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Moss trunnion short one rotation

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Moss trunnion short one rotation
#1
  This topic is about my 1964 Triumph TR4
abhlott Avatar
abhlott Silver Member Terry Ledden
Ottawa, ON, Canada   CAN
Installing a new replacement (moss) trunnion and it seems to be short by one rotation. When fully seated on the bottom threaded shaft of the upright, the steering lock stop barely makes contact. The trunnion binds up if i raise any further. Could this be a defective unit? Also noticed there are no part numbers on them. Came in a labelled plastic ziplock bag from moss. See pic.



Previous experience:
1962 TR4
1960 TR3
1972 TR6 w/ OD & Hard top
1971 GT6
1976 TR7
1974 TR6 V8 Chev 383

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Britnut Avatar
Britnut Randy DeRuiter
Nacogdoches, TX, USA   USA
I hate to bring potentially bad news - but look at the threaded section carefully. The symptom you describe is common for a bent upright. The old trunnion may not show it because it’s worn out enough to accommodate. If you carefully rotate and watch the upper hole you may see a wobble. Or fingers crossed it’s a bad trunnion and you should get your money back

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abhlott Avatar
abhlott Silver Member Terry Ledden
Ottawa, ON, Canada   CAN
Actually a bent upright could be the root cause of a couple of other conditions. In checking camber before disassembly that particular wheel read neg 2.5 while the passenger side read pos 1.5. Turning right, the steering would not come back to center by itself, but turning left would recenter on corner exit. Also have a pretty ugly shake that comes on at about 65mph, no fun. All the above, and looking for about a neg 1.5 - neg 2.0 camber is what prompted the front end rebuild.

Whn i turn the trunnion through its range of rotation, it “tilts” or leans frm one side to the other. When i compare left and right, the other trunnion - upright does the same. Is that what you mean by wobble? Could,both uprghts be bad?



Previous experience:
1962 TR4
1960 TR3
1972 TR6 w/ OD & Hard top
1971 GT6
1976 TR7
1974 TR6 V8 Chev 383

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Britnut Avatar
Britnut Randy DeRuiter
Nacogdoches, TX, USA   USA
The axis of the threaded section goes right through the center of that upper hole - so when you turn you should see the hole turn but not lean much either way. Some movement is pretty common as these links are pretty weak. On the one I replaced you could actually see the bend in the threaded section near the top.

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abhlott Avatar
abhlott Silver Member Terry Ledden
Ottawa, ON, Canada   CAN
I’m looking at a couple on ebay for about $75 ea for 4A - 6. Ive got a 64 late tr4 with 3 deg castor. Moss only show one for tr4 (not handed) so im thinking i need the handed L/R fitment for the 4A?



Previous experience:
1962 TR4
1960 TR3
1972 TR6 w/ OD & Hard top
1971 GT6
1976 TR7
1974 TR6 V8 Chev 383

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Britnut Avatar
Britnut Randy DeRuiter
Nacogdoches, TX, USA   USA
No for a late tr4 you need a link for a Tr3-4, they weren’t handed. The castor was built into the handed trunnions for late 4s. People have used 4a-6 uprights but it lowers the front suspension. Also you would need 4a-6 trunnions and a few other pieces. If you want to see a racer writeup google Tony Drews. He has a nice writeup for his TR 4 vintage racer.

Edit: found his writeup. Kind of a side topic but pretty interesting I think to see the design change on those uprights.

http://www.tonydrews.com/Front_Suspension/tr4_front_suspension_upgrade.htm



Edited 3 time(s). Last edit at 2019-02-23 08:18 AM by Britnut.

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abhlott Avatar
abhlott Silver Member Terry Ledden
Ottawa, ON, Canada   CAN
Thanks for the Tony Drew link. I had seen that article and bookmarked it in my triumph folder. Of course reading again now after i’ve taken the front end apart and reassembled a few times, i understand it. So today, i ordered used tr6 assembled suspensions less the rotors. Comes with sway bar brackets (bonus) trunnions, spring pans etc. Not building a concours car. This is to be a street legal track car for lapping days.



Previous experience:
1962 TR4
1960 TR3
1972 TR6 w/ OD & Hard top
1971 GT6
1976 TR7
1974 TR6 V8 Chev 383

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