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MG MGB Technical - Rear Brake Adjust

I need to adjust the rear brake shoes and according to Bently, you adjust using the square shaft on the brake back plate. It turns very hard and doesnt seem to move the shoe outward, with the drum off. Is it normal for the shaft to turn hard? Thanks
CW Strong

CW,
Normal - No
Usual - Yes (depends on who owns the car)

Since you have the drum off, remove the side retainer caps and springs (with pins), grab your brakeshoes on both sides of the adjuster and pull them apart and out (away) from the adjuster. As you release them and they come back together, the upper springs will probably fall out. Now you will be able to remove the adjuster. It's secured with a pair of nuts on the backside of the plate. The screw adjuster come out the front side. You might need some spray lubricant to loosen it up. Clean it well and lub all internal parts and threads. Check function before you reinstall. Should work fine after.
Steve Buchina

I typically squirt the adjuster with penetrating oil a few minutes before I attempt to adjust. A few drops of engine oil after adjustment is complete doesn't seem to hurt either.
Barry
Barry Parkinson

CW,
I back the square adjusting shaft all the way out. Coat the threads with red grease and tighten all the way in until the wheel will not turn. Then I back the adjuster shaft off two quarter turns. Wheel should be just free to turn. Has woked a treat for me the last 15 years.
Dave
Dave Kalp

I can't take credit for this idea, but here's a quick & dirty adjuster tool:
http://www.mgcarz.com/adjuster.html

HTH!
Rob Edwards

The adjuster needs to be fully unscrewed (shoes removed), greased, fully screwed in, then more grease applied on the outside of the threads. Then as you screw it in to make the adjustment it forms a sealing ring round the threads which helps prevent the ingress of water, salt etc. On a daily driver this needs to be done at least once per year. The internal end of the adjuster is conical with four flats on it, so you have to move it in increments of a 1/4 of a turn. When getting near to too tight it does get much harder to move it from one flat to the next as between the two flats the shoes are being pressed tight against the drum. You will have to experiment as to how much it needs to be backed off, my V8 needs to be backed off one more flat than the roadster or they tend to bind. When adjusting I also pump the pedal, pull up and release the handbrake a couple of times, then tap the drum with a mallet to reseat the shoes like road vibrations will. If you just turn it until it doesn't drag (it will still rub) it may end up coming looser on the road. After adjusting check the drums after a short run to make sure they are not too hot.
Paul Hunt 2

Paul Hunt, thanks, I took the shoes off, and the adjuster, it was frozen and took a while to unstick it using pentrating oil and muscle with the shaft in a vise. It spins freely now, Im sure that is first time in years it has been worked over if ever.

What kind of grease should one use on the shaft?

What brake fluid is suitable for filling the master cylinder, IM told Dot 3 isnt good, Dot 4 is. Any thoughts?

thanks again
CW Strong

I use copper anti sieze on mine, I just carried out the annual out 10 clicks smear with copper grease back 10 clicks on Monday evening. They are a fine thread and are prone to freezing but this pair went on in 1996 and so far so good
Stan Best

Castrol LMA DOT 4 brake fluid. Ray
RAY

I use copper grease as well, although any grease will be better than none. Every BL car I have been involved with has come with these either siezed or very stiff, but never again during my ownership.
Paul Hunt 2

Paul I did as you suggested and took them off on cleaned them on the work bench, what a difference. When adjusting one can actually feel the indentations click. I used anti galling copper permatex grease on the shafts and conical heads. Seems good to me.

Now on to the other problem with the brakes, when I took the other hub off it was leaking oil. A big huge greasy mess. I replaced the seal and reinstalled the hub. The manual calls out 150 ft lbs on the nut which isnt a big deal but I dont see that it does much/critical. Am I missing something?
CW Strong

The splines have a certain amount of clearance, else you'd have to use a press to fit the hub. If not adequately tightened, the hub works to and fro on the splines, wearing both hub & shaft spline, and also the tapered collars. This causes evil things, including an oil leak that bypasses the seal - different from through a worn seal. Effectively, the car is driven by the tapers if all is right.
FRM
FR Millmore

This thread was discussed between 25/08/2006 and 05/09/2006

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