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My LJ's master cylinder made a mess!

Master Cylinder leaks

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#1 Brent J

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Posted 17 April 2017 - 12:13 AM

So unfortunately a leaking master cylinder has made a mess of what was a relatively tidy engine bay :cry:

 

Fluid has leaked pretty badly from the master cylinder seal and cap, but it also looks like it has leaked between the master and booster flange... bit hard to tell. Paint is damaged along the inner guard, and also the right hand front suspension components.

 

I've done some reading through the various threads and there appears to be a range of areas that could cause this...

 

Here is what I know:

 

  • Brakes seem to still currently work on the car, but;
  • I jacked up the rear of the car and got my wife to stand on the brake pedal and only a small amount of resistance was applied to each rear wheel when I spun the tyre by hand. Definitely would lock up the rears. Pedal felt fine though.
  • The car has been sitting for about a month since my last drive. When I took the master cap off, the rear reservoir was more of less empty, the front was full!
  • When I re-filled the reservoir and pumped the pedal with the cap off, brake fluid squirted up out of the master (couldn't tell if it was front or rear. Luckily I lined the engine bay with rags...
  • The master cylinder was "re-built" by the previous owner... Not sure if it was sleeved and a kit put through it or not..
  • The rubber gasket looks new and the cap pulls down pretty hard

 

So where do I start...?

 

Could I assume the rebuild previously done wasn't done correctly?

Could sticky wheel cylinders cause this?

Could the brake lines be part blocked and cause this?

 

I'm thinking of taking off the master and sending it off for another overhaul .... makes sense since most of the paint has been stripped from it and it looks worse for wear! I was thinking of trying Knights Old School Brakes..

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#2 S pack

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Posted 17 April 2017 - 08:48 AM

Sounds like the fluid from the rear reservoir has been pumped through into the front reservoir and pushed out past the cap seal.

Most likely a faulty m/cyl piston cup on the rear brake circuit.



#3 Brent J

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Posted 17 April 2017 - 10:32 AM

Sorry - edit to my above post...

 

I couldn't get the rear brakes to lock despite my wife standing on the breaks. I could still spin the rear wheels by hand.

 

Thank you for the reply S Pack. sounds like I need to remove the master cylinder and send it off for overhaul...?



#4 S pack

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Posted 17 April 2017 - 02:15 PM

The rear brakes should not lock up but you should have to exert some effort to turn the wheels with your foot hard on the brake pedal.



#5 Brent J

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Posted 17 April 2017 - 06:35 PM

Righto.

 

So I pulled the master off and plugged the brake lines straight after I pulled them out of the master hoping that I don't get too much air in there...

 

I really don't know what I am looking at from here other than to say there was a lot of crud around the pin that comes out of the booster. See pics below.

 

Would you guys recommend that I now send off the master for a re-build? Could someone from QLD suggest a good brake shop who will be able to refurbish my master?

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#6 Ice

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Posted 17 April 2017 - 07:39 PM

Big nut get it rebuilt for sure

#7 S pack

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Posted 17 April 2017 - 08:20 PM

Would you guys recommend that I now send off the master for a re-build? Could someone from QLD suggest a good brake shop who will be able to refurbish my master?

Are you in QLD? Your Forum user location says Melbourne?


Edited by S pack, 17 April 2017 - 08:20 PM.


#8 grumpy xu1

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Posted 17 April 2017 - 08:30 PM

Hi Brent, looks like a drum/drum master, if it's got disc's on the front the little valve is the problem, kunda park brake & clutch ( kunda park sunshine coast qld ) sleeve & kit them. Probably a good idea to kit the booster & I'd spray some brake clean through all the lines & compressed air until they're squeaky clean. May as well do it all at once mate, then you can get the paint matched & touch up the inner gaurd. Gary.

#9 Brent J

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Posted 17 April 2017 - 09:47 PM

S Pack - sorry for the confusion mate. I literally moved to QLD 5 days ago from Victoria. Ill change my location now!



#10 Brent J

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Posted 17 April 2017 - 10:13 PM

Gary - yes it has drums on the front. I have read on this forum that the residual pressure valve is hidden in the master and needs to be removed if there are disks on the front..

 

Any idea how I can tell if has been removed or not? I suspect it is behind the brass inserts? I suppose I can ask the re-builder to check it!

Thanks for the contact Gary. Ill give them a call tomorrow and go from there.



#11 S pack

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Posted 17 April 2017 - 10:47 PM

Hi Brent,

yes the residual check valves are behind the brass flare seats. You should be able to feel the rubber valves with a piece of wire or similar instrument inserted through the hole in the brass seat.

I've always used Stopmasters at Brendale for brake booster repairs https://www.yellowpa...48-listing.html

and BHSS at Capalaba for cylinder re-sleeving and repairs, they also do steering racks. http://bhss.com.au/



#12 Brent J

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Posted 21 April 2017 - 07:55 PM

Edit to my post above - my car has disks on the front (must have been late when I wrote that).

 

I took the master in today to get it refurbished. The shop rang me back and they said that it has already been sleeved. They also said that the timing of the pistons inside were not quite right and that groove for the assembly retaining circlip was too far back, likely skewing the adjustment of the booster pin..

 

They have corrected what they found, machined the top sealing surface to ensure a positive seal with the cap, and gave it a paint ready for me to pick up Monday. 

 

On another note - the big nut on the front has Drum written on it but also is dated 5th February 1974. Therefore is not the original nut, or master or both which is disappointing..

 

Don't suppose I can get a Feb 1972 from anywhere? :<_<:



#13 S pack

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Posted 22 April 2017 - 12:03 AM

Edit to my post above - my car has disks on the front (must have been late when I wrote that).

 

I took the master in today to get it refurbished. The shop rang me back and they said that it has already been sleeved. They also said that the timing of the pistons inside were not quite right and that groove for the assembly retaining circlip was too far back, likely skewing the adjustment of the booster pin..

 

They have corrected what they found, machined the top sealing surface to ensure a positive seal with the cap, and gave it a paint ready for me to pick up Monday. 

 

On another note - the big nut on the front has Drum written on it but also is dated 5th February 1974. Therefore is not the original nut, or master or both which is disappointing..

 

Don't suppose I can get a Feb 1972 from anywhere? :<_<:

I thought it was a little strange that you have an 'Early 72 XU1' and you said your car has drum front brakes. Unless of course you have two Toranas. :spoton:

 

The big nuts can be machined, re-stamped and re-zinc plated to change the date code but need to do this before you refit to the car.



#14 Brent J

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Posted 22 April 2017 - 04:54 PM

Thanks for the tip S Pack.

Do you have a contact who can do that work on the big nut?

Brent

#15 S pack

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Posted 22 April 2017 - 05:55 PM

Thanks for the tip S Pack.

Do you have a contact who can do that work on the big nut?

Brent

No, I'm just repeating info that other members looking for a date code correct big nut m/cyl have been told.

BHSS at Capalaba (I posted a link to them in a previous post) may be able to do the machine and re-stamp at least. :dontknow: 


 



#16 Brent J

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Posted 24 April 2017 - 07:13 PM

Do I went to pick this up today. Very pleased with the result. Will be even happier if I get it back together and manage to keep my engine bay free of brake fluid!

 

I need to check the pin length and make sure I have the correct clearance before I bolt it up and bleed the system.

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Edited by Brent J, 24 April 2017 - 07:23 PM.


#17 grumpy xu1

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Posted 24 April 2017 - 08:00 PM

May aswell zinc plate the pushrod too, whilst you're going & lubricate the adjustment, easy as while it's apart. Looks good, Gary.

#18 Brent J

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Posted 19 May 2017 - 04:25 PM

So it has been a while since I posted. Work has been pulling me from pillar to post!

 

I finally got my reconditioned master bolted up, lines reattached and have half filled with fluid and left for a while to gravity bleed. Just needs a proper bleed at each corner and it is ready to test.

 

I also cleaned up the paint damage on the booster, inner guard and rail. Paint matching was a challenge and while its not great, it looks a lot better than what it looked like before!

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#19 grumpy xu1

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Posted 19 May 2017 - 06:46 PM

Lime green metalic "super sexy" colour on an xu1, did you get the nut re stamped at all Brent ? Brisbane built car ? Just pm me if you like. Gary.




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