing options...
Colin Lindsay Posted April 1, 2021 Report Share Posted April 1, 2021 I've just tried the polybushes for the first time; certainly a lot simpler than juggling shields and rubber seals. Only time will tell how they perform (could be a lot of time, the body isn't on yet...) https://www.jamespaddock.co.uk/rear-trunion-bush-kit-axle-set-polyurethane Incidentally the old bushes weren't wasted; they went on either side of a wheelbarrow axle and stopped the most annoying squeaking... 2 Link to comment Share on other sites More sharing options...
Pete Lewis Posted April 1, 2021 Report Share Posted April 1, 2021 just to firm up yes the tube is clamped by the upright and the bushes rotate on the tube never a loose tube to rotate on the bolt or the holes in the arm Pete Link to comment Share on other sites More sharing options...
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