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MG MGB Technical - rear brakes

I have troubles in getting my rear breaks working very well. One of the brake drums is scorred. Does anyone know what the max diameter is? I'm thinking of having it turned out.

The second problem is that the handbrake is not working properly. I suspect that the notches in the handbrake levers are worn out. Has anyone the dimensions the notches have to be, so that I can weld them up?

Thanks,

André
André

Andre',

The maximum diameter is stamped on the brake drum, although I think it is expressed in minimum wall thickness. Your machinist can tell you whether is can be turned. If you can turn it, turn both.

As far as handbrake lever--If the teeth are worn, I'd renew. If just not grabbing, I'd wait till rear brakes are reassembled. It may be related to generally worn shoes, unadjusted shoes, or stretched cable. HTH

Paul
Paul Hanley

Paul,
I am just new at this and went through brake rebuild recently.
I am not mechanically inclined, so these guys helped me through it.

You didn't say what car you have, but on my 72 mgb roadster it just seems spring loaded and no teeth.

I originally had the drums turned down, ordered new wheel cylinders (used a 5/8" snap ring instead of clip that came with them) and replaced all the springs, cleaned and lubed adjuster assembly.

Once I got the drums on and adjusted to just a slight touch of the shoes statically, I put the wheels on.

My emergency brake wasn't holding. So I pulled the emergency brake cable about 4 clicks and turned in the adjuster until I got a decent grab on the drums. Then I took off the emergency brake and spun the wheel by hand. I still had about 1 1/2 revolutions before it came to a slow stop. Seemed about right. The emergency brake and running the car, brakes seems about right.

Paul is correct, it has a minimum wall thickness stamped on the drum and they checked it at the shop. It cost me $7.00 per drum. First place I called wanted $28.00. So, can save a little money calling around for drum turning.

Best regards,
Doug
DT Toms

Another possibility is that I messed up the handbrake levers. I'm a bit confused about the handing: how can I find out wich one goes on the LH side and wich one on the RH side?

Is the picture in the haynes manual correct?

Is the short part of the lever on top, or under the longer part?

Thanks for your help

André
André

Hmmm, an interesting point. My first thought is that it should be fairly obvious as there isn't much space there and one way round might foul something else more than the other. I've got some pics of shoe orientation at http://www.mgb-stuff.org.uk/wn_brakesframe.htm and click on 'Rear Shoes' but they don't show the levers. My Leyland Workshop manual and Haynes both show the shorter lever over the longer lever, with the bend in the long lever going up over the slave cylinder and back down again to the front shoe, which is why I'm thinking it wouldn't fit the other way.

As far as the notches in the levers go yes they do wear down, and for the best effectiveness of the handbrake they should be such that when it is applied the cable should be at right-angles to the part of the lever it attaches to. When the notches wear you have to pull the lever out further, which increases the angle between cable and lever, and the further away from 90 degrees it gets the more braking effort you are losing. I have welded mine up a bit, you will have to gauge yours by eye to start with then use a bit of trial and error, I suspect, they were never a precision item. It also depends on how close the shoe dimensions are to the originals, lining thickness etc. i.e. don't weld up the notches to the ideal point if the linings are nearly worn out or the angle will be too much the other way with no shoes, which until they bed in will be even worse than good old ones.

For best effectiveness the cable must be lubricated in its sheath, and I always remove the shoes and put a smear of grease on every metal-to-metal contact point between cable, levers, shoes and backplate.

But the handbrake was never very effective anyway, certainly not an 'emergency' brake as some call it, it is only ever a parking brake. Whilst I can't lock my rear wheels with the handbrake (as hard as I'm prepared to pull it anyway) when driving if I push either car out of the garage and down the short slope of the drive, when I lean in the cabin to pull up the handbrake and stop the car they do lock then.
Paul Hunt

Paul,

Thanks for your reply
I had your website already in my favorites (and printed out a few objects to have in my workshop), but looked again at the pictures .

I think that it is possible to see that the part of the lever that goes thru the backing plate is on the UNDERSIDE: i believe that the longer part of the lever can be seen the the hole in the brake shoe...

What do you think? Maybe you have the original picture to compare...

I'm sure that it IS possible to get the handbrake working properly. With my previous setup it was no problem to make (even high speed) handbrake turns...


Thanks,

André
André

No originals showing anything any clearer, and the Parts Catalogue drawing does show the short lever through the back plate under the long lever, so you could be right, but that contradicts the other drawings. My back doesn't allow me to go and have a look at mine at the moment, one way almost certainly will fit better than the other.
Paul Hunt

Hi All,


Problem solved!

Powerfull handbrake is back!

yes indeed, the picture in the Haynes manual is wrong: The short side of the lever has to be on the UNDERSIDE

Paul,

Your you are right. It can be fitted in both ways, but it is easier if the lever is on the underside.
I greased every contact point as you suggested.

Take care for your back.

Marius,

Thanks a lot!
I will contact you off-line on monday


Regards,

André
André

This thread was discussed between 28/09/2004 and 02/10/2004

MG MGB Technical index

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