[Mgs] Front subframe mounting pads

Peter Schauss rpschauss at gmail.com
Wed Jul 25 11:25:05 MDT 2012


Shortly after replacing the front brake pads and all four tires on my
1980 MGB I found that the car would pull to the right whenever I
applied the brakes at speeds higher than 50 mph.  At about the same
time I noticed a distinct "clunk" whenever I went over a bump or when
I let up on the brakes after a slow speed stop.  I spent nearly two
years trying to chase down this problem.  Finally, when I had the car
up on the lift to do an oil change a few weeks ago, noticed that one
of the mounting pads for the front subframe was loose.  When I went to
replace the pads with new ones, I ran into a couple of minor issues:

1.  Based on the Moss part number and the drawings in my shop manual,
the upper pad is supposed have a part which is shaped to fit into the
hole in the subframe while the lower pad is completely flat.  Although
they were quite worn, the lower pads on my car clearly showed that
they had the raised section which fit into the hole in the subframe.
I did not want to remove the entire subframe so I did not check the
upper pads, but I could not see any evidence of rubber from the upper
pad extending into the holes.  In any event, I installed the pads
which Moss had labeled as "upper" in the lower position.

2.  After I installed the two new pads, I could see that they were
still loose, so I added the old pads between the new ones and the
plate to take up the slack.  The double ended bolt which secures the
subframe has an unthreaded section which is too wide for the plate,
and thus limits how much you can compress the rubber pads.

In any event, replacing these pads cured both the "clunk" and the
pulling-to-the-right problem.  Apparently, there was enough slack in
the whole mounting system that when I applied the brakes the subframe
was turning slightly causing the car to swerve in that direction.  I
have owned this car for 21 years and it only had 38k miles on it when
I bought it. I have never removed the front subframe and I don't
believe that either of the previous owners would have had reason to do
so, so I believe that my car was shipped from the factory with the
mounting pads reversed.  Either that, or Moss and my shop manual are
wrong.

I hope this will save someone else a bit of trouble.

Peter Schauss
1980 MGB


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