Brake problems

[Phil73]

I've been struggling with a problem in my brakes for a number of months now. The symptoms are a soft pedal, pulling to the right under hard braking and a rattle in the front end over rough pavement (goes away if the brakes are applied).

A month ago I completed a full rebuild of both front calipers but that had no impact. I re-bled the lines to no effect. I also replaced the flexible lines a year ago.

Yesterday I attacked the problem again. I've pulled everything from the front junction forward out of the car. I plan to thoroughly clean and check all the lines. I'm also going to switch the flexible lines from one side to the other and see if the pulling move to the left side (unlikely but I might as well eliminate the question).

As I was pulling things off I got to thinking about the bearings. 15 years ago when I restores the car I cleaned and repacked them but they have not been touched since then. Wondering if the source of my problems might not be in the bearings causing the disk rotor to wobble slightly. I feel no play when I check the bearings by rocking the wheel but I'm not all that familiar with good vs bad bearings so I might be missing something.

Should I just go ahead and pull the hubs, clean/repack the bearings and put them back together? Anything in particular I should look at when they are off? Given that the bearing are at least 15+ years old (more likely they are 35+ years old) should I just replace them? Hate to sink hundreds of dollars into parts I'm not sure need replacing though. Like I said, not much experience messing with bearings so I'm a little blind here.

 

[tomgt6]

My guess is one of the cups is stuck or not pushing even so this is causing the issue.

 

[Phil73]

That was my original thought but after removing both calipers, splitting the halves, cleaning out all passages, replacing the pistons and reassembling with all new seals I have to think my calipers are working right. If not I can't think of what else to do to them.

 

[Marvin Gruber]

Are your rubber hoses new, old ones swell up and cause big problems. If you can't blow thru them, change them out.

Marv

 

[TFB]

Phil,
You said soft pedal,which could mean
leak by in the master,or more likely to much travel in the drums from the shoes not being adjusted,usually not a problem with disc brakes ,as they always are dragging a little.
Air would pump up.and you said you bled, and the oft pedal is more noticable on first stroke.
The car pulls to to the right-thats the side thats probably working.
I would suggest check left rear brake(or both r/l) clyinder for movement,and check rear brake adjustment.
Have Fun
Tom

 

[Phil73]

Interesting. The front brakes are on one hydraulic circuit and the rears on another so I assumed the proper (or improper) functioning of one would not impact the other. Was that a bad assumption? I've paid zero attention to the rear brakes throughout this brake odyssey I've been on.

 

[TFB]

Phil,I have general mechanical knowledege,but am just getting into my tr3,so excuse any incorrect assumptions on my part.
You said two circuits,but I think it is only one,as one master cyl,with a restrictor,balance valve,porportioning valve or whatever they call it but its one circuit.
if you can get all 4 off the ground and have someone lightly apply pedal while you spin the wheels to see difference it might reveal the problem,or an inspection of drums mightr reveal problem.
Lots more stuff to rattle in the drums also.
Have fun
Tom

 

[Phil73]

I'm going to have to research this more. Certainly easy enough to poke at the rear brakes while I'm at it. The TR6 has a single master cylinder but the reservoir has two sides to it. Currently, with things apart as they are, the front system is drained of fluid but the rear is still completely full.

 

[TR3driver]

The TR6 has two separate brake circuits, fed by a special master cylinder with separate pistons and outlets for each circuit. However, the MC construction tries to balance the pressure between the two circuits within limits, so if one circuit does not have pressure, the brake pedal will go much lower before the other circuit comes into operation.

The rattle that goes away as the brakes are applied would worry me, as it means something is loose. One possibility would be the brake rotor being loose on it's bolts, which could rapidly deteriorate to no brakes on that wheel (which can cause the car to pull violently to the other side, a dangerous situation). If it were my car, I'd focus on the rattle first.

Certainly wouldn't hurt to pull the hubs for inspection, but I would not bother replacing the bearings unless they are visibly damaged, worn or discolored (although I consider the slightest visible wear to be grounds for replacing them). FWIW I was able to source bearings through Rockauto.com for about 1/2 what the usual suspects charge.

 

[Phil73]

Thanks for the info. I'll pull the hubs, inspect and repack the bearings just as one more thing to do "while I'm in there". I'll also check the disk rotor bolts while I'm at it. I'm 99% certain the rattle is up in the front end somewhere and it definitely goes away if the brakes are applied (even very lightly) while going over bumps.

 

[Phil73]

Update:

Pulled the hubs, cleaned and inspected the bearings, checked the bolts securing the rotor to the hub, ran brake cleaner through all the brake lines in the front...nothing unusual. The bearings and races look great, brake lines ran clean, the rotor bolts were tight. Decided to pull the rotors off the hubs and have them turned anyway just to make sure they are true.

Beyond that, I guess I reassemble and turn my attention to the rear brakes.

 

[hondo402000]

did you check the pressure differential valve, could it be stuck to one side and blocking pressure to one caliper? seems you have everything else covered

Hondo

 

[Phil73]

Forgot to mention that. Rebuilt the PDWA in spring because it was leaking. It should be all good now.

 

[Andrew Mace]

did you check the pressure differential valve, could it be stuck to one side and blocking pressure to one caliper?

Unfortunately (at least as pertains to this situation), the PDWA doesn't "block" anything. All it does is actuate the warning lamp as it "detects" a significant difference in pressure between the two circuits.

 

[hondo402000]

only thing else I can think of is maybe your brake pads on the drivers side are contaminated with brake fluid, that happend to me, had rebuild my calipers and one started leaking, and the car would pull toward the non leaking side

Honod