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MG MGB Technical - Bad handbrake
|I am not happy with the handbrake on my ´63 MGB. It will hold the car on a not too steep hill if I pull hard enough, but as an emergency brake it is useless. I will have to work through the system to see if it can be improved.|
Drums and shoes are about two years old, and the rear brakes work well on the pedal. Any suggestions?
|Hello Tore, have you checked the the handbrake mechanism inside the brakes, if the pivot is siezed that will cause the brake to bind, but if the pivot is badly worn the handbrake will struggle to hold the car because it has lost a lot of tgravel taking up the wear. I had a similar problem with a mini years ago when excessive pivot wear caused the car to fail it's MOT test.|
Hope this helps
|The rear brake shoes need to be adjusted against the drums. When you do, you may find that the handbrake works much better. Brake pedal feel will be better also. It is a once a year task which looses its effectiveness gradually, so the change isn't real apparent until the rears are adjusted again.|
Just out of curiosity, when you had the drums and shoes renewed, did you have them arc the shoes to the drum? If you did, did you keep each pair of shoes with the drum they were arced to? It makes a difference.
|First tighten up the shoe adjuster on the back of the wheel until it binds, then back off a notch. This small square rod thing is located 180 degrees from the hydrolic piston. It screws in a cone/wedge that pushes the shoes apart. You'll probably have to take the wheel off to get at it comforably.|
Then tighten up the hand brake cable, where it attaches to the hand brake, under the car on the RH side of the transmission tunnel. The cable may have stretched over time (or be one of those "wrong lenght" versions) and you've run out of thread, so you might consider putting in spacer as I have done. A stack of nuts. If you put in a spacer then you will need to use a locking nut as well as the main one. This becomes obvious when you are adjusting.
Also keep in mind, 1960's English cars are not renown for their powerful handbrakes!
|The handbrake was *never* an emergency brake, and that goes for any car I have had in the past or now. It is a parking brake, no more, no less. If you go to apply the footbrake and find it doesn't work so grab the handbrake, prepare for impact! The amount of braking effect you will get from the rear alone is minimal, and they lock much more easily than the front. That is why the handbrake offers so little retardation on any car, if it locks the rear wheels easily you will probably get loss of control.|
Having said that BL handbrakes were never brilliant, and unless they got regular cleaning and lubrication they get even worse. First you have to remove the drum, shoes and springs noting carefully where everything goes and which way up/round. Then you clean everything and make sure the pivot on the handbrake levers (inside the drum) is free. Then you check the cable is free in its outer, grease the nipple, make sure the compensating lever on the back of the diff casing is free, and oil the pivot and where the cables attach. Then check the pivots between the cable ends and the handbrake levers are free, and grease. Then you work a *little* grease into the pivot on the handbrake levers, wiping off any excess. Put a thin smear of grease onto every metal-to-metal contact point between levers, shoes, slave pistons, springs and back-plate, and reassemble. Turn the adjuster as necessary, pulling and releasing the handbrake lever in the cabin a couple of times, and pumping the foot pedal, and tapping the drum with a mallet to settle the shoes, before checking the drum rotation. You will almost always get rubbing, but shouldn't get binding. Practice will tell you how much slack your car needs, I find my V8 needs one more click of free-play than the roadster or they bind. Finally count how many clicks you get at the handbrake lever in the cabin to fully apply the handbrake, should be about 5 or 6, but it should always go 1 or 2 without applying any braking effect at the drum to avoid binding. Having had many BL cars over the past 40 years I do this at each 3000 mile service.
|Paul Hunt 2|
|Thanks for your replies. Work to do!|
|The equalizer mechanism on the back of the rear axle is another place where efficiency can be lost on the hand brake. On all of the MGBs that I have owned, I have had to disassemble, clean and lubricate the equalizer to get the hand brake to work well. Cheers - Dave|
|I've had to heat some brake equalizers until they glowed to get them to free up. Of course did this with them off the car! Followed this up with a good wire wheel session and then some paint then grease. They worked well after that.|
|Paul I have to disagree with your statement that the handbrake is not an emergency brake, on a "B" this old it will have a single line braking system, therefore the handbrake has to be the emergency brake, if you have a dual line braking system then the secondary line is the "emergency brake". I agree that most handbrakes are fairly average in there performance, but they only have to achieve 25%g or above to be legal, any more performance from the rear brakes as you said would be very dangerous. It's important that the brake balance front to rear is kept as near to the design settings as posible.|
Thre biggest problem is owners buying no name brake components and then bitching that there brakes are no good. If you buy pads and shoes from a well known OE manufacturer then you stand a chance that they will have tested there products on both a vehicle and a dynomometer extensively.
|The handbrake on my car is quite effective, it always passes it's MoT holds on hills and when I have tried it to see how it would work as an emergency brake it stopped the car in straight line although nothing like as quickly as if the front anchors were available. It seems sensible to try this out in advance of actauly needing it on any car, even modern split hydraulics ones . It's the usual story of everything up to original spec, and maintained to stay that way, eg regular greasing of the equaliser which is easily accesible from underneath the car.|
|I meant from the point of view *retardation* the handbrake can only be regarded as a parking brake. But having said that if the footbrake fails then of course you are going to do everything you can to stop the car. But if you rely solely on the handbrake to stop you hitting the car in front, then either you fortuitously braked very early and very gently to discover the footbrake had failed, or you are going to have to take avoiding action, regardless of what you call it. The handbrake on *any* car is pitiful at slowing forward progress in comparison to the footbrake, and can never be regarded as a remotely satisfactory alternative in the event of failure of the footbrake.|
Single/split systems of the MGB are irrelevant, one circuit is the front and the other the rears, so it depends on which circuit has failed as to how much retardation you get. If the rear circuit fails you might not even notice, if the front circuit fails you are no better off than using the handbrake. More recent cars have diagonal braking i.e. one front and the diagonally opposite rear on one circuit and vice-versa on the other, but try that on the MGB and as well as losing have the braking effort it will throw you into the nearest hedge or crash-barrier. Even more recent is dual circuits to each caliper, which results in balanced braking but effectiveness is still reduced by about half.
One of the silliest 'improvements' is where people fit uprated calipers and pads thinking they are going to get better braking. Braking effectiveness - unless something is very wrong with the braking system - is solely dependant on tyre to road surface contact on road use at least. Uprate caliper performance and all you gain is the ability to lock the front wheels with lower pedal pressures. And all that does is reduce overall braking performance, because you have reduced the effectiveness of the rear brakes.
|Paul Hunt 2|
|Adjusted the brakes and had a good look underneath the car today. Everything is moving freely, but the two year old cable is at the bottom of its adjustment. It has the right part number, but probably just is too long. I will try some spacers, and I will also have a look inside later to see if wear in the mechanism is the reason.|
i bought two hand brake cables only to learn that reproductions of this item are too long.
If you take off the seat and drill a new hole a bit more to the rear, it will work fine.
For closing the old hole you can use a rubber plug or tape, as i did. In my car (1973 V8) it has workd since more than a dicade up to now.
|When my V8 handbrake cable started break strands from corrosion I replaced it with the one I had taken off my roadster when I converted it from steel wheel axle to wire wheel axle. That had been on the roadster many years, and they do stretch over time. I just shortened the inner that runs from the pivot on the diff casing to the right rear wheel, by clamping a 1" block betwen the nipple on the end of the cable and the pivot. Much easier than removing the seat and redrilling the tunnel, for which when the cable is replaced you will have to put it back again.|
|Paul Hunt 2|
|All the hanbrake cables seem to have the outer too short these days. Last time I changed mine I went to a lot of trouble to get the right one, it was worse than the one I took off. I went back to Summit where Mike went into stores and laid out every part number in stock on the floor. I took the one that looked closest and it worked fine, but it was not the one specified.|
|Also check that there is no oil leaking into the drums from the rear axle. I replaced my brake shoes and they were shot after just 2 months due to oil a leak, because I forgot to change the rear axle seal.|
|Or the brake cylinder is leaking.|
I just had to change mine yesterday. I went to drive it after 2 weeks and the pedal went almost to the floor!
This thread was discussed between 24/04/2007 and 30/04/2007
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