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Thread: L/S Vertical Link Resistance

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    L/S Vertical Link Resistance

    I've been rebuilding the front suspension on my 3A frame-off and have a concern. I first completed the left side (minus the spring/spring pan) and noticed some resistance when rotating the vertical link back and forth. Believing I mixed up the left and right vertical links, I switch to the other one - no change in resistance. So I decided to finish the right side for comparison with the left. It seemed to rotate with about half the resistance of the left (I think this light resistance is probably normal). This led me to believe the there is nothing wrong with the other vertical link, so one-at-a-time I replaced and adjusted the left side ball joint, and the trunnion - still no change in resistance. There does not appear to be damage to any of the suspension parts or the frame, so I am not sure what to do next. Will the trunnion simply wear-in? I know my original trunnions seemed to have significantly more play than the new ones. I would appreciate any advice.

    Joel

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    Re: L/S Vertical Link Resistance

    The resistance should not be in the trunnion. Any bind in the brass trunnion is a concern. That said, it is likely your new ball joints causing the resistance. New ball joints are under a good bit of compression and tend to feel like they bind a bit.

    I guess you figured out the vertical links are identical for the TR3...no left or right.

    Once you install the springs, if you can turn the links by hand, then they are about right. If they will not turn one or both directions by hand, then you have a concern.
    John

    1955 TR2

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    Re: L/S Vertical Link Resistance

    I unscrewed the vertical link from the trunnion and it easily rotates back and forth in the ball joint. The resistance only occurs when I screw it back in. Should I install the spring and see if I can move it by hand?

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    Re: L/S Vertical Link Resistance

    Check to be sure the VL isn't bent. They can get bent in minor accidents (like hitting a curb) without doing any obvious damage; the result is binding when a new trunnion is fitted. Herman van den Akker once wrote that he had to go through 5 of them, to find one straight one (for his daughter's TR3A).
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: L/S Vertical Link Resistance

    How do I check the vertical link? I can't chuck something that big in a drill press. It seems like I would need a lathe. Is there an easy way to detect with basic tools?

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    Re: L/S Vertical Link Resistance

    Screw it into the trunnion, but dont attach the upper ball joint. Hold the trunnion steady (or if you want, you can snug down the nuts to hold it) and watch what the hole in the top of the VL does as you turn it. If it moves in a circle, the VL is bent.

    Also make sure you have the upper arms assembled properly. I forget the rule offhand, but they aren't mirror image as you might expect, so one side overlaps front to back and the other side back to front.
    Randall
    56 TR3 TS13571L once and future daily driver
    71 Stag LE1473L waiting engine rebuild
    71-72-73 Stag LE2013LBW waiting OD gearbox rebuild

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    Re: L/S Vertical Link Resistance

    Thanks Randall, I will check it out this weekend. Regarding the upper arms, I followed the service manual which states that the right side should overlap the left when facing from the ball joint side.

    Joel

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    Re: L/S Vertical Link Resistance

    I turned the VL in the trunnion while watching the hole in the top, but the VL seemed to rock back and forth too much to keep it centered (I tried 3 new trunnions - all with similar play). So I applied upward force on the stub axle and rotated about the typical range for the wheel in operation. With a dial indicator, I detected about 10mils of wobble. Assuming the test method is valid, I think my vertical link is sufficiently straight. I guess I will go ahead and install the spring and check to see if I can rotate by hand. Is there anything else I should look at first?

    Joel

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    Re: L/S Vertical Link Resistance

    I put the new trunnions in a vise, screwed in the vertical link and used a dial indicator to observe any eccentricity at the upper hole for the ball joint. Probably not feasible while on the car.

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    Re: L/S Vertical Link Resistance

    Here is the thread when I was preparing the links and trunnions for my TR2:

    https://www.britishcarforum.com/bcf/...iumph-spindles

    I cannot tell from your post how you held your links and trunnions. If you are measuring the .01" at the bottom of the trunnion, then that is amplified several times at the ball link hole. You will note that I worked mine down to about .003" max at the ball link hole. Anything more than 1/4" will cause a very bad bind when turning the wheel. Any runout at all places high stress on the trunnion threads.

    Once I have my links straight, I trial fit many trunnions until I get the thread play down below .008". I have had many trunnions with .020" or more play in the thread to the trunnion...which is equivalent to wear before you put your first mile on the car! Play in the thread also allows the trunnion to impart an impact load to the vertical link threads while driving, which can result in broken links at the thread radius.

    I have sent many trunnions back to the big 3 for having too much play.
    Last edited by CJD; 09-01-2018 at 09:11 PM.
    John

    1955 TR2

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    Re: L/S Vertical Link Resistance

    Thanks for the link John - it's great information. I think a 1" capacity chuck would be required to hold the spindle, and I don't currently have the equipment for that.

    For the measurement I detached the ball joint from the vertical link, rotated the vertical link and trunnion out somewhat, tightened the trunnion bolts to lock it in position to the wishbone arms, and measured the runout with a dial indicator on the top of the ball link hole. This measurement was carried out while placing upward force on the stub axle and rotating about the angles seen during normal operation to get the 10mils. If I rotated 360 degrees, the runout was greater than 25mils. Again, I'm not sure if this was a valid way to measure.

    I decided to go ahead and install the spring on the left side to see how it affected the rotational resistance. I can still rotate the stub axle back and forth, but the resistance has probably doubled. For comparison, I installed the right side spring. There was no noticeable increase in resistance, and the stub axle rotates easily.

    Since I don't have the equipment to chuck the spindle, I'm thinking I should just purchase a replacement vertical link to see if that fixes the problem. Are replacement units considered good? I would probably purchase through TRF.

    Joel

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    Re: L/S Vertical Link Resistance

    .025” does not sound too terrible. I would tend to just use it. If it was very bad, you would not be able to turn the link more than a few degrees with the spring in. So long as you can turn it and it doesn’t pop back to one angle when you let go, I think you are good. I have looked at buying new links previously, but they were not actually available, even though the big 3 listed them. The prices were pretty obscene too. Worth looking into, but I woudn’t get my hopes up until you talk to TRF directly.

    Your method of checking should get you close, or at least let you know if the link was badly bent. It is a bit hard to measure radial runout while the link is moving up and down on the threads...so some interpretation is in order?!?
    John

    1955 TR2

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    Re: L/S Vertical Link Resistance

    Won't the resistance seen on the left side make steering difficult? Can I expect it to wear in with use so that it's similar to the right side?

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    Re: L/S Vertical Link Resistance

    Remember that the leverage from the worm and large steering wheel gives you a lot of mechanical advantage at the wheels. In general, if you can turn the link under the load of the spring by hand, then it will be almost unnoticeable from the steering wheel.

    That said, the steering is the sum of it’s parts. Every part that imposes drag is cumulative. You could spend a lot of time and money trying to get the left side better...but my feeling is that you are already past the point of the time you spend being worth the gain you’ll get.

    I am also questioning, after reading your initial post, that the bind is not in the link, but may be an upper ball joint that is not quite lined up on center with the lower trunnion. You mentioned that changing the links did not change the side with the bind. Add to that that some ball joints, even new, will have different resistance between them. So it very well could be the ball joints or upper arms. It’s hard to tell, but I feel confident saying the drag will not get any worse as the steering wears in...and it very well could eventually eliminate the bind altogether.
    John

    1955 TR2

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    Re: L/S Vertical Link Resistance

    I previously replaced the ball joint and ensured it was lined up - no change. I also tested the ball joint resistance by unscrewing the vertical link from the trunnion and rotating with the stub axle - there was essentially no resistance (similar to the right side).

    You mentioned it could be the upper arms, so I took a closer look. I noticed that the left side goes down farther with the spring installed and no weight on the suspension (frame is on jack stands). Is this just a discrepancy between the two sides as to where the upper arm lands on the shock tower, and of no consequence? Or could this be indicating something else that might be the cause of increase resistance on the left side?

    Upper Arms.jpg

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    Re: L/S Vertical Link Resistance

    The difference in drop could be your cause. Picture a ball joint with a stud coming out. It sits in a cup, and there is a limited range of motion. If the left side is dropping enough, the stud will ride on the side of it’s cup, while the right side has the stud suspended in it’s cup with a layer of grease.

    I would not be too concerned about the difference in drop. The towers are made of rather flimsy sheet metal, so slight differences can cause larger differences like you are seeing. Once the rebound stops go in, then everything should look more symmetrical.

    The steering stops are little washers that are bolted to the lower A-arms. They have an off-center hole that has a bolt through it. By loosening the bolt and turning the washer, it controls the angle that the vertical links can turn. They are important, as without them the steering tie rods start to hit suspension parts first. Each side turn stop controls the angle in one direction. They are best installed and set later, with the weight on the suspension, and set them so they just prevent the steering from hitting the suspension.

    I do not know what to say about the center adjustment. It is very tricky, even with the box on the bench. With everything connected, you can easily confuse another part dragging as the center drag. My impression is the adjustment is loose...but that is preferable to it being too tight.

    The best way to attempt to remove the silent block stud is to place one hammer on one side of the arm hole, and rap the other side of the arm hole with another hammer. The resonance of the 2 hammers will normally free the tapered stud. If it doesn’t after a few good raps, then there is a tool for it, that goes over the arm end and has a bolt to press the stud out of the hole.
    John

    1955 TR2

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    Re: L/S Vertical Link Resistance

    Thanks for all the advice John. I will begrudgingly go ahead and complete the installation as is. I guess it doesn't make much sense to spend more time and money if it's not going to make a noticeable improvement in the steering. Too bad things aren't more cut and dry.

    Joel

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    Re: L/S Vertical Link Resistance

    Honestly...I think you are good. And that’s from someone who’s pretty picky when it comes to cars. When dealing with cars this old, that have been through so much, with limited availability and quality of replacement parts...you have to make some tough decisions and accept when things are very close but not perfect. I think you can sleep on this decision.
    John

    1955 TR2

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