servo brake problem

Talk about the E-Type Series 1

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Polse7317
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Location: FRANCE Aquitaine
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#1 servo brake problem

Post by Polse7317 » Mon Oct 02, 2017 11:22 am

I have a problem with the brake booster ( servo brake ?): The brake pedal is quite hard to be pushed down, , i have tried at the beginning ( engine stopped) to pump on the pedal until it is very hard and then i start the engine and i have not any difference on the pedal. (The car is then hard to move by hand... ) I have checked the vacuum hose and i have a good succion with my finger at the end of the hose while the engine runs . i have not noticed a hissing noise anymore
I have dismantled the servo........and i don't find some thing wrong, any damaged rubber or something that i can see , may be a litle leak that i can't see ?
I have ordered new rubber seal , valve balancing diaphragm (2) and rubber buffer in case ? but i can't order the little rubber seal at the end of the air valve assembly(1) ( SNG can't sell it )
Any advice will be very appreciated :policeblue:
Image
Yves, happy XKE 63 fhc , w113 280sl owner
Looking for a OTS 4.2 serie 1....! :scratchheadyellow: and now have found a fhc xk 140 :lol:

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Topic author
Polse7317
Posts: 693
Joined: Tue Oct 02, 2012 12:41 pm
Location: FRANCE Aquitaine
France

#2 Re: servo brake problem

Post by Polse7317 » Tue Oct 10, 2017 2:53 pm

I have replaced the rubber seals and diaphragm and noticed no change on the brake pedal movement....
I'll see on the road the feeling with the foot pressure :shrug:
Yves, happy XKE 63 fhc , w113 280sl owner
Looking for a OTS 4.2 serie 1....! :scratchheadyellow: and now have found a fhc xk 140 :lol:

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rfs1957
Posts: 1314
Joined: Sat Jan 15, 2011 2:52 pm
Location: Languedoc - France
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#3 Re: servo brake problem

Post by rfs1957 » Tue Oct 10, 2017 5:29 pm

Salut Yves,

I gave up on my Kelsey Hayes, probably unnecessarily with hindsight, and fitted this :

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so can't help you.

But I do know that in the Knowledge Base there is an article that puports to explain step by step how it works and how to adjust it.

Part 1: https://www.dropbox.com/s/9hzpaajjoce0w ... 1.pdf?dl=1
Part 2: https://www.dropbox.com/s/xqevilada92wy ... 2.pdf?dl=1
Part 3: https://www.dropbox.com/s/v571pwvdeitzh ... 3.pdf?dl=1
Part 4: https://www.dropbox.com/s/j9n3vzpxdbo0v ... 4.pdf?dl=1

Some of the theory of how the master-cylinders work, and split the front-rear effort, it total, utter, and arrant nonsense, but since nobody has - to my knowledge - criticised the rest it might help you ?

Bonne chance !
Last edited by rfs1957 on Wed Oct 11, 2017 7:27 am, edited 1 time in total.
Rory
3.8 OTS S1 Opalescent Silver Grey - built May 28th 1962

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abowie
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#4 Re: servo brake problem

Post by abowie » Tue Oct 10, 2017 10:27 pm

The small seal comes in the kit from Here
Andrew.
881824, 1E21538. 889457. 1961 4.3l Mk2. 1975 XJS. 1962 MGB
http://www.projectetype.com/index.php/the-blog.html
Adelaide, Australia

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Polse7317
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#5 Re: servo brake problem

Post by Polse7317 » Wed Oct 11, 2017 9:36 am

Thank's abowie for the right link.... I'll test the servo on the road and will see .....
Yves, happy XKE 63 fhc , w113 280sl owner
Looking for a OTS 4.2 serie 1....! :scratchheadyellow: and now have found a fhc xk 140 :lol:

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Polse7317
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Location: FRANCE Aquitaine
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#6 Re: servo brake problem

Post by Polse7317 » Tue May 29, 2018 11:14 am

I have tested the car during 10 miles and all my wheels were jamed after 3 or 4 pressure on the pedal.....! they were free after +- 1/4 hour . Each wheel was blocked so the problem is obviously coming from the servo.

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Did the measurements of "A" between 9.3 mm and 8.5 mm when the brake pedal is under pressure are correct ?
I can't measure the depression as the service manual says but i have a good succion at the end of the vacuum hose . I have tried different positions to the eccentric adjusting nut without succes , and the different parts under that eccentric nut seem not realy moveable.... i have no measure to refer to

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I think it must be safe to send all the servo to a professional who will check and solve the problem.... :shrug:
Yves, happy XKE 63 fhc , w113 280sl owner
Looking for a OTS 4.2 serie 1....! :scratchheadyellow: and now have found a fhc xk 140 :lol:

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