Allen:
Several quick thoughts, based on my recent complete rebuild of TR6 brake
hydraulics...
1. You may have a bad flexible hose. They can go bad and swell on the inside,
while looking normal on the exterior. Disconnect just ahead of the right hose
and check for fluid flow out of the rigid pipe.
2. In spite of what you described, you may still have a PDWA that's gone
off-center. If it was off-center, it would allow fluid from the front hoses,
but
not from the rear. If it went off-center the other way, the opposite would be
true. Can you re-check to verify that it is centered properly?? If it is not,
your attempts to bleed completely will be futile.
3. I would also remove the flex hose at the right rear cylinder, then put a
gradual amount of compressed air into the hole for the hose fitting, and watch
your brake shoes to see if they are moving. If yes, then you shouldn't have
blockage in the cylinder itself.
On my TR6, after perfroming all of the above checks, it did turn out to be the
right rear hose that had gone bad - internally.
Martin Libhart
1972 TR6
1970 Spitfire
Allen Nugent wrote:
> Dear Listers,
>
> Having repacked the bearings, rebuilt the calipers, turned the discs,
> reassembled and bled the front brakes, I was in the act of purging the rear
> circuit with fresh fluid, when I made the following discoveries.
>
> (NB. My TR7 rear brakes are bled only from the left-hand wheel cylinder, as
> the hydraulic line goes to the right one first, and another line goes from
> it to the left.)
>
> 1. It is almost impossible to get any fluid to come out of the left-rear
> bleed nipple. In 40 minutes, I got about 10 ml, using both Eezibleed and
> much pumping. The pedal was very hard when pumping.
>
> 2. Slightly opening a front bleed screw (thinking to fool the line-failure
> valve, if it was being cute) had no effect, other than making the pedal move
> easier and letting fluid out the front.
>
> 3. Disconnecting the line _into_ the right-rear allowed fluid to leak out;
> disconnecting the line _from_ the right-rear did not result in fluid leakage.
>
> 4. The %^$#@*^* fitting on the line that goes between the rear wheels is
> stripped, so I guess I will have to replace the line.
>
> Has anyone experienced such a problem? I can think of further tests to do
> (ie. disconnecting unions and making sure fluid flows from them), and I'm
> suspecting that the right-rear wheel cylinder has a blocked input passage. I
> replaced the wheel cylinders with rebuilt/exchange units, 3 years ago.
>
> TIA.
>
> Allen Nugent
> Graduate School of Biomedical Engineering
> University of New South Wales
> Sydney 2052 Australia
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