Trunnion torque.

[trrdster2000]

Hi all,
It's been a while but getting ready to replace the seals and plastic bushing on the TR6 trunnions on the rust bucket my buddy got a month or so ago. I generally tighten the nut until it looks like the top seals are just before getting ready to crush and put the split pin in. I can find no torque setting for the application and just wonder if I have been doing it wrong all these years. I do know I will be using the copper non seize on all parts, found this stuff working on BMW's with all the aluminum parts that want to oxidize together.
Any help greatly appreciated.

Wayne

 

[Darrell_Walker]

50-65 ft-lbs.

 

[trrdster2000]

Darrell, I see and just don't see!! If I do torque this to say just 55 lbs, what is going to happen to the thin cups with a small rubber seal/washer inside. The movement inside the trunnion is restricted by just snogging up. I'm really relating to a wheel bearing type torque as it seems to me the stress would be in the up and down motion or towards the rear of the "A" arm.
I know I must be over thinking this, it's just been a while and that torque just gave me food for thought.

Regards, Wayne

PS OK, I'm guessing the solid sleeve allows this torque and prevents the seals from being crushed. DUH.

 

[JerryVV]

The friction surface of this assembly is the large washer against the nylon bushes on either side of the wishbones. There should be no movement of the long bolt inside the trunnion.You need the 55# to assure that.

 

[Darrell_Walker]

It's been a while since I did mine last, but as I recall the rubber seal goes around the outside "brim" of the nylon bushing, filling the space between it and the thin metal cup. The washer might compress the rubber seal a bit, which I think is to keep moisture from between the inner surfaces.

 

[KVH]

Without the benefit of my Manual, I recall raising this issue years ago, and being told that 55 LBS was too much. Somewhere I seem to recall someone producing an article showing a much lower recommended torque. My concern was like Wayne's.

 

[Darrell_Walker]

For some reason the page appears to have shrunk, here is hopefully a bigger version.

 

[mgNOT]

I believe the trunnion bolt is meant to clamp the two outside washers, the "ferrules", or distance pieces, and the trunnion itself. I believe there should be no movement between the trunnion and the bolt, as this would possibly wear the bolt, causing a stress area and possible breakage. You should see the trunnion and bolt move as one. I have nylatron in the uppers and lower arms, and can raise and lower the entire suspension (minus spring) with one hand. You can't do that with rubber upper and/or lower bushings however. Remember for rubber pivot bushings, they are tightened at ride height only. They are the same, clamp the metal sleeve so it doesn't turn.
Dennis

 

[Darrell_Walker]

It actually wears the brass trunnion if you don't torque correctly. I followed the TR4 instructions (5 ft-lbs, back off a flat), and had that problem. While the TR4A front suspension is nearly identical to the TR6, the factory manual for the TR4A (which is just a supplement to the TR4 manual) doesn't mention any difference. And those trunnions are not cheap!

 

[JerryVV]

I'm doing a rebuild on my 4A currently and asked these same general questions. My opinion and confirmed by several others is to follow the TR6 instructions and clamp at 55 + pounds. Darrell and I corresponded as well and his experience supports clamping to the TR6 specs.

 

[trrdster2000]

It will be the TR6 specs I use and thanks to all who gave some input.
I must have been getting the early cars confused with the later TR6, can't seem to shake this age thing.

Wayne

 

[KVH]

Fifty (and certainly 55) foot lbs is excessive on a TR4A, and for what is involved here. There should be play and end float. Not sure how to explain the differences of opinion here unless I'm not understanding the question or the TR6 setup is different in some manner, but the TR4/4A Manual says: "The outer fulcrum bosses must have . . . . end float. This is obtained by tightening both slotted nuts to a torque of 5 lbs . . . ; then slackening the slotted nuts 1 to 2 flats before inserting split pins."

 

[Darrell_Walker]

Fifty (and certainly 55) foot lbs is excessive on a TR4A, and for what is involved here. There should be play and end float. Not sure how to explain the differences of opinion here unless I'm not understanding the question, but the Manual says: "The outer fulcrum bosses must have . . . . end float. This is obtained by tightening both slotted nuts to a torque of 5 lbs . . . ; then slackening the slotted nuts 1 to 2 flats before inserting split pins."

Yes, but note that the TR4 is quite different in that area (more like the TR3), and Triumph didn't write a TR4A manual, they just provided updates to the TR4 manual. And the updates don't mention the from suspension. On the other hand, the TR4A front suspension is identical the TR6.

 

[KVH]

OK, but the updates are in the Manual, and show the TR4A suspension, and the difference between 5 and 55 when compressing rubber and thin steel spacers and nylon washers seems unrealistically huge to suppose they just forgot to give a new spec--and this is a component that must move properly. I called Moss Tech Support when I installed my new kit about 6 years ago and I know the torque suggested was nowhere near 55. I may call again so I get a comfort level on this--I just repaired one side and torqued nowhere near 55.

 

[JerryVV]

Ask yourself this question. If the 4A front trunnion is identical to the TR6 system and not identical to the TR3 and Tr4 system should I follow the instructions for the TR 6 or the TR4? I think the answer is obvious. That's my deductive reasoning on the subject. That plus the obvious differences in the design of the trunnions and the through bolt.

 

[KVH]

Yes, we're missing posts here. Just to update, I spoke to Moss and to my local mechanic, and the consensus seems to be to match the TR6 torque.

I just disassembled my passenger side which, 25K miles ago, I had torqued to about 15 lbs. My parts all seem fine with no odd wear, but I'll almost certainly reassemble with 55 lbs of torque. I still wonder about that, but if that TR6 spec isn't wrong it seems the 4A must match it. Even the repair kits for the TR6 and TR4A are the same.

The completely different system must explain it. The pivot bolt for the 4A probably leaves enough play since the movement would be uniform around that bolt, whereas with the TR4 any differences, or even any "binding up," could cause possible issues from each side of the trunnion, making end float on each side an important consideration. Anyway, too much over-thinking. I find nothing indicating that the TR4 torque has any relevance, and the consensus seems to be 55 to 60. I'll try it and see how it fares.

 

[trrdster2000]

Thanks to all concerned and I hope this will clear up a issue that has been in question for not only me but apparently many who work on these cars as professional or enthusiastic hobbyist.
Sometimes it pays to question yourself.

Wayne