Brakes slack on first push

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Sidney'61
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Brakes slack on first push

Post by Sidney'61 »

Hi,
A friend of mine has been having problems with the brakes, a couple of cylinders and pipes have been recently changed, the system seemed to bleed fine and the brakes work but only on and after the second push of the pedal, it is still quite slack for the first push. There doesn't seem to be an obvious leak anywhere. What is the likely problem, does it just need more bleeding?

Andy :)
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PSL184
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Re: Brakes slack on first push

Post by PSL184 »

If the pedal will pump up hard and hold pressure then there is still air in the system. If the pedal pumps up hard then sinks to the floor there is a leak somewhere....
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bmcecosse
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Re: Brakes slack on first push

Post by bmcecosse »

Probably just needs the shoes adjusted up more tightly to the drums.
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kennatt
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Re: Brakes slack on first push

Post by kennatt »

as above,air in the system generally causes a springy pedal because air can be compressed fluid can not so if there is air in the system the pedal may pump up but will still feel soft.Lack of adjustment means the first pumps push the shoes out onto the drums then the last one will be hard.
T100SS
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Re: Brakes slack on first push

Post by T100SS »

kennatt wrote:as above,air in the system generally causes a springy pedal because air can be compressed fluid can not so if there is air in the system the pedal may pump up but will still feel soft.Lack of adjustment means the first pumps push the shoes out onto the drums then the last one will be hard.
Ah, scuse me for just thinking out loud. My Trav has pump problems, despite new pipes, cylinders (inc master), drums and shoes. All I have not replaced are the shoe reatining springs and perhaps more significantly, the flexible hoses.

Having thoroughly checked for leaks, I had begun to suspect that the flexible pipes were perhaps expanding (swelling) and therefore absorbing effort. Not least because I assumed the shoes (fitted within the last three months) would be barely bed in, let alone in need of adjustment. That and the fact I've bled the system through three times, each time following the three different procedures as laid out in Haynes, BMC and Hopkirk respectively (you start and finish in different places).

I'll get my other half to have a pump at the weekend (sic) while I scrawm about below looking for swollen pipes.

bmcecosse
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Re: Brakes slack on first push

Post by bmcecosse »

Could be bulgy hoses but I doubt it. new shoes bed in very quickly - high spots wear off/shoes adapt to the diameter of the drum. So they are very likely to need adjusting now.
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kennatt
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Re: Brakes slack on first push

Post by kennatt »

to check just adjust the shoes up tight(All four) so that the wheels as stuck.then try the pedal if there is still a long travel and a need to pump then yes it could be the flexys ,but I doubt it,If the air is out then 99% of the time it is down to adjustment.99% of the time air in the system causes a springy pedal it never gets solid.
Neil MG
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Re: Brakes slack on first push

Post by Neil MG »

T100SS wrote:
kennatt wrote:... Not least because I assumed the shoes (fitted within the last three months) would be barely bed in, let alone in need of adjustment...
Not sure if I understand you correctly, but even new shoes must be adjusted when fitted.
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kennatt
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Re: Brakes slack on first push

Post by kennatt »

kennatt wrote:
... Not least because I assumed the shoes (fitted within the last three months) would be barely bed in, let alone in need of adjustment... Ho No I didn't :D :D
T100SS
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Re: Brakes slack on first push

Post by T100SS »

Thanks to all for comments and suggestions.

Thankfully even I had the wit to adjust the brakes when I fitted the new parts. The idea of adjusting up the brakes to test for bulge is a good one.

Thankfully I circumnavigated that by following existing advice and adjusting - they had indeed settled considerably and the pedal inspires confidence rather than panic now:) Ali, my other half intends to drive it and what with the cog juggling and other foibles I didn't want her to have to contend with fiddly stopping.

So off I went shopping smuggly when the Moggy cut out, after a prolonged fuel pump effort. Lid up, ignition on, pump works but no fuel. New guage says almost 1/4 full. So pump must be US? I walk home, grab a can, a plastic bottle and some pipe (to create a gravity feed), jump on the bike and go and rescue myself.

What was that I'd said about the Broquet elsewhere? Anyway, contents of fuel can in tank produces fuel at carb, so I lock it up and take bike home. Walk back to car, it gets to garage but only just. A top-up gets it going again thankfully but one wonders why I bothered buying a guage:)

Nuisance as it might have been to run out of petrol (am I first bloke in uiverse to admit that?) at least with the Mog it wasn't a crisis.

bmcecosse
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Re: Brakes slack on first push

Post by bmcecosse »

Carry a spare gallon......... Thought it was a Traveller -why did you not just put the bike in the back ??
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rayofleamington
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Re: Brakes slack on first push

Post by rayofleamington »

I ran my Astra out of deisel a week ago. (I was rushing to get to DIY centre before it closed, and figured I could get fuel on way back, nothing ventured nothing gained.. :roll:).
It doesn't have a manual baloon pump, so as soon as it started gurgling I didn't keep it going (to avoid filling it all with air), and therefore managed just about to crank the fuel through. I keep easy start just in case but was glad not to have to use it.

Fuel priming - Never something to be stressed about with a Minor :)
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