MG-Cars.net

Welcome to our resource for MG Car Information.

Recommendations

Parts

MG parts spares and accessories are available for MG T Series (TA, MG TB, MG TC, MG TD, MG TF), Magnette, MGA, Twin cam, MGB, MGBGT, MGC, MGC GT, MG Midget, Sprite and other MG models from British car spares company LBCarCo.

MG MGB Technical - Rear Brake Adjustment

I adjusted my rear brakes until I felt a good drag, turning the drum by hand, if I take 1 turn back the drum turns freely. I noticed that I can only pull up the handbrake about 2 clicks, prior there were more clicks required to set the brake. My feeling is that the brakes will wear themselves in, and if I can turn the drum by hand, it will be OK. Still, I would hate to have to much drag slowing me down. Another click on the adjuster and the drum will lock tight. Is this how most of you go about adjusting the rear brakes?
Joe

Joe - Your method is good. Just make sure that the wwheel turns easily once the adjustment is made. Any drag will cause the brake shoes on that side to heat up and increase the drag, which causes more heat, which... I think you get the picture. I had this happen to me once when I tried to get the last little bit of adjustment on the brakes. Wound up stopping on the road to back off that last click when I started smelling the brake shoe burning. Cheers - Dave
David DuBois

Joe, I would also back the handbrake cable adjuster off to insure the cable isn't affecting your normal brake shoe adjustment. After the brakes are adjusted you can adjust the handbrake adjuster for 4-5 clicks to set the brakes. Normally the handbrake cable doesn't require adjusting but 2 clicks is too tight.

Clifton
Clifton Gordon

The Bentley's workshop manual advises 3-4 clicks rather than 4-5 clicks. I have been following this for years with no problems.

I recently adjusted my brake cable to achieve this after a brake adjustment and noticed both a firmer pedal and a more consistent pedal height before getting firm. The cable adjustment does indeed affect the overall brake adjustment.
Richard Smith

Joe,

Someone has tightened the cable adjuster rather than adjusting the shoes at the backplates. As this has happened you now need to go over both cable and backplates adjustments. In future you will then only need to adjust at the backplates;

The cable should be fully slackened off; the lever down and cable adjuster slackened. Tighten the brakeplate adjusters to just lock the brakes, then back off 1 or 2 flats so the wheels are free to revolve.

Then the cable should be adjusted to give about 5 clicks. I say about as all that really matters is that the cable releases the brakes so the wheels are free when released, but still has "reserve travel" left when engaged.

This last point has changed or been clarified, in the UK at least, but you may want to check local law. 30 years ago some MOT examiners would fail a car with 6 or more clicks and B handbrakes always needed tweaking to get through.

Now though the regs say there needs to be reserve travel and Bs will pass with 10 clicks. Don't ask me how an examiner is expected to know how much travel's left in the system??! but that's the case. With a B there are about 17 clicks available.

I bought my car from the PO last year after he had put a new MOT on it. I showed the skyward pointing lever to my friend who is a Rover MOT examiner and he explained the UK regs.

Rich.
Rich

I see the shop manual also reads 3-4 clicks I looked at Haynes for my first post and it does say 4-5 clicks.
I don't agree the handbrake cable should be adjusted so tight it pulls the brake shoes off their adjusters. Even if it is too tight I don't see how it could affect the pedal firmness.

Clifton
Clifton Gordon

I am not sure myself how it can affect pedal height, but on mine it does. 3-4 clicks is not too tight as I still have a tiny amount of slack when the brake is off.

You MUST, however, ensure that the cable is sliding freely in the sheath and that the equalizer lever on the axle is well greased and moving freely. If this is not the case, you will have a problem with full release at 3-4 clicks when the handbrake is off.
Richard Smith

Richard

It's affecting pedal height as you are effectively using the handbrake to adjust the rear brakes. That is, because you've tightened the cable, the backplate levers no longer return enough to allow the shoes to push the wheel cylinder pistons back.

In effect, you have transferred the adjustment from the top adjuster to the bottom handbrake levers. This may be no big deal but if the cable does stick pedal height may vary.

I'd slacken the cable, adjust with the backplate adjusters correctly (locked then back 1 or 2 flats til wheel free) then readjust the handbrake cable to 4 or 5 clicks. This will put adjustment back onto the brakeplate adjusters.

Rich
Rich

Rich,

What I have been trying to say is that with a truly free cable, I have been using 3-4 clicks for years without dragging and the brakes shoes are free when the handbrake is off. Yes, it is true that, to some small degree, this affects the brake adjustment.

However, I have had complete success with it for several years and that is what the factory recommended. I have had better brake performance and there certainly has not been any more brake shoe wear (current shoes have at least 40K miles and have been on the car for about 7-8 years and they are fine right now with almost 1/4 inch of lining left).

I do not understand the resistance to using the factory spec. I have been only reporting what I have been doing for years and that it has been successful.

Another small point is that the brakes MUST be adjusted using the adjusters PRIOR to adjusting the cable.

Also, it might be wise to confirm that the shoes have been assembled in the correct orientation on the backplate. Check the picture in your Bentley's manual and you might be surprised to find that someone in the past has not correctly assembled the brake. The shoes must have their leading and trailing edges in the correct orientation and the springs must be in the proper holes. Otherwise, you can get the situation you describe.

Just what is 'reserve' travel anyway? I live in a hilly area and the handbrake must be fully applied to prevent the car from rolling. If the handbrake is fully applied there is no 'reserve' travel left as both ends of the shoes are fully up against the adjuster at the top and against the handbrake lever at the bottom. When my handbrake is applied, the top adjuster cannot be turned any tighter at all but can be when the handbrake is off.
Richard Smith

Hi Richard

<<The cable adjustment does indeed affect the overall brake adjustment.>>

This is the point we differ on. If your cable is truly free when the handbrake is off then the cable should make no difference to the foot pedal.

Following the manual is the best way as you say but many find you can only get a handbrake that works on 3-4 notches AND releases the cable fully if the shoes are very closely adjusted, ie to the "loosen only 1 notch" that the manual also says.

If you adjust the cable to get that 3-4 notch handbrake but the shoes are not very closely adjusted then the handrake takes over as adjuster.

Rich
Rich

<<Just what is 'reserve' travel anyway?>>

Movement (notches) available in the lever after the brake has been put on hard enoough to meet the braking spec. A B has around 17 handbrake lever notches so if it took 10 to put the brake on it would have 7 in reserve.

<<When my handbrake is applied, the top adjuster cannot be turned any tighter at all but can be when the handbrake is off.>>

The top adjuster should only be adjusted with the handbrake off and slack in the cable. It should be tightened til the wheel locks then backed off just 1 notch according to the manual - though you may need 2 notches to let the wheel revolve freely. If the shoes aren't adjusted closely like this first, and you then go on to set only 3-4 notches on the handbrake cable, the handbrake levers on the brakeplates will be adjusting the shoes instead. This is when you find <<The cable adjustment does indeed affect the overall brake adjustment.>>, forgive the quoting.

I've done these adjustments many times on many Bs. If the wheels are free with only 1 click backwards on the brakeplate adjusters then yes, you can get a 3-4 notch handbrake. If the backplate adjusters need 2 clicks to free the wheels you will only get a 5-6 notch handbrake without holding up the shoes on the handbrake backplate levers.

Rich
Rich

Are we talking about notches or quarter turns here ? The backplate adjuster works in quarter turns, yes it feels like notches if well lubricated but the tappets ride down four 90 degree opposed flats on a taper wedge. Having got that out of the way the footbrake must be initially adjusted with the handbrake fully released or disconnected if you wish. I dont believe that one notch(flat)is sufficient as there is too much binding. Two, if right in the middle of the flat is fine and that is the closest that you can set the shoes whilst avoiding any binding. It is also beneficial to set the handbrake with the rear wheels on and tightened as this ensures that the brake drum is in full and firm contact with the axle flange,

Then adjust the well lubricated handbrake assembly until it just about starts to move the lever arms which protrude from the backplate and that's it. If it takes 3, 4, 5 or 6 notches then so what. I suspect that 3/4 is not achievable but that 7+ becomes an MOT issue.

Don't forget that the handbrake link pivot inside the drum is a b----r for seizing. Make absolutely sure that it is free if not, remove it, free it and lubricate with a little copper grease.
Iain MacKintosh

We used to have problems every year getting the right handbrake to pass the MOT over here. Back then, every tester new Bs well, and knew they were set up with 3-4 clicks, so they would only pass them with 5 or 6 clicks max even if it worked fine and there was still lots of movement left.

BMC set them up so tight as they're not self-adjusting rear brakes. As the linings wear, both handbrake lever and foot pedal will have more movement in them and they had to ensure the amount of movement stayed serviceable til next time.

Rich
Rich

Hi Iain

All agreed exactly, except that you may be surprised at how many clicks you can now get away with in the MOT.

<<Are we talking about notches or quarter turns here ?>>

The BMC manual calls both the backplate adjusters and handbrake actions "notches".

I usually call them "flats" on the rear adjusters and "clicks" on the handbrake lever.

Rich
Rich

Rich, the handbrakes on both my cars are very good. I donn't reckon that you could drive off with them on. I never have MOT problems with h/brakes but I guess mine may come on about 5 notches when applied hard. I'm sure you'll agree that's hardly important though.
Iain MacKintosh

Ah, we have now gotten to the meat of the matter - the initial brake adjustment.

And I have never had any problems with backing off 1 notch (flat or quarter turn) and having the wheel free. For those that do, I again recommend a close inspection of how the brakes are assembled. This is an are I overlooked for years and can be confusing. You must have the leading and trailing edges of the shoes oriented correctly.

If you can achieve 1 notch back-off, have the handbrake system completely free and lubricated, you can achieve the 3/4 clicks on the handbrake. And this situation does indeed improve the overall feel of the brakes because the pistons in the wheel cylinders are not withdrawn as far. If the pistons withdraw all the way into the wheel cylinder then more fluid is pushed back to the master cylinder. When you next push the pedal, the fluid will have to be pushed all the way back into the system and the first stroke will go down further. The second stroke will then be firm.

Granted, this situation creates its own problems as the pistons then do not travel as much over their life and this can lead to stuck or frozen pistons due to lack of movement.

As far as a 'reserve' requirement goes, I think the MOT folks have a screw loose and are not thinking. The only requirement for the handbrake, safety wise, should be simply that the brakes are indeed fully engaged when the handbrake is applied.

For goodness sakes, ANY MGB owner should be able to tell something is amiss if his/her handbrake is taking 10 clicks to set! If mine gets to 6-7 clicks, I know my brakes need adjusting and I will also be having a long first stroke on the pedal (another indicator that the brakes need adjusting).

Since they are not auto-adjusting, brake adjustment is just another facet of proper MGB maintenance, similar to the 1,000 mile lube requirement and all part of the owner's responsibility as an MGB owner.

I defy anyone who does not have prior knowledge that the B handbrake has 17 clicks in it to tell me what the 'reserve' travel is. When the brakes become fully engaged, the lever will no longer move and 'reserve' cannot be determined without unadjusting the cable or otherwise disassembling something.

Another application of poor logic that seems so apparent in the world today...
Richard Smith

Ah ha. So the moral is that if you have a 17 click handbrake get the rear seat passenger to pull it on !! Seriously though Richard, glad you agree with it all.
Iain MacKintosh

Whilst the adjustment of the rear brakes and handbrake does affect the foot brake, if you look at the design taking the slack out of the shoe adjustment actually pushes the pistons *further* back into their cylinders. What makes the difference is that they then don't have to move so far out to apply the shoes to the drum.

Once the drum adjuster is set for minimum slack *and* minimum binding, you then set the adjuster screw up by the handbrake lever to give the required number of clicks. The thinking behind the MOT requirement is that anyone who puts up with 17 clicks on the handbrake isn't taking care of their car and deserves to be awarded with a failure.

Orientation of the shoes has no effect on pedal and handbrake travel, but it *does* have an effect on rear brake effectiveness. Get them the correct way round and you get maximum forward retardation and minimum reverse retardation! Each shoe has the lining material offset to one end. When they are correctly orientated, and when travelling in a forward direction, a point on the drum will pass over the 'empty' end of the shoe before it reaches the lining. All four shoes i.e. both sides should be orientated this way.

But at the end of the day it is only a parking brake. Whilst rolling either of my cars out of the garage and down the slightly sloping drive, and leaning in to pull on the handbrake will lock the rears, when I am sitting in it they will not, neither do they give much retardation in comparison, and I'm no great weight! Some call it an emergency brake, but if you need to use the foot brake and find it has failed, pulling on the handbrake is about as effective as Wile E. Coyote flapping his arms after being suckered over a cliff by Roadrunner.
Paul Hunt

This thread was discussed between 10/04/2005 and 15/04/2005

MG MGB Technical index

This thread is from the archive. The Live MG MGB Technical BBS is active now.