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TR2/3/3A tr3 trunions

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sp53

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Has anybody heard of a supplier who sells just the shackle pin of the trunion. I was reading in an old book that said, “Make sure that you center the shackle pin when you hook up the lower wishbones.” After reading that, I took an old trunion, put a bolt on the end of the shackle, and drove the pin out with a sludge hammer. I know I am cheep; I blame my Scottish heritage, but I do not trust the after market stuff. Besides the old ones, look cooler and they do not look that much worse for wear other than the shaft. I wonder if that was a part you could buy years ago. In the day, I was so poor that I got all my parts at the junk yard. It has only been the last couple of years that I have been buying parts from the suppliers.

sp53
 
Hi again,

Hey, I have a lot of Scot in me, too... So I fully understand!

It's an interesting question. You are asking about part #101557 "Trunnion assembly", per the TR2/3 factory spare parts catalog. It appears Triumph themselves didn't offer the horizontal pin as a separate item. TRF offers #101557 TR2/3 "Trunnion assembly" for $90 each.

I suspect what is meant in the repair manual by "centralizing" may not refer to replacing the pin but means to be sure to arrange the thrust washers on either side evenly, so that the trunnion is neatly centered between the lower a-arms (aka wishbones). A mismatch would effect the built-in caster, and might possibly cause binding and strain on the vertical link/steering.

The pin is pressed into the brass trunnion, so might be replaceable, but I'd think twice about doing that even if you could buy the horizontal pin separately. I would guess there is a heating process during assembly, along with pressing it into place with a high degree of accuracy. Also, the acme threaded portion of the trunnion that serves as the steering pivot (along with the vertical link) can wear, too, right along with the horizontal pin.

In fact, by the time of the TR4A, the pin in the trunnion had been replaced with a large and easily replaced bolt. It's just possible that bolt could be made to work with the earlier trunnions, after their horizontal pin were removed (which would probably better done with a shop press than a sledge hammer!). However, I really have never seen or heard of this being done and can't say if it would work. I don't have the parts to compare if the TR4A-6 replaceable bolt is the same diameter as the TR2-4 pressed-in pin. The bolt is #139835 ($8.50 at TRF), if you want to give it a try. Note that if the bolt is used, the bushings in the outer end of the a-arms are different, too. They are white nylon with steel sleeves, most similar to what's used on the *inner*/ lower a-arms on all TRs, rather than the bronze hone-to-fit bushings used on the outer/lower end of a-arms on the earlier cars. There might be some other part differences, too. (The trunnions themselves were changed in early TR4, to 3 degrees of camber, but that shouldn't matter in terms of replacing the pivot pin.)

Another possible alternative for us Scots, maybe there is a machining process that could be used to carefully and accurately "clean up" a lightly scored horizontal pin. If there were, the new bushings that are pressed into ends of the a-arm are sold oversize and always need to be honed for a precise fit, and so might just be honed a little less to compensate for taking a skim off the pin and reducing its diameter slightly. But, this all assumes that there's just a little wear on the pin *and* that some accurate machining could be done to correct it. And, will reducing the diameter of the horizontal pin weaken it? Will machining it remove temper that's important for strength? I dunno.

Experimenting with these ideas would probably cost lots more than just buying a new assembly! So, I'm afraid I'd be inclined to just get a pair of new trunnion assemblies and not try to refurbish the old ones. But, if you do decide to try something "Scottish", let us know if it works out. Heck, I'm sure I've got a couple old trunnions stashed away that might turn out to be rebuildable too!

/ubbthreads/images/graemlins/cheers.gif
 
I seeem to remember someone placing a speedi-sleeve over the pin at each side. The bushings in the control arm will have to be reamed. I don' t know what the disadvantages of this method.
 
[ QUOTE ]
I seeem to remember someone placing a speedi-sleeve over the pin at each side. The bushings in the control arm will have to be reamed. I don' t know what the disadvantages of this method.

[/ QUOTE ]

Great idea! My only concern would be that the speedi-sleeve be a tight fit and not start turning on the pin, itself. That would wear pretty badly. If it can be kept from turning, that would work great and would even allow reusing existing, somewhat worn bushings... a very "Scottish" suggestion! /ubbthreads/images/graemlins/cool.gif
 
All this discussion on "Scottishness" makes me smile.
I suggest that cheapness is more of a Triumphishness characteristic or heck even more likely it's an LBC trait.
Let's be realistic, if we weren't all cheap we'd likely be driving around in Boxsters and such.
Sorry, I've just come to my senses, modern cars don't have the charisma and sheer cussedness to attract this crowd at any price. /ubbthreads/images/graemlins/wink.gif
 
As some of you have surmised, the sleeve technique does indeed work. The guy who built my race car was a first class tool and die man and did just that (in the 70's). He would press out the pin on his monster arbor press, turn it down and press on the sleeves using I believe some sort of epoxy for good measure. He had a mechanical engineer racing buddy, who concluded that it could be done, safely that is. I've rebuilt the front on each car at least once and only had to renew the A arm bushings. Can't remember how thick the sleeves are or what the hardness was, etc., and don't know if I have a set laying around anywhere to measure. The point is, it can be done.
Tom Lains
 
I just completed rebuilding mine on my TR3 by using some 5/8 fine thread grade 8 bolts. If you want photos I could take them and send them off line. I have not installed them back onto the vehicle yet. I was doing that this week.
 
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