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LC/LJ Brake Setup


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#1 lctriples

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Posted 10 November 2020 - 07:48 PM

Just wondering if I could trouble the brotherhood for some friendly help or advice. I'm having trouble getting brake pedal feel in my lc/lj project. All four wheel cyclinders/calipers bleed perfectly but have no brake pedal feel at all, Manual says that adjustable bolt should be slightly inside outer edge of booster (say .3 to .5 mm), but I couldn't get rear brakes to bleed and made a "clicking/clunking sound everytime pedal was depressed with this setup. Experimented with a home made bolt that prodrude enough to sit plush with master cyclnder plunger (protruding about 25mm) but I presume this wont let plunger return to normal position in m/c? Funilly enough, the longer bolt helped get rear brakes to bleed, got some brake pedal feel, but only with pumping brakes up. A mate dropped in the other day and noticed m/c was not level (running downhill) so I = jacked front of car up to around 30*, bleed system but still no cigar. (he though might be an air lock in m/c due to angle). He suggested "bench bleeding" m/c but I forgot to ask him best way to do this before he left. Any help with be most grateful, paul

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#2 sibhs

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Posted 10 November 2020 - 09:14 PM

Hi Paul,

brakes are a nightmare.

I'd firstly get the correct plunger, no point getting it working with a bolt and having to re bleed when changing over.

I bled and bled and bled mine trying to get pedal feel and the rears activating. The rears only activate deep into the pedal pressure with engine running.

Where is the clunking noise coming from? sort that out too.

 

Marty



#3 lctriples

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Posted 10 November 2020 - 09:34 PM

Hey Marty, great to hear from you. Changing plunger bolts is an easy job, without having to re-bleed system as master cylinder unbolts from vacuum booster as a sealed unit/system. (You can see in photos) "Clunking" seems to be from within m/c, plunger area. I tried brakes with engine running as thought might be better like modern cars are, but it actually had less or softer pedal feel. I might ring "old mate" tomorrow to see how to bench bleed m/c. How is your project/Torana no 2 coming along? Thanks again, paul


Edited by lctriples, 10 November 2020 - 09:40 PM.


#4 S pack

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Posted 10 November 2020 - 11:42 PM

Paul, sounds to me like you have an LJ master cyl and an LC master vac unit (booster). I suspect the clunking you can hear with the short pushrod in the booster is the pushrod engaging into the master cylinder piston at probably near the end of the brake pedal travel. See if you can measure the depth of the pushrod seat in the back of the master cylinder.

 

This would account for why you have virtually no pedal feel and unable to bleed the brakes. You need to get the booster front pushrod to suit an LJ which sits approx 1" proud of the booster/master cyl mounting face.

Also I wouldn't be too concerned about what the pedal feels like without vacuum assistance, can guarantee you won't like the driving experience without the booster working.



#5 lctriples

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Posted 11 November 2020 - 07:44 PM

Hey dave, you may be right, I am going to bench bleed m/c tomorrow and try the longer pushrod, will let you know how it goes, cheers paul



#6 Balfizar

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Posted 11 November 2020 - 08:02 PM

You Tube will show you the 5 ways to bleed brakes:

 

Normal - pump /hold - crack caliper bleed nipple - repeat until no air comes through

Vacuum -  with a vacuum tool, attach to bleed nipple , crack pump up vacuum -  keep pumping until no air is pulled through. (Start on left rear/right rear/ left front/right front)

Gravity - crack bleed nipples wait til no more air comes through (watch reservoir level and top up as necessary) messy and slow.

bench - pipe the ports back up into the reservoir with flare nuts and clear hose,  M/C in vice, pump with screw driver til you don't see any air come out of clear pipes.  replace M/C on car and bleed as normal.

Reverse -  syringe inject brake fluid into ports until no air comes into reservoir  (last resort) but sometimes necessary. (especially on new M/C with a stubborn air lock)

 

You tube has all of these videos available.  Find the ones that look like a professional workshop ,  amateur ones get half of it wrong.

 

Sounds like you have a mechanical engagement problem.   Measure the depth of the M/C and the protrusion of the rod.  should not engage but be very close.

You can also use a small washer (Down the M/C Rod hole) to pack out the engagement point of rod and M/C,  If you don't feel resistance when seating the M/C on the booster there is something wrong,  Keep packing until you feel resistance, remove packing and measure thickness.  thats how far you are from the correct engagement point. That generally means rod/booster incompatible with master ( one of them is wrong)


Edited by Balfizar, 11 November 2020 - 08:10 PM.


#7 sibhs

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Posted 12 November 2020 - 10:27 PM

Hey Marty, great to hear from you. How is your project/Torana no 2 coming along? Thanks again, paul

 

Hi Paul,

Mojo has run out, hope to find some soon.

 

Marty



#8 Indy Orange

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Posted 13 November 2020 - 12:58 AM

Fat bastard took it Marty , get it back!

#9 S pack

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Posted 13 November 2020 - 06:45 AM

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#10 lctriples

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Posted 20 November 2020 - 07:00 PM

Quick brake system update, bench bled m/c, used longer pushrod. Much, much better, put still not 100%, should be good enough to get "on the road" and hopefully sort out later down the track. Obviously brakes are something you can't do half arsed, so will get sorted as a priority.



#11 grumpy xu1

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Posted 20 November 2020 - 10:17 PM

The woah,needs to be sorted before the go, bro !!!!!

#12 lctriples

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Posted 21 November 2020 - 10:37 AM

100% need to brake before you break!



#13 grumpy xu1

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Posted 21 November 2020 - 06:44 PM

100% need to brake before you break!



I was referring to your "not 100% but SHOULD be good enough to get it on the road & sort it out later"
Yeah nah ! Fix it properly before the engine drives. Sorry mate, but brakes save lives to me & it's the most important thing on a vehicle.

#14 lctriples

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Posted 22 November 2020 - 06:33 AM

Hey Gaz, sorry I should have re-read my post on 20th, what I meant was I whole heartily agree with you. Brakes will need to be tickity -boo for the roadworthy anyway, and safety always overrides performance in my eyes, cheers paul



#15 S pack

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Posted 22 November 2020 - 07:17 AM

Paul, with the engine running, meaning the booster has vacuum, does application of the brake pedal start soft and low (almost goes to the floor) and with a few quick pumps rises and firm under foot?



#16 grumpy xu1

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Posted 22 November 2020 - 02:50 PM

Hey Gaz, sorry I should have re-read my post on 20th, what I meant was I whole heartily agree with you. Brakes will need to be tickity -boo for the roadworthy anyway, and safety always overrides performance in my eyes, cheers paul


Good to hear Paul, i was a little worried about the wording. But all good now.

#17 lctriples

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Posted 26 November 2020 - 08:17 PM

Dicked around with brake gremlins over the weekend. Was telling a mate about brake pedal feel and he told me to crimp off brake lines to see if master cylinder or wheel/s issue. Crimped off rear brake hose (x1) and front brake lines (x 2): instant full brake pedal feel, then after removing crimps from bake to front pass side then front drivers side, worked out drivers side front brake caliper was the culprit. Pulled apart and had a lot of moisture, slight rust, crap ect . Cleaned all that up and after bleeding system, brakes pedal pretty good. Then couldn't get rear brakes to operate properly, replaced wheel cylinders as they had also accumulated moisture, rust ect. Now they work fine without drums on, but cant get them to grab (ie stop wheel spinning when brakes applied.) Harder to spin with brakes on, but can still turn by hand with pre-load adjusted as far out without seizing wheels. Maybe rear brakes need to "bed in" or with work much better under vacuum, (is this was you were alluding to Dave?) Front brakes work like a charm even without engine running. I can't remember if brake pedal pumps up when engine running as ran out of time on Sunday, but will check this weekend. Thanks for eveyones help and advice so far, slowly getting there, Paul.

Moral of the story is: don't do brakes up replacing lines, wheel cylinders, calipers ect until car ready to roll (ie: not 4 years ago) as obviously moisture gets into system when sitting idle for such a long period of time.



#18 grumpy xu1

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Posted 26 November 2020 - 08:36 PM

I can remember building a torana say 20 years ago, thought about doing the brake system & an older friend dropped round by chance & said, always brakes last, as he'd seen booster diaphragm's tear after sitting & obviously that can end bad. It's certainly stuck in my memory from his description. I like to hydroblast those parts & make sure that they're "completely" dry, before starting assembly. Obviously use the correct lube, per item that you're assembling aswell. Now don't torana drums self adjust in reverse ? Just letting it roll backwards, providing the fronts are now good & the system is thoroughly bled, on a slight angle, you should be able to get complete adjustment, i would imagine ?

I'm assuming that you have fitted new rubber or braided hoses, with that suggestion though.

#19 lctriples

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Posted 27 November 2020 - 06:00 AM

Hey Gaz, yes all new brake hoses (4 years ago) Car has not actually been "driven" yet so when I have confidence in brakes and car is running well, will try your suggestion as our driveway has a pretty good angle on it.  Paul.






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