This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
- Thread starter
- #3
Thanks for the reply,
I bought this fj62 about a month ago and have been working on issues, one have been the brakes.
I replaced rear brake cylinder and new pad and adjusted them as far as they can go the drums and the front calipers seems to working correctly with good pads, but the vehicle pedal will go almost to the floor when brakes are applied and they feel pretty soft.
It is consistent on the pedal so I don’t think there is air in the system.
I’m not sure how one could tell if the booster is bad…
I bought this fj62 about a month ago and have been working on issues, one have been the brakes.
I replaced rear brake cylinder and new pad and adjusted them as far as they can go the drums and the front calipers seems to working correctly with good pads, but the vehicle pedal will go almost to the floor when brakes are applied and they feel pretty soft.
It is consistent on the pedal so I don’t think there is air in the system.
I’m not sure how one could tell if the booster is bad…
- Thread starter
- #4
I’m wondering if the piston are sticking in the front calipers while driving and that maybe the issue. I noticed when I drove it the other day and pulled it in the shop to remove the front wheels I have a hard time turning the wheel to remove the lug nut,( like the brakes were sticking )I removed the calipers to look and see if the were working properly reinstalled them and wheels were easily like they should be..
I remember how my 60 braked when it was only two years old - in 1988. It braked fine. Really good. No problems. Car was completely stock.
So when everything is working as it should, braking is fine and safe on these vehicles. No ‘upgrade’ is required.
So when everything is working as it should, braking is fine and safe on these vehicles. No ‘upgrade’ is required.
Had similar issues for a while. I have tons of armor and pull a fully loaded trailer. Now I can stop it on a dime. Here are my upgrades, it wasn't cheap.
Converted the front to a 2017+ 4 Runner brake calipers and disks, you'll need 17in wheels for that.
Replaced the rear axle with an fzj 80 axle, so it has disk brakes in the back. I did this more to have full floating axles, but the brake improvement was a huge benefit.
Upgraded the master cylinder to a one inch bore.
I zip tied the proportioning valve all the way up so the truck assumes its always fully loaded.
Truck now can stop in a downhill steep slope on the trails or stop with a fully loaded trailer after doing highway speeds.
Converted the front to a 2017+ 4 Runner brake calipers and disks, you'll need 17in wheels for that.
Replaced the rear axle with an fzj 80 axle, so it has disk brakes in the back. I did this more to have full floating axles, but the brake improvement was a huge benefit.
Upgraded the master cylinder to a one inch bore.
I zip tied the proportioning valve all the way up so the truck assumes its always fully loaded.
Truck now can stop in a downhill steep slope on the trails or stop with a fully loaded trailer after doing highway speeds.
Last edited:
Zip tie it all the way. See if that improves anything.
Principal symptom of a bad brake booster is pedal is stiff or won't depress easily as the booster is an 'Assist'. If booster not working, your pedal becomes more difficult to depress.
If pedal is going down half-way, does it stiffen up if you do 4-5 quick pumps? If yes, there's still residual air trapped in system. It's common.
You'll need a helper for this (Wife/GF/BF are the last people you should ask
):
Bleed 1st from the most distant wheel cylinder from the MC - That's the rear Driver's side because of the routing of the brake lines.
Have someone hold the pedal down before you loosen the bleeder and gently tap the lines and wheel cylinder before opening bleeder. Rapidly Pump the brake pedal 4-5 times between each open/close of bleeder. Repeat until fluid runs clear with clear hose into a glass jar filled with fluid. Rinse/Repeat at each successive wheel, tapping as you go. Tap the residual valve with a rubber mallet. Can take a couple of large cans of brake fluid. I've found it's often the calipers that are the issue. Rapid tapping with rubber/plastic mallet seems to release the trapped air.
OR-- Buy a Motive Pressure Bleeder. ($$$).
If pedal is going down half-way, does it stiffen up if you do 4-5 quick pumps? If yes, there's still residual air trapped in system. It's common.
You'll need a helper for this (Wife/GF/BF are the last people you should ask
):Bleed 1st from the most distant wheel cylinder from the MC - That's the rear Driver's side because of the routing of the brake lines.
Have someone hold the pedal down before you loosen the bleeder and gently tap the lines and wheel cylinder before opening bleeder. Rapidly Pump the brake pedal 4-5 times between each open/close of bleeder. Repeat until fluid runs clear with clear hose into a glass jar filled with fluid. Rinse/Repeat at each successive wheel, tapping as you go. Tap the residual valve with a rubber mallet. Can take a couple of large cans of brake fluid. I've found it's often the calipers that are the issue. Rapid tapping with rubber/plastic mallet seems to release the trapped air.
OR-- Buy a Motive Pressure Bleeder. ($$$).
I just had the same experience, had plenty of air in my second bleeding.
One thing I was told with rear brake pads they need a longer breaking in period, after which you should re-adjust them.
At the moment my car is brake front heavy, so It feels the back brakes are doing less then front, kind of a tilting forward sensation when heavy breaking certainly weaker than what feels comfortable for me.
I am also changing rims for 16 inch as to swap at some stage brake pads and disc to 80 series but for the moment one more adjustment to the rear brake calipers and will check result.
One thing I was told with rear brake pads they need a longer breaking in period, after which you should re-adjust them.
At the moment my car is brake front heavy, so It feels the back brakes are doing less then front, kind of a tilting forward sensation when heavy breaking certainly weaker than what feels comfortable for me.
I am also changing rims for 16 inch as to swap at some stage brake pads and disc to 80 series but for the moment one more adjustment to the rear brake calipers and will check result.
Last edited:
don’t forget to bleed the proportioning valve after the rear brakes and before the front.
does the pedal slowly creep to the floor once you feel the brakes engage? that’s a sign of a bad master cylinder. hard brakes could be a sign of bad booster. squishy brakes probably air in the line
if you have a proportioning valve it’s a weight sensitive valve. it compresses when there is more weight in the rear and gives more rear braking. with a lift it may screw up the position of the proportioning valve giving only partial rear brake. i had to put a little spacer under mine the same height as the lift to locate it where it’s supposed to be at it’s normal resting point
does the pedal slowly creep to the floor once you feel the brakes engage? that’s a sign of a bad master cylinder. hard brakes could be a sign of bad booster. squishy brakes probably air in the line
if you have a proportioning valve it’s a weight sensitive valve. it compresses when there is more weight in the rear and gives more rear braking. with a lift it may screw up the position of the proportioning valve giving only partial rear brake. i had to put a little spacer under mine the same height as the lift to locate it where it’s supposed to be at it’s normal resting point
I had very similar issues for years. Throwing all types of parts at it. The one thing I failed to look at was the brake booster. Sure enough I adjusted the linkage bolt behind the pedal. Completely cured my nagging issues. You have nothing to lose. Good luck
diesellibrarian
SILVER Star
From the FSM:
In my (admittedly somewhat limited) experience, issues with a low pedal have been as a result of the rear shoes being out of adjustment.
Have you confirmed that the self-adjusting mechanism is working? Often the bell cranks are seized and not doing their job. Another thing that I did once in reassembling the rear brakes was I forgot to run the parking brake cable over the cam (or "pulley" as it's called in the FSM) at the bottom of the rear brake assembly. This cam (circled in red) is critical to the self-adjustment mechanism but is mostly hidden by the axle flange and easy to miss if you're not careful:
In my (admittedly somewhat limited) experience, issues with a low pedal have been as a result of the rear shoes being out of adjustment.
Have you confirmed that the self-adjusting mechanism is working? Often the bell cranks are seized and not doing their job. Another thing that I did once in reassembling the rear brakes was I forgot to run the parking brake cable over the cam (or "pulley" as it's called in the FSM) at the bottom of the rear brake assembly. This cam (circled in red) is critical to the self-adjustment mechanism but is mostly hidden by the axle flange and easy to miss if you're not careful:
Great feedback so here is where i am atm:
1- changed pads front
2- changed brake pistons back and pads
3- initial air bleed
Result almost no change at first, after driving a bit better braking
4- 2nd air bleed
BIG improvement, i can now lock brakes (i couldn't before)
Current lingering issue is excessive force needed on brake padel.
Would that be booster wear ?
As mentioned in a previous post. I bad brake booster would result in a harder pedal. There are several checks outlined in the FSM.
There is also an adjustment rod inside the brake booster. You would need to remove the master cylinder from the booster. The adjustment is for the amount of gap between the booster rod (the rod comes out of the Brake booster and pushes the master cylinder piston when pressing the brake pedal) and the master cylinder piston. You want the smallest gap possible. Example: A large gap would require more time for the booster rod to contact the master cylinder piston and may not apply your brakes fully. Not enough gap, and the booster will not release the brakes when you take your foot off the pedal.
That being said. If master cylinder and brake booster are original. Then it is not likely this adjustment will make a difference.
Did you also bleed the LSPV. Bleed the passenger rear 1st, then driver rear 2nd, then LSPV 3rd, then passenger front 5th, then driver front 6th.
In addition to the brake rod adjustment. If the master cylinder is new; you would need to bench bleed the master cylinder prior to installation. If you bleed the master dry by accident, you would need to bleed the master cylinder using a master cylinder bleed kit from your local auto parts store. The bleed kit has fittings and 2 hoses. You connect the fittings/hoses and route them into the master cylinder reservoir. add fluid to the reservoir and pump the pedal to clear any trapped air inside the master cylinder.
Also, you can find a digital copy of the FSM by clicking on the "Resources" tab in the header line at the top of your screen.
There is also an adjustment rod inside the brake booster. You would need to remove the master cylinder from the booster. The adjustment is for the amount of gap between the booster rod (the rod comes out of the Brake booster and pushes the master cylinder piston when pressing the brake pedal) and the master cylinder piston. You want the smallest gap possible. Example: A large gap would require more time for the booster rod to contact the master cylinder piston and may not apply your brakes fully. Not enough gap, and the booster will not release the brakes when you take your foot off the pedal.
That being said. If master cylinder and brake booster are original. Then it is not likely this adjustment will make a difference.
Did you also bleed the LSPV. Bleed the passenger rear 1st, then driver rear 2nd, then LSPV 3rd, then passenger front 5th, then driver front 6th.
In addition to the brake rod adjustment. If the master cylinder is new; you would need to bench bleed the master cylinder prior to installation. If you bleed the master dry by accident, you would need to bleed the master cylinder using a master cylinder bleed kit from your local auto parts store. The bleed kit has fittings and 2 hoses. You connect the fittings/hoses and route them into the master cylinder reservoir. add fluid to the reservoir and pump the pedal to clear any trapped air inside the master cylinder.
Also, you can find a digital copy of the FSM by clicking on the "Resources" tab in the header line at the top of your screen.
Jusy my 2 cents, had the same issue. Changed pads, pistons in the rear etc.
Better but still no where near what i wanted.
Yesterday took the rig to a mechanic and we swapped the servo motor from and 80 series with duel diaphragm as apposed to single in the 60.
End result probably the best upgrade i ever did. I mean worlds apart not even compareble.
The brakes are far far more responsive with so much less effort. I kept the same master cylinder to avoid having to bleed the brakes and to also make sure it was indeed the servo.
This single upgrade in my opinion is a must. Moving forward there are more improvements but thia by far is a game changer.
P.S they fit exactly, no fuss no drilling nothing.
Better but still no where near what i wanted.
Yesterday took the rig to a mechanic and we swapped the servo motor from and 80 series with duel diaphragm as apposed to single in the 60.
End result probably the best upgrade i ever did. I mean worlds apart not even compareble.
The brakes are far far more responsive with so much less effort. I kept the same master cylinder to avoid having to bleed the brakes and to also make sure it was indeed the servo.
This single upgrade in my opinion is a must. Moving forward there are more improvements but thia by far is a game changer.
P.S they fit exactly, no fuss no drilling nothing.
