series free brake trouble

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Series71

Space man
Posts
17,374
Location
Dorset
got a S3 and found out one of the wheel cylinders was duff fixed all new cylinders then the master cylinder started leakin ! So have a new master cylinder in now.Spent 3 hours bleedin the brakes tonight.....absolutely no air innum at all but brakes still int that good . One pump and theyre fookin excellent ????
 
Ah dunno, ahm not God FFS! Servo ok? Could even be glazing/contamination on the pads. Yeah, adjust them up, but dun't be surprised if it dun't work & yer back ter scratching yer 'ed.

I only said not nessercelery!
 
check the springs are on right, some should be fixed to the post across a cylinder not shoe to shoe this would explain the extra pump on the pedal as the springs pull the cylinders in
 
Adjusting the shoes is a good start, but series brakes are notoriousely bludy hard to get all the air out of, as the ruddy nipples are in the wrong places!
Worth trying a couple of tricks;
First one, doing a wheel at a time, drum off, shoes out the way. compress the wheel cylinder as hard as you can with a G-clamp (or two on a TLC front drum), then bleed through.
compressing the cylinder minimises the volume in the system meaning theres less room for trapped air to 'hide', so is more likely to head out the bleed nipple.
Next, after purring the shoes and socks..... sorry drums back on, and adjusting the snails, leave the car over night with a weight on the brake pedal, or a jack or something holding the pedal down, so that the fluid in the system is under pressure.
This has a similar effect, and tries to make any hidden air in the system 'boil' to the top, and settle, so you can get a bit more out bleeding the brakes the following day.
Then adjust the shoes again..........
 
Hi,

It is absolutely amazing the difference that setting your pedal to the right height will have.

Set the push-rod so that the pedal is 6.25" above the floor, measured vertically.

Yes, I agree that the twin-leading shoe slave cylinders on all Series LWB and some later SWB have the bleed nipple set too low, causing an air pocket which is imopssible to beed. But of course I agree ...... I reckon I'm the bloke who discovered this problem, and got laughed at until somebody checked it and agreed with me.

My initial solution was to remove the back plate, leaving the hoses connected, lay it flat with nipple pointing upwards, then bleed it. A real fenestrated donkey. Eventualy I decided that all it needed was for the adjusters to be screwed right off, let the springs pull the shoes in. There shouldn't be any need to clamp the wheel cylinders ..... repeat....shouldn't

If anyone is interested, I once sawed a Triumph Spitfire master cylinder in half, endways. Yes, there is a similar air pocket there, too, unless you park on a VERY steep hill.

602
 
Try this Remove back brake drums, Inspect the top springs they should only be fitted from the leading shoe to the post on the brake plate not across the shoes the trailing shoe is then free to be adjusted which will then not allow the piston on the cylinder to retract therefore when you apply the brake your not pumping initially into fresh air

Geoff
 
Adjusting the shoes is a good start, but series brakes are notoriousely bludy hard to get all the air out of, as the ruddy nipples are in the wrong places!
Worth trying a couple of tricks;
First one, doing a wheel at a time, drum off, shoes out the way. compress the wheel cylinder as hard as you can with a G-clamp (or two on a TLC front drum), then bleed through.
compressing the cylinder minimises the volume in the system meaning theres less room for trapped air to 'hide', so is more likely to head out the bleed nipple.
Next, after purring the shoes and socks..... sorry drums back on, and adjusting the snails, leave the car over night with a weight on the brake pedal, or a jack or something holding the pedal down, so that the fluid in the system is under pressure.
This has a similar effect, and tries to make any hidden air in the system 'boil' to the top, and settle, so you can get a bit more out bleeding the brakes the following day.
Then adjust the shoes again..........

I've had a proverbial nightmare with my SIIa swb. I had to replace the front shoes, all 4 cylinders, make two brake pipes up, new flexi-hoses and had to replace the rear flexi which was an MOT fail. I've done this to hopefully eradicate a braking imbalance (brakes were very good otherwise).

Bleeding just isn't working. Tried using a gunson pressured system, also had both my Brother-in-law and a local mechanic bleed it up too.

We even stuck the back wheels up on ramps in the hope that would help - but each time I get a decent pedal whilst bleeding, then afterwards it's only good after a pump.

I'll check again in daylight for any leaks before trying your method Teflon. Is this quite normal for series brakes then or should I be suspecting any other parts of the system - the master cylinder and gubbins up the top does look like it's seen better decades although I could detect no leaks when I pressurised it using the gunson system before putting the fluid in it.

Just looking for pointers as this is the only thing stopping me getting the bugger back to the mot centre.
 
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