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Lhf brake calliper locking up under light brake apply Ln Torana


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#1 natcamp10

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Posted 19 November 2017 - 01:36 PM

Hey guys
Recently did some upgrades to the front brakes , the list as follows
Purchased a 7" s2 dual diaphragm booster and 1" master cylinder from eBay .. The chrome job
Fitted the standard booster anchor bracket
Also got the twin piston girlock gtr calipers and fully over hauled with new pistons and seals
Fitted new flexible brake lines and associated steel pipes to suit
I've also fitted the spacer plates to the calipers and I'm running the thicker slotted discs
My old brake setup was a remote boosted pbr setup vh44 with a firewall mounted master cylinder running hr front discs with single piston .
So I took it for a run yesterday and started running in the discs and I noticed it's really easy to lock up the front left side .
Any thoughts here guys .. I'm thinking possible the adjustment on the rod between the booster and master cylinder . I assume the car came out with drums and was modified before I owned it to the remote setup.
it is running a proportional valve but being only on side locking up I'm not suspecting this
After bleeding the brakes the first time I had to adjust the rod running threw the firewall a bit the get the pedal a nice feel at the top of its travel , could this be a issues where I've over adjusted this and not set the rod length correctly between the master cylinder , to tell you the truth I only realised between reading up on the fault all the different adjustment between the booster and master cylinder but again I'm running aftermarket stuff so I'm not sure what the length should be
Any help would be much lay appriecated
Thanks guys

#2 dron

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Posted 19 November 2017 - 05:48 PM

Hi Nathan

 

               When you adjust the push rod for a master cylinder you must have a small amount of free play in the rod. Never over tighten it. If you do the brakes will not release and can pump up to the point they drag or even lock up. The same applies to a  clutch but in the clutch you run out of drive (slipping clutch) as it pumps up.

 

         The reason is in the way the master cylinder works. It has a small hole drilled in the bore that is blocked when the piston moves forward. only when the piston returns complementary can any fluid return to the reservoir. You need to check the peddle adjustment 1st and then the rod between the booster and cylinder. Both need to have just a little free play.



#3 Bigfella237

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Posted 19 November 2017 - 06:15 PM

Assuming you have both left & right front brakes on a common circuit (as the factory did), that basically eliminates any booster / master issues as the problem would affect both sides if it was, not just one.

 

You say you've fitted all new lines and hoses so let's assume there's no blockages or swarf or other crap floating through the lines, which only leaves a caliper problem.

 

Did the system bleed okay, starting with a bench-bleed of the master, then longest line first on the car, working around to the shortest line (I usually like to go around one more time after that just to make sure)? Are there two bleed nipples on each caliper and if so are you sure you got all the air out of all of them?

 

You say you reco'd the calipers, are you sure all the parts on the kit were correct, and there were no pinched seals, and everything moves as it should? Lastly these spacers, are you certain they didn't block or restrict any ports through the caliper (if they're that type of caliper)?

 

Maybe take some photos and load them up here?



#4 rodomo

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Posted 19 November 2017 - 10:14 PM

I noticed it's really easy to lock up the front left side .
Thanks guys

Dunno about your new booster??? but you may have lost the reaction disc behind the master cylinder pushrod in the booster?

This causes harsh application and locking, the reaction disc is a cushion so to speak.

#5 UCSLE

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Posted 19 November 2017 - 10:21 PM

what stub axles and hubs are you using , HR or LJ ?



#6 natcamp10

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Posted 20 November 2017 - 12:39 AM

Hey guys
Thanks for the reply.. I will ansewer all questions here
Yes they system seemed unusually hard to bleed
The lines are clear ( the system was only apart for a day and the lines were sealed as well when it was opened .. with tape)..i replaced the lines that run from the front brake master cylinder to the proportional valve ..left and right are common to the front system . but I've noticed already on the lh disc a unusual pattern starting from the inner of the disc ,possibly where it's locking up
Only the flexiable lines were replaced ( the main steel lines running in crossmember are origanel )and the link lines running from the stub axles to the calipers .. the small one have been changed
The stub axles are from a a disc front end lj
The booster was complete so the push rod booster etc was brand new so the reaction disc should be ok
There no signs of leaks at the calipers and they're not dragging . Eg car jacked up and brakes applied no spin on the wheel , release brakes all seems ok
New pistons fitted with seals and measured the pistons before assemble and they were same as the old ones
In regards to the spacer plates in the calipers . it's bullet proof , there's only 1 cross flow port between each side ..
One thing I did notice was in regards to the kits supplied with the spacer plate and the seal kits for the calipers ,the spacer plates came with orings but the kits came with what I call d rings or square cut seals , now I remember fitting the square shaped seals to one side because I had missed placed a oring , it still protruded nicely but could this be my fault ?.. I cannot remember which side I fitted it to .. in saying that I've never seen a system suck air but not leak I could be wrong tho ..
Thanks for the replys and let's nut this sucker out πŸ‘

#7 Bigfella237

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Posted 20 November 2017 - 01:03 AM

That mark on the effected disc sounds like it may be a clue, depending on what kind of a mark it is of course?

 

I wonder if there is some foreign matter embedded in the pad?

 

Or something hinky with the caliper mount on that side, maybe it's not quite square or not bolted flush to the stub?

 

Maybe you have one pad with a different compound that somehow got mixed up from the supplier?



#8 S pack

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Posted 20 November 2017 - 08:00 AM

Did you buy one of these HG GTS kits with the long curved caliper to stub axle spacers and did you install those spacers? If so remove them immediately.

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Edited by S pack, 20 November 2017 - 08:01 AM.


#9 S pack

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Posted 20 November 2017 - 08:06 AM

That mark on the effected disc sounds like it may be a clue, depending on what kind of a mark it is of course?

Probably the caliper rubbing on the inside face of the disc.



#10 S pack

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Posted 20 November 2017 - 08:13 AM

Hey guys

One thing I did notice was in regards to the kits supplied with the spacer plate and the seal kits for the calipers ,the spacer plates came with orings but the kits came with what I call d rings or square cut seals , now I remember fitting the square shaped seals to one side because I had missed placed a o ring , it still protruded nicely but could this be my fault ?
 

If the fluid passage between the caliper halves was restricting fluid flow you would have an outboard pad dragging.



#11 natcamp10

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Posted 20 November 2017 - 03:35 PM


Did you buy one of these HG GTS kits with the long curved caliper to stub axle spacers and did you install those spacers? If so remove them immediately.



#12 natcamp10

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Posted 20 November 2017 - 03:37 PM

Did you buy one of these HG GTS kits with the long curved caliper to stub axle spacers and did you install those spacers? If so remove them immediately.


Hey s pack
Yup these are the ones I fitted to space the calipers out to fit the thicker xu1discs , I don't seen to have any leaks . What is the issue with running these ?

#13 natcamp10

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Posted 20 November 2017 - 03:51 PM

what stub axles and hubs are you using , HR or LJ ?

Hey ucsle
I'm not 100 Percent sure now . The discs that came off the stubs you couldn't unbolt them from the hubs , when I purchased the Girlock calipers they came with the hubs so I purchased new discs and mounted them to the hubs and fitted them to the stub axles . Nothing seemed abnormal when mounting the hubs , discs and calipers .
Are able to explain the difference so I can check , I will be disassembling the lh side to check everything but again it all went together nicely .. now I'm only assuming to it was a HR setup .. the calipers were pbr single piston , the booster was a remote mounted vh44? Small looking thing lol, and the master cylinder was a pbr brand mounted to the firewall
Cheers

#14 natcamp10

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Posted 20 November 2017 - 03:59 PM

If the fluid passage between the caliper halves was restricting fluid flow you would have an outboard pad dragging.

Hey s pack
Yup looking from the outside of the wheel and comparing both sides the lh side has funny lines starting on the disc on the inner part closest to the hub the outer half looks ok I'm gonna pull it Down and see what's happening on the other side of the disc

#15 S pack

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Posted 20 November 2017 - 07:14 PM

Hey s pack
Yup these are the ones I fitted to space the calipers out to fit the thicker xu1discs , I don't seen to have any leaks . What is the issue with running these ?

To be 100% clear, I'm not referring to the spacers that are installed between the caliper halves, they are same part for LC/LJ XU1 and HG GTS.

It's the two long curved spacers that the HG GTS requires but not the XU1.



Hey ucsle
I'm not 100 Percent sure now . The discs that came off the stubs you couldn't unbolt them from the hubs , when I purchased the Girlock calipers they came with the hubs so I purchased new discs and mounted them to the hubs and fitted them to the stub axles . Nothing seemed abnormal when mounting the hubs , discs and calipers .
Are able to explain the difference so I can check , I will be disassembling the lh side to check everything but again it all went together nicely .. now I'm only assuming to it was a HR setup .. the calipers were pbr single piston , the booster was a remote mounted vh44? Small looking thing lol, and the master cylinder was a pbr brand mounted to the firewall
Cheers

Sounds like you had LH/LX Torana discs and calipers.


Edited by S pack, 20 November 2017 - 07:14 PM.


#16 natcamp10

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Posted 20 November 2017 - 08:50 PM

Sweet s pack
They didnt fit so they never went in

#17 LJ RB30

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Posted 20 November 2017 - 09:27 PM

Different set up but similar symptoms.
Years ago my HJ ute started locking up the left-hand front under light brakes in the wet.
I replaced the calipers with rebuilt ones and bled multiple times.
Replaced the discs with machined ones.
But nothing changed 😞😞
I purchased a front end bush kit but put it off the road before I fitted them.
Years later I put it over the pits and of course they knocked the front end bushes and body to chassis & shackle rubbers plus a list of other things.
I replaced them all and it drives fantastic (always did ) as it's lowered & firm😁
But to my frustration it's still locked up the Lhf in the wet under light brakes 😩
When I was underneath fixing a fuel hose I noticed that the rear right leafspring had sagged slightly !!!( The rear springs have the thick overload leaf bolted on top of them upside down to lower them and stiffen them up!) 😁😁The sagged rear right is not allowing enough weight on the lhf wheel under light braking!
One day I'll get another set of springs reset to fix it lol
Does your car have a stiff suspension??
Just a thought!

#18 natcamp10

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Posted 21 November 2017 - 02:52 PM

Yeah it does has stiff suspension with air riders in the back and lowered at the front , the back right leaks over time and was down When i tested The fact.. you might be onto something here

#19 LJ RB30

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Posted 21 November 2017 - 07:46 PM

sounds like the culprit! :spoton:



#20 flygtr028

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Posted 22 November 2017 - 12:20 PM

Don't forget the rear brakes, as sticking wheel cylinder pistons or weak shoe return springs wont help.

Also brake proportioning valve did not come out in LJ only brake fail warning light switch/valve.

Check fitment of inner hub seal for leaks,I have found no after market ones suitable, if using the all rubber seal it interferes with the backing plate. 



#21 natcamp10

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Posted 25 December 2017 - 01:22 AM

Hey guys
Bit of a update , so I checked the spacer setup between new booster and master cylinder, adjustment good , set rear air shocks at the rear independently and made sure they were the same height , removed lh calliper disassembled and reinspected , all seems good , what I have noticed between The lh and rh sides is that Alignment of the discs don't seem the the same , when you look down the through the caliper where the pads go I noticed that the lh disc sits approx 2to 3mm further over to the outside pad , although when it's all assemble it's does feel like its dragin , but it is the side on the discs with a funny wear pattern on it , I've tried to remove the dust seal for the bearings and reassembling etc but the nothing changes the caliper position and I cannot seem to think of a way to space the caliper over a bit . If the clearance issue was the other way I could use some small washers to space over a bit , the only thing I have come up with is machining a small amount off where the inner wheel bearing backs onto which in turn would move the disc over. Has anyone got a spec on what the stub length is for lj disc front end stub axle as the only other thing I can think of is that they're not lj stub axles , they did measure the same as a drum stub axles for a lj . So I'm measuring from where the inner wheel bearing backs onto and the start of the stub . If anyone has anymore ideas it would be much appreciated
Thanks all
Merry Xmas

#22 S pack

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Posted 25 December 2017 - 06:34 AM

Have a read, sounds like could be a similar problem. May help, may not.

http://www.gmh-toran...-front-disk-lj/


Edited by S pack, 25 December 2017 - 06:34 AM.


#23 S pack

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Posted 25 December 2017 - 05:01 PM

Just re read your post #21 and see that you have tried the disc without the grease seal and it made no difference.

Have you checked to ensure the inner wheel bearing race is fully seated into the hub?



#24 natcamp10

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Posted 01 January 2018 - 06:56 PM

Yeah it's fully seated in the hub and goes all the way onto the stub axle . Is there a post somewhere explaining how to upload photos so I can put a picture up , also is there a way for g telling if the stub axles are lj or HR ? But if that was the case I would have the same fault on the drivers side but I don't , maybe I could remove the discs and swap it all around from lh to rh and see if that makes a difference

#25 Rockoz

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Posted 01 January 2018 - 08:19 PM

Go to the bottom of the text box for replies and hit more reply options.

Right beside the post button.






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