Morris Minor Owners Club

Willie - the slight residual pressure in the Minor system is counteracted by the return springs. Discs of course don't have return springs. Most peeps who fit discs seem to need servos to make them work. The arguement can go on for ages - disc pad area is much less than drum shoe area so that too must be a consideration, as much as disc piston area is more than shoe piston area. Also the 'hardness' (= coeff of friction) of the lining material be it disc or drum must be a factor.
It's the need for a servo with discs that gives the game away for me !

Need? Used by some people, surely?

I don't have a servo with my disc set-up OR drum setup as I don't like them. After driving the drum braked car for a while when you get in the disc braked car you nearly fire yourself through the windscreen!

Excellent - I don't have servo on Minor or Mini.

No servo on mine either

surely a servo would improve braking more and make the pressure needed on the pedal less making for a more relaxing car. i would rather have a car with disc brakes, because they are easier to maintian.

Servo wouldn't improve the braking, just reduce the effort needed on the pedal. I prefer discs because of maintenance issues - and being let down by drums once very scarily - and no, that wasn't my maintenance.

so if i fitted discs to the minor its really a case of, if u want it fit it. Is it worth the hassle to put a servo in? I have never driven a car with drum brakes all round is there really a big difference?

disc pad area is much less than drum shoe area so that too must be a consideration,

nope - the area of he lining has no bearing on the pressure. The coefficient of friction lining material is not so different between disk pads and shoes as they are basically the same types of material.

As mentioned by Cam - with the same pedal load (same pressure), a disk braked Minor will stop quicker (based on current available disk kits) - therefore for same braking 'g' the Minor disk set up will have lower pressure.

People use servo's with disks because they can - rarely because there is a 'need'. It reduces the pedal effort and as modern cars are so over-servo'd this makes it more easy to swap between cars (although some people with poorly legs may need servo'd disks).

its really a case of, if u want it fit it

i am talking about the servo

...and that is the case, yes. They really aren't much hassle to fit, and if you're used to modern cars you may like them. I find they reduce 'sensitivity' somehow and make the whole process more remote - having said that, the Ford discs I'm fitting next WILL have one - I can always take it out later if I don't like it

bigginger wrote:...the Ford discs I'm fitting next WILL have one - I can always take it out later if I don't like it

Why's that then?

'Cos I've got one - and feel like seeing if I get on with it. No logic or sense, really

Fair enough.

bmcecosse wrote:Willie - the slight residual pressure in the Minor system is counteracted by the return springs. Discs of course don't have return springs. Most peeps who fit discs seem to need servos to make them work. The arguement can go on for ages - disc pad area is much less than drum shoe area so that too must be a consideration, as much as disc piston area is more than shoe piston area. Also the 'hardness' (= coeff of friction) of the lining material be it disc or drum must be a factor.
It's the need for a servo with discs that gives the game away for me !

I'm with BMC on this one.
The energising effect of the brake shoes makes a big difference to the pedal pressure required.
Ever tried to stop a Minor flat out in reverse (not that you do this everyday ) ? The pedal pressure is very high due to only 2 instead of 6 shoes self energising.
This energising effect is lost with discs which is why the pedal pressures are usually higher.

In reverse the front shoes are all trailing! i.e. the braking load acts AGAINST the piston - hence needing more effort to stop.

On a disk braked car I've never needed to press the pedal so hard that I was off the seat and pulling on the steering wheel! I'm with Cam on this one, as he has both on the road so can make a fair comparison.

rayofleamington wrote:In reverse the front shoes are all trailing! i.e. the braking load acts AGAINST the piston - hence needing more effort to stop.

Fair point, but you get my drift.

and wrote:On a disk braked car I've never needed to press the pedal so hard that I was off the seat and pulling on the steering wheel! I'm with Cam on this one, as he has both on the road so can make a fair comparison.

Me neither but the pedal pressures are noticeably higher. Some like it but others don't.

My van & '62 sedan both run Tarago disc brakes. The sedan has a booster, the van doesn't.
It's always a lot nicer operating the sedan brakes after driving the van everyday.

I have never understood the argument that servos do not improve the
braking which admittedly does depend on your interpretation of 'improve'.
the usual pedal pressures of cars in the 50's was over 100 ft lbs, in the 60's
and 70's it came down to around 80 to 90 ft lbs and modern cars are around
60 ft lbs which means that is you continually swop between your Minor and
your modern car as I do then the difference is rather noticeable. A servo must make a Minor easier to drive as it reduces the effort needed to achieve maximum braking effect which adds up to much less leg effort during the
average journey. Many years ago I bought one of those new fangled Austin
1100's with unservoed disc brakes and was bitterly disappointed because they
seemed no sharper than the drums until I twigged that they did not fade with
severe use unlike the drums. The difference is that if you servo drum brakes
you can negate the improvement by increasing the brake fade whereas if you
servo the discs you will not suffer noticeable fade under normal driving conditions, you just reduce the pedal effort on any journey. When I fit my
eagerly awaited disc brake kit I will certainly retain my servo.

Willie wrote:A servo must make a Minor easier to drive as it reduces the effort needed to achieve maximum braking effect which adds up to much less leg effort during the average journey.

EXACTLY! Easier to drive and less leg effort does NOT add up to better braking! Just easier on the driver.

I personally prefer a firm pedal. My legs are also in good health and I don't mind using them, so for me, non-servo is ideal.

I'd go servo everytime, I believe a servo'd system gives greater feel through the pedal, and for us old foggies less effort on the o'l legs is a good thing. I'm sure some will argue my first point from the other perspective, and quite right too. We are all different and have individual preferences, all perfectly valid.