TR2/3/3A TR3 Trunnion - vertical link play

[Adrio]

Quick question (I hope).

If there is some play down where the trunnion meets the vertical link (I seem to be able to rock the trunnion about the longitudinal horizontal axis), would that be because of a worn trunnion or a worn vertical link or both?

Adrio

 

[TR3driver]

The trunnion is much softer metal, so the wear would almost certainly be in the trunnion casting threads (by design).

 

[Adrio]

that is good news. now for the suplimental questions. Are the reproductions available from the usual suspects any good or should I be shopping at some specialty place. AND, are the 3 degree caster ones worth is (I have never found it a problem with the originals but then again there is the play in the system I am trying to get rid of that may be affecting my opinion)

Adrio

 

[Andrew Mace]

The trunnion is much softer metal, so the wear would almost certainly be in the trunnion casting threads (by design).

However....

If these are anything like the "small car" (Herald, Spitfire, etc.) vertical links, lack of maintenance -- read: lack of lubrication over time -- can lead to some pretty significant damage to the threads on the vertical link as well. In other words, as you prepare to renew the trunnion, take a very close look at the vertical link for any damage or even possible cracking of the link. Again, I don't know if it's common with the TR series, but the small car vertical links are prone to breaking off at the top of the threaded portion if the lack of lubrication is allowed to go on too long. I've also seen severely rusted thread areas on Spitfires, again due to lack of lubrication.

 

[TR3driver]

Certainly worth inspecting the area, as I have seen vertical links that were damaged by rust badly enough that I refused to use them. But the TR links are pretty beefy, I've not heard of one breaking. Generally the hubs & stub axles break first :laugh:

Possibly not relevant today, but I was unhappy with the TR3 trunnions I got from Moss many years ago. The plate at the bottom was staked so poorly that it leaked, and I couldn't force grease through the threads when lubing them. I was able to improve them a bit on the car, but couldn't solve the leak entirely. They also were not drilled for cotter pins as the originals were; and for some reason were cut for the metal "shims" used on the later trunnions (next to the sealing rings).

If you do want to implement the 3 degrees of caster, there are a lot more components to change than just the trunnions. Upper A-arms are different, as are the upper ball joints and steering arms. Some people do like the result (including the increased steering effort), but I've never tried it myself (even though I have all the parts somewhere).

 

[CJD]

I agree with the quality issues Randall is talking about. I went through 4 iterations with Moss to get 2 trunnions I was happy with. They were nice working with me, but the quality was terrible. One was drilled and tapped crooked, one would not screw on the vertical link, one was more loose than my worn out one. I settled on one good looking one, and the other fit well but had the grease cup issues reffered to.

John

 

[TR4nut]

I've been running with trunnions from the Roadster Factory now for about 4 years on my TR4, and so far, so good. They also drill the pins in the trunnion so you can use cotter pins and castle nuts as original. Not sure if the Moss versions have that feature.

I have installed the 3 degree castor versions on my 3A project, but I'm contemplating reverting completely to original. That was after driving a friends TR3A and I found the lack of castor to not be a problem. Randall is right, you have to replace upper arms, balljoints at a minimum to make this change.

 

[CJD]

TRF was back ordered last fall, so I didn't get to try them. The moss were not drilled, but use nyloc nuts instead. I tried to drill them, but they were hard as rock...no luck with a drill. That should be good for wear, though.

John

 

[toysrrus]

Howdy Folks,

I`m ready to "Re-Assemble" my Front Suspension. I`m down to the "Trunnions" and was wondering if there is anyone who "Rebuilds" them?

What is the "Tolerance" (Fit) between the "Stl. Bushing & Sub-Axles" on the Trunnions? How critical is the that?

I have "Everything" either "New or Refurbished" on the entire suspension.

Also; Is there an "Cross-Sectional View" of a Trunnion anywhere?

Thanx in Advance,

Russ

 

[Twosheds]

Also; Is there an "Cross-Sectional View" of a Trunnion anywhere?

Thanx in Advance,

Russ

Page 228 - 229 of your Bentley.

Also a bigger section on page 240.

 

[TR3driver]

I`m ready to "Re-Assemble" my Front Suspension. I`m down to the "Trunnions" and was wondering if there is anyone who "Rebuilds" them?

In a sense, yes. To "rebuild" one, you have to replace every component. This is called "new", but the effect is the same.

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]What is the "Tolerance" (Fit) between the "Stl. Bushing & Sub-Axles" on the Trunnions? How critical is the that?[/QUOTE]
I don't recall the clearance offhand, but it is built into the pin. Just ream the bushing to size using a standard fixed reamer (5/8" IIRC).