Tr6 servo faulty?

[Ziggy]

Tr6 1973.  After finding my rear brakes had not been working for a long time, I have removed both adjusters, cleaned and refitted them, replaced both cylinders  and springs and renewed both rubber hoses, and now they work very well, but after bleeding them the pedal travels half way down even though the brakes work well. There is no leak from anywhere and the reservoir stays full. I have replaced the rubber washer on the front of the servo and fitted new pipes  above the injectors, so does this only leave the servo that could be faulty, or am I missing something? 

[Pete Lewis]

did you lock up the adjuster with the handbrake cable still attached 

if so you need to disconnect the cable   really lock up the drum /adjuster  and reset the cable to suit

only then de adjust the adjuster to free the drum 

its my guess  the cable is holding the shoes open gives you a low firm pedal 

Pete

 

 

[Nigel Clark]

All TR6s have dual circuit brakes. The symptoms you describe could be due to air trapped, not having bled fully, in one of the hydraulic circuits.

Nigel

[Pete Lewis]

good call is the pdwa valve actually working and was it set /reset when bleeding 

Pete

[dougbgt6]

Doesn't the pdwa have a warning light when it senses an imbalance? Bulb could be blown of course.

Doug

[Pete Lewis]

yes if the nasty push button is actually working the warning lamp gets a blip from the oil pressure switch to test the bulb is working when you first switch on 

you should bleed F & R together or the shuttle moves (as it should)  but  if not you have to manually reset it by  remove switch and a prod with a screwdriver 

to recentre the shuttle piston

Pete

 

[Nigel Clark]

Early TR6s didn't have a PDWA or warning light, though Ziggys 1973 car probably does.

Nigel

[Pete Lewis]

1 hour ago, Nigel Clark said:

Early TR6s didn't have a PDWA

Gosh  was the early warning system  a tree or a ditch ???

Pete

[Nigel Clark]

5 hours ago, Pete Lewis said:

Gosh  was the early warning system  a tree or a ditch ???

Pete

Soft brake pedal is the only warning, well that and reduced brake efficiency. Still better than a failure in a single line hydraulic system!

Nigel

[Ziggy]

On 15/06/2021 at 12:14, Pete Lewis said:

good call is the pdwa valve actually working and was it set /reset when bleeding 

Pete

Thats only on LHD cars, so mine does not have one.

[Pete Lewis]

so a bleed is best quick down stroke  nip the bleed  slow back stroke   and reopen the bleed and repeat ???

best to have the bleed bottle up high above the wheels  so air always rises .yes you need 6 pairs of hands so some assistant required 

when you push down is there/was there any small bubbling in the M cyl reservoir ????

make sure the hand brake cable  is not holding the rear shoes open ,as i said discon the cable and fully /hard adjust to lock the drums  fit the cable to just a nice fit and then de adjust to free the drum 

Pete

 

[Peter Truman]

also make sure you don't slacken the bleed nipple to much that you can draw air in down the threads into the bleeding poly pipe, some people use plastercene or blue tack to seal the bleed nipple during bleeding.

The biggest problem I have is keeping the bleed hose on the bleed nipple, gawd it makes a mess when it slips off!