[Raccoon]

Recently got my Esteem's oil changed at an MASS. While the car was on the ramp, I noticed the rear left wheel wasn't rotating freely. Pointed this out to the supervisor, and he asked the mechanic to open the wheel assembly. On opening, one of the drum brake shoes was found to be binding.

The reason for the bind was that the brake cylinder had jammed. They also pointed out that the brake drum had many grooves on it. They asked me to change the whole wheel assembly including the brake cylinder. That would also involve bleeding the brake fluid and replacing it.

Since it was late in the day, and the job would be time consuming, they asked me to bring the car the next day for the job.

Meanwhile, I went to another MASS for some other job. Asked them to look into the above matter. They opened the assembly again but this time the supervisor told me that only the brake cylinder may be replaced. He said the grooves on the brake drum will not affect anything and need not be changed. However, they did not have the parts and hence they said we will try to fix it without replacing anything. The mechanic just removed the rubber casing around one of the brake cylinder pistons and dabbed a rag soaked in KBX brake fluid, and then just tapped the piston with a hammer. The piston was rendered free without much effort. I was told that it was working fine now (I checked myself too), and its not really necessary to change the brake cylinder. While on the ramp, the wheel was now rotating freely and the wheel stopped rotating as it should, when brakes were applied.

My question is do I really need to replace the brake cylinder AND drum? Or would it be safe to continue using it, since everything seems to be alright? Is it likely that the cylinder that was tapped with a hammer may start leaking and lead to loss of braking? And is it ok to keep using the drum which has grooves etched on it? Will this cause premature wear of the brake shoes?

Hoping for advice from those who really know, as brakes is a serious issue and I'm getting conflicting advice from both the service centres. I'd rather not open everything again and spend more, unless of course safety/component life/efficiency is involved.

Thanks a heap in advance.

[CrackedHead]

The fact that the brake cylinder jammed indicates that the brake fluid is ancient (never drained and replaced as part of preventive maintenance). A thread exists on this topic - please search.

Also, the rubber parts in the brake cylinder deteriorate over time and the cylinder tends to leak.

The minimal work that I would recommend would be to remove and inspect the wheel cylinder - if the cylinder walls show signs of scouring then the cylinder must be replaced.

If the insides of the cylinder look ok then you can change the rubber kit and use the same cylinder. In either case, drain the brake fluid and refill with fresh fluid.

You haven't mentioned the age of the car (and the last time the brakes were overhauled). Please update the thread with these details. If the brakes haven't been looked at in the last 4-5 years then I strongly recommend that you follow the same advise for all the wheels and the master cylinder.

The old rubber parts could cause a leak in the cylinders and leaky brakes are extreemly dangerous when it comes to panic braking situations as the car drifts (sharply) to one side.

[Raccoon]

So sorry for leaving that bit of info - the car is about 7 - 8 years old. It has done over 47 k km. I'm not sure when the brake fluid was replaced as my dad was looking after the car for sometime. The car was however given at the MASS for 40 k km servicing last year and its pretty likely they replaced the fluid as part of that. But since I can't be sure, I guess I better get it replaced soon. I don't feel any "sponginess" in the brakes though.

The minimal work that I would recommend would be to remove and inspect the wheel cylinder - if the cylinder walls show signs of scouring then the cylinder must be replaced.

So the small cylinder can actually be taken apart to look at the cylinder walls?? I Hope they will be ready to do that at my usual MASS... they are all about straightaway replacing parts and not repairing them.

So a jammed cylinder almost always means the brake fluid hasn't been replaced?

And is it ok to keep using the brake drum in spite of the grooves on it? Any idea what caused the grooves? Particulate dirt, I reckon?

[CrackedHead]

The brake cylinder has two pistons (one on each end) that get pushed out and press the brake shoes against the drum. These pistons have rubber rings that ensure that the cylinder does not leak (just like the piston rings in the engine).

But if the cylinder walls are too badly damaged - then replacing the rings will not help, you'll need to replace the cylinder. See - http://www.team-bhp.com/forum/1344590-post21.html

IMHO - MASS don't replace the brake fluid - they tend to overlook things like that and the age of the fluid would have caused the brake cylinder to jam. Read thru the rest of that thread.

Yes - the brake cylinders can be taken apart to look at the insides. For the re-assembly, you'll need whats called the "rubber kit" or the "wheel cylinder kit". This "kit" consists of new rubber rings that fit onto the pistons and the boot that goes on the outer end of the piston (to prevent dirt from entering the cylinder). These kits are in-expensive, should be less than Rs 50 per cylinder. The re-assembled cylinders work well. Ditto for the master cylinder.

The MASS that I take my car to has done this for the rear brake cylinders of my M800 a couple of times. If any cylinder shows signs of wear and tear on the inside surface then you must replace it. Buy only the original parts and replace the brake fluid also.

[Raccoon]

Thanks so much for the insight.

The pic on the link you sent is however too small to make out anything useful. :(

From what you have described, I can tell that the mechanic removed the outer boot and then dabbed the part with a rag dipped in brake fluid.

I wish either of the MASSs had adviced me on the lines of what you said. The MASS where I do the regular servicing simply said that we don't repair, we only replace... so just replace the whole cylinder! That makes me think, is this "wheel cylinder kit" you mentioned a MGP? Apparently neither of the MASSs have that kit. But if it is in the cataloge and has a part number, I could get them to order it.

Also please do advice on the following if possible - Is it ok to keep using the brake drum in spite of the grooves on it? Any idea what might have caused the grooves?

[CrackedHead]

Originally Posted by Raccoon

That makes me think, is this "wheel cylinder kit" you mentioned a MGP? Apparently neither of the MASSs have that kit. But if it is in the cataloge and has a part number, I could get them to order it.

I don't know if the "wheel cylinder kit" is available as MGP but iv'e used such kits. These are freely available in spare parts shops and come packaged from the OEM brake supplier. "TVS-Girling" is the brand and the friendly neighbourhood spare parts dealer should have these in stock.

The metal surface on the inside of the brake cylinder deterioriates over time (due to mechanical wear and tear from the moving piston) - so the insides of the cylinder must be looked at before deciding if its safe to rebuild them with the kit.

If the insides of the cylinder are showing any groves/visible damage then replacing the rubber rings is not safe - the cylinder must then be replaced.

[Raccoon]

^^^ Thanks a heap again! If the kit is not MGP I'd be very wary, esp since its a brake component. But if it is from the OEM brake supplier and is genuine, I guess it should be safe enough. Will try to see if available somewhere...