Conference terri::cars_uk

    Has it been "stood-up" for a while? Has this problem suddenly occured?
    Am I correct in thinking that the rear brakes are drums? What does
    "thx" mean?
    
    For a starter, if it's been laid-up, then it could be either rust on
    the braking faces, and/or the pistons (master or slaves) are sticking.
    Most likely the latter. It is unlikely to be springs or servo, unless
    it happened suddenly.
    
    Laurie.
    
    PS. Actually, I know what "thx" means, I just think it belittles the
        word and the meaning to abbreviate it like that.

    ...As an ace mechanic once said to me :
    
    If it moves oil it.
    
    If its dirty clean it.
    
    I would go along with .1, pistons are favourite. Use only HMP grease
    in the brake area. Anyway, a stripdown is required. Never let brakes
    bind as the heat can cause brake fluid to boil, resulting in immediate
    loss of hydraulic pressure. Nasty !
    
    An aside, TOP GEAR recently warned of the carcenogenic effect of 
    rubber used in hydraulic components which has been allowed to burn.
    Handling of these burnt components can result in limb amputation to
    arrest the condition.
    
    	Tony.
    

    I've said this before regarding starters,  I would NOT recommend using
    grease in the brake area as it will allow the brake dust to stick to it
    and cause things to clog up.
    
    Another possible cause of your problem could be that the brake fluid
    hasn't been changed for some time.  Refering to normal brake fluid,
    this is hydroscopic and in time absorbs water, it can get to the point
    that there is enough water to rust the pistons in the wheel cylinders.
    
    I would agree with an earlier reply, and that is to take it all apart
    and clean it.  Then reassemble and bleed.
    
    What I used to do to check that i had changed all the fluid was to use
    Red fluid for the bleeding if there was Yellow stuff in there before.
    
    Cheers Ian...

thank you laurie. sorry about the abuse to the language. i'm a scriptwriter, so 
verbal shorthand is a learned vice.

the TR had not been laid up when the braking problem first reared its ugly head.
and, yes, the onset of the problem was not gradual. the wheel cylinders are 
relatively new, so i doubt the pistons are sticking.

i was hoping that someone had experienced a similar problem and could enlighten 
on magical cure before i start replacing things wholesale. that not being the 
case, any ideas on what to throw away first?

kirby

    It is very unlikely that both rear drums will be sticking due to
    piston/brake shoe seizure as the car has not been laid-up.
    
    Take a close look at the handbrake cable and check that it is not
    binding on. If this is ok, then remove each wheel, drum and shoe
    assembly. Clean (very carefully) all the components AND the back
    plate. Use coppa-slip where the shoes meet the back plate. 
    
    Before re-assembly ensure that the w/cylinder pistons are moving freely
    in their cylinders. Make sure that the adjusters are working ok and
    that you have not adjusted them up too much. When the wheel is off the
    ground "pull" the adjusters up until the shoes begin to bite, then back
    off the adjuster one notch.
    
    Always remember to pump the foot brake after you re-fit the drum, and
    BEFORE making the aforementioned adjustments. This aligns the shoes
    correctly. Coppa-slip should be used lightly, and is great for ensuring no 
    further problems.
    
    If you have not bled the brake system for 2-3 years, I would advise that
    you do it now. Always start with the bleed nipple nearest to the
    servo/fluid reservoir (front o/side) 
    
     

    I would explain your problem like this:
    The brake return springs can only reliese the shoes from the drum,
    when they can pump back brake fluid from the wheel cylinder into 
    the master cylinder. If for some reason this way is blocked or
    nearly closed, you get this effect. When you press the brake pedal
    there is enough power to press brake fluid through the closed pipes.
    The narrowing in your brake system can be in the mastercylinder, or
    in rubber brake hoses which can swell up caused by the brake fluid.
    I have this problem with clutch and brakes on my old BMW.
    Hope you will find it.
    
    Klaus
    
    
    

    sounds to me like a faulty non-return valve in the master cylinder
    (thats what lets you 'PUMP' spongy brakes -- Its usually not possible
    to pump a hydraulic clutch). Probably a rubber corroded. 
    
    Im not familiar with Tr's but above applies to Lockheed brakes as
    fitted to most Bl's of period.
    
    Brian.

    The problem is most likely corrosion in either the master cylinder or
    booster.  
    
    You could easliy narrow down the problem by driving the car, waiting
    until the problem occurs and then jacking up the car and checking each
    wheel for resistance of movement.
    
    Here are my guesses for how that might work out.
    
    All four:
    		Master cylinder or booster
    
    If all four should be blocked, crack the fitting on the outlet of the
    master cylinder, bleed off a little fluid after covering the junction
    with a rag to avoid accidents and check to see if the car can be moved
    by  hand. Tighten, pump the brakes a few times and do the same for the
    booster. Also, as mentioned in the previous notes, the shuttle valve in
    the master cylinder or booster is likely not returning fully to it's
    rest position or the return valve is plugged/stopped up and the fluid
    flow is restricted, that's why it takes a  while after parking to
    become unstuck. And for what it's worth, if it does turn out to be the
    booster, rebuilding them only works about 50% of the time, even when
    your competent local garage does the repairs.
    
    Two front wheels or two rear wheels:
    		PWDA (unlikely because once it trips, it doesn't release)
    		Also, PWDA could cause one front and one rear to lock up, 
    		but TR-6s aren't set up that way.
    	
    Two rear wheels:  
    		rust, wheel cylinders, hand brake cable, swollen rubber
    		pipe as mentioned in previous notes.
    
    One wheel:
    		corroded caliper if in the front, same as above for rear,
    		damaged steel brake pipe.
    
    
    Even if it fixes itself, through some miracle, change the fluid.