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hoobby

Still no rear brakes

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Ok just plugged the top of valve (rear feed) pedal the same.plugged the rear feed at master pedal same left this n place and plugged the front feed from m/c to valve and pedal is hard as it should be so the problem lies on this part of the circuit.got to go work now :( so tomorrow will leave front plugged see what the rears are like after bleeding and investigate this circuit . funny all this time just assumed the problem was on the rear circuit :rolleyes:.

Edited by hoobby

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hi i had problems with rear brakes once i replaced the rear shoes and could not get a good pedal.

it turned out the rear drums was so badly worn the new brake shoes was only catching on the edges so the new brake linings was acting like they was made out of rubber.

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 So it's something on the feed from master cyl to valve or from valve to front caliper By the sound of it. 

If you clamp that hose or plug the valve you will know. 

That valve works by monitoring how hard you are appying the front brakes and reduces the rears accordingly to prevent them locking up and skidding.earlier cars didn't have that style just a simple 2 pipe limiter.

never heard of the valve going faulty that particular way so it's either got some air still stuck in it or something caliper wise.

im intrigued now ! 

Ps I'm sure you know and I think you will have probably done them anyway but those stupid  calipers with the sliding sleeves seize up on the sleeves regularly . Making a springy pedal !

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Calipers had total overhaul the only thing that's old is the body will start on this soon now it's cooling down a bit.just Finnish the rear brakes then I'll have a look not sure what I'm going to find hopefully something to do with the caliper but did get a lot of rust out for a while from the valve when I flushed it with clean fluid.

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Ok rears finnished and still the same so blanked off both front feeds at m/c pedal very firm now but still the same so bypassed the valve so it's m/c to rears and wound out the adjusters until they dragged and  just a little better couldn't rotate by hand but overcome  with a bit of wood between the studs.brakes worked fine before it's 10 year rest.all I can think of now is the master is not displacing enough fluid to complete the process maybe that's what that bolt is for reducing the amount of displacement to fronts and increasing the rear?.what do you think.????.

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It’s turning out to be a saga alright.🤯

If when you connect the MC to rears directly bypassing the proportioning valve, then lock the off fronts you are still not getting the volume to rear cylinders, then it is a miss match of fluid volume for sure.

as a very last resort swap the outputs on MC. 

 

 

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Just done that blanked off rear and o/s/f feeds at master and bypassed valve and yes still the same...really really getting fed up of this now sweety and covered in brake fluid going have a bath and call it a day but please any theory's any at all would be welcome will even entertain ghosts aliens and cursed car theory's.

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Yes it’s odd, it is a volume issue, but where 🤯

was there a spring in rear cylinders that pushes pistons out ?

 

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have you taken the car for a drive.

have a good drive use the foot brake and the hand brake try and bed the shoes in. see if it makes any differance with them bedded in

if the rear brakes are bleading easy the flow to the rears should be fine.

esp if you have fitted new flexis

Edited by droop snoot hp firenza

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Mot expired over 10 years ago and yes new flexis besides hand brake will hold the drums solid.

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can you get a large pair of water pump pliers on the rear wheel cylinder.

then get someone to put pressure on the brake pedal with the engine running,

you should not be able to hold the pistons in even with a huge pair of water pump pliers.

then you no you have good pressure to the rear calipers.

IMG_20190825_204304.jpg

11 minutes ago, hoobby said:

Mot expired over 10 years ago and yes new flexis besides hand brake will hold the drums solid.

if you aplie the hand brake so its just binding.just grabbing the wheel a little.

then pump the pedal a few times . do the rears work of then

also are the shoes the correct size for the drums

Edited by droop snoot hp firenza

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Hi Graeme,

Sorry to hear of your continuing brake problems.

This is certainly a very long shot, but knowing you have replaced your MC, I thought I should link it for you.

Check out the last post by Moodoo, who kindly provides the solution to his braking problem.  

 

Good luck matey!

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21 hours ago, droop snoot hp firenza said:

can you get a large pair of water pump pliers on the rear wheel cylinder.

then get someone to put pressure on the brake pedal with the engine running,

you should not be able to hold the pistons in even with a huge pair of water pump pliers.

then you no you have good pressure to the rear calipers.

IMG_20190825_204304.jpg

if you aplie the hand brake so its just binding.just grabbing the wheel a little.

then pump the pedal a few times . do the rears work of then

also are the shoes the correct size for the drums

I will try that but today my wife's birthday so no car today going out for a curry and a few cobras tonight and I honestly need some time off have spent a lot of time with this problem and has defied all attempts to recertify.please correct me if wrong ( with fronts blanked at m/c and bypassed valve)  as the pedal will descend when bleed nipple is opened this shows the m/c has more volume to offer so must be a pressure issue? The line between the valve and flexible hose was replaced (not by me) maybe a kink or internal rusting of the old lines?.

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wow this is definately turning into a challenge .

i assume after trying all that you have covered every possibly scenario. you have blanked off the master,bypassed the pressure valve ,clamped every hose,run rears on their own,run front n/s on its own,run front o/ on its own ?.

with master all sealed off you get a solid pedal.

with everything plumbed in and bled and all 3 hoses clamped you get a solid pedal .

everything good untill you open the line from master to valve to caliper 

is it solid with other 2 hoses unclamped and front n/s clamped ?

if it was a displacement issue pedal wouldnt be good with rears and front o/s working .if im reading all this correctly it sounds like an issue with either the pressure valve but you have had it bypassed .yes ? 

just stop a bit and have a breather. you will get there

one final thing but might not be related 

if i recall the rear circuit connection on the master has a valve / of some sort which screws in before the pipe .not 100% sure if its a limit or a return valve of some sort but both mine have got it .pipe wount fit without it as the thread is too big ?

Edited by cam.in.head
mis spelled !

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Pedal is now firm and stays firm .Fronts are very good the problem is just the rear brakes. So far bypassed the valve and  with rear feed and blanked both front outputs.given the rears a feed from front output on m/c to the rear drums with valve bypassed still can be easily overcome hand brake is good I have tried every configuration possible and wound out the adjusters until they dragged badly and still very poor rears.to me the problem is from the drums to back to the valve as they still won't work with the front feed which I know is good  so going to jack it all up and get underneath in the week so I can get a good carefull look at all the brake lines looking for any kinks as this would reduce the pressure.IMG_20190828_063952.thumb.jpg.8847c6dbf3c263ebdc5e6c5ed747926b.jpg

Edited by hoobby

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Could the 'T' connector on the rear axle have some muck in it?

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I think Graeme mentioned previously about the flex, so this and the T would be a good place to start checking. Replace the flex initially.

If it has started to separate internally, then it could be restricted, or ballooning, or even have a trapped air pocket, although highly unlikely, it is possible.

Once replaced I would then reverse bleed the rears with an eze bleed etc.

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Just stripped out the t-piece and steel line from Flexi got lots of small bits of rust out so going to bin all the old lines and make new up new lines and check the Flexi to valve pipe. new Flexi ordered as braided hose I used is for a 300tdi and way to long

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New hose arrived (mapco 3846) and it has unions for double flares.....:angry:.....fantastic.so thought I would check the new wheel cylinders against old both 19mm gubbins inside are different but can't see what difference it would make just a different way of doing things.IMG_20190829_173317.thumb.jpg.2d89275f4f27f9f1df9e41a590c8138e.jpg

Edited by hoobby

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2 hours ago, Jessopia74 said:

When fitted into the drum are the bleed nipples upwards?

yes there on the top...i wish it was that easy

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Yeah I know, but sometimes worth asking as it’s frustrating me, so god knows how you must be🤯

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220px-AS_HMAS_Canberra_1.jpg.c95c7540ad5a4c7198c2c9a052bad182.jpgas a last ditch thing do you think this would do as a replacement for rear brakes to get a mot..not sure if i have thought this through but the pieces are there...i'll work it out. 

Edited by hoobby
  • Haha 1

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Cylinders appear correct. Can't see from the pic but they do have the recess in the end and have the bullet type insert thingy tha locates into the shoes dont they ?

otherwise see what happens when you put the new pipes and flexi on .

this is certainly an unusual one ! But we love a challenge !

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