Brake bleeding order

[carthago ian]

I replaced both rear brake cylinders today , whats the correct order to bleed them ? I'm thinking the longest run 1st ... But I'm not too sure !

[California Dreamin]

As you say....furthest from the master cylinder first, so for a R/H/Drive van that's the nearside rear, then the O/S/R, followed by the N/S/F and finishing off with the O/S/F....might be opening a can of worms but you should also bleed the clutch (at the slave cylinder) whilst your at it. 1.5 litres of DOT 4 will do it.



Martin

[max and caddy]

As there are in fact two independent circuits it's not really all that important as long as the end result is no air is left within..gravity can be helpfull of the system is empty...rather than lots of pumping just fill the tank, open the nipple and wait..the fluid will self bleed to a degree and will mean less chance of air entrainment in the fluid.

Pressure bleeding is preferable...if available...gunsons easi bleed for example.

[itchyfeet]

If you are using a pressure bleedng kit don't go to the max psi stated on the kit, keep it low say 10psi.

[max and caddy]

As above...20 year old plastic tanks can burst..

[carthago ian]

Thanks ; simple low tech stuff sorry , don't own a pressure bleed kit .. I used a tool to gently crimp the small flexible brake hose , the amount of fluid loss was slight I'll start with gravity method then old school method pump brake peddle ...

[max and caddy]

If you can ...build pressure in the system...then using an assistant..open the nipple quickly ...this will shift 'sticky' bubbles...also on front calipers give the caliper a few whacks with a sutible blunt instrument to loosen any bubbles that may be stuck to the sides...a 19mm spanner as an example..

[carthago ian]

Thanks for the sound advice given all went well . I used a simple one way valve self bleed kit it's simple an it works, yes slow i know but that suits me ...
Only bled the rear brakes , did the slave cylinder some time back ... But the brake failed on a test run ; still very hot too hot to touch ... so a complete strip down is all I can think of see what going on , replaced both hand brake cables this week so I can rule them out set the handbrake as per Bently

[kevtherev]

Are the shoes in right

[carthago ian]

The rear brakes never gave any problems until I pulled the handbrake on fully whilst on the ferry ... I just normally pull the hand brake a coulpe of clicks then leave it in gear ;On my way home from the ferry, pulled in for a cuppa after a couple of hours driving & could smell somit hot like burning brakes the drums too hot to touch.... I never took the shoes out during the hand brake cable or cylinder replacement, all I can think of now is to strip the brakes down, clean up or replace parts as required..

[carthago ian]

Well thats that job done , not too sure what I achieved other than I now know how to strip down the rear brakes and put them back together ..... As per Bently I greased the contact points , need to work out how to properly set the brakes by means of the adjuster , my thoughts drift towards keep moving the adjuster until there is slight contact between the hub & shoes : I'm not a mechanic by any means hence the daft questions as in can the shoes be fitted the wrong way ?? ( I'm an Instrumentation technician ) use to taking stuff to bits To late for a test run that I'll keep for Saturday afternoon

[nevill3]

Did you check the wiki page for stripping the back brakes....http://wiki.club8090.co.uk/index.php/Br ... _servicing

It has a couple of invaluable pictures of the correct setup of the springs for the rear shoes.

[carthago ian]

Thanks .. Thats brilliant stuff

[California Dreamin]

If you can ...build pressure in the system...then using an assistant..open the nipple quickly ...this will shift 'sticky' bubbles...also on front calipers give the caliper a few whacks with a sutible blunt instrument to loosen any bubbles that may be stuck to the sides...a 19mm spanner as an example..

I'm afraid this method combined with 'old fashioned' pumping of the brake pedal is the easiest way to damage the 'tadem' seals in the brake master cylinder as they ride over the 'bur' (wear lip) inside the cylinder....Don't do it! if you have to manually bleed? then the bleed nipple should always be a good third to a half turn open on the down stroke of the pedal....nice steady action (avoid pushing with fluid resistance as the lip of the seals can turn inside out).

Martin

[California Dreamin]

Well thats that job done , not too sure what I achieved other than I now know how to strip down the rear brakes and put them back together ..... As per Bently I greased the contact points , need to work out how to properly set the brakes by means of the adjuster , my thoughts drift towards keep moving the adjuster until there is slight contact between the hub & shoes : I'm not a mechanic by any means hence the daft questions as in can the shoes be fitted the wrong way ?? ( I'm an Instrumentation technician ) use to taking stuff to bits To late for a test run that I'll keep for Saturday afternoon

Brake fluid HAS TO BE changed every TWO years to avoid 'vapor-lock' which is a brake condition where the brake pedal goes extremely spongy or worse still, goes straight to the floor. This is a result of a high level of water having been absorbed in to the fluid which lowers its boiling point. (brake fluid is hygroscopic..which basically means it attracts and absorbs water) so when the brakes get very hot, fluid starts to boil (lower than it would normally due to the water contamination) resultant air bubbles are then 'compressible' leading to the spongy pedal.

Retrospective I know...as a rule the brake cables need to be slack to ensure the brake levers have fully returned to their resting positions on the shoes...it is only then that you adjust the 'balance bar' through the backplate hole. This should be adjusted till the drum 'locks up' then in the opposite direction take off the adjustment notch by notch checking the drum for binding each time, this will probably be 4 - 6 loud 'bongs' as the adjuster is forced un-naturally against ratchet direction. Once the drum rotates free, you should give the adjuster a further 2 clicks for 'Clearance' which allows for heat expansion.
Take most (but not all) of the slack from the hand brake cables (the cables shouldn't be pulling).
This should result in a reasonable handbrake travel.


BIG NOTE* the brake shoes will take anything up to 10,000 miles to bed in properly, the shoes will need re-adjusting at this point.

Martin