braking point

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braking point

Post by padollman on Fri Jul 24, 2015 5:27 pm

Hi All,

First off, apologies for the epic post!

I've had my '07 bi fuel Porter van (originally MPV, now camper) for about 6 months, and the info on this site has been amazing in helping me get to grips with it's various 'quirks', the Smart seat upgrade in particular made my van a much happier place... So thanks for your help so far!

I've recently had an issue with the brakes, replaced rear cylinders and shoes after a cylinder failed and leaked massively, so far so easy! But I'm having a bitch of a time bleeding it after finishing (ha, so I thought!) the job. Had a battle with a rounded bleed nipple on the load sensing valve, finally got it so bled fronts, then the LSPV, but I'm not getting anything through the back left at all when trying to bleed that nipple... frustrating!

Bit of reading here suggested that the LSPV could be seized, had a look, lever moves freely enough, but the piston which the lever pushes in and out does not move, it's stuck in the 'fully retracted' position (piston pushed all the way in to the cylinder type part) I noticed this before but assumed that as this would be the same position as when the van is heavily loaded this would make this the 'fully open' position, not the 'almost no rear brake effort / impossible to bleed position.' Have I missed something?

From the lack of anything making it downstream I'm guessing my diagnosis was wrong and the LSPV is seized in the bad position and thus dead?

The reason I'm not sure it that despite bleeding the fronts, and the line to LSPV thoroughly (like until I was sure there were no bubbles at all in the fluid coming through, then a good bit more for good measure, the brake pedal still feels like the system is pretty empty, very little resistance and bottoms out - must be air in the master cylinder still? Is there a bleed nipple on the MC? Couldn't see one but it's in such an awkward spot I'm not sure, not keen to pull the dash off to find out if I can avoid it!

Anyone got any suggestions? Thanks in advance!


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Re: braking point

Post by HighlyJetted on Fri Jul 24, 2015 11:42 pm

All your troubles lie in the lspv.

I guess it failed its mot on rear service brake effort below requirements.

Remove spring bar from axle.

Flip arm down.

Remove rubber cover from lspv.

Pull inner pin downwards with pliars to ensure valve inner works.

Spray pin with lube and keep working it, it only moves a few mill.

Replace rubber.

Swing arm back to lspv, and cable tie it in uppermost possition.

Bleed rear brakes.

Rebolt spring arm to axle in upper most possition.

Test rear brakes by jacking vehicle by the axle.

If it does not brake, then remove spring bar, and pack up the spring with a spacer under lower cup, to thus increase spring tension.
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