Brake overhaul but no rear brakes

[hoobby]

 New master (20.64mm)and wheel cylinders (19mm)fitted fronts are fine  but can't get rears to come on there trying but only dragging on the drums with brakes applied have the self adjusting type both have moved since fitting system is all bleed including the master so do I have a duff master or could it be the pressure control valve?.  Brake system left for 10 years with fluid in a real mess!.

Edited September 8, 2018 by hoobby

[cam.in.head]

If there is still air in the system or if the rears are out of adjustment the pedal will be soft or have a lot of travel.if the pedal is firm with very little movement then it would possibly suggest a problem with the limiter valve although I have never seen one fail other than leak.

confirm that the pipe connections are correct to the said valve,confirm that the rear cylinders are not seized and everything assembled correct and adjusted manually as far as possible .

i suppose to confirm this valve you could make up a small pipe with two female ends to loop-out the pressure valve and see if the rears work..if this valve is found to be faulty then there are a few versions available.  

Very early with only two pipes(limiter only)

standard approx19777. To 1982 approx cast iron type,prone to leaks thou.

and the later version that looks like a tall cylinder. (Also a brass tall square type later version too)

 But that’s if it’s actually faulty. Could even be the new master cyl ?  Worth another bleed and some good hard pedal presses !

[hoobby]

I have just moved the auto adjusters a lot to take the slack up and it's not till the drums are dragging I get good solid brakes don't think the pistons are moving far enough hopefully due to air just got to wait for my wife to get in then bleed down the old reliable way.

[cam.in.head]

Ah hopefully that sounds a little less serious. If you havnt got a lip on the drums you should be able to manually click up the auto adjusters till the shoes are just dragging ( centralise them now and again with the handbrake) and then back them off till just free.

sounds like a final bleed should sort them hopefully.

 P.s.  If you are doing a lot of bleeding i find a much better way is with an old fridge compressor. Suction into a glass jar with twp inlets and the other pipe to the bleed nipple.this way sucks all the fluid and air through the pipes and gives no chance of any air getting in. Works a treat !

the old pedal method works too but the vacuum idea makes it a one man job 

[hoobby]

I have noticed in the past that these one way bleed valves work but often air is drawn back in via the bleed nipple thread.

[hoobby]

I have bypassed the the pressure unit giving the rears a direct feed from the master on both front and rear outlets and it's the same result very little braking there.auto adjusters do work when the drums are off all I can think of now is an issue with the new wheel cylinders which I have just checked and have a piston of 24mm not 19mm as listed .

[simon p]

How have you piped up the master cylinder ?

[Snowy]

1 hour ago, hoobby said:

I have bypassed the the pressure unit giving the rears a direct feed from the master on both front and rear outlets and it's the same result very little braking there.auto adjusters do work when the drums are off all I can think of now is an issue with the new wheel cylinders which I have just checked and have a piston of 24mm not 19mm as listed .

I think you've found your problem. 

[IanMc]

I remember years and years ago I had a similar problem on my Uncles Sierra, turns out I had connected the feed and bleed nipple into the wrong holes...

Swapped them around and the problem was fixed in minutes.

Another one of my schoolboy errors, but in my defence I was only about 19 or 20 at the time.

[IanMc]

Did you manage to get this sorted out matey?

[hoobby]

New cylinders arrived today going to fit and bleed on Sunday hopefully that will be it can't think of anything else it could be I have even checked the brake lines for kinks. 

[cam.in.head]

Rears should be 19mm as you so rightly thought. Didnt know they even made 24mm ones.wonder what they should be for ? .it makes sense that would be your problem as to move the piston out a given amount would require more fluid displacement hence more pedal travel. 

Funny thing is ive seen smaller bore cylinders.wonder what effect that would give ? ?

[hoobby]

 aaaaaaaaaaaah it's still the bloody same aaaaaaaaaaaah .sorry I feel better now.looks like my new master cylinder is duff all the air is out I have put lots through and no air bubbles fronts feel good rears awful.pump the pedal a few times then squeeze and pedal goes down a long way rears at first grip a little but easy to overcome and then can be turned by hand.

[cam.in.head]

Is there anyway you can make up / weld up etc. A blank to try in the master cyl in place of the rear line ?

this would confirm cylinder providing you are 100% sure that all air is out

[hoobby]

I will try that but ran out of time for now will get back to it next weekend.many thanks for now and will keep you informed of any progress.

 

[hoobby]

Well ain't that a thing just tried to start and no start I've replaced all the fuel hoses (2.0e) round the fuel pump,filter and feeds think I may have got them crossed have feed as o/s and return n/s

[cam.in.head]

Just remember Haynes book is wrong anyway so don’t go by the pics.

fuel feed goes to t piece between injectors and return to tank from centre of pressure relief valve 

[hoobby]

Ok thanks for that will swap them back as have them the wrong way round..oh and thank you Haynes.