TR4/4A TR4 front end rebuild - trunnion bushing question

[TR4nut]

Hello-

Well its beautiful weather here today, but instead of driving I am in the middle of the front end rebuild on my TR4. I have one side disassembled completely and I've been inspecting various pieces. A problem I have is that I see that there is significant play between the trunnion and the lower wishbone due to worn wishbone arm bushes.

I have replacements bushes in hand - I was considering trying to do this myself but a very preliminary attempt to press the old bush out failed - I didn't try too hard, but these bushes are much tighter than the inner nylon ones.

Is this a job for a machine shop? My kit was bought from TRF, Moss notes in their catalog that the bushes have to be reamed to fit after installation anyway. I'm about to get the yellow pages out to look for a shop, but if anyone has done this on their own, please let me know. In particular, I'd like to know how to:

1) Press the old bushes out. Normally I use a vice and two sockets, works great for the nylon ones.
2) How to ream to fit. I was considering just patiently working the trunnion in with ample lubrication as the fit is close unpressed.
3) If I shouldn't do this, I'll take recommendations on a shop in the Houston TX area.

Thanks,
Randy.

 

[Alan_Myers]

Hi Randy,

I don't know your skill levels with this sort of work, so would have to say that, yes, it's generally a job for a machine shop.

The old bushings need to be pressed out, the new ones pressed in with the grease holes aligned properly and then the bushings are squarely reamed to the correct size (shop will also need the trunnions in order to measure for size). Fit is close with no play.

That said, shop around. I had to get one side done in a hurry and took the arms and trunnion to a local store that usually is a good place for services. They work with a number of machine shops, so seemed a likely source since I needed the job done right away.

Turned out it wasn't a good source. None of their shops were very knowledgeable about this kind of work and the first quote was $160 ($80 apiece to press and ream two bushings!) *and* they asked if they could just run a drill bit through there!

We finally got someone to agree upon $40 apiece, which I felt was still quite ridiculous but I needed the job done, and they agreed to hone the bushing, not drill it.

In the end, I still waited over a week. One arm came back perfect, the other was a bit over-reamed and IMHO has a bit more play than it should being freshly re-bushed.

The moral of this story is to shop around for a machinist. I'd look for someone "experienced" with older style suspensions and not just some young kid who installs modern kits per the instructions.

The job for all four should be an hour's work at the local shop rate and you are supplying the parts. So, watch out for ridiculous price quotes and don't trust anyone who asks to use experimental methods sizing those bushings!

Next time I think I will just bite the bullet and buy a set of adjustable reamers to do it myself. But that will be a learning experience so I can't give you "how-to" guidance or warn you of any pitfalls in the process.

It *seems* very doable and easy, the hardest part might be finding the reamers and buying them (pricey!). If you feel like giving it a try, Harbor Freight has a set of adjustable reamers that run $70, but I still need to check if they have the right size for this job. Eastwoood has a set for $100 that does appear to have the right size.

An alternative is to get a set of pre-sized bushings from RevingtonTR, pay the ovreseas shipping and wait for them to arrive from England. No reaming required. I haven't used these, but I would think that to use these bushings you'd need trunnions with little or no wear and tear (the ones on my TR4 are new, so would qualify).

Another option would be to just install trunnions from TR4A or later which use the large bolt instead of the pressed-in horizontal pin, and use sleeved nylon bushings which are easily fitted, no reaming required. I suspect these would need service more often, but that it would be more easily done. It would be "non-original", if that's important.

Hope this helps!

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[TR4nut]

Alan-

Good note, thanks. I'm going to try to do this myself, at least the bush removal and refit. I figure I can't screw up the removal that badly if I take my time, and I have pressed in bushes before (knock on wood).

As to reaming, I ordered a basic reaming bit (5/8") and may attempt reaming if it looks like it will be easy to do on a drill press.

I wasn't sure on the 4a trunnions being compatible with the TR4 suspension geometry - wish I knew about it before I ordered my TR4 replacement trunnions which are staring at me right now - it would have made it a lot easier.

Randy.

 

[Alan_Myers]

Hi again Randy,

I've personally not done the conversion from TR4 to TR4A setup, but have often heard of it being done and it appears pretty straight forward.

Only the very early TR4 had the 0 caster setup that would be more involved to modify. Both your and my TR4 are later, with 3 degree caster, so most parts are very similar to 4A.

- The trunnions themselves are different, of course.
- And there is the large pivot bolt used, along with it's nut.
- Plus the nylon bushings themselves and some associated seals, shields, washers and distance pieces.
- Besides that, there might be some slight mods to the lower control arms (they have different part numbers from TR4... but that might also be due to the different inboard mounts which don't concern us here).

Overall, it looks pretty straight forward to make the conversion and I might try it next time my car needs a rebuild. (Don't hold your breath... the car was 40 years old the first time it had its trunnions replaced!)

Let us know how the pressing and reaming works out. Sounds doable.

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