Brakes!

[radioactiveman]

So I've got a weird issue, it feels as if my brakes are a little on all the time. If I move off slowly the car doesn't roll smoothly to a stop it sort of gets to a low speed and stops prematurely almost as if the brakes are slightly on. I have drums and one of those servo things.

I've not really investigated anything yet. My initial plan was to start jacking up corners and see if any of the wheels don't turn completely freely. I understand from various YT vids that the shoes can be adjusted, so I did wonder if it could just be that?

[simmitc]

I think that you have the first stage of a plan - jack each wheel off the ground and check that it is turning freely. As you have drums and not discs, it is most likely a sticking cylinder or a seized handbrake cable. To check the adjustment, you need to remove each wheel to access a hole in the drum to reach the adjusters. Grab a manual for detailed instructions with pictures.

[radioactiveman]

Thank you for your response.

I did some investigation. The front two wheels spin as I would expect. I spin them and they rotate with no resistance (there's a small 'ch ch ch' but that's probably fine )

However, the back is very different one turns but with quite a lot of effort the other I can't spin (so that would probably explain the sensation when I drive).

(...and yes I took the handbrake off... )

So, I guess the next step is to take the wheel(s) off and see if anything's obviously wrong inside the drum?

Side note. When jacking....

For the rear I stick the trolley jack under the diff (no wood?) and put axle stands under the axle near the wheels (again, no wood)? Then a good shove to make sure it's stable.

[James k]

I suspect you have a seized cylinder on that wheel although it's plausible that it's just adjusted too tight. Probably seized, though.

Jacking under the diff is fine, as far as I understand. Just remember to chock the front wheels as you have no handbrake or gear on them. Axle stands under the rear axle and I always put the wheel I remove under the car as belt and braces.

[ManyMinors]

Well done so far. The problem could be caused by seized up handbrake cables, seized up wheel cylinders or the rear flexible hose could be perished and swollen up inside so that it acts as a valve, holding pressure in the rear braking system. For peace of mind, you could replace the lot of course as none of these items are expensive

[oliver90owner]

So I've got a weird issue, it feels as if my brakes are a little on all the time. If I move off slowly the car doesn't roll smoothly to a stop it sort of gets to a low speed and stops prematurely almost as if the brakes are slightly on. I have drums and one of those servo things.

I've not really investigated anything yet. My initial plan was to start jacking up corners and see if any of the wheels don't turn completely freely. I understand from various YT vids that the shoes can be adjusted, so I did wonder if it could just be that?

A little tip. Whenever you suspect something like this, check the drums when you stop after a run. A rubbing brake drum will be warmer than t’others. It can give you a head start for the diagnosis. Care needed if the problem is very serious, as the drums can get very hot.

[radioactiveman]

Thanks for the help everyone

Is there any way to narrow down the issue, or do I just need to start replacing stuff?

[simmitc]

It's examination. With the handbrake off, check that the cable is slack. Where it connects to the lever at the brake backplate, you should be able to move the lever back and forth with your finger. Ideally get an accomplice to operate the handrake inside the car whilst you watch at each wheel, and check that the cable pulls up and moves the lever.

Next, remove a wheel, rotate the drum so that you can see the adjuster and slacken it. If the drum is stuck then that's easier said than done, but you will need to slacken the adjuster in order to remove the drum. Also remove the drum retaining screws.

You can now remove the drum and examine the cylinder. When working, observe safety precautions detailed earlier. Also wear a mask to guard against dust inhalation and use a vacuum cleaner to suck away all dust that you find inside the drum. Gloves are always a good idea.

In the very worst case, you might need to destroy the drum in order to remove it, but I've never found one yet that was that bad.

[radioactiveman]

I did some more investigating...

I've checked the handbrake cable at the drum end. With the handbrake on the cable feels tights, with the handbrake off it feels different and waggle-able... which suggests to me it's not that the handbrake isn't coming off.

So I guess the next step is trying to remove the drum! Any tips for making it turn?

[Monty-4]

I had to do this on another classic revently. First I tried leverage - refit the wheel and see if it turns with the wrench on a nut once the car is off the ground. Alternatively put something long against the front of the drum and use it to turn the drum by pressing against the studs, try to use something softer than the metal so not to damage the threads (i.e. wood).

If it's stuck on after adjustment and/or if the drum has to come off - with a tube connected to the end and some fluid in a bottle at the other end of the pipe, loosen the bleed nipple to release any pressure in the brake cylinder. Tap the outside of the drum with a mallet to shock it (hopefully retracting the piston in the cylinder).

If you need to tap the ridge on the back of the drum forwards to get it off then be careful not to chip chunks off it, that was certainly done on my original drums.

If the piston is seized I would replace it.

[radioactiveman]

Good advice. At least I'm mentally prepared for this to take a long time!

I've just been out to have a look and compare with the myriad videos I've been watching and it doesn't look like I've got flexible hoses at the rear it seems to be solid all the way to the bleed nipple. Is that not normal?

[kevin s]

There is a single flexible hose near the centre of the axle just to the right of the differential.

[simmitc]

If you look at the workshop manual or one of the parts suppliers' catalogues, then you will see some very helpful diagrams depicting the layout of the system. Solid pipes on the axle, then a flexible pipe in the centre to another solid pipe on the body.

[jaekl]

The half shaft retaining screw should be accessible if the drum was put on correctly. It can be used as a jacking screw to get the drum starting. The drum will be crooked. After working it back and forth a bit with clocking the drum around, the drum might be able to be pulled past the shoes.

[radioactiveman]

Thank you all so much for your help. I'm very grateful!

I've been digesting the Haynes and BMC manuals (plus YT videos). I sometimes find the manuals can be a little esoteric; phrases like 'banjo union' and 'clevis pin' are somewhat new to me

Just a couple of things I'm not clear on.

Any DOT4 brake fluid is fine? I've seen debates about synthetic/mineral/silicone but I'm understanding that using DOT4 is just fine.

Bleeding.... My understanding is

1. Pop some tube over the nipple
2. Put the free end of the tube in a container with some fresh brake fluid
3. Crack open the bleed nipple
4. Pump the brakes until the clear tube is without any air bubbles
5. Close the bleed nipple
6. Remove the tube
7. Pat myself on the back

[panky]

That's how I do it, it's easy with a remote reservoir so keep a close eye on the master cylinder level if you haven't got a remote.

[simmitc]

Which fluid depends on what is in there at the moment - you cannot mix DOT4 and Silicone. If your current fluid is yellowish then it's DOT4, if it's mauve then it's silicone. DOT4 should be changed completely every few years, flushing the whole system. Silicone is better, but DOT4 is adequate.

[radioactiveman]

Hello everyone.

So, I went out today to look inside my rear drums. I was eventually able to get the stuck side free and once it was adjusted off using the pedal brake resulted in no resistance at the wheel so it seems that the cylinder is indeed stuck. So I will replace both sides when I can next be bothered

The second thing I noticed, potentially more concerning, is that the 'mating plate' behind the drum was a little wet with what seemed like oil. This was exactly the same on both sides...

I did a search through previous posts and it seems like that could be the axle seal leaking. I then also noticed that I have a bit of a leak from my 'pinion seal'... it seemed odd that all three were leaking so I wanted to check for overfilling and breathing. I took the filling plug out and I got a bit of a dribble of what seemed to be nice fresh oil so it was perhaps a little overfull but nothing dramatic. However, the breather was completely gunged up. It's impossible to tell if it was able to do its job, but it was very gungy. Could this have caused my leaking woes? It seems slightly wishful thinking...

Thank you

[oliver90owner]

Could this have caused my leaking woes?

Of course, it could. They did not fit the breather without good reason?

[philthehill]

The churning of the diff causes a pressure build up in the diff/axle housing and that pressure has to be relieved otherwise the pressure overcomes the hub and pinion seals and leaks.
The breather must be kept clear at all times.
Also there are drain holes at the rear of the backplate just under the axle tube. The drain hole allows any oil that has managed to get passed the seal to exit the brake assy and not contaminate the brakes. Any oil showing from the drain hole is a good indicator that the rear hub seal needs replacing.