Low Brake Fluid

[af3683]

I took my TR-3 for a ride today and the brake pedal seemed mushy and needed to be pressed almost to floor. I checked the brake fluid and noticed that there is maybe 1 1/2 inches of fluid in the reservoir. Is it worth filling the reservoir up and see if that "solves" the problem? Maybe I should assume it is a rear wheel cylinder (both rebuilt 1 year ago) and get the car up on jack stands and take off the wire wheels, hub adaptors and brake drums. Any help would be appreciated. Thanks.

Art

 

[Geo Hahn]

That (1.5") is enough for brakes (should be fuller though). I would be looking for a leak -- on a clean floor is should be easy to spot. If no leak and the problem persists I would begin to suspect the master cylinder.

 

[Andrew Mace]

With disc brakes, the fluid level in the reservoir will drop somewhat as the pads wear and and the pistons push (and stay) just that much further out. Also worth checking -- beyond any obvious leaks -- is rear brake adjustment, of course!

 

[af3683]

I felt around the rear wheels and did some sort of fluid inside of the right rear wheel and tire. I guess it is the wheel cylinder. My mechanic disassembled and cleaned both wheel cylinders about a year ago because they were frozen due to the car sitting for several years. I wonder if I should attempt to clean it or rebuild it once again. Probably should just buy 1 or 2 new wheel cylinders.

Art

 

[Andrew Mace]

I felt around the rear wheels and did some sort of fluid inside of the right rear wheel and tire. I guess it is the wheel cylinder. My mechanic disassembled and cleaned both wheel cylinders about a year ago because they were frozen due to the car sitting for several years. I wonder if I should attempt to clean it or rebuild it once again. Probably should just buy 1 or 2 new wheel cylinders.

Even if the mechanic renewed the seals at that time, there's a good chance that those cylinders have lived a long and fairly useful life...and that it's time for them to step aside in favor of new replacments!

 

[Geo Hahn]

I agree, with replacements less than 20 bucks there isn't much point in futzing around with rebuilds.

 

[TR3driver]

All depends on the quality of those replacements. $20 seems awfully cheap for an alloy casting with precision machining and a steel insert. But some alloys are cheaper than others, and non-precision machining costs less, and ...

It's your choice of course, but personally unless there is something definitely wrong with it (like, in this case, pits in the bore), I lean towards rebuilding rather than replacing. And rebuilding a TR3 rear brake cylinder is trivial.

 

[Andrew Mace]

Rebuilding usually is my preference as well, unless there is physical damage that cannot be corrected...and I probably should have finished my thought thusly in my earlier post above. Several years ago, I tried to save a friend of mine some money by opting for the "aftermarket" wheel cylinders instead of OE Lockheed on his MGA. Aside from the fact that the rear wheel cylinders took a good bit of filing and reshaping of the backside to get them to fit and slide in the backing plate properly, I just didn't have a good feeling about overall quality and durability of the replacement cylinders. In this instance, the original wheel cylinders could not have been saved, so replacement was the only option. But if I were to do it again, I would do it only with genuine Lockheed (assuming -- given the price -- that they are still of the same quality they've always been). And I'm pretty much the same way with OE Girling (Lucas, TRW and/or whatever other name they go by and/or are sold under these days)!

The other "issue" these days with rebuilding is finding good rebuild kits. In the case of Girling (Lucas, TRW, etc.), apparently some rebuild kits simply are no longer available, and some aftermarket rebuild kits just don't cut it (IMO)! :frown:

 

[af3683]

Thank you all for your help. I'm looking to purchase some Castrol GT LMX Brake Fluid which is extremely difficult to find. Besides ordering it through Moss or TRF does anyone know of any retailers who sell it? Also, does anyone know what the capacity is of the TR3 braking system? I'm trying to figure out how many 12oz or 32oz containers to get. Thanks again.

Art

 

[Andrew Mace]

Here in the Albany (NY) area, Pep Boys stores have carried GT LMA for years, and at a pretty decent price for the quart bottles!

 

[af3683]

Is it absolutely necessary to replace brand new rear brake shoes if a leaking wheel cylinder causes some brake fluid to get on the shoes?

Art

 

[TR3driver]

Only if you want the brakes to work.

 

[Andrew Mace]

To some degree, DOT3 or DOT4 can be flushed away with lots and lots of water, but even that probably won't really get rid of it all (and I very much doubt you could do anything like that with DOT5). I'd replace the linings, especially if only one side leaked, as I'd worry about the resulting imbalance from one set of linings not working as well as the other side! Of course, I would replace both sides to keep a matched set!

 

[TR3driver]

To some degree, DOT3 or DOT4 can be flushed away with lots and lots of water, but even that probably won't really get rid of it all

We tried that (along with soap and a scrub brush), years ago, on a buddy's MGA. Got the shoes to where they looked and felt dry, not oily. But the fluif had apparently soaked into the pores of the lining material, and when the brakes got hot it would ooze out and coat the drum again. When we tried heating the shoes with a propane torch, we could see the fluid oozing out. Spent a long time alternately heating them and wiping the fluid away, never did get them completely dry.

The experiment with trichloroethylene in a heated ultrasonic bath was inconclusive though, as it also dissolved the bonding between the linings and the shoes.

The worst part is that it can be hard to tell if the rear brakes are doing their part or not as the front brakes do 60-70% of the stopping anyway. But in a panic situation, it can be really unpleasant to only have 70% brakes!

 

[Andrew Mace]

Again,

I think the only real chance for success in flushing brake fluid off (not necessarily out) of linings is if you catch the leak as it has just started and certainly before there have been many (any?) cycles of brake application that might warm up the shoes and/or otherwise help to get the lining material well soaked with the fluid.

And yes, while front discs really do most of the braking, having uneven braking from the rear can still create some interesting situations (and laundry chores)! :shocked: