Morris Minor Owners Club

As part of the Import test regulations , my '69 Traveller had a number of things to be seen to.

The braking System is the headache. Front Brakes were considered ok at 160 daN but the rear values were miserable with one side recording no measurement at all. The handbrake values were also too low.

As such I have replaced all the shoes with Mintex. On the LHS the cylinder had siezed and the drum was badly scored. Replaced both. ( pattern cylinder).

Before I take it for the official retest, my local Workshop has just tested the brake Performance for me. Front Brakes, after additional adjustment by me are better and ok as before but the rear Brakes not. They work in as much that they record stopping power but not enough, I am told.

Having adjusted the shoes (without handbrake on !) fully , I would like to think that the combination of new shoes and (on the LHS anyway) new brake drum with Zero km on the clock only needs bedding in. Wishful thinking?

The brake pedal is firm with no excess travel but seems to be even more firm with a "second" push ( indicating more adjustment needed somewhere which is strange as adjustement has been done). I did wonder whether the master cylinder was operating sufficiently but the fronts are ok and the handbrake test is also borderline.

It has a brake servo fitted (whether it works is another Thing) and a remote fluid Reservoir.

Anything I may have missed?

What's the condition of the rear flexi hose like? These can collapse internally and restrict fluid flow, although that should have been evident when bleeding the brakes. Was it hard to get fluid to through the cylinders when bleeding them?

Not really, they seemed to bleed quite normally. I did have to replace the front hoses about 3 years ago as they were the source of binding Brakes - a quite different Problem.

You will not get the best brake reading until the brake shoes have bedded in.
If you cannot drive the car to bed the brake shoes in - lightly apply the brakes whilst turning the wheel and then take the drum off and see if there are any high spots showing on the lining which need removing - repeat until the brake linings do not have any high spots.
A good lead in on the leading edge of the brake lining also helps.
The Minor 7" dia rear brakes are more than adequate to stop the rear wheels from rotating when the linings are bedded in and the shoes adjusted properly.

Thankyou Phil - of course this is what I want to hear and I do like the idea. I can drive the car on a private road for a few km and then do the test you describe.

I do not understand though what you mean by

A good lead in on the leading edge of the brake lining also helps.

could I Trouble you to explain?

A good lead in on the leading edge of the brake lining means that the first part of the brake lining to make contact with the brake drum is wedged - so the first part of the lining in the direction of rotation in thin and gradually increases in thickness in the direction of rotation until max thickness of the brake lining is reached.
I would suggest that the lead in is no more than 20mm in length and the thinnest part of the lead in is no less than 60% of the brake lining max thickness.
The wedge should be blended into the max thickness of the brake shoe and not a sharp change of angle.
Phil

I understand now, thankyou.

It has also since occurred to me that it may be possible to install the shoes the wrong way round - If it is indeed possible and I do have a talent for doing the wrong Thing as per the 50% rule. - ( i.e. if there is a choice, I usually do the wrong one ), then perhaps this may also reduce effeciency.

Remember to take the handbrake adjustment off completely. Even with the handbrake in the 'off' position it could still be holding the shoes on slightly, best to either the cable disconnect at the hubs or wind the adjusters off a few turns so the cables are completely slack before adjusting the shoes.

The rear shoes set as supplied should have two shoes with circular cut outs which fit over the snail adjusters and two shoes without which fit on the top of the wheel cylinder. The front shoes should have a cut out on all four shoes.
Check that the wheel cylinder is free to slide in the slot on the back plate and also that the handbrake inner cable moves freely within the outer cable and lubricate the exposed inner cable to prevent rusting.
To adjust the rear brakes jack both rear wheels clear of the ground, release the handbrake and adjust the brake shoes.
Fit the rear wheels and apply the handbrake. Check that both the wheels are locked. Release the handbrake one notch and check again, there should be equal resistance on both wheels. If not then adjust the handbrake cables and check again.

Good tips. thankyou.

Hopefully get time at the Weekend to check and re-do as suggested.

If one drum was scrap due to scoring, I would be checking that the other has not been skimmed beyond the oversize service limit. I would need to be sure that a used drum was fully serviceable before changing only one of a pair.

oliver90owner wrote:If one drum was scrap due to scoring, I would be checking that the other has not been skimmed beyond the oversize service limit. I would need to be sure that a used drum was fully serviceable before changing only one of a pair.

Agree, I was taught always to replace both sides at same time when dealing with brakes or likely to have an imbalance. May not be so noticeable at rear as the front.

Good Point chaps, but I did have a good look at the other side which seemed to be in quite acceptable condition. The drum was not really scrap per se, more of a deep ( ca 1mm) gauge. Probably reparable in a lathe. As you mention, any imbalance you would not be noticed from the back - confirmed by the fact that when tested last October, the LHS (i.e that with the now replaced brake cylinder and new drum) had a Zero reading !! ....and I never noticed.

If, on adopting the tips given, no real improvment is to Hand on the brake values, then most definately have to consider othe rmeasures.

for info - the total value of the braking System per engl MOT is 50% of the gross weight for vehicles registered before 1 jan 2010. In Germany for the TüV it is 48% ( and 16 % for the handbrake). The gross weight of my Traveller is given as 1250kg, thus a braking figure of 600 is needed.

At the Moment the two fronts together are giving a value of 380 but the rear only 150. Not enough.
Maybe even the fronts have room for improvement. They have also new linings and cylinders, albeit with max 100km usage.

Weiter machen !!

1250kg, I thought moggies were around 3/4 of a ton. Perhaps travellers are heavier than saloons.

The 1250kg refers to the max. allowable weight fully loaded. The 806kg (~3/4 ton) is the kerbside weight.
Both are mentioned on the German papers but as Nikol mentioned it is the total weight which determines the required brake rating.

Regards
Declan

I see, thanks for that Declan.

We had an almost identical issue with our back brakes about 3 years ago. Nothing seemed to work until one of the restorers at the rally had said they'd encountered similar problems with new cylinders. The idea they suggested was to bleed the brakes again only this time pump the brake pedal hard and fast a few times to build pressure, keep it as low as it would go and then release the bleed screw. Tighten the nipple and release the brake pedal. After doing this a few times the final air pockets must have come through and the brakes were definitely improved. Not perfect, but good enough to be able to drive around knowing we could stop and bed the new linings in.
Just a thought in case the other suggestions don't work out.

Yes, i think I remember now seeing other threads in the Forum which mention this Problem with new cylinders. Someone also had a Problem with air in the line, where the stop Switch is. The Late Roy A. wrote to me in my "left Hand drive conversion thread" that "....bleeding Brakes with a servo assist can sometimes be a challenge..."

Will give this a go as well - will only take a couple of minutes.

Air in the system is a red herring. Air leads to a 'spongy' brake pedal, or perhaps no pedal at all. If the pedal is there (not to the floor) the pressurs within the system should be reflected in the force applied to the pedal by your foot. The problem with air in the system is compressing it sufficiently before the pedal becomes solid. A 'hard pedal' is achieved because a liquid is (virttually) incompressible.

Very true, even though with movement losses , pedal mechanics, wheel cylinders (6 in total), brake shoes, there is bound to be some free movement - I wonder why we do not use distilled water in the braking System?