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MG MGB Technical - Front shock mounting bolts

In my normal maintenance checks I check various critical fasteners are tight to the correct spec. I've found very little change over time with one exception, the bolts that attach the front shocks to the cross member. The spec I use for these is 44 ft lbs this being in the middle of the book spec of 43 – 45 ft lbs. I check them at approx 6 month intervals or when I have the wheels off and invariably I find at least a couple that move a few extra degrees when I apply my torque wrench.

I first tried thread lock in case they were coming loose but this didn't seem to make any difference. I then marked them with Tippex, this seemed to show they weren't loosening but still a couple of bolts required a bit extra to bring them up to spec.

The only possibly I can think of, is when I had the subframe off approx 10 years ago I painted it with smooth black Hammerite and this has been settling over the years, or has anyone else seen this?

Bob
R.A Davis

I've found this, too, Bob, and wondered the same. And on mine it's not down to paint settling! I put it down to vibration. A few years ago, on the nearside, it'd loosened enough to have been picked up at MOT time, which is why I now check them every time the front wheels are off.

Also worth checking are the screws/nuts holding on the wishbone inner pivots.
Peter Allen

If they are not turning (as indicated by the Tippex) either something between the two is compressing, or the threads involved are stretching. The former still happening after 10 years seems unlikely.
paulh4

Check the head markings for bolt grade, should be T, not S or 3 hashes. S/3hash will deform at the torques involved.
Paul Walbran

Paul W, that's a good point, so I removed one to check and they're rated T. In checking around I see there are different bolts for CB and RB cars, mine is CB and appears to have the correct part 53K1025. The part for RB cars according to MGOC spares, is BTB198 and appear to be a bit longer.

I also found this John Twist video that although it's only partially related to my issue is a reminder to anyone with a front shock conversion to check the bolts.

https://youtu.be/H5WJZl_RZPg

Bob




R.A Davis

FWIW the Leyland Parts catalogue only indicates one bolt for all models - 53K1025, with no indication of a difference on either Moss or Brown & Gammons, only MGOC. It's quite common for fasteners to have an updated designation e.g. B&G shows the latter, I've not found any spec for the two as to how they might differ. I don't know why it would be different anyway, unless they *had* decided to extend the threads. With one of each I could always take one out and compare them ...
paulh4

Bolt length - just be careful, if they are too long they will tighten up but that can be on the circular cup under the crossmember. 2 of the bolts will touch if too long. They can become 'too long' if you use a thinner spring washer.
Just assemble very carefully.

Colin
Colin Parkinson

This thread was discussed between 22/09/2021 and 23/09/2021

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