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Hey guys! Been awhile since I’ve posted here. But I’m at my wits end here on this issue and I don’t want to turn to the Facebook groups again. So I’ve decided to come back to the place where I found most of my troubleshooting information since I was 16/17 lol.
I have a 1993 KZN130 Hilux Surf I imported early this year from Canada. The truck was used and pretty much never really maintained correctly. I spent the last few months going through it fixing things as I went.
Here’s what I replaced on the brake system so far.
-Front Calipers (when I got it one was seized so I did them both)
-Front Rotors and Pads
-Master Cylinder was replaced with a USDM VZN130 1inch Non ABS master
-Rear Shoes and drums are new
-Wheel Cylinders are new.
So I’ve bench bled the master before installation. Then all of the brake bleeders starting furthest from the master and then the LSPV. The pedal is still low and feels as if all of the braking is done up front. Then there’s the light pulsation I can feel in the pedal. I’ve determined it’s coming from the rears. With the drums off, the pulsation is no longer there. I assumed it was a warped drum and exchanged them to only have the same issue. The rear shoes are adjusted to where I think they’re fine.
I’ve had the rear on jackstands while running it in drive and when I step on the brakes it takes a lot of effort to get the rears to stop. The right rear wheel stops before the left rear. If I hold the brakes and give it some gas the left rear breaks free easier.
Now I’m wondering. Does a failing LSPV play into any of these issues altogether? I’ve adjusted the axle side rod up a bit to see if it made a difference and it really hasn’t. When I street drive the truck it dives forward and definitely feels like the fronts are doing all of the braking. Does a failing LSPV start bleeding pressure back where I’d feel it into the pedal? Is the pushrod at the end of the booster something I should be looking at as well? I know everyone usually concludes the LSPV is always the issue and go with a manual valve. But before I even spend the time I’d like some more insight.
Sorry for the long post but I’m hoping I have all of the required information here so someone with more experience can help me here. Thank you!
I'm not a brake guy, and don't play one on TV either.
You've ascertained your rotors are true? Have you checked the drums are circular? Many years ago I worked at a brake and alignment shop and they would also true the arc of the shoes, so it presented a uniform surface to the truly round drum. Either of those could contribute to your pulsating. As for low pressure, I thought I remember bleeding started at nearest point first, and work your way to furthest point as air will travel to it eventually. But let smart guys chime in on that. I usually can't even remember where I put my keys.
Do you have a manual? The 99 has a procedure for attaching what looks to be two pressure guages, stepping on pedal yada yada and comparing pressures, and then gives specs and a procedure to adjust properly.
The plan is to find a shop nearby that can check the drums. The issue with living in NYC, is that finding one that can do that is gonna be difficult. Most shops are just gonna replace them and not turn them like what was once the norm. Im definitely going to get them checked in the near future before I change any other component.
However im still at a loss for the low pedal/weak rear brake issue. Given that I have all of these new items and the brakes are still weak.
I can understand the pulsation possibly being due to terrible manufacturing. But the brakes should be fine otherwise. Ive bled it the regular manual way, ive used a pneumatic bleeder that pulled the fluid from the bleed nipples. And recently used a vacuum bleeder on the nipples to no difference in feeling. Every time Ive seen no air come out of the system.
I forgot to mention this truck is non-ABS. And even the parking brake seems to need to be pulled hard to stop the truck while its slightly rolling in reverse. Im not sure if the cable is stretched for that issue. But Im pretty sure the drums are adjusted to where they need to be. Ive over adjusted them once and tried not to make that same mistake again.
Dumb Q, but you did adjust out the shoes correct? Turn the self-adjuster out until the drum just starts to drag. At least thats what I would do. And any machine shop or auto store (maybe not any more) can turn the drums. Even new ones will likely be a bit out of round.
A low or soft brake pedal usually points towards air in the brake lines or rear drum brakes that are not adjusted correctly. It can also be caused by warped rotors pushing the pads back into the calipers so every time you hit the brakes you have to move the pads before they start clamping down on the rotors.
On a front disc/rear drum setup the best way to verify where your vibration is coming from is to (very carefully) ease on the parking brake making sure you don't lock up the tires or lock the parking brake on.
If you feel a vibration when doing this it is 100% guaranteed that the rear drums are warped since you are applying ONLY the rear brakes.
This doesn't mean that there isn't ALSO a vibration from the front, but if you fix the problem with the rear and is still vibrates...
The best way to ensure proper rear brake adjustment is to first loosen the parking brake cable and make certain that the cables or bell cranks at the backing plate (not all models have these) don't stick, turn the star wheel adjuster (you should hear it clicking when you turn it in the correct direction and not be able to turn it the other way) until the brake JUST begins to drag. Then readjust the parking brake.
This makes it so that the rear shoes don't have far to travel before contacting the drum (gets you a solid pedal if there isn't any air in the system).
If the parking brake cable is adjusted too tight the rear brakes may not auto adjust properly, I have seen them over adjust and burn up the rear shoes and drums... wasted new parts.
I should ask a couple of questions at this point, did you do the brakes yourself? Did you do one side at a time so you were certain not to mix up parts and had one to reference where everything goes?
11-17-2019, 04:45 PM
