Jerry Kaidor scribed:
Subject: Antique MG brakes
> **** Sounds like MG TC brakes. I saw somebody rebuilding his at an MG rally
> once. "Does that really stop the car, or is there something else in there?"
>
> Of course, I understand that the TC's *stop* just about matched its *go*.
> Maybe Mr. Garnett will tell us how are the brakes on his 'PA?
They're, shall we say, reasonable? All the OHC MG's came with cable pull
brakes. Earlier MMM cars had 8" drums, until they were upgraded to 12"
for the heavier, more powerful 6 cylinder L around '33. The 4 cyl P and the
6 cyl. version, the N, as well as the hy-bred 4 cyl. racing Q-type, got the
same 12" drums. The drums are finned around the outside, for better heat
dissipation. There was even an cast aluminium version, with steel liners
used on some of the racing and record breaking cars. MG's brakes were
considered quite good for the day. There were still many cars which only
had 2 wheel brakes, (rear), as balancing front-to-back was a bit more
complex to design with mechanical systems.
The brake pedal operates a shaft positioned transversly between the
chassis siderails. Arms from this shaft pull the cables for the front and rear
brakes as the shaft rotates. Brake action and adjustments are similar to
later parking brakes. There are 2 shoes, pivoting on one end, and operated
on be a common cam at the other. These shoes are themselves interesting,
being of cast aluminium, with lead "anti squeal dampers" fixed to their sides.
The dampers are listed as Patented, and have the MG logo cast in them.
My own car has been "modernized" at some point, by fitting a TD master
cylinder to the brake pedal, and TD rear slave cylinders in place of the
cable cams on all 4 wheels. I hesitate to revert to the original setup,
as the the job was very well done, and necessary parts would cost a
few pennies. I also imagine my current system requires less frequent
adjustment, and may need less pedal effort. As long as I'm not trying
for concours (no thanks), or under stiff vintage race restrictions,
(there's a lot more to do before I could think of racing it), I'll
stick with what I've got.
So, how does it work? Well, due to some play in the steering, and
wire wheels which need re-lacing, I get a fair amount of wander
under "hard" braking, as well as occasional lock up of a wheel,
which may be due to uneven adjustments, plus irregular weight transfer,
as the front (friction) dampers need proper adjusting, and the rears
(hydraulic) need to be rebuilt. Stopping, as I said is "reasonable",
and fade probably isn't much of an issue, with the P being the lightest
road car the 12" drums were fitted to. The biggest problem, is the
delay encountered while I work my big foot off the throttle and out from
under the brake pedal in the very narrow space available. I don't
mind that too much, after watching another PA driver furiously working
the handbrake lever for stopping during the "driving tests" at
Farmington this fall, because his main cables desperatly needed adjusting.
He did quite well, just the same!
________
/ _ \ Roger Garnett (sggy@crux1.cit.cornell.edu)
/ /|| \ \ Agricultural Economics |
| |\/ || _ | 3 Warren Hall | South Lansing Centre For
| | || | | Cornell University | Wayward Sports Cars
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