FJ62 Stopping distance and "OEM" brake improvement project (1 Viewer)

[WoodnotRust]

I've never been really comfortable with my brakes. I can stop OK it seems, but I really have to use a lot of force and it worries me that my wife or daughter might have trouble if they have to make an emergency stop. My best guess is that the vacuum booster isn't 100% so replacing that and the Master Cylinder seems like a given. After reading the 4Runner front caliper upgrade threads I decided not to go that route, but to basically restore the OEM parts with the closest equivalent. I'll replace most everything in the rear and replace/tune the LSPV. I'm not going to touch the front brakes for now since the front disk pads/rotors are relatively new.

I posted that part list on a @poptart thread and I'll do it again on this thread once the job is completed.

Before I actually do the work I thought I'd test how my current brakes are working. I headed to a not-so-busy stretch of highway and below is a chart that shows the results of my stopping distance test. I'll do the same test once I do the brake repairs and I sure hope there is a noticeable improvement. It is worth noting that I am currently unable to lock up any of the wheels, at any speed, no matter how hard I slam on the brakes.

 

[jesus888]

This thread looks fun... and you've got my attention. #following

 

[duncanrm]

Have you confirmed correct operation of your rear brakes.. the front discs wont get any significant pressure until the rear shoes are contacting (ie. rear circuit has pressure) and the most common cause of poor 40/60 series braking performance is poor condition rear brakes or poor adjustment of rear brakes.

If you can find an isolated road, clamp off your rear brake soft line and see how your pedal feels with just your front brakes at a slower speed. Dont drive on the highway like this though, the rears will lock on eventually through the clamp.

 

[HMP]

subscribing.

 

[OSS]

There’s very few 60 series Land Cruisers that can lock up the wheels during an emergency stop.
Locking up the wheels in a hard stop is reserved for the cruisers running the original 225/75R15 tires (28”)

 

[BurntToast]

There’s very few 60 series Land Cruisers that can lock up the wheels during an emergency stop.
Locking up the wheels in a hard stop is reserved for the cruisers running the original 225/75R15 tires (28”)

Why? Do the calipers not have enough pressure from a stock MC to not lock them?

 

[WoodnotRust]

Have you confirmed correct operation of your rear brakes.. the front discs wont get any significant pressure until the rear shoes are contacting (ie. rear circuit has pressure) and the most common cause of poor 40/60 series braking performance is poor condition rear brakes or poor adjustment of rear brakes.

If you can find an isolated road, clamp off your rear brake soft line and see how your pedal feels with just your front brakes at a slower speed. Dont drive on the highway like this though, the rears will lock on eventually through the clamp.

I'm not sure how the Load Sensing Proportion Valve in the FJ62 changes the feedback between front and rear brakes. I know this valve controls the relative pressure between the two systems in a way that is different than in the 40 and early 60 series trucks.

That said, I'm pretty sure that the LSPV on my truck is not properly adjusted and I doubt that my rear brakes are balanced with the fronts. I have a 2" OME lift and that radically changes the adjustment of the LSPV. The valve is mounted on the body, but the spring arm shackle is mounted on the rear axle. A body lift has the effect of reducing the relative pressure to the rear brakes.

So, I know I've got to add a 1" to 2" spacer to lift my shackle off the axle and adjust it from there. I don't have the capability of using pressure gauges to set the LSPV as described in the FSM, so I'm just going to fiddle with it until it seems right.

Here's a thread started by @poptart that shows how he adjusted the LSPV: Master Cylinder and Brake “Upgrade” Questions - https://forum.ih8mud.com/threads/master-cylinder-and-brake-upgrade-questions.1263539/

 

[bentonrover]

I adjusted my LSPV and it seemed to work alittle better. From what I been told is that brakes on these rigs were never the best but functional. Learn your rig and know when to start slowing down and braking.

 

[Michael Hanson]

Hi, I’ve got great brakes in ours. As said before back brakes must be adjusted correctly though the rear adjustment hole. Drums must also be in good shape. I have ome heavy lift springs On 3 of my rigs. I keep a maintaince book on all my cruisers and do scheduled maintaince.check and make sure your proportioning valve is not leaking into its black rubber boot.Also are any of your brake lines swelled up?

 

[WoodnotRust]

@Lead Head mentioned that Motorweek said the FJ62 brakes were pretty good (60-0 in 130'). @bentonrover I just found the video for that retro review here: and it's fun to watch. My current stopping power at 60 mph is only about 10% worse than the Motorweek test so I don't expect huge improvement. I do hope the new vacuum booster makes the pedal feel better, and adjustments to the LSPV and rear brakes gets me 10% better stopping power.

Of course, I'm curious to know how much better the brakes are with the best upgrades. Do trucks with the full 4Runner kit stop in 110' at 60mph? Can the OEM set-up handle the increased friction of the bigger tires and stop the truck better than new? I think @OSS is right and locking the brakes with the bigger tires and OEM set-up may not be possible. It still might stop better though...

@Michael Hanson : In the last couple of years as I've been restoring my truck I've lost all notion of scheduled maintenance. What's that? Until recently I was working on my truck all the time. When I was younger I always kept a notepad in my glovebox and recorded every bit of maintenance and the mileage for each fill-up. But that's different than having a nice list of the regular maintenance one should do to keep these ancient trucks running. That's a good idea.

And no, my soft lines to the brakes are not swollen. I doesn't appear that my LSPV is leaking either, but since it's almost 35 years old and the FSM suggests replacement when worn, I just figured it was time to replace it while these are still available.