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Allmost no brakes after adjusting rear brakes


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Can not imagine this is related. With adjusting rear brakes, that could lead to make the brake pedal go to the floor.and allmost no braking power. seems impossible. Just strike of bad luck I think. brake fluid ok in the resovair. Or Am I missing something. Should I order an new brake master cylinder?

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Obviously there could be a coincidental fault but most likely you have made an error of some sort whilst working on the rear brakes.

Did you remove the handbrake cable from the drums whilst working on the adjustment? It is possible to have the cable hold the shoes out in a false "off" position.

The shoes need to return off pushing the slave back as far as the adjuster will allow. Then fit and adjust the handbrake cable.

Alan

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21 minutes ago, Holmgren said:

Displaced? what do you mean?

Its a shuttle in the valve and if one or other brake line has a leak or similar the valve moves over so only one brake line is functioning, if its fitted as its normally only on US models or European (Malines) built cars. Have a look to see if its fitted,

Stuart.

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TR6 has the brakes in diagonal pairs front left and right rear etc. 

Your first post refers to a replacing master cylinder. That is a terrible way to diagnose a fault at the first stage. After a fault appears when you have carried out some work always, always retrace your steps and systematically work your way through the system. 

If you have badly adjusted the rears then yes the pedal may hit the floor before the travel in the slave cylinders is taken up.

Handbrake cable off, tighten the rear adjusters until the rear brakes bind, is there pedal pressure now?

If so back off adjusters 1/4 turn until wheel just binds slightly. Then back in car and press pedal very hard to centralise the shoes. Then back to set final adjustment on rears. Then fit and adjust handbrake cable to both sides.

Alan

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.Are you certain you turned the adjusters in the correct direction to wind the adjuster inwards and thus move the shoes closer to the brake drum? The adjusters on both sides have a normal RH thread. As you will have seen the adjuster spanner can only be fitted from below the adjuster as the hub is directly above it. So, for the RH side of the car the adjuster should be rotated so that the adjuster spanner is moving towards the front of the car. On the LH side of the car the adjuster spanner should be rotated towards the rear of the car. In both cases rotate the adjuster until it goes tight and the brake drum locks as the shoes are applied, then rotate the adjuster in the opposite direction until the drum can just be rotated without the brakes "dragging". The adjuster cone is square in shape, as you tighten the shoes against the drum you will be able to feel the square head rotate against the shoes. The fact that when adjusting the rear brakes you are probably facing the brake drum and reaching underneath to adjust the brakes can easily lead to turning the adjuster in the wrong direction. If you have rotated the adjuster in the opposite direction that is 'winding the brakes off" then all brake pedal travel will be used moving the rear wheel cylinders through their excessive travel. If you have moved the adjusters in the wrong direction the they will eventually come to a hard stop as the adjuster head meets the brake back plate, possibly making you think you had adjusted as far necessary. As someone else has alluded to, make sure the handbrake wasn't applied as make the adjustment.

 

Ian

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Try clamping off the brake hose to the rear. This will eliminate any mechanical fault with the rear brakes, then try the fronts. It’s conceivable you have not bled the MC sufficiently or it is just faulty. Also, are you sure one of the adjuster blocks which make contact between the shoe and adjuster is not either seized or missing?

Kevin

Edited by boxofbits
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On the rear brakes the wheel cylinder has to slide on the backplate and the piston in the cylinder has to move. Check the cylinder is sliding freely on the backplate. If not then some WD40 or similar and you should be able to slide it from side to side by hand on the backplate. Best way to adjust rear brakes is to jack up rear of car so both wheels are off the ground. You can then get the adjustment 'balanced' so each side locks up the same. Move handbrake up one click at a time and try to rotate wheels by hand and you should have resistance each side more or less the same. To tighten as stated in above posts turn adjuster clockwise and to loosen anticlockwise. Note the adjuster should also be easy to move and has 4 flats. You can tell when the adjuster is on a flat and with the brake hub off you can see how the adjuster works. Make sure also that the brake shoes move freely on the 3 raised dimples on the backplate behind the shoes. Copper or brake grease smeared lightly on these raised points will help.

Next step if none of this cures the problem would be (for me) to bleed the brakes. I use a pressure bleed kit. Just because there is fluid in the MC doesn't rule out air locks. I prefer the pressure bleed to having an assistant pumping the brake pedal. 

I have a 4A which has a simpler MC so cannot advise on fixing a TR6 MC. Sometimes it is easier to fit a new unit rather than messing about with new seals and springs. Similarly for rear wheel cylinders although they are quite easy to fit new seals in.

Good luck. Brakes can be one of those jobs.............. Had to fix a problem on the brakes on a new MiNI. On those the callipers slide on pins that go through rubber grommets. Slight corrosion of the alloy between the rubber and the housing stopped the brakes working properly because corrosion expands, presses on the rubber grommets and that is enough to stop the callipers sliding. Took me ages to identify that one.

Keith

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1/. Brakes adjusted wrongly so that all the pedal travel is used up in moving the pads/shoes in to contact with no movement left for actual braking.

2/. PDWA activated so that only half the brakes are working - one front one rear.

3/. Air bubble in the system. 

4/. Combination of all the above.

Have you tried the suggestion of clamping off the flexible hose to the rear brakes?  If you have a firm pedal then, it means there is excessive travel at the rear brakes.  

Have you tried adjusting the rears right up until they bind - the pedal should then be solid with not much travel. 

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Are you aware that there are two chambers to the master cylinder. The front chamber is for the rear brakes and the rear chamber for the fronts. It’s not easy to spot the front chamber.  It could be that there is no fluid in the front chamber resulting in no rear brakes and the fronts need bleeding.

Roger

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Hi X,

I don't know your name,

you have 12 posts on this forum since 2018, 8 of them on this thread,

from the other posts I can't rate your skills,

your questions on this thread are relatively desperated,

this is about brakes.

Maybe it could be better you bring your TR on a trailer to a car repair workshop?

Ciao, Marco

 

Edited by Z320
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With a single system like the TR 4a No brakes but no leaks usually means faulty valve between reservoir and master cylinder. When you adj rear brakes you normally push fluid back into the master cylinder reservoir. Any ingress of dirt to the valve within the system can cause the valve not to seal resulting on no pressure on the brakes because the fluid is free to return to the reservoir.

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  • 1 month later...

Hi

 

The car is back from the garage, And yes it was the brake master cylinder that was causing my problem.. and the pdwa was overhauled, Now I have great brakes again, the rear brake lines changed at the same time and the slave brake cylinder. They sucked out my old differential oil. Very black and sludge.

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On 9/18/2021 at 6:37 PM, barkerwilliams said:

TR6 has the brakes in diagonal pairs front left and right rear etc. 

Your first post refers to a replacing master cylinder. That is a terrible way to diagnose a fault at the first stage. After a fault appears when you have carried out some work always, always retrace your steps and systematically work your way through the system. 

If you have badly adjusted the rears then yes the pedal may hit the floor before the travel in the slave cylinders is taken up.

Handbrake cable off, tighten the rear adjusters until the rear brakes bind, is there pedal pressure now?

If so back off adjusters 1/4 turn until wheel just binds slightly. Then back in car and press pedal very hard to centralise the shoes. Then back to set final adjustment on rears. Then fit and adjust handbrake cable to both sides.

Alan

+1 Bruce.

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