brake servo spring position

Technical advice Q&A
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MarkRado
Posts: 341
Joined: Fri Jan 26, 2018 9:13 am
Location: Graz
Austria

#1 brake servo spring position

Post by MarkRado » Sat Apr 20, 2024 11:04 am

Hi all,

I am just rebuilding a 66' brake servo.
The servo push rod is fixed in the primary piston by a pin, and there is a small coil spring in the piston.
The manual says that " the spring should be loaded between the heel of the piston and the pin".
I am not sure if I understand correctly what the heel is and I have to admit that I dont understand the function of the spring at the moment (should it dampen the servo kick-in?).
Is this the correct position of the spring?
Image


Thank you
Mark
Mark
1963 OTS 880436

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Jaguar12
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Joined: Thu Feb 16, 2012 4:18 am
Switzerland

#2 Re: brake servo spring position

Post by Jaguar12 » Sat Apr 20, 2024 8:12 pm

Hello Mark,

The following link, which helped me when I had pedal kick back (Thanks Ralph), has a drawing with the correct position. Additionally, there is a description in the S3 Workshop Manual.

Hope this helps and greetings.
Daniel

viewtopic.php?f=3&t=7346&hilit=Pedal+kick+back

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MarkRado
Posts: 341
Joined: Fri Jan 26, 2018 9:13 am
Location: Graz
Austria

#3 Re: brake servo spring position

Post by MarkRado » Sun Apr 21, 2024 6:12 am

Hi Daniel,
perfect, thank you!
I found a similar drawing, albeit from a different servo model.
To make it short: my foto shows the wrong position

Regards
Mark
Mark
1963 OTS 880436

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Paul bow
Posts: 158
Joined: Fri Sep 25, 2020 7:00 am
Great Britain

#4 Re: brake servo spring position

Post by Paul bow » Sun Apr 28, 2024 8:09 am

Hi.. for what’s its worth I bought a brand new servo that I just could not get a peddle .. in the end I stripped the new one down to look for any obvious defects, studying carefully pics and had another knowledgable person on here look at it as well.. couldn’t see anything wrong but everything pointed to servo.. anyhow I bought another new one, bolted it on in 1/2 an hour job done..perfect brakes.
The other got sent the other back faulty.
My thoughts are these are so temperamental, unless you’ve got a lot of time on your hand my advice would be get a new one, job done in no time.
Previously...S1 OTS E type (sold)
S1 2+2 manual. (Sold)
S2 rhd OTS full resto finished 8/23
S1 3.8 coupe (full restoration yet to start!)

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