Leaking Girling Mark 2B (removable band) Servo

PostPost by: Gordon Sauer » Thu Oct 22, 2009 5:24 am

Any help trying to troubleshoot a recently rebuilt Girling servo would help--looked in the forum and seems most people discard them or do a blanket rebuild, but having rebuilt mine about a year or so ago and now recently installed, it's pushing fluid through the vacuum line out the one way valve I presume? I'd like to know what's wrong with it before just going through it again. Have not put vacuum to it, just tried to bleed the brakes only to find unit for front brakes (front servo on the double +2 servos) is pushing fluid with brake pedal pressure out the vacuum line. Studying the diagrams, it looks like only way for fluid in top piston assembly (where the lines come in from the master cylinder via differential pressure unit) to get to vacuum area is through toggle valve area--correct? Will applying vacuum and getting piston moving after just sitting for a year or so, likely to help sealing? Any thoughts? Thanks. Gordon Sauer
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PostPost by: robertverhey » Thu Oct 22, 2009 11:36 am

Hello wondering if you may have put one of the seals in back to front? From memory they are fitted in opposing directions.
Robert
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PostPost by: oldelanman » Thu Oct 22, 2009 6:27 pm

Hi Gordon,
I agree with Robert. It's the seals on the control and output pistons which keep the fluid from entering the vacuum side of the servo and it seems most likely that one or more of the seals is missing, damaged or fitted the wrong way round. Applying vacuum will not rectify the problem and may suck any fluid that's got into the booster can into the engine. Unfortunately I think you will have to dismantle the unit to sort the problem and I would want to do that anyway for peace of mind. Probably not what you wanted to hear but I don't think there is an alternative.
Hope this helps.
Best regards,
Roger
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PostPost by: alaric » Thu Oct 22, 2009 8:15 pm

My Girling unit is in a pile of bits at the back of the workbench where I left it in disgust. I had it rebuilt then when it failed to work learnt that the shelf life of the mkIIB is quite short (3 months I think was quoted to me on this forum). I stripped it to find congealed grease all over the valve components, and couldn't find the small ball bearing non return valve. So, my plan is to complete the restoration of the car then either have the Girling servo re-rebuilt, or just buy one of the alternatives off ebay - see item number 390050227655 for example. It seems a lot cheaper to buy a new alternative servo than refurbish the Girling. I'm a bit concerned that the Lockhead based items on ebay are too cheap and are a copy of the original Lockhead item. Others on the forum have fitted the original Lockhead which is a lot more expensive - I think Sean Murray has one fitted. They have the same 3:1 pressure gain as the Girling unit.

I'm some way off having to make this decision so'd be interested to hear what people think of the Lockhead.

All the best.

Sean.
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PostPost by: nigelrbfurness » Sat Oct 24, 2009 12:23 pm

I bought one of the Lockheed Indian-made replicas from Moss about a year ago, ?50 on special offer so I thought it was worth a go; wish I'd bought a couple more now. I did find that the air valve was incorrectly assembled (brakes locked solid with engine running) but since fixing that its been perfect, very progressive assistance. Providing you check the air valve assembly before you fit it, you probably won't have any problems though the fact that mine passed its QC check is a bit worrying....

Nigel Furness
1970 S4SE/1760cc big valve/SA-AX block, L2s, 45DCOEs, 1978 Jensen GT, 1962 AH Sprite, Alfa-Romeo 159, 1966 Bristol Bus, 1947 AEC Regal bus.
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