HJ brake issues (at my wits end)

[dieselDaryl]

Well I'm back at trying to get the brake issues figured out on my 88HJ61. The issue I am having is less than optimal stopping power and a spongy brake pedal.

Here is what I have done over the past 6 months or so, all to no avail:
-Bled and Bled and Rebled the brakes (10 times at least over the past 6 months, see below). Bleeding has been done using both one man bleeder kits, and the two person process.
-Replaced the rear wheel cylinders
-Replaced the rear pads
-Checked the auto adjusters at the rear
-Checked the e-brake cable
-Adjusted the rear shoes manually through the inspection hole
-swapped out the m/c for the bigger toyota truck one (1" bore) (twice)
-swapped out the front calipers for the bigger toyota truck ones
-changed the shoes and pads
-replaced the front rotors
-turned the rear drums
-checked the system for leaks
-swapped back to original m/c and calipers
-bench bled the m/c each time it was replaced
-cleaned off the pads and shoes each time they were replaced

So needless to say I'm kind of at my wits end with this. Does anyone have ANY ideas? My current theory is that it is something at the rear.. I clamped off the rear brake line tonight and the brake pedal is super super tight when I do this.
-Maybe the drums are out of spec?
-Maybe the rear soft line needs replacing?
-Maybe the rear shoes aren't contacting the drums correctly?

My next step is to swap out the shoes and drums from a BJ60 I have sitting in the backyard. But any other theories are welcome at this point!!

Thanks..

 

[Jan-78FJ40]

Well I'm back at trying to get the brake issues figured out on my 88HJ61. The issue I am having is less than optimal stopping power and a spongy brake pedal.

Here is what I have done over the past 6 months or so, all to no avail:
-Bled and Bled and Rebled the brakes (10 times at least over the past 6 months, see below). Bleeding has been done using both one man bleeder kits, and the two person process.
-Replaced the rear wheel cylinders
-Replaced the rear pads
-Checked the auto adjusters at the rear
-Checked the e-brake cable
-Adjusted the rear shoes manually through the inspection hole
-swapped out the m/c for the bigger toyota truck one (1" bore) (twice)
-swapped out the front calipers for the bigger toyota truck ones
-changed the shoes and pads
-replaced the front rotors
-turned the rear drums
-checked the system for leaks
-swapped back to original m/c and calipers
-bench bled the m/c each time it was replaced
-cleaned off the pads and shoes each time they were replaced

So needless to say I'm kind of at my wits end with this. Does anyone have ANY ideas? My current theory is that it is something at the rear.. I clamped off the rear brake line tonight and the brake pedal is super super tight when I do this.
-Maybe the drums are out of spec?
-Maybe the rear soft line needs replacing?
-Maybe the rear shoes aren't contacting the drums correctly?

My next step is to swap out the shoes and drums from a BJ60 I have sitting in the backyard. But any other theories are welcome at this point!!

Thanks..

how did you adjust the rear drums?
did you turn the adjuster through the inspection hole till the drums bind, and then back off a little?
and what exactly do you mean byb spongy pedal? that it always goes down far? what happens if you pump?
j

 

[BURGER]

Spongy feel could definately be failing rubber hoses. You have done every thing else multiple times. Why not try them. If that does not work then I guess youll have to just sell the truck to me, I need another

 

[The Dude]

Daryl,

I have done the same to my HJ. Bigger calipers up front, bigger MC, new drums/shoes in the rear and bled a million times with a spongy feel never leaving. I alsway thought it was a back brake adj from all the research I had done.

I then switched to stainless soft lines. Problem solved. I did it both front and rear. I used Marlins extended lines as I am SOA.

I can now stop my big michelins without using two feet.

 

[dieselDaryl]

how did you adjust the rear drums?
did you turn the adjuster through the inspection hole till the drums bind, and then back off a little?
and what exactly do you mean byb spongy pedal? that it always goes down far? what happens if you pump?
j

Yes, thats exactly what I did with the adjuster.. just in case, but like i said it made no difference (other than warming up the drums a bit too warm after a test drive)

Spongy pedal = pedal that bottoms out quite easily. I.e. In a panic stop I jam the pedal to the floor and just wait for the truck to slow down.. no lockup of tires and WAAAAY to long to come to a stop.. However I'm pretty sure the pedal is adjusted propery because at a gentle roll (like at a stop light) i can feel the brakes pick up with very light touch (a couple mm) Like I said, clamping the rear soft line makes the pedal very hard. Very little travel and very solid feeling. So I think things from the master cylinder back to the rear lines are good

I will try the SS hoses.. Failing that I will try a different set of shoes and drums on the back.. THanks for the suggestions guys...


Two aditional things:
-The truck has no LPSV at the rear.
-I was thinking the problem could also be the proportioning valve at the master cylinder? Are those known to 'go'?

 

[Jan-78FJ40]

Two aditional things:
-The truck has no LPSV at the rear.
-I was thinking the problem could also be the proportioning valve at the master cylinder? Are those known to 'go'?

they can die, but it would not cause a spongy pedal-just the rears would lock up before the fronts.
when you pump, does it stay spongy?
j

 

[bigbrowndog]

Daryl,

I have done the same to my HJ. Bigger calipers up front, bigger MC, new drums/shoes in the rear and bled a million times with a spongy feel never leaving. I alsway thought it was a back brake adj from all the research I had done.

I then switched to stainless soft lines. Problem solved. I did it both front and rear. I used Marlins extended lines as I am SOA.

I can now stop my big michelins without using two feet.

Did you adjust your load sensing valve? I understood once a lift of 4 inches or more was done the valve needed something like a quarter turn to increase the bias on the brakes or is this only on the hj75 with the valve at the back. cheers

 

[dieselDaryl]

they can die, but it would not cause a spongy pedal-just the rears would lock up before the fronts.
when you pump, does it stay spongy?
j

I will try that and let you know. Problem is once you use up all the vacuum, funny things probably happen.

Did you adjust your load sensing valve? I understood once a lift of 4 inches or more was done the valve needed something like a quarter turn to increase the bias on the brakes or is this only on the hj75 with the valve at the back. cheers

This truck does not have a LPSV at the rear axle..

 

[bigbrowndog]

I will try that and let you know. Problem is once you use up all the vacuum, funny things probably happen.



This truck does not have a LPSV at the rear axle..

I thought I asked in the Pm if it had one in the engine bay.My understanding is the valve also retains the brake fluid in the wheel cylinders under slight pressure to stop excessive fluid coming back in the lines as well as increasing the bias under load.cheers

 

[dieselDaryl]

I thought I asked in the Pm if it had one in the engine bay.My understanding is the valve also retains the brake fluid in the wheel cylinders under slight pressure to stop excessive fluid coming back in the lines as well as increasing the bias under load.cheers

Ahh, I gotcha. I see a little nut and a big nut on there.. I know I have section in my FSM showing a cutaway view of it, maybe I'll look into that. Still, would this affect the tightness of the pedal or just the differential between front and rear lockup?

 

[2rivers]

Following with interest...(mine suck also). Good tip on the stainless lines from Dude.

 

[bigbrowndog]

when I replaced mine which works off the back axle it took the spongy feeling out of the pedal. On the back I replaced the wheel cylinders,Linings and put on new drums.Front had new HZJ calipers and new power booster and master cylinder.I flushed it with metho until clean then when I filled it with fluid I bled it all again, while doing this crap and rust came out of the valve. I replaced the valve and rebled it again and it was rock solid.I was told the valve holds fluid in the rear wheel cylinders to keep it balanced with the pistons in the caliper as they move less. How high is your lift as I am sure this effects the bias also.Also with the larger calipers this gives a bit more pedal travel but can be corrected as explained in the Pm. Set the pedal to the spec in the manual then check out the valve. Does your valve have a bleed nipple?

 

[bigbrowndog]

Following with interest...(mine suck also). Good tip on the stainless lines from Dude.

will post the pages on brakes, may help cheers

 

[bigbrowndog]

 

[bigbrowndog]

 

[bigbrowndog]

 

[bigbrowndog]

 

[dieselDaryl]

when I replaced mine which works off the back axle it took the spongy feeling out of the pedal. On the back I replaced the wheel cylinders,Linings and put on new drums.Front had new HZJ calipers and new power booster and master cylinder.I flushed it with metho until clean then when I filled it with fluid I bled it all again, while doing this crap and rust came out of the valve. I replaced the valve and rebled it again and it was rock solid.I was told the valve holds fluid in the rear wheel cylinders to keep it balanced with the pistons in the caliper as they move less. How high is your lift as I am sure this effects the bias also.Also with the larger calipers this gives a bit more pedal travel but can be corrected as explained in the Pm. Set the pedal to the spec in the manual then check out the valve. Does your valve have a bleed nipple?

Lift is 4" but like I said, don't have a LPSV. No bleed screw on the Proportioning valve on the front. I have been tempted to get a manual one but am not at that point yet... I've got a new rear brake line on order for the rear and am going to try that in combination with new(er) drums. New ones out here are $150 a piece so I'm going to try different used set (measuring first). I have a feeling it might be the drums as i recall the problems coming up around the time that i had the drums turned..

Daryl

 

[lshobie]

Did you bleed the master cylinder?

 

[dieselDaryl]

Did you bleed the master cylinder?

Yes I did. I've actually swapped the MC several times. When I put the new bigger calipers, I also installed a bigger (1" bore) m/c. It was a rebuild and some people have said they've had problems with rebuilds in the past so I bought a new Raybestos one. I ran that for about 6 months.. Now I am back to the factory one with factory calipers. Each time I've bench bled the master cylinder with the adapters and hoses... I also bleed the brakes from farthest wheel to closest. I've even jacked up the front end of the truck to the level position (front springs are slightly lower than rears) and bled..

No difference any time..

Daryl