Cameron :
I'd say from your description that you have a blockage in one of the
hard lines, possibly a chunk of something acting like a check valve.
Since the bleeding at the master didn't free the brakes, the MC,
booster, pedal, etc. are not the problem. I would suggest further
isolating the problem to a specific length of hard line (or possibly the
PDWA, or residual pressure valve if your car has one), by bleeding at
different points and observing whether it (temporarily) solves the
problem.
DOT 5 won't help, except to not eat your paint when you bleed a line.
Randall
Cameron Greig wrote:
>
> Hi All
>
> .On my way home last week
> I stopped at a friends house for two mins to drop of some papers
> and when I left the car seemed down on power.There was no pulling
> left or right and the brakes seemed to stop the car just fine.Luckily
> I was only half a mile from home once the car was under cover
> I realised from the smell and heat that bother front callipers had
> seized on.I left the car for a few hour to cool down after which
> both callipers had freed themselves. I jacked up the car and found
> after I applied the brakes it took a while for the callipers to return.
> The only other difference I noticed was that the pedal had less
> travel than normal
>
> The master cylinder was new 4 months ago ( 1500miles) and I'm
> using standard fluid.
>
> I removed the master cylinder striped it down,found nothing wrong
> so reassembled and filled with fresh DOT 4. All was OK for a few
> days but then the pedal started to harden after the brakes had been used
> a few times.
> Thing came to a head last night.The car had been sitting all day at work
> in the sun.When I got in the car the pedal felt hard before I even started
> the car.After driving only 2 miles I could feel the brakes catching.I
> stopped the car and the fronts where tight.I then tried to move the car
> a few feet to a more suitable location both the front wheels where seized
> solid and the pedal was rock hard.I loosened the brake pipes for
> both the front and rear brakes at the master cylinder and allowed a little
> fluid to escape.Fluid came out both but not under pressure.This did
> not release the front brakes.Next I removed a front wheel and opened
> the bleed nipple.Again fluid flowed,but no apparent release of pressure.
> The pedal was know softer and the front wheels free.I think the brakes
> freed only because of the reduction of fluid and for some reason my
> brakes are working on the limit of seizing and it only requires
> a small increase in temperature to lock then on.
> I did remove the servo when I replaced the master cylinder,this was
> to repair the damaged paint.As far as I can see there is no adjustment
> for the pedal,and I can't see what I could have missed out that would
> reduce the travel.I don't think the flexible front hoses are the problem
> because it's effecting both front brakes the same.
>
> The only answer I have is to move over to DOT 5 and enjoy a spongy
> pedal.
>
> Any ideas
>
> Cameron
> 71 TR6
>
> Any ideas!
>
> Cameron
> TR6 150bhp
> UK car
|