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MG MGB Technical - Fitting the Trunnion to the KingPin

I am rebuilding the front end on a 77 mgb roadster. Sent out the swivel axles complete with kingpins and swivels for disassembly and new bushings. Now I am trying to put them together and can not get the trunion down over the kingpin to line up correctly. Properly alligned, it still has about 1 inch to go and won't budge. I can get it down 180 deg out, but then it will only swing about 10 deg either way. This is true of both my right and left units.

I can observe some very slight buildup on the inner wall inside the trunions and wonder if I should take a file to the trunions until I can get them to slip down in correct alignment? Is there some technique that I am missing here?

Thanks,
Paul
77 MGB

Paul Hinchcliffe

Paul,did you send the assemblies out to a generic machine shop to be re-bushed?Did they have the proper king-pin bushing reamer?This tool reams both upper and lower bushings to the proper size in perfect alignment.That way they fit over the king-pin and turn without binding.
Dave

Dave,
I sent the assembly out to Apple Hydraulics. The bushings were seated fine - all parts assemble fine except that when I place the trunion on the top of the kingpin, I can not slip it down to where it should be with proper alignment.

-Paul
Paul Hinchcliffe

Paul. Is it clean inside? I have seen rust and crud build up that, if not cleaned out, would interfere with the proper assembly. It would seem strange that it will fit on one way and not the other unless there was some form of interference. Perhaps a burr on the kingpins? Les
Les Bengtson

Paul. Having some time to think about this, and more germaine, having taken the time to go out to the shop and dig out the kingpins and trunnions I am currently working on, I have a question. With the kinpins by themselves, will the trunnion fit onto the kinpin in proper relationship? On my stripped kingpins, the trunnions slip right on. If the trunnions slip on with the kingpin stripped, but not when the swivel axle is assembled, there is a problem with the assembly or the trunion is buggered in some fashion. I pulled the assemblies from an 80 parts car and, due to rust, was not able to disassemble the parts without damage to the trunnions. Since you state you sent the parts out for disassembly, I wonder if they could have been damaged in the process? Do you see any signs of deformation on the lower portion of the trunnion? Les
Les Bengtson

Les,
With the kinpins by themselves, the trunnion will not fit onto the kinpin in proper relationship? They will only slide down 180 degrees out of sync and rotate sone 10 degrees either way. This is the same when I place the swivel axle in place and also true for both left and right and even when interchanging parts.

I believe from your responses that I should be able to slip the trunions down over the kingpin in any direction - that's what I needed to know. So I believe my next step should be to look for any burrs on the kingpin preventing this or any significant buildup inside the trunion! Pull out the files!

Thanks!

-Paul
77 MGB
Paul Hinchcliffe

Paul:

Just a thought, but don't have something in backwards do you? When I rebuilt the front end on my B, at first I put the kingpin in 180 degress wrong. It was several steps later that I realize something was wrong. After a quick check with the other side I realized what I had done. You might want to check the workshop manual closely.

And, you might want to hold off on the files, until you understand what the problem is.

See 'ya in the garage...
Aconite Blue
Bryan Prindle

Thanks one and all for your responses.

I did apply a round file to the trunnion - there was a metal protusion built up on the inside of both of the trunions about midway up.

Under close examination I found that for both of the kingpins, the top of the kingpin had a bit of thread crush on one side near the base of the thread, I also found that the top of the kingpin had an ever so slight bend (only noticable by watching the trunnion slip down over it) at the base of the thread. I can only imagine that this may have happened when the folks disassembled my "frozen" assemblies for rebushing and may have had something to do with the metal protusion built up inside the trunnion.

I put two castlenuts on the top of the pin over the threads, locked it in a vice and applied a bit of body pressure to the remainder of the pin in the "right" corrective direction. While I could not observe any significant difference by looking at the pin, it was enough to allow the trunnion to move into position correctly and rotate around the shaft. I found this the case for both kingpins.

I also, used a thread cutter to clean the threads.

Thanks again for the responses!

=Paul
77 MGB
Paul Hinchcliffe

Paul. If it were me, I would go with new kingpins. If they were damaged in the disassembly process and then you were able to straighten them by hand, I would not use them on my car. Moss shows a King Pin Set, part number 264-418 for $79.95. Do not know if this is for one or two kingpins, but it would not matter. If a kingpin breaks while you are driving along the highway, $160 plus shipping would have been money well spent at the time. If the part was damaged, replace it. It is not worth your life or anyone elses. Les
Les Bengtson

Les,

You are absolutely right! Sometimes one can get caught up in a detailed mechanical fix and lose sight of the bigger safety picture!

Thanks for the focus!

-Paul
77 MGB
Paul Hinchcliff

Paul. Not a problem. I am currently rebuild a spare front end off an 80 parts car to install on my daughter's 77 over Christmas break. Having destroyed two of the original kingpins and trunions in the process (because they were so badly rusted together), I can understand your frustration. Bob Ford, at Brit-Tek has sold me two of his front end rebuild kits over the last couple of years and he is my first choice for parts. Also up in your neck of the woods. I have two more cars to do over the next couple of years and will buy his kits for both of them. He should be able to have the parts to you rapidly if you call him today. His phone number is 1-800-255-5883. Les
Les Bengtson

As a point of interest, while rebuilding my frone end, I noticed that the 1972 British Leyland MG Workshop Manual shows the trunnion in a position 180 degrees reversed, horizontally, from what is shown in Haynes, Clymers, and the Moss catalog. If the trunnion is installed in the manner shown in the BL manual you'd have some crazy wheel geometry, and the mistake should be obvious right away, but it seems odd to me that it would even be shown like that. An honest mistake, or a disgruntled draftsman at work during the labor strife of this period? I usually consult all three of my manuals on a given job, so as to avoid any stumbling blocks or weak explanations that could lead me astray.

Joe
Joe Ullman

This thread was discussed between 11/12/2001 and 13/12/2001

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