Brake issue

Technical advice Q&A

Topic author
Landcrab
Posts: 26
Joined: Thu Oct 05, 2017 8:51 pm
Sweden

#1 Brake issue

Post by Landcrab » Tue Apr 16, 2019 4:54 pm

Hello everybody!

I have just restored the master and servo cylinder on my 1966 4.2 fhc. The problem now seems to be that the fluid have some return issues. With engine off at first there are perfect pedal preassure but slowly when pumping the pedat it builds up brake preassure. If I then start the engine it only takes 1 pedal movement to become totally stiff and I have to loosen a pipe to unleach the fluid to let off the preassure. So My theory is that something is wrongly assembled in the master cylinder. I just wanted to see if someone have experienced something similar?

Greatful for any help

Regards Johan
1965 fhc

Link:
BBcode:
HTML:
Hide post links
Show post links

User avatar

politeperson
Posts: 876
Joined: Tue Jun 07, 2016 8:26 pm
Location: Boston UK
Great Britain

#2 Re: Brake issue

Post by politeperson » Tue Apr 16, 2019 7:33 pm

I would guess it sounds like you have a fluid return issue indicating a problem with either

1) The reaction valve sticking ( 10 minute job)

2) Perished flexible brake hoses or (1 hour job)

3) Incorrect master cylinder push-rod length clearance (1 hour job)

First off check you have some (couple of mm ) clearance on the brake pedal before the cylinder is engaged. To do this look under the dash on you back whilst shinning a torch on the inside if the master housing and see what is going on.

If you have pedal clearance, undo the screws holding the reaction valve cover. Pull the vale with pliers and check it is sliding freely. You should not introduce and air in the system if you are careful.

Then apply the brakes. If there is still pressure in the system, crack open a flexi-line an see if fluid squirts out from the caliper side. You only have three flexi hoses, so a return problem should make itself known fairly quickly.

If all this fails, you may have a sticking caliper which needs a rebuild.

James
James

L.J.K. Setright was right.
"You just cant beat a good E-type"

Link:
BBcode:
HTML:
Hide post links
Show post links


Topic author
Landcrab
Posts: 26
Joined: Thu Oct 05, 2017 8:51 pm
Sweden

#3 Re: Brake issue

Post by Landcrab » Tue Apr 16, 2019 8:14 pm

Thank you very much I will try and see what might help the situation
1965 fhc

Link:
BBcode:
HTML:
Hide post links
Show post links


johnetype
Posts: 268
Joined: Sun Feb 26, 2012 11:54 pm
Location: Worcestershire
Great Britain

#4 Re: Brake issue

Post by johnetype » Fri Apr 19, 2019 8:04 am

politeperson wrote:
Tue Apr 16, 2019 7:33 pm

3) Incorrect master cylinder push-rod length clearance (1 hour job)
(5 min job) there is a bolt at the rear of the pedal box housing that sets how far the brake pedal returns. You need to adjust that bolt to allow the brake pedal to return far enough so that the brake master cylinder is fully retracted, otherwise pressure can build up as you are experiencing.
John

1969 Series 2 FHC

Link:
BBcode:
HTML:
Hide post links
Show post links

Post Reply Previous topicNext topic