XJ6 & XJ12 Series I, II & III 1968-1992

Soft brake pedal

 
  #1  
Old 03-12-2019, 02:27 AM
Senior Member
Thread Starter
Join Date: Jan 2013
Location: Sydney Australia
Posts: 944
Received 153 Likes on 114 Posts
Default Soft brake pedal

My series 3 has been getting the ocassional moment where the brake pedal will be suddenly soft and go steadily all the way to the floor. It comes good again if you pump it and it’s fine with a sudden hard application. I had the brake fluid flushed and changed as I was thinking it was happening mostly when hot and the fluid looked quite contaminated. I assumed this would,likely fix it but it doesn’t seem like it has.

any ideas what else it might be? Can see any obvious leaks anywhere.
 
  #2  
Old 03-12-2019, 03:19 AM
Join Date: Feb 2010
Location: Adelaide Stralia
Posts: 19,263
Received 5,667 Likes on 4,069 Posts
Default

Master cylinder by-passing internally, very common.

No idea in your market, but down here, resleeve and rebuild, simple.
 
The following users liked this post:
AnD3rew (03-12-2019)
  #3  
Old 03-15-2019, 09:51 AM
Dutch-Cat's Avatar
Senior Member
Join Date: Jan 2017
Location: Kerkrade, South Limburg, The Netherlands
Posts: 266
Received 87 Likes on 59 Posts
Default

I have to second Grant Francis.
Mine blew completely when driving on the off-ramp of the highway, doing 90 mph......pedal to the metal, literally....no braking action whatsoever, except for the good old handbrake and engine torque...

replace it all together, it's an easy fix really.
SNG Baratt's has them new for around US$ 125, part number CAC1229
Click here for a direct link
 

Last edited by Dutch-Cat; 03-15-2019 at 09:55 AM.
The following users liked this post:
AnD3rew (03-19-2019)
  #4  
Old 03-15-2019, 12:23 PM
Veteran Member
Join Date: Jul 2012
Location: Walnut Creek, California
Posts: 5,672
Received 1,923 Likes on 1,552 Posts
Default

Dutch:

Odd that you had nothing for braking other than the park pads. teen little things!!

I thought that the dual master cylinders were for that purpose. Lose two, have two left.
Two caliper braking from 0- still dicey!!!! But, beats none all to h....

Decades ago, I borrowed a company car for a site seeing trip in SOCAL A 68 or so

Comet six cylinder four door. Dear departed and two kids aboard. Malibu Canyon . Picturesque winding mountain road toward the beach. I did go easy on braking. but, brake fade came in!!!! Good pedal, no retard!!! No chaos, they came back as the drums cooled. Would be a great place to "test" my Jaguar .Only 8, not 12, but still quite agile...
Carl
 
  #5  
Old 03-17-2019, 07:24 AM
Fraser Mitchell's Avatar
Veteran Member
Join Date: Dec 2009
Location: Crewe, England
Posts: 7,297
Received 1,565 Likes on 1,302 Posts
Default

Also it could be a sticking caliper piston. On longer trips this heats up the fluid that eventually boils, then when you need the brake, the pedal goes to the floor. I had this on a rear caliper, the ones that don't get much attention.
 
The following 2 users liked this post by Fraser Mitchell:
AnD3rew (03-19-2019), Grant Francis (03-17-2019)
  #6  
Old 03-19-2019, 08:28 AM
Dutch-Cat's Avatar
Senior Member
Join Date: Jan 2017
Location: Kerkrade, South Limburg, The Netherlands
Posts: 266
Received 87 Likes on 59 Posts
Default

When you are absolutely sure that the mechanics work nicely, the only thing that can cause brake fading is water in the brake fluid.
Brake Fluid is hygroscopic, meaning that it attracts moisture over time.
A fluid change every two years is recommended...
 
  #7  
Old 03-29-2019, 07:03 PM
Senior Member
Thread Starter
Join Date: Jan 2013
Location: Sydney Australia
Posts: 944
Received 153 Likes on 114 Posts
Default

Thanks all, it was the master cylinder. Replaced and all working fine.
 
The following 2 users liked this post by AnD3rew:
Grant Francis (03-29-2019), Saemetric (04-03-2019)
 
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Mueller
F-Type ( X152 )
16
06-13-2017 05:01 PM
wardf
XJ XJ6 / XJ8 / XJR ( X350 & X358 )
31
01-23-2017 10:06 AM
Tcasmarcus
XJ XJ6 / XJR6 ( X300 )
14
10-20-2016 04:21 AM
AlexJag
XK / XKR ( X150 )
23
05-17-2016 01:00 PM

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 

Thread Tools
Search this Thread
Quick Reply: Soft brake pedal


Advertising
Featured Sponsors
Vendor Directory

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

© 2019 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.
 
  • Ask a Question
    Get answers from community experts
Question Title:
Description:
Your question will be posted in: