Hard breaking pulls hard right! (1 Viewer)

[TEQ]

(OOPS: Title should say "pulls LEFT". Brain fade.)

My '78 has discs on the front and drums on the rear. The disc conversion was done by CCOT in the '90s but I replaced the calipers when I rebuilt the front end (see my Fix-it thread in my sig for details).

A few times recently I had the opportunity to really stand on the brakes and was surprised to find the truck suddenly veering to the left. The truck normally tracks perfectly and handles well.

I am assuming this is most likely air in brake line to the right front. Is that an ok assumption?

If not, what else could be the problem?

If it IS the brakes I'm prepared to bleed the system. Anything I need to know about bleeding the brakes on FJ40s? I've never done it before.

 

[rusty_tlc]

Go to a dirt lot, do a panic brake. Look at the tracks. Most likely the left rear tire is locking up.
Adjust the rear brakes.
99% of the time it is the adjusters.

 

[shelfboy1]

check for leaking wheel cylinders or rear axle seals.

 

[jmdaniel]

If it IS the brakes I'm prepared to bleed the system. Anything I need to know about bleeding the brakes on FJ40s? I've never done it before.

I bought Speed Bleeders last week, and will be doing mine this weekend. Seems like a nice way to do it with a one man operation.

 

[subzali]

Your '78 should have come with front disc brakes from the factory. Anyway...

I agree with Rusty, a lot of the time it's a mismatch in adjustment of the rear drums. Make sure those are in good shape first. If not, then pull your front wheels off and check the pads for uneven wear. If one pad has more material on it than the other, then it's probably getting hung up on the pins it's supposed to slide on. Pull the pins out (you don't have to unbolt the caliper, it's just like if you were going to change the brake pads), clean them up, and put a light coat of brake grease on them.

 

[bsmith123]

brakes

(OOPS: Title should say "pulls LEFT". Brain fade.)

I am assuming this is most likely air in brake line to the right front. Is that an ok assumption?

When air is in the system generally that will make it weaker---also you might get that spongy, low pedal until you pump up ---the air is compressible and the fluid not so the loss comes in the time it takes to pressurize the air to the point where you get enough pressure.

I might suspect underbraking on the right rather than overbraking on the left if it was air, so maybe some air on the right side---but bleeding never hurts anything does it? might as well do the whole job

If it IS the brakes I'm prepared to bleed the system. Anything I need to know about bleeding the brakes on FJ40s? I've never done it before
Bleeding is easy, my main rule of thumb is I have never bled it enough the first two times I think 'that is enough"!

if you drained the mc in the work you did then search on bench bleeding the MC --I just read a post about doing it by installing a hose to the brake line outlet and running it back into the reservoir for the fluid without removing the mc

do the lube as suggested, then just a good look over the whole system externally, hoses and all and have somebody operate the brake while you eyeball them

do you have a poportioning valve and residual valves? you havent made any changes to the brake sys since it worked fine right?

I had a hard right pull and found the rt front wheel hub locked in ---set it unlocked and the pull went away

 

[bsmith123]

Go to a dirt lot, do a panic brake. Look at the tracks. Most likely the left rear tire is locking up.
Adjust the rear brakes.
99% of the time it is the adjusters.

I like that, might just do it with mine too just to see if all 4 lock up evenly at the same time

 

[edwjmcgrath]

Your '78 should have come with front disc brakes from the factory.

Non US vehicles still had drums in 78. It may be an import.

 

[lostmarbles]

I've never equated "air in the lines" to "pulling left or right". The beauty of the hydraulic system in my mind is that fluid pressures will still be equal for the LH and RH wheels (on any one axle) no matter where any air-contamination happens to be.

And my experience is that any SIGNIFICANT left or right pull tends to come from a FRONT axle problem.

And furthermore, the pull can usually be attributed to "lack of grip" on the friction surfaces on the wheel situated opposite to the direction you veer towards (rather than excessive-grip on the side you veer towards).

So I'd be suspicious of your RH front.

Is any fluid leaking there? Are the piston(s) in the calliper there free or seized?

My 2c