Bud Weaver

My '90 SR5, 3.0 powered (or underpowered depending on how you look at it ) ext. cab, 4x4 has what I would best describe as some of the worst brakes I have ever had.
I have to nearly mash the damn thing throught the firewall to get it to stop decent.

Let me start off by saying that there are new pads up front, shoes in the rear, new master cylinder, completely bled icluding the LSPV with all new DOT3 fluid. The drums were turned although they were really good beforehand. The front calipers show no sign of problems as the pads wore evenly and have no leaks anywhere. The only thing I have not done is turn the rotors but I might just for the heck of it.

The booster is fine, there is no apparent trouble with the rear ABS as I have toroublshot that entire system. All rubber flex hoses are good and do not "bulge" anywhere when the pedal is to the floor.

My truck has the stock sized, 31/10.50-15 BFG All Terrain TA's which are in excellent shape.
With the engine running I can push the pedal hard enough to bottom it out as I can feel it. Maybe the assist helps me to do this--I dunno. I could not get this truck to lock the wheels up if I tried to.

It does stop okay but not as well as I think it should. Is there some commonality of these similar trucks to suffer from inadequate braking?

I might opt for a little better brand of pads but I stick with the organics so I don't have to replace the rotors from being chewed up by the more aggressive compound pads.

Is there something you folks can recommend in the way of pads/shoes or the like?
Do any of you share the same maladies with your truck?
Thanx,
Bud

1styota4X4

i run autozone duralast gold (ceramic lifetime warranty) and duralast rotors up front(2 year warranty) I can lock up the front easly they work great...

Maybe your rotors are hazed or is the shaft adjustable from the booster to the master cyl? if it is did you keep them the same length?

UncleBob

There's definitely something up. I'd concentrate on the front, for sure. Even with poor rear brakes, the front's should lock up. Plus, they provide the majority of your braking force, of course of course.

If it were mine, and I'd done as much troubleshooting as you have, I'd be inclined to have the rotors resurfaced (or replaced) as well.

By the way, you said you had new pads up front. Did you have the non-stop issue before this, or did you just recently aquire truck and do a full brake job on it?

Just for $h!ts and giggles, did you swap the front/rear lines at the master?

GSGALLANT

First of all, you shouldn't be bottoming out your pedal - under any circumstances if your brakes are set up properly. I'd say there's either a bit of air left in your system, or your rear brakes are not adjusted properly. Have you adjusted the rear brakes since you finished your swap so that the shoes are just a slight bit off of the drum when the brakes are not applied? If not, that's likely your problem. Give that a shot if you haven't done it. If you're unsure of how to do it, search on here. There are plenty of threads on how to adjust your rear brakes. Good luck.

MudHippy

You mentioned bleeding the LSPV, did you also check and/or set it correctly?

Bud Weaver

Wow!
Lots of great help!
Let me elaborate a bit more. The rears are adjusted up to the point where the shoes are lightly contacting the drum surface when I spin the wheel and the very few "clicks" that I get out of the parking brake when I pull the handle reflects this close adjustment. The LSPV is set to 120mm between the eyes as referenced in the FSM.
The brakes "do" seem to get better as they all warm up from use. As UncleBob pointed out I do need to turn the rotors which might help---it can't hurt and besides I am getting a very slight "warped" feeling when I hit them so it's time. And yes, this truck has always braked like this but it seems to be more prevalent since I put the new pads/shoes on it. I did this as part of routine maintenance--the fronts started to "squeal" because the tell-tale indicators were starting to contact the rotor.

To answer 1styota4X4, yes, the adjuster nut on the end of the shaft out of the booster is set right to spec. When the booster is evacuated after about 3 or 4 pumps once the engine is off I can feel no play except the free play at the pedal itself which is normal.

I am hesitant about running ceramics on the factory rotors because it will chew them up and I really should'nt have to shell out some more dead presidents for rotors when mine are fine.

I agree that you should'nt be able to mat the pedal (it actually bottoms out in the master or the booster) but I know I can't do it with the engine off!
I guess the power assist is that good!

Thanx,
Bud

waskillywabbit

iTrader: (-1)

All OEM equipment is what I always run on my braking systems and I could lock up my stock 87 and my 85 on 40s.

You either still have air in the lines from not bench bleeding the new master cylinder or the new master cylinder is a crapper.

GSGALLANT

Slight warped feeling on braking... that may explain why you're getting so much pedal travel. When your rotors are good (warpage within spec), your pads are in "constant" contact with your rotors, even when the brakes aren't applied. When you apply the brakes, very little travel is required to get friction between the pads and rotors.

If your rotors are out of spec in runout, the pads will be pushed away from the rotors slightly while you're driving, so that only the "high spots" of the rotors touch the pads each revolution. In this case, when you apply the brakes, you get some initial "wasted" pedal travel to get your pads back into full contact with your rotors before any braking force gets applied to the rotor.

When I changed my pads, I measured the rotor runout, and I was right on the high side of the acceptable limit, so I had them turned. They ended up doing a terrible job, and the runout was actually 10 times the acceptable limit when I got them back. Each time I wanted to brake, I had to pump the pedal once, then apply the brakes. If I tried to apply the brakes without pumping the pedal once before, my pedal would go to the floor with very little braking force. I promptly bought and installed new rotors and now it's back to normal (the place that had turned my old ones gave me my money back, and paid for one of the new ones which was nice.)

Bejiita

Sorry but I gotta jack the thread for a question >< I recenty did my brakes also and didnt turn the rotors because they were within spec but I just noticed today going down a hill at like 5mph to a stop with the brakes lightly applied itd kind of lurch forward every couple feet? Is this a braking thing or is it a tire out of balance?

GSGALLANT

Could you be a bit more descriptive in what you mean?

Bejiita

Well it will like jerk forward but very lightly not violent at all just kind of like if I tapped the gas lightly repeatedly?

CJM

Jerk to one side or just shake the wheel. Jerk to one side could be pad related, make sure you got the same pads on both sides and installed right. Or its the rotors b/c of being warped.

CoedNaked

So a visual inspection confirmed that your calipers are in top shape?
I was told that a good OEM tech can visually inspect them to ensure they are working 100%

Bejiita

No lol it wasnt visual I used a micrometer and a runout indicater. It doesnt pull either direction just kinda lurches to a stop, but it was only noticeable that one time on a steep downhill. I think its just my tires are out of balance, seeing as the tread is completely worn on the sides and theres bumps in the sidewalls the size of tennis balls lol. (Dont worry Im getting new tires tomorrow lol)