TR4/4A Early TR4 - Front Suspension Trunnions

[TRDejaVu]

Three questions in a day - this is sad. I know that I have seen this question before, but it's been a long day and I can't find it.

I am replacing the front suspension trunnions (3 degree version) with Moss ones. They screw on nice until about 1/2 inch from the end of the vertical link then they bind up. By the time that they are at the bottom, they are very hard to turn. The old ones were nice and smooth all the way down. Any suggestions?

Also, once I am past that (hopefully), how do you adjust the steering lock stop as it is offset?

Yet again, thanks.

 

[TR6oldtimer]

Awhile back I replaced my trunnions with a set from TRF and a vertical link from Moss on a 6. They too were snug. Prior to assembly, I buffed the vertical link with crocus cloth to remove old gum and deposits. I also found the new trunnions had milling burrs on the treads. With oil, I assembled, rotated, and disassembled. Each time cleaning the debris from the inside. After three or four times, they turned freely and clean.

"how do you adjust the steering lock stop as it is offset?"
Not sure what you mean here. Once the vertical link, with seal, is fully inserted in the trunnion, I backed it off just enough to install the stop, insuring the link rotated without binding from stop to stop.

 

[Harry_Ward]

Ian,

Still learning how this works read next post first.

I'm also not sure if the vertical link and lower trunnion should be replaced as a set but I remember reading that somewhere (This may be your problem).

Otherwise,

It's been about twelve years since I did this job but you may want to check and see that you did not over - tighten the bottom trunnion mounting nuts. The bottom trunnion should be equally tightened on both ends to the lower wishbone arms. The lower trunnion should move freely with the vertical link removed. If the bushings of the bottom trunnion are too tight it will affect the vertical link. If you installed new bushings and also sometimes even existing bushings may need to be reamed because of the new trunnion shafts not being worn. I would also make sure that all the moving parts are greased throughly because it helps but it is extremely messy. Hopefully some TR4 owners will see this and reply with what they think but the end to end lock on my car is basically to adjust so the wheels move freely and do not hit anything. very scientific!

 

[Harry_Ward]

I really have to start reading these more closely!

They are suppose to be replaced as a set. Clean thouroughly and check thread as recommended in previous post if not replacing as a set. Screw vertical link down to bottom of trunnion and then back up just enough until full free swing achieved from lock to lock. Make sure both the trunnion and v-link are greased thourghly. Some use oil. I like grease. If binding occurs after connecting to upper wishbone see previous post.

 

[TRDejaVu]

Thanks for the responses.

My Haynes also says that they should both be replaced, but I think that is more regarding wear than anything else. I have the suspension completely apart. Nothing is assembled yet, so there are no outside forces that could affect it. I think that it has to be a manufacturing defect on the new trunnions.

Both sides start to bind when the gap between the trunnion end and the vertical link is 5/8 inch; there are still a couple of threads showing. They were thoroughly cleaned and then lubed with EP90 so I wouldn't have a dry fit. I took one of them down by hand to about the position that the old one was and when I removed it and inspected the interior threads there was some damage on the opposite side from the longitudinal groove. The original vertical links both have good threads, which I have thoroughly cleaned, with no damage. They have worn a little, but that should make it easier for the new trunnion to run down the thread. The original trunnions run really nicely all the way up and down. I need to change them because the wishbone mounting surfaces are
corroded and pitted.

I saw this question on another forum, but it didn't get any responses, so I appreciate any feedback I can get.

 

[Alan_Myers]

Hi Ian,

I think that fit should be pretty tight with new parts. For one thing the soft brass of the trunnion will to some degree conform to the steel threads on the v-link. Plus it will all function differently once the car's full weight is back on the ground. (That's really the only time you can judge if the steering is binding.)

Be sure to use some 90W gear oil in the threads during assembly, both to lubricate it now and to make it much easier to squirt in some grease (or more 90W gear oil if grease won't go it) later once re-assembled. I.e., don't assemble these parts "dry" and try to lube it after assembly. (Re-reading your post, it looks like you are already doing this.)

It might be possible to "lap" the parts together, but I think I'd rather have them a bit tight to start with, than at all loose. I'd also be very worried about doing any sort of abrassive work around the acme threads, since it would be very difficult to be sure any and all traces are cleaned out, and any little bit remaining in there after it's all reassembled would continue to abraid and quickly wear out the parts.

I recall it is also very easy to screw the v-links into the trunnions too far, and thus get some binding when the male acme threaded portion of the v-link bottoms out in the female threaded hole in the trunnion. In other words, if it's threaded in deeper than was ever intended, iot will bind.

One reason this happened with the parts I was working with was that the replacement rubber dust/grease seals I got seemed quite undersize (perhaps there are more than one type, some of which I am just not familiar with). Because of this, it appeared I needed to thread the trunnion in further, since there was still an obvious gap at the seal.

The last time I did the job I carefully rebuilt one side at a time (1st time it had ever been disassembled, judging by the ancient bushings in there), and this particular question is one reason I'm very glad I left one side intact, for reference.

I forgot to measure the length of the trunnion/v-link assembly before taking it apart. So, I quickly checked the other side found I'd screwed the v-link in one or two turns too far, fooled by that ill-fitting seal! (I also had the benefit of a second TR4 frame sitting nearby awaiting disassembly, mostly stripped, but that still had what appeared to be the original front suspension intact. Measuring this 2nd set also helped confirm the correct dimension.)

It's been a while, but I'm fairly certain I measured the combined height of the two pieces to be almost exactly 11" from the very top to the very bottom (not counting the grease zerk). Yes, the measurement varies a lot depending upon exactly where you put the ruler or tape measure, due to the shapes of the pieces. I was just using the most extreme edges of each part. The trunnion threads are so coarse that being a single turn too tight or too loose makes quite a noticible difference in overall length. (Measured "length" would be vertical/top-to-bottom, if the parts were actually on the car.)

Once I had set the assembly adjusted to the measured length, I found there was quite a gap in the brand new dust/grease boot I'd installed between them. That meant taking it all back apart and improving the boot with a secondary seal on top, then putting it all back together again.

Regarding your other question, I don't have the numbers handy, but the factory service manual shows the adjustment of the steering stop in total degrees of turn for both inside and outside wheels/tires (they are different). On my car I just removed the stops or left them loose until assembly was far enough along to test fit a tire and wheel, then turned the steering fully one way and fully another, adjusting until there is no tire or wheel interference with any other part of the car on either side. Also check that neither the brake hose or the tie-rod appear to be over-extended at full turn. Do this with wheel and tire temporarily mounted, but the springs and shocks not installed, so clearances can be checked all throughout the up and down range the suspension, from upper to lower stops.

Not very "scientific" I know. But the supension on my car is pretty far from stock now, so the dimensions in the service manual mean little and I know I had to fabricate stops that were slightly larger than original.

Hope this helps!

/ubbthreads/images/graemlins/cheers.gif

 

[TR6oldtimer]

From your description, I agree the binding you are experiencing is probably a manufacturing tolerance issue. I believe these parts are all after market items and there may be more then one manufacture source. TRF claims theirs are made to TRF specs and superior to other sources (at least for 250's and 6's), but who knows. When looking for a vertical link to fit my new trunnons, I contemplated driving down from Santa Cruz, CA to Moss in Goleta CA with parts in hand to insure a good fit. Instead of a 530 mile round trip, I just went with having it shipped and everything worked out. You will probably want to work with Moss for a resolution, however, if it were I, given everything is apart, I would contact TRF for availability of their trunnons and contemplate a visit to them taking along the vertical links to check the fit. If you go the shipping route, keep in mind that while TRF allows 2 months on returns, they are not easy to deal with when it comes to refunds, rather preferring a store credit.

If TRF parts work out, hopefully Moss will take their parts back.

Good luck

 

[TR4nut]

I also suspect a manufacturing tolerance issue - there is a chance though that some of it is slight bending of the vertical link itself, from prior life abuse,etc.

When I changed out my trunnions, I could not get the drivers side trunnion and vertical link together. Hard binding with about 1" to go. When I looked at the link, I noticed a very slight bend to the threaded portion of the link (hit curb perhaps?). I bought a used on and was able to thread on with no problem.

My trunnions were from TRF. It doesn't sound like you have near the problem I had as you are able to get the pieces together. I'd go with Alan's comment and put them together stiff, but perhaps lapping the last few threads could help if it is much too tight.

Also, side comment to Alan's about the rubber seal. Yes there are two sizes, so watch out. The TR3/early TR4 0 degree trunnion uses a thin seal, but the later 3 degree version is thicker. I bought a full rebuild kit which unfortunately had the earlier kind so I had to reorder the thicker version.

Randy

As to adjusting lock to lock, I didn't get to that yet but I think the original manual had a pretty good technical description of how to adjust. Oops, just noticed Alan already said that!