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MG MGA - Dunlop vs Lockheed brakes.

I was on the MGA Gurus website the other day and was reading about the MGA "Deluxe", how exactly it differed from the pushrod MGA, particularly the brakes.
I wondered if anyone knew how the two systems compared and if the 4-wheel Dunlop disc brakes actually performed any better than the Lockheed disc/drum setup?

I have always struggled to get the brake balance right on my 1600 Mk I and after about 15 years of fiddling about with them, I have finally achieved a reasonable right and left balance.

Under very hard braking, there is now barely any pull to one side.
However, to achieve this, I have had to screw up the rear drum brake adjusters pretty tight so there is definitely some detectable rubbing of the rear brakes.

This does go against the grain a little bit with me because, for years I have been trying to find that bit of extra bhp to make the car go a bit faster.
But now with the 1950cc engine, the car has plenty of oomph and I now think it is worth losing a bit of it to have better brakes.

However, it would be more satisfying solution if the rear brakes were not rubbing and the wheels were spinning more freely.

This post is more to satisfy my curiosity on the subject rather than to begin the process of converting to some kind of self-adjusting rear disc brakes.
But knowing me, if there is a very definite braking improvement to be achieved in converting to rear disc brakes, I may just be tempted to give it a try.

Cheers
Colyn





Colyn Firth

Not to go too far off on a tangent, I wonder how MG did the parling/emergency brake on the Twin Cam/MkII Deluxe.

Just wondering.

Jud

ps: I drive a MkII but I'd love to have a deluxe just for the wheels.
J K Chapin

Hi Jud
The handbrake is roughly the same as a Lotus elan with an extra pair of pads swinging off the caliper





William Revit

The problem that causes brake imbalance is that the new brake shoes do not have the same arc as the drums, so only part of the material is in contact and doing any work.

I had to get my shoes machined to match the arc of the drums and the effect on braking and balance was immediate and very noticeable. I believe Mintex can do this if you supply them a set of shoes and the matching (or not) drums. No need to have the shoes rubbing to wear them down to fit!

And having driven a Twin Cam and my car back to back, the 1600 brake system was just as effective as the TC once the shoes were modified.
Dominic Clancy

Colyn, it's an interesting issue which had the attention of the MGA guru very early on. There is no doubt that rear brake balance left/right - front rear becomes increasingly important as power is increased. It's years since the twincam and I parted company but I don't recall being unhappy with the allround discs but my impression probably influenced by the arrival of the more powerful B is that front discs are more effective and therefore a more important upgrade.
Despite the problems with the shoes to which Dominic refers, the B appeared with rear drums and the introduction of a servo proved a very effective combination. Bottom line; rear drums are OK.

With my current A, I have followed the B's arrangement influenced by a problem with the A's front suspension reported from Malta and the conversion listed by the Guru on the web. The balance is good although my driving style is not as spirited as in the past. Bottom line; practicing as preached.
Roger Walker

Thanks everyone,
Hi Dominic, do you have any contact information for Mintex and who can machine their Mintex 1144 material to match the brake drums?
As you know, I already run with M 1144 material front disc pads and rear brake shoes, but I would really like to have the rear brakes to be as good as the front ones already are.

Roger,
can you expand on your comment about the "front suspension problem reported from Malta" and your "conversion listed by the Guru on the web" comments.

I am not sure that I have come across these before.

Cheers
Colyn

Colyn Firth

I talked with the MD of Mintex himself, who was quite happy to line the shoes with the best stuff and said that matching the shoes to the drums was normal practice. I suspect that any brake shop could do it

Dominic Clancy

Perhaps as most of the recent entries on this thread are about drum brakes they should be replicated on a thread with a more appropriate title. Clearly I read it but almost didn’t having a drums all round car hence not interested in title.

Not only is it interesting to owner of all drum cars but far more interesting to them as having your front brakes working well is more important than rear ones.

By the way after struggling with pulling brakes for years I have now got a good set up so I am not going to touch anything in near future. Of course sticking cylinders tend to be an issue with drums, particularly front ones with two cylinders, and often over the winter. I now do a brake service before the winter including lubrication of pistons which is a lot easier than sorting stuck cylinders in the spring. I also drive car up and down drive at least monthly with several brake applications. I don’t take car on road as we live on a 1 in 4 hill which is kept very well gritted/salted, possibly because we have an ex prime minister living above us!

Paul
Paul Dean

I have run both ways on the track.

For street, the drum brake rear gives you a more reliable hand brake for parking that needs far less adjustment, as long as you have the brake shoes arced to the diameter of the drums.

OTOH, being enclosed in a contained volume inside the druml plus the more restricted availability of racing compounds for brake shoes (VG95 works but it also eats drume) leads to more change in brakebalabce as the rears fade.

No problem with that on the Dunlop set up as long as the less effective handbrake doesn't bother you. The Dunlop system with suitable pad materials (I always ran Ferodo DS11 and latterly Porterfield R4) can run with any modern car and the limiting factor is the rubber to pavement interface.

I run 4 wheel discs on the race car and on the Mk 2 deluxe coupe but intentionally left rear drums on the Jamaican with 3.4 V6.
Bill Spohn

Generally speaking, drum brakes work quite well on the rear. The front does the majority of the work in stopping the car. Converting to discs will make little to no difference. From what I understand, the primary reason manufacturers went to rear discs on modern cars was cost, not performance, along with the public's idea that discs are newer so they must be better.

Arcing the shoes to match drum wear has been standard practice for 100 years but seems to have been somewhat forgotten in recent years. Eventually they will arc themselves with use, but it can take many, many miles.
Steve Simmons

Thanks Bill and Steve,
after very many years of putting up with poor rear brake balance, I have only recently managed to get them to pull up the car in a relatively straight line, with very little steering correction needed under heavy braking.

As I mentioned earlier in this thread, I have had to adjust up the rear brakes so much that they were rubbing quite a lot.

But, even though the present drums are not very old, it is obvious that there must be quite a bit of ovality in them and they both rub heavily in one spot but run freely for the rest of the circumference.

My plan is to buy a new pair of perfectly circular rear drums, some new rear shoes lined with Mintex M1144 material and then have the linings machined to exactly match the drum

Can anyone recommend a supplier of decent quality drums that are perfectly circular?

Cheers
Colyn



Colyn Firth

Hi Colyn, You could contact the brake mechanic you are going to use to do the machining and see if they can supply the brake material you prefer, if they can't ask them for the dimensions of the material so you can supply it. the material is usually thicker than standard shoes so that it can be machined as desired. The mechanic will also check your current drums to ensure they are within tolerances and if they are the old drums will be machined round and the reconditioned shoes shaped to exactly match the drums. If the brake mechanic requires new drums then supply these so the new brake shoe material can be machined to match the new drums.
I Hazeldine

Colyn
The event as I recall was reported here and involved the steering lever becoming separated from the steering pin. The weakness probably attributed to age led to the conclusion that the MGB kingpin arrangement is stronger and more durable. This allied to the fact that steel and aluminium react when mated thereby making the normal disc conversion kit for the MGA unsound in principle together point toward converting the MGA to the MGB disc brake arrangement tried out by Barney.
Events have prevented me responding to your question earlier. Sorry.
Roger
Roger Walker

I raced a Twin-Cam and a pushrod for 20yrs.
The Pushrod car was very much a hybrid. Originally a T-C coupe ex competition car (John Heppenstal). It cost me 45 in 1971. It had a 1622 gold seal engine but a CR gearbox and full T-C running gear.
Eventually the chassis was scrapped (I know :( ),
and a roadster was built using various parts from a 1500 and the T-C brakes etc.
Both my cars had Dunlop discs with Ferodo DS11 pads which I had made and distributed around the globe.
The T-C had dual masters and a balance bar the pushrod a tandem master with a proportioning valve.
Both cars could and would outbrake disc/drum A's and B's consistently but the hand brake was pretty useless. In fact an friend with an E type parked his on a hill in Halifax to see it impale itself on a car down the road as the discs cooled and the handbrake didn't.
J Halton

This thread was discussed between 18/01/2023 and 08/02/2023

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