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TR6 Brake questions

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ichthos

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This is only my second time in working with disc brakes, so I have a few questions I am hoping you can help me with. 1) Can rotors be surfaced off of the car, and what kind of shop does this? 2) Why would groves form on just one of the rotors? 3) Any ideas on why a piston would stick in just one of the calipers? 4) How difficult is it to rebuild the calipers, and is there anything I should be looking for, especially in the piston that is sticky? 5) My brake pads still have plenty of wear, but there are some groves in them. Can these be lightly sanded down, or am I foolish to try and use old pads? Any help would greatly be appreciated.
Kevin
 
Any decent auto machine shop can turn rotors for you. It's not as common as it used to be, because new rotors are so often too thin to turn, but the machines should still be around.

Grooves generally indicate a problem with the pads; like letting riveted pads wear down to the rivets. But since small grooves won't hurt anything, it's possible that someone changed the pads without refinishing/replacing the rotors.

Not sure why pistons stick; seems like sometimes the seal just "becomes one" with the piston. But it's not uncommon for only one to stick.

Triumph calipers are reasonably easy to rebuild; usually the only tricky part is getting the piston started back into the bore with both the dust seal and the hydraulic seal in the right place. But if you split the calipers (which Girling warned not to do), be sure to have new seals on hand to go between the halves. I believe both Moss & TRF have the seals, but they are not usually included in the rebuild kits.

We've debated long and hard over why Girling said not to split the calipers, with no clear consensus. But most of the professional shops do, and I've not heard of anyone having problems from doing so. (Haven't done it myself, as mine are the early one-piece calipers).

The seal rides against the surface of the piston, so make sure the surface is perfect where the seal rides. Any rust or visible pitting is reason to replace the piston, IMO. Otherwise, it's pretty much obvious, I think. Be sure to clean thoroughly, and make sure there isn't any solvent left over inside before you close them up.

Sanding pads seems like a bad idea to me, you wouldn't want to get particles from the sand paper embedded in the pad material to wear out the rotors. Minor grooves won't hurt anything and will quickly wear away anyway, so I'd either leave them or replace the pads.

Last time I bought generic aftermarket organic pads for the TR3, they were horrible, seemed to have no grip at all. My suggestion is to either look for some NORS asbestos pads, or get the 'Kevlar' fiber ones from TSi (which is what I did). They work great even cold, and I've never managed to get them hot enough to notice any fading. Another option is EBC "Greenstuff", but I've heard mixed reviews about them.
 
I took off the dust seals, but I am not able to pull out the pistons. There was a rusty powder under the seals. When I use compressed air into the piston, I can feel a little movement, but they are not coming out. I am going to try finding something to seal off the pipe end and blow through the bleeder screw. After that I am going to try forcing in grease. I may very well end up splitting to get better access to the pistons. Any other suggestions? If I get stainless steel pistons will that stop this from happening again?
 
Ichthos, Stainless is better and if you live near the coast even better, lots of rain and TR's don't really go together. I believe your pistons are shoot, so grabbing them with a vice and twisting them should work them out. I bet all the chrome finish is gone on the walls.

Wayne
 
Yeah, sacrifice the pistons as you probably need new if they are that stuck. Channel Locks or a big pipe wrench may also do in lieu of a vise -- its the twisting that sets them free.

Pads are cheap enough that I would never be tempted to reuse -- I just got a set of ceramics from Rock Auto for about 14 bucks and so far have been pleased with them. I was getting a lot of dust even with the metallic, the ceramic are much cleaner. Braking is fine, time will tell how the rotors hold up to them.

When you get to the point in reassembly that Randall mentions (getting the piston in with the seal in place and the boot over it there are a couple of tricks that make that go well. Search when you get there or ask again (don't want to send you into overload at this point).
 
Is this the same car that just got rear ended ?
If so has the insurance adjuster paid you a visit yet ?
 
Yes, this is the same car that was rear ended. The adjuster should be here any minute. I figured since it is just sitting here, that I might as well get some work done on it as long as it is not in the proximity of the damage. Got the steering back together, although I need to make a little more adjustment. At least I can drive to a shop now. I have finally decided on three shops I am going to visit next week.
 
Okay, I got my brake calipers all apart. There is corrosion on the chrome pistons, and I am definitely going to rebuild them with stainless. I ended up have to take the two halves apart-not sure what the big deal with Girling is. A few more questions. 1) I have a couple small marks in each of the areas the piston sit in. Is this okay? I plan on taking them into a brake shop tomorrow, and I am hoping they will help me. 2) If they are not acceptable the way they are, has anyone had any luck having them bored and sleaved? If this is possible, I will probably go for stainless.
Kevin
 
Since the seal is against the piston, marks in the chamber that the piston sits in should not matter.

Scott
 
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