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MG MGA - Shocks

Out for my first drive of the season Sunday, and only about 150 miles on it since it was finished. Developed a front end clonk towards the end, both sides by the sound of it.
Inspection showed loose shock mounts! LH more than RH. So they are now tight, and they have lock washers, which they had before.
Is this likely to be an on-going issue? I hope not.

ArtPearse

Very possible. The studs or bolts get loose, and begin to wear the threads in the cross member. From what I can tell, the factory generally did a good job of getting them tight, but once somebody has removed a shock for any reason, all bets are off.

My MGA's tale of woe and repair can be seen here on Barney's site:

http://www.mgaguru.com/mgtech/frame/fr106.htm

When I contacted Peter C (World Wide Auto Parts) about overhauling my shocks, he identified them as replacement units that had been available in the 1960s. So, they had definitely been replaced, possibly prior to my father purchasing the car.

I have since made the same repair to my brother's frame, because I found the threads loose on one side. The shock on that side was attached with non-original hardware, so it, too, had been removed at some point.

I took some additional measures to hopefully prevent future occurrence... Instead of the original studs, or Moss' reproductions thereof, I located some grade 8 exhaust studs that would work, and the lower threads were slightly longer, giving full engagement. The originals did not extend fully to the bottom of the tapped plate, which is only 3/8" thick to begin with. I had to shorten two on each side slightly so as not to interfere with the top of the coil spring. I installed them in the frame with thread locking compound, and I also used "Nord-Lock" washers which Peter supplied with my rebuilt shocks, but they are also available from McMaster-Carr. I installed the nuts using a torque wrench set to grade 8 torque specs.

For an in-service repair of loose threads, you have a few options. First, you could drill and tap for oversize studs as my father did. This has the disadvantage of having to drill out the holes in the shock body oversize as well, although Peter assured me that my shock body could be repaired (I chose to send him an unmolested shock from a parts car).

Second, you could install heli-coil inserts, or third, if the holes have already been drilled oversize, there are threaded inserts available that should work.

Hopefully you will not have any further problems, but it warrants regular inspection. The consequences of a failure such as my father experienced are potentially disastrous.

-Del
D Rawlins

Thanks for those words of comfort Del!
Its a long time ago I mounted them (20 yr resto) but I'm sure the studs were original, tight in the hole and in good shape. I might change to Nylok nuts.
I'm hoping I was negligent in tightening them properly in the first place.
ArtPearse

Highly recommend the Nord-lock washers, even if you switch to self locking nuts. One problem with studs, is even if you install lock nuts, or even castle nuts with cotter pins, etc... You've only addressed one end of the fastener, and basically created a bolt. The lower end can still loosen. The Nord-lock washers are more effective at keeping the nut from turning against the shock body than split washers, which can help keep the studs from coming loose from the frame, given that the nut and stud will be essentially locked together by the nyloc.

-Del
D Rawlins

In addition you could use a Loctite product. (It can later be released with a little heat.) Have to be careful with longer studs, if they're too long they can push against the spring cup. From what I remember they have a coarse thread which screws into the frame and a fine thread at the nut end of the stud.
J Williams

That is correct on all counts. The inboard studs won't interfere with the springs, but the outboard ones will if they are too long. I used a Loctite product on my studs, but that won't help if the threads in the frame are worn.

-Del
D Rawlins

Well, after I tightened the shock mounts I noticed that my steering wheel, which had been pretty well centred, was now about 45 deg off centre!!
Art Pearse

Well, done another 100 miles after tightening the shocks, and they are still tight. Thats 200 total since it went on the road.
I found I had about 1/16 toe out after tightening the nuts. Now at zero again, and I centred the steering wheel again (still mystery)

As an aside, I think my steering is heavy. I know I'm aclimatized to power steering, but I don't remember my A of 45 years ago being heavy. Up on the jack with both wheels off the ground, it is quite free moving all the way lock to lock. Trunnions are full of grease.
When driving, it is like on rails and needs to be coaxed round bends. Not much return action. Tyres are 165's radial with 28 psi. Any suggestions?
I haven't tried it yet since the toe adjustment.
Art Pearse

Radial tires will often require more steering effort than the original bias ply tires.
D Rawlins

It should feel much better after getting rid of the toe out. Steering should feel pretty light once you are moving.
Neil MG

Art
After my rebuild I found the steering quite stiff and it doesn't self centre very freely. It all felt free when fully assembled wheels off the ground. However, I found that the new trunions were very slightly stiff on the king pins and I freed them off with some grinding paste. I think they should be a completely free fit. I have only done one side so far and it still not as free as I remember before the rebuild. It is possible that prior to rebuild everything was really loose. Disconcertingly my steering seems to go much freer at about 70mph plus and I'm not sure why. I wonder if there is some lift on the front of the car unloading the steering but that may be unlikely.

John Francis

Art, Congratulations on finishing up the project. Sorry to hear about the shock issue. At Queen's English there was a concern from a member about this issue and he had a near catastrophe on his racing car about this. So I guess it does require a regular inspection and torqued to 40 lbs-ft I recall. I have yet to do the coil test you sugguested, but I intend to do that and change the plug wires. For now all is running well. Good luck going forward. Do you have a photo of your car posted? Steve
Stephen Lofaro

This thread was discussed between 16/04/2015 and 11/05/2015

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