Remote servo woes!

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e21Mark

Original Poster:

16,205 posts

172 months

Friday 9th October 2015
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I have spent the past couple of years putting together a much modified E21 BMW. I ditched the OE braking system and convoluted linkages but this also meant using an aftermarket remote servo. As BMW brakes are dual circuit, there was only one suitable servo available. (link below)

http://www.s-v-c.co.uk/product/dual-remote-servo/

Once fitted, we bled the system through, but the pedal just feels hard, as it would on any car when the servo isn't giving any assistance. Added to this, the front brakes would remain on after any more than a few pumps of the pedal.

After checking the master cylinder and adjusting the push rod, we cured the problem of the brakes staying on. Unfortunately though, there still seems to be no assistance from the servo.

I've spoken with the supplier and it's not looking like another unit will be available any time soon, so just wondering if there's anywhere else who could fix it, or is it a DIY possibility?

Another thing is that I couldn't hear any air leak but could it be that not enough vacuum is being generated?

Does a lack of assistance point to a problem on the vacuum side, if all seems well with the hydraulics, or is that too simplistic? If I run the engine for a while, turn it off and listen for a whoosh as I pull the rubber hose off, there's nothing.

Sorry if I haven't explained myself clearly but am just unsure what's going on?

If anyone knows somewhere or someone who deals in servo repairs, please post details.

chammyman

123 posts

111 months

Sunday 11th October 2015
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Have you confirmed theres actual vacuum to it?

Does the vacuum pipe actually pull negative pressure?

If so do you have a 1 way valve inline? If so is it the right way round?

Simple stuff first.

e21Mark

Original Poster:

16,205 posts

172 months

Monday 12th October 2015
quotequote all
Yes, as you say, I went through all the simple checks first. I'm pretty sure the fault lies with the servo unit itself. I split the reservoir over the weekend and it was pretty poorly assembled. The two halves are joined with 6 bolts and a paper gasket, but wasn't very tight so hard to see how a vacuum could be maintained? The diaphragms inside all appeared intact though and could be moved fairly freely. I'm going to continue to strip, clean and reassemble properly, in the hope it cures the problem. I'm relient on the net for info, with regard to the workings though, so am being slow and methodical.