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TR4/4A Broken Vertical Link

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mcmillal

mcmillal

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I had been really enjoying my freshly rebuilt engine and O/D transmission in my TR4. Everything was fantastic, when just as I'm turning into my driveway, the front driver's side suspension gives out. Luckily, I was moving fast and I was already home. However, the car was half in and half out of the driveway. After some investigation, the vertical link bar broke right where it enters the trunnion. A clean break. The car won't be going anywhere for a bit now, as I intend to replacement both vertical links just to be safe. So now the question. What is the best option? Replace them with the standard part or something else. What options are available for improving the front suspension in these cars. I don't want to blow the budget, which hasn't been set yet, but would really appreciate some thoughts from the forum.

.........Cheers, Alex
 
mcmillal said:
After some investigation, the vertical link bar broke right where it enters the trunnion. A clean break.
.........Cheers, Alex
Click to expand...

I'd love to see a pic. I've always figured those were bullet proof beyond destruction.
 
If you read the British forums...your's is a pretty typical failure of the link. Our brothers on the other side of the pond mostly attribute the failure to lack of lubrication of the link. Lack of lubrication doesn't necessarily mean that you didn't lube it...but that the lube was not penetrating into the threads of the link.

Very glad to hear that it happened at low speed and you are OK!

There is nothing wrong with the stock style links. I would replace the trunnions while you are there, and make sure the play is within tolerance between the 2 parts.
 
Thanks for the responses. Any preferred retailer? Moss? BV? TRF? etc.
 
Here is a picture of the trunnion where the vertical link broke. I happened to notice that the trunnion was missing the grease nipple. Hmmm? Think that might have had something to do with it? Ah, ya.

broken vertical link.jpg
 
Yikes x 2! I remember a TR4 V-link snap incident during a road rally back in the early 90's. The experts decided the trunnion pins and overly tight on the lower control arms (Should be 5 ft/lbs per side). Instead of rotating during driving movement, the vertical link was being put under stress and finally snapped. Is it easy to rotate he brass trunnion?

Jeff
 
The lube journals in the vertical line are very small. If not lubed on a regular basis the grease can dry up, and not allow new grease to pass. Eventually, things can seize and break.
I believe the manual recommends lubing the front end every 3000 miles.
 
Seem to remember that the books says to tighten the nuts tight on the trunnion then back off one or two flats then center the trunnion. Can see how that could put a lot of force on the Vertical link if that was too tight. Each bump could flex the link.

David
 
The trunnion does move easily by hand. I'm pretty sure the missing/broken grease nipple had something to do with it. I managed to disassemble the front end this weekend. Now just trying to find a replacement vertical link. The new ones are NOT cheap. Also, I'm having a **** of a time trying to remove the stub axle from the broken link.
 
The vertical links show up on ebay regularly...just checked and not seeing any right now. I may have a serviceable one if you have trouble tracking one down. I'll have to dig in my storage to know for sure.

When you get a replacement, be sure to check for alignment. When chucked in a drill press by the threaded end, the tapered ball joint hole should spin true and not wobble. A bent vertical link also heavily loads the trunion as the wheels are turned from straight forward...and can also lead to a broken joint.

There is a recent thread on removing the axle. I've always used a press with no problems, but Mike found a cool way to pull the axle out that seemed to work great in this thread:

https://www.britishcarforum.com/bcf/showthread.php?105553-TR4A-front-suspension-quesions
 
Make sure you get trunnions that match the upper control arms, and install them on the correct sides. Early TR4 had the same setup as the TR3 with 0 caster; but fairly early on they changed the trunnions, upper A-arms and upper ball joint to give 3 degrees of caster. You have to look closely to see the difference in the trunnions (which are 'handed' for the later setup), and you wouldn't be the first to order one thing and get something else.

A 63 would normally have the later setup, the change was in 62; but sometimes the year on the paperwork is later than the actual build year.
It is also possible that a DPO installed the wrong control arms for your commission number, so it's important to check what you actually have.
 
Yes, I was warned about that. I do have the later setup. Thanks.
 
I rebuilt my late TR4 front end and used 3 degree trunnions from TRF. They have the grease nipples, and I was pleased with the quality. Another thing to be aware of is that you need to ream the new bushings in the lower control arms. I believe that it a 5/8" reamer that is necessary.
 
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