Minor 1000 coping with MOT Roller Brake Test

[LobbyLudd]

Since driving my first owned Minor in 1964 (then a break from the mid 70s until last year, being then very pleased to resume again with my present1969 saloon) I always accepted the original braking system was 'adequate' and reasonable for stopping the car probably with a driving style described as 'thinking ahead' sensibly. Then when I get into my wife's modern car after a run in the Moggy I have to be careful at first not to send myself towards the windscreen until re adjusted to the feel of the modern servo assisted brake system, pedal and disc brake performance comparison.

Now here's one aimed for a kindly testers opinion perhaps - I understand the present requirements for the MOT roller brake test requires a recording of 50% min efficiency reading of the service braking effort equated to the vehicle weight, and a 25% on the parking brake covering the Morris Minor. Modern car discs must have an advantage in grip/pressure over the old our old shoe/drum system presumably in more easily acheiving a 'good' % reading figure for the statutory MOT requirement ?

If the Minors braking system is well maintained as it should be on presentation to a MOT test how near down to the 50% minimum should we all expect to achieve as an average % reading I wondered, is the old system struggling to achieve this figure or is there still a fair margin of acceptable braking efficiency for a well maintained Minor in all this ?

Everything o.k in general with the car but - Unfortunately my car has just been 'failed' on a low reading on just the o/s rear wheels braking efficiency (just had new shoes and checked all cylinders, also hub oil bearing seals prior to test (I thought carefully) Fluid level has remained full in M/Cylinder. Will be carefully re-checking and adjusting brake system again before the re-test, all assuming the tester has the correct weight available on the modern database for the brake test formula. Presumably the machine will always take a weight measurement (Should I will take a note of the vehicle weight just in case to check, if this is permitted as it is tax classed as 'Historic Vehicle' ?)

How confident are others that the Minor is 'easily' capable of achieving the requirements modern roller test in general with our Minor's originally designed system if the % efficiency figures are possibly increased from the 50% efficiency figure as has been muted for sometime in the future ??

Interested with any feedback.

[bmcecosse]

Yes - it can easily achieve the figures -IF - everything is in good order. Did it fail on handbrake efficiency - or footbrake - or both?? At the rear brakes - it's important to slacken the cables off - then tighten the internal adjuster till 'slightly rubbing' and THEN retighten the handbrake . Make sure the cables are good of course and well lubricated - and the connection of cable to cylinder lever should be pivotting - not bolted up tight. Handbrake should lock both rear wheels at 20 mph on a smooth/dry road. You may of course be falling foul of the 'new' MOT rules that are a bit tighter - and came in to force today!

[LobbyLudd]

Thanks BMC thanks for adjustment setting info reminders.
It was the service (foot) braking that 'failed' on the one drum only - although I am having new handbrake cables fitted before re-test as well just to be on the safe side , as there is now maximum ratchet travel on old cables (but it did not fail due to this??) Just to be sure. Was told 'parking' brake efficiency o.k.

So have the brake efficiency % figures actually just been 'ratcheted up' (forgive the pun) and does this have any a significant or special concern or meaning for Minor owners to have their brake system serviced up to the very highest possible condition possible just before MOTs from now on (even more than before??)

[Trickydicky]

Hi,

I had my 4 door saloon mot`d last week, the tester asked me for the u/l weight which is 787kg. Brakes are standard and adjusted as per the manual and BMC`s instructions for the handbrake. It passed ok.

[simmitc]

If your handbrake worked OK, then the shoes and drum should be OK. I suggest that the wheel cylinder may be seized if the foot brake failed - the foot brake should push on the cap that is operated by the handbrake (easy to see if you look at a diagram).

[mike.perry]

It can be tricky to check the rear brake cylinder as the handbrake lever on the cylinder can obstruct the operation.
It is possible that the rear cylinder piston is not retracting fully, this can be caused by the lever pivot pin moving and obstructing the dust cover which can affect the adjustment. See Workshop Manual diagram M12.
I had the same problem on my Traveller despite adjusting the brakes the day before

[bmcecosse]

Yes - could be seized cylinder - but suggestion is they are new? And yes - the handbrake lever if adjusted up excessively will block the action of the hydraulic piston - hence the need to slacken the cables before setting the internal adjuster. I suspect that is all that's wrong.

[LobbyLudd]

Very useful guidance and reminders - thanks all!
It seems reassuring that our great little Minors that we care for so well are still able and so capable of measuring up to the strict requirements of 'modern' vehicle testing being thrown at them !
'

[bmcecosse]

So -has it passed??

[LobbyLudd]

Not yet - all hopefully will be 're fettled' brake wise with the expert eye of a very 'Morris Minor knowledgable' friend within another week before re-test is booked - any new part found to be needed will be fitted on this issue, (seeing its brakes - even including new drums if their condition should require i.e. if worn/scored perhaps)

[bmcecosse]

You only get 10 days for the free re-test!

[LobbyLudd]

Yes thanks for reminder bmc - it has already been booked in again before expiry of the statutory 10 days.

Did anyone know if the % of measured brake efficiency has actually been increased from the 50% for service braking and the 25% for parking brakes on the single line system on the annual MOT
'bmc' inferred that certain test requirements had been 'tightened up' in his previous post , if so any indication what has actually changed that Minor owners may need to be aware of please, particularly if it is likely to effect older cars with the original older systems in place. (i.e.anything stricter on braking efficiency requirements than before )?

[ASL642]

http://www.mmoc.org.uk/viewtopic.php?f= ... 72&start=0

I believe Drivewasher mentions it in this thread.

[LobbyLudd]

Thanks for the cross reference to a similar thread mentioning this point.
'Drivewasher' indeed does state he has 'heard through grapevine' that there is a liklyhood that this coming July service brake efficiency may be increased and to be required to be within 58% effort efficiency from the present 50%. (I wonder if this is indeed fact) with parking brake remaining at the same 25% figure.?
If so I presume it will be even more important to have a very 'thorough' check of our old original style braking systems??

[bmcecosse]

58% is still pretty desperately low...... But often the 'efficiency' will depend on how hard the pedal is pushed - is there any limit on this? My TR7 needs a good hefty push (even with a servo) but the brakes do work - rather better after they have warmed up I have to say........

[LobbyLudd]

So -has it passed??

YESSSS ! Re tested and Passed (with No advisories)

How could I be so dumb for such an obvious thing! - Wanting to look for something much more complex perhaps, or just another senior moment!!

Moral of story for me ......'Dont take the Minor straight to have its MOT "without' first making sure the just fitted brand new brake shoes are sufficiently ' bedded in' ( It then easily achieved 95% av on reading)

Did not seem to have all this very strict concern in the late 1960s they seemed to take your word a bit more easily on such matters then

[E J W Harrison]

Just had a recorded brake failure on 1960 2 door saloon due to imbalance (at a different testing station).
Brakes are in very good condition with all cylinders operating (no leaks)and fully bedded and adjusted shoes.The car has never before failed a braking test!
Have been advised to de-adjust front brake on offside to try and 'even up the balance' - I believe it will still fail.
Can I suggest that the examiner tests the braking system 'on the road' with a decelerometer as has been done previously?

[bmcecosse]

If it fails on 'balance' there IS something wrong -and I have to say fiddling with the adjustment will do nothing useful, unless one shoe has been rubbing all the time and has heated up and is therefore partly 'faded' . Another test after a brisk run with braking - feel the drums - are they equally hot?? So - where is this unbalance - front brakes? There must be a sticking piston - OR possibly shoes that have previously been contaminated. On a road test - if you brake hard 'hands off' (but hovering over the wheel) does it truly pull up in a straight line? One trick is to swap shoes around -putting one from each side on the other side...... This AFTER checking that each wheel cylinder really is free moving. Also check the rears - one stuck rear cylinder can unbalance the brakes too..... just an after thought - if there is any looseness in the suspension - especially tie bar front rubbers - this will cause the car to move on the road when braking.

[rayofleamington]

Generally the modern brake lining materials have a lower 'grip' factor as more materials have been banned (including asbestos..)
Therefore new shoes can reduce the braking ability vs foot pedal pressure.

Added to that, most new shoes I've seen recently are badly made - the diameter doesn't match the drum and the shoe ends at a different position to the originals, and the stiffness is different etc..
The diameter problem goes away when the shoes are bedded in, however until that happens they are even more ineffective.

Therefore, if you need to replace brake shoes, the best recommendation is NOT to do it just before the MOT

I've had all kinds of problems on brake tests at MOT's - including brake balance. A few years ago I had an unused Minor fail on brake balance despite the cylinders not being seized/stuck etc.. To get it to pass I took it out in the evening and drove hard for 30 miles - that settled the brakes back in.

[E J W Harrison]

Thanks, both for your ideas.
Having exchanged one of the shoes of the LHF brake for the same shoe on the RHF brake, miraculously the brake balance appears to have been improved and the car has now achieved an 'MOT pass'
This was the tip from the Morris Minor owners club website.
This is still strange as it has done virtually no mileage since the last MOT which it passed