In need of brake help!
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In need of brake help!
Hey guys, I am new to the forum and have a pretty serious issue concerning the Jaguar braking system currently used in a Cobra Replica we are building for a customer. The kit uses the suspension and brakes out of what we believe to be a 1979 XJ6 or 12.
I am looking for any references to technical brake information concerning these cars, known issues, or maybe just a specialist shop that you can refer. Any tid-bit of info will be helpful.
This thing just seems like it doesnt want to stop!
Obviously the car has been assembled completely now...
Thanks guys,
James
I am looking for any references to technical brake information concerning these cars, known issues, or maybe just a specialist shop that you can refer. Any tid-bit of info will be helpful.
This thing just seems like it doesnt want to stop!
Obviously the car has been assembled completely now...
Thanks guys,
James
Senior Member
Joined: Oct 2009
Posts: 654
Likes: 4
From: Albuquerque, NM
Hi James. I'm new to the forums, also...as well as being a first time Jag owner.
I have a 76 XJ12, and a Haynes manual. They have the same brake setup. I will try my best to answer your questions, although I can't promise anything.
I don't know what you have tried, nor what your exact problem is. Can you give a little bit more info on it "just seems like it doesn't want to stop." Here is a section from my Haynes manual on the brake system failing (fault diagnosis):
Pedal travels almost to floor before brakes operate -
- Brake fluid level too low
- Caliper leaking
- Master cylinder leaking (bubbles in master cylinder fluid)
- Brake flex hose leaking
- Brake line fractured
- Brake system unions loose
- Pad linings over 75% worn
Brake pedal feels springy
- New pads not yet bedded in
- Brake discs badly worn or craked
- Master cylinder securing nuts loose
Brake pedal feels spongy and soggy
- Caliper leaking
- Master cylinder leaking (bubbles in master cylinder reservoir)
- Brake pipe line or flex hose leaking
- Unions in brake system loose
Excessive effort required to brake car
- Pad lining worn badly
- New pads recently fitted - not yet bedded-in
- Harder pads fitted than standard causing increase in pedal pressure
- Pads or discs contaminated with oil, grease or hydraulic fluid
- Servo unit inoperative or faulty
Brakes uneven and pull to one side
- Pads or discs contaminated with oil, grease, or hydrolic fluid
- Tire pressures unequal
- Brake caliper loose
- Brake pads fitted incorrectly
- Different types of pads fitted at each wheel
- Anchorages for front or rear suspension loose
- Brakes discs badly worn, cracked, or distorted
Brakes tend to bind, drag, or lock-on
- Air in hydraulic system
- Caliper pistons seized
- Handbrake cables too tight
- Fault in servo unit
After typing all that out, I'd first check your vacuum lines. The brake system is connected to the vacuum system.
I have a 76 XJ12, and a Haynes manual. They have the same brake setup. I will try my best to answer your questions, although I can't promise anything.
I don't know what you have tried, nor what your exact problem is. Can you give a little bit more info on it "just seems like it doesn't want to stop." Here is a section from my Haynes manual on the brake system failing (fault diagnosis):
Pedal travels almost to floor before brakes operate -
- Brake fluid level too low
- Caliper leaking
- Master cylinder leaking (bubbles in master cylinder fluid)
- Brake flex hose leaking
- Brake line fractured
- Brake system unions loose
- Pad linings over 75% worn
Brake pedal feels springy
- New pads not yet bedded in
- Brake discs badly worn or craked
- Master cylinder securing nuts loose
Brake pedal feels spongy and soggy
- Caliper leaking
- Master cylinder leaking (bubbles in master cylinder reservoir)
- Brake pipe line or flex hose leaking
- Unions in brake system loose
Excessive effort required to brake car
- Pad lining worn badly
- New pads recently fitted - not yet bedded-in
- Harder pads fitted than standard causing increase in pedal pressure
- Pads or discs contaminated with oil, grease or hydraulic fluid
- Servo unit inoperative or faulty
Brakes uneven and pull to one side
- Pads or discs contaminated with oil, grease, or hydrolic fluid
- Tire pressures unequal
- Brake caliper loose
- Brake pads fitted incorrectly
- Different types of pads fitted at each wheel
- Anchorages for front or rear suspension loose
- Brakes discs badly worn, cracked, or distorted
Brakes tend to bind, drag, or lock-on
- Air in hydraulic system
- Caliper pistons seized
- Handbrake cables too tight
- Fault in servo unit
After typing all that out, I'd first check your vacuum lines. The brake system is connected to the vacuum system.
Last edited by m0t0rm0uth; Oct 8, 2009 at 04:04 PM.
Guest
Posts: n/a
Sorry about the blandness of my first post. 
There is excessive effort required to bring the car to a stop. From looking around I almost feel like we should be trying new rotors first.
Does anyone have suggestions on a reputable shop to deal with for Jag rotors? Experience is key since this setup is rather strange.
M0t0rm0uth - thanks so much for the time you put into your responce. It is greatly appreciated.
There is excessive effort required to bring the car to a stop. From looking around I almost feel like we should be trying new rotors first.
Does anyone have suggestions on a reputable shop to deal with for Jag rotors? Experience is key since this setup is rather strange.
M0t0rm0uth - thanks so much for the time you put into your responce. It is greatly appreciated.
Junior Member
Joined: Jul 2009
Posts: 11
Likes: 0
From: Wilkesville, Ohio
I know that you are looking for the best parts possible, but I just picked up a set of drilled and slotted rotors from a dealer on ebay. They came with ceramic pads too for about 120 bucks shipped. I just installed them today and they work like a dream. You might want to look into a similar setup. I know that the front calipers on mine (88 Jag) are a four piston design while the older ones are 3 piston ( I am assuming). You might look at upgrading to a 4 piston if you dont already them. That would be my guess.
To be honest I am kinda a Mustang guy. My first was a 79 and my mom has an 88 Jag Convert (then I found my 88). Never thought of using a Jag setup in a Cobra kit, looks like it should work really well. Hope this helps you out.
To be honest I am kinda a Mustang guy. My first was a 79 and my mom has an 88 Jag Convert (then I found my 88). Never thought of using a Jag setup in a Cobra kit, looks like it should work really well. Hope this helps you out.
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