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MG Midget and Sprite Technical - Rear trailing arm bush

It's one thing after another. The Frogeye has now developed a very loud and annoying creak from the O/S rear suspension. I can induce it by grasping the wheel arch and heaving the car up, then sitting on the wing to push it down. Much worse on potholes of course. I have checked all fixing bolts and found nothing wrong. Soaked the springs in penetrating oil and spray grease (while jacked up to relieve the spring leaves). Disconnected the damper (I have telescopics), the panhard rod (my own design) and the rear end of the trailing arm. Still creaks. I now need to release the front end of the arm, but the bolt has rusted solidly into the bush. I suspect this is the problem area. I have been hitting it with a lump hammer for 2 days and it will not move. Made sure of course that the nut is on the end so I don't damage the thread. Tried to get penetrant into it but I can see how much rust there is. Had to remove the electric fuel pump to make room to swing the hammer - didn't help. I've rebuilt the rear end a few times and remember that the axle has to be tipped back to get the arms in, so this looks like a big job. I wonder if I can get the 3 bolts out that attach the arm bracket to the bulkhead. 2 are fairly accessible but what about the third? I may end up replacing the arm but that's the least of my worries as I can't get it out. All advice gratefully received.

Les

PS Why is it so convoluted to log into this BBS? I can never go straight to the log-in page, and the link for this forum goes to the archive not the live one.
L B Rose

if you bookmark the right page you are already logged in - or at least that's how it works for me.
David Smith

WHS ^^
Jeremy MkIII

Nobody replied to this, but I have done the job now so I thought you might like to know how I did it. No amount of brutality would get the forward training arm bush out, so I had to be a bit more logical. I ground off the head of the bolt and tried drifting it from the outer end. No joy. I then drilled it out as far as possible - the drill won't line up perfectly so the drilling is a bit askew, but I could free the bolt from the outer side of the bracket. I got a lot of metal out of the rubber bush. I then pulled the remains out from the inner end using a succession of collars and the existing nut. Once the bush was free I could raise the arm and get at the bolts securing the bracket. The rear end of the arm was easy as the bolt came out cleanly. Just as well I did this job as rust was beginning to take hold between the bracket and the bulkhead.

Of course, nothing is straightforward and after cleaning up and restoring everything the reassembly was not easy. The forward bush did not line up and was about 2mm to the rear of where it should be. So I retrieved the old bolt from the recycling bin, cut off the mangled end and turned the clean end to a taper. I slightly tapered the new bolt to give a bit of a lead, and took the sharp edge off the new bush inner tube with a countersink bit. I inserted the now bullet-shaped old bolt into the bracket and it lined up the bush with fairly gentle hammering. I could then follow this pilot tool with the new bolt, which was tapped in quite easily.

I am pleased to have done this before the corrosion became serious, but did it cure the creaking? Not really. It's quieter but is still there.

Les
L B Rose

Creaking can be a sign of metal stressing and fatigue. Look for other parts that should move but aren't. I had a creaking sound from the front end that I ignored until the A frame broke in two. Frozen lower pin. Young and foolish.
J Bubela

Exactly my thought, but I can't spot anything. Everything moves freely now. No broken spring leaves, all bolts tight. Might try pulling out the spring shackle pin.

Les
L B Rose

OK folks, I have taken the spring out and rebuilt it. No cracks, just a lot of rust. Each leaf cleaned and sprayed with PTFE dry lubricant. Reassembled with Waxoyl on every leaf. All back together now and so far there is no creaking. Haven't road tested yet, and I want to do the other one while it's up on axle stands.

When you think about it, it's not a very good design. Water is guaranteed to seep along the leaves by capillarity, into the spring boxes. The rather useless rubber seal is never going to work for that reason. All I can do is to squirt more Waxoyl into the box and jam bits of dense rubber foam into the gap, with Waxoyl underseal on top. Just hoping that the Waxoyl between the leaves inhibits the capillarity.

Les
L B Rose

Job and half that Les and objective it seems has been met!
Vaguely seem to remember others with early Sprites discussing those spring boxes and how to protect them from further rusting.
I think earlier this year Guy or Nick may have started/contributed to the discussion about them as they restored their Sprites.
A trawl through the Archives may yield some nuggets.
Jeremy MkIII

Thanks for encouragement Jeremy. I have done both sides now. N/S was even rustier. After cleaning the leaves my wife commented on my orange face and hair. Help, I am looking like Trump. Will try on road tomorrow. This seems to be a 5-yearly job, and I'll have difficulty finding the motivation next time.

Les
L B Rose

Been out on road a few times. Rear end blissfully quiet. Very unpleasant job but had to be done. Glad to replace those bushes even though nothing to do with the noise.

Les
L B Rose

My old Mk1 had the original 1/4 elliptic springs fully encased in what I think was Denso tape from the PO. Maybe you could consider doing something like that? Or I think you can actually buy leaf spring covers, you see them more on pre war cars though.

I'll be fitting my presumably original 15 leaf springs soon so will be treating the spring box area to a good bit of protection beforehand. The rubber seals you mention have perished so I might look at gluing some form of rubber to them and adopting your idea of stuffing the box with foam.
John Payne

http://www.wefco-gaiters.com/
Tom Coulthard

This thread was discussed between 13/05/2018 and 18/08/2018

MG Midget and Sprite Technical index

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