Morris Minor Owners Club

I would be interested to know if anybody has fitted remote brake servo to an MM, whilst retaining original brake drums etc.- I feel that the standard set up is OK but would appreciate a bit more stopping power. If anybody can help would be interested to hear. Alan

A servo wont give you any more stopping power, it just means you have to push the pedal less hard. If this is the limiting factor then do so, however in most cases it is not. New adjusted brake pads should do the job. If set however on it, the plumbing will be the same as for any other minor.

A vacuum brake booster gives an appreciable increase in stopping performance.
In theory, the previous post is correct, in practice however the theory does not hold water, stopping distances are dramatically decreased and it is so much easier to stop in a hurry or avoid a collision.
The unit used in Australia is a PBR VH40 (from memory). you will have to get a vacuum connection into the intake manifold which will involve removing the manifold from the block.

To get the full benefit of a servo you should fit harder brake shoes - not pads- if they are still available.
I would like to know if there are any larger front drums with the same PCD which would fit.

kotemaori wrote:A vacuum brake booster gives an appreciable increase in stopping performance.
In theory, the previous post is correct, in practice however the theory does not hold water, stopping distances are dramatically decreased and it is so much easier to stop in a hurry or avoid a collision.

Can you explain the reasoning and logic behind this? Why would it give an appreciable increase in stopping performance? This would only be the case for the same amount of force applied through your leg, which should not usually be a limiting factor at all, the brakes will work better if you just touch them lightly comparing a servo to non-servo, however this is not a realistic situation.
Also easier to stop in a hurry/avoid collision? Why's this? In this situation you are basically slamming on the pedal, to its maximum point, in which case the servo assistance will not help this. Secondly the reduced feel given by the servo will surely make it more difficult to feel when your brakes are locking, which is crucial in this situation. to be able to pump the pedal/reduce force applied to unlock the wheels.

As far as I know Mike, there are no bigger drums/backing plates that fit.
You are right about the pads, I noticed this and thought perhaps it was a slip of the pen.
Harder compounds for shoes are now difficult to find, at least in Australia, due to asbestos no longer being used, but there are race compounds available at horrific cost, they probably need a servo/booster to work properly.

Whatever the theories that the bench racers espouse, boosted brake circuits are superior to the standard setup reliant on the muscles in ones left leg.
The booster obviously increases the force applied to the fluid in the circuit, the standard master cylinder and wheel cylinders do a poor job unassisted. I think because cars were designed to operate at lower speeds than today.
The ratio of master cylinder bore to wheel cylinder bores is not optimum for good braking, the pressure required at the brake pedal for efficient braking cannot be applied by a mans leg let alone a ladies, but when a booster helps to increase the pressure in the circuit we will see a big improvement

But its easy enough to lock the brake pedals on a minor, regardless of make/model. This is as standard, with a well maintained brake system, so I dont see why extra force would help? If you can lock the wheels then surely the maximum is easily obtainable? I agree though it is somewhat speed dependant, but on a standard engined car, I can't see why the speed would be considerably higher, justifying the need for a servo.

Thanks guys for all the info, seem to have stirred up a small hornet's nest. Any info on fitting servo would be be greatly appreciated. Regards Alan

Make sure it operates on front and back brakes, needs a tee piece.
My feeling are that it makes it much easier for you, or anyone else to drive the car without feeling that the brakes don't work.
Nothing remotely modern needs so much pedal effort.

When decending a steep hill in my Series MM towing a loaded camping trailer it is necessary to select 3rd gear as the standard brakes on their own would not safely hold the speed down.
I am not sure how long a standard set of shoes would last with the extra servo force applied.
The servo vs non servo effect can be studied from the other end of the spectrum by slowing down with a normal servo/disc braked car and then trying the same thing with no servo. The leg muscles would not exert sufficient pressure on the disc pads to be able to stop safely.
On a standard front disc, rear drum set up are the drums servo assisted?

mike.perry wrote:The leg muscles would not exert sufficient pressure on the disc pads to be able to stop safely.

Just as a general point, this is not the case on a minor with marina discs, the car can be easily stopped, and the wheels locked without a servo.

I am not sure how long a standard set of shoes would last with the extra servo force applied.

It just depends how much you slow the car down, not if a servo is fitted or not.

MarkyB wrote:

I am not sure how long a standard set of shoes would last with the extra servo force applied.

It just depends how much you slow the car down, not if a servo is fitted or not.

Hmmmm...Maybe it depends on how often you brake and how hard you brake. Brake boosters increase the rate of wear imho

The brakes convert forward motion into heat and wear in the process.
To stop a Minor from 60 mph to a stand still will create the same amount of heat and wear whether a servo is fitted or not.

Can I point out that the original poster specified "retaining the original drums"? Some of you are assuming discs, which WOULD make a huge difference to the force needed at the pedal. Drums would, of course, be further limited by heating and fading, but would make driving in a modest minor-style less tiring if servo-assisted.

OK, sorry if I have broken protocol in any way with my first post. I am a newbie here, but not with Minors. I should have said, Hi, guys....