Front Brake Issue

[mrlocksmith]

Hi:

On my way to Surf and Turf I really noticed that my brakes were not working well, I had a few folks at SNT look and them and I thought I would post Up here and get some advice for my 1985 FJ60 Expo Build

Symptom:

I cannot lock up my brakes if I wanted to and most of the braking is comming form the rear. The brake pedal goes down and stops hard, when I push harder I only feel the rear brakes

1) Emergency brake stops at 5-6 clicks, I do not think it is dragging but I have to check one I get home.
2) Front pads are not shiny, I cannot tell what type of pads they are (non metalic etc), when expanded the calipers contract ok
3) The rotor surface has little fissures in it, very similar to the look of a flywheel that needs resurfacing. Does that mean that the rotor got too hot at some point???
4) I am loaded to the gills with gear, custom cabinets etc and do not plan to lighten the load much so whatever mods I do will be done with the extra weight in mind
5) I am Running 33's
6) I do not have an LSPV
7) I did pump the brakes w/ the motor off and then started the motor w/ foot on brake and the pedal did move an inch or so.

Any Ideas, I was thinking about getting the Man-A-Fre sloted rotors and semi metalic pads. Or something similar that Marlin Crawler might cook - up for me.

Thanks


Mark

 

[NocalFJ60]

I like the 4runner caliper upgrade and would of done that if I knew about it back when I rebuilt my front brakes. From what I have read it sounds like the slotted rotors don't do much on a cruiser but you can still have them turned down like regular rotors. I would try bleeding the system good if you haven't done that and get some new/clean fluid in the system. Also measure the rotors thickness and check the FSM and make sure they are in spec. The rotors could have been turned down (resurfaced) to just the min. thickness and now might be too thin. You can pull a tire and check the rotor thickness and pull the pads easily and measure them. It sound like your front brakes have been doing a lot of work being loaded down and now ready for some work. I would be careful about driving until you get your brakes in good working shape.

Hope you had fun at SNT. I wanted to make it but couldn't.

 

[mrlocksmith]

I read abbout the upgrade but did not understand what made the 4 Runner better?

Mark

 

[Mr. Toad]

Perhaps a problem with the front circuit of the master cylinder?

 

[ntsqd]

I read abbout the upgrade but did not understand what made the 4 Runner better?

Mark

The 4rnnr parts have a slightly larger piston area. So more clamping force for a given line pressure at the expense of slightly more pedal travel.

Having seen some of the pics of your rig I think that you're treading on the edge of needing rear discs. You can no doubt make the rear drums continue to work, but at the expense of working the fronts harder.

Those little cracks are heat checks. Exactly the same as on a flywheel. Eventually they will grow to the point that the rotor will fail. They come from the brake being worked pretty hard, though all disc rotors will eventually do it if given enough time in service. Turning the rotors can remove them if they are not too deep, but these rotors are thin to start with and do not have much meat in them for turning. In turning them you also remove some of the already in short supply Thermal Mass, making them very likely to heat check even faster the next time.

The most ideal way to extend the rotor's life and prevent brake fade is to duct air to the center of the rotor ala road racing cars. Not the outer edge or the inner face of the rotor as that will do nothing good. Unfortunately this isn't very practical on an axle of this type, though I am keeping it on my list of possible tricks should I run into troubles.

 

[Jan-78FJ40]

General note: 60 series brakes, when functioning properly, are just fine for the wagon. no 'neede' to upgrade to the 4 runner calipers.

In your situation, something is very wrong. most likely they have overheated at some point, and rotors and pads are shot. fissures in the rotors are a bad thing, as has been said-they will eventually lead to cracking and complete rotor failure. nothing you want to happen during driving.
the slee rotors are great, but regular ones will do fine as well.
when changing them, make sure all the fluid gets changed too-it could have boiled at some point.
j

Hi:

On my way to Surf and Turf I really noticed that my brakes were not working well, I had a few folks at SNT look and them and I thought I would post Up here and get some advice for my 1985 FJ60 Expo Build

Symptom:

I cannot lock up my brakes if I wanted to and most of the braking is comming form the rear. The brake pedal goes down and stops hard, when I push harder I only feel the rear brakes

1) Emergency brake stops at 5-6 clicks, I do not think it is dragging but I have to check one I get home.
2) Front pads are not shiny, I cannot tell what type of pads they are (non metalic etc), when expanded the calipers contract ok
3) The rotor surface has little fissures in it, very similar to the look of a flywheel that needs resurfacing. Does that mean that the rotor got too hot at some point???
4) I am loaded to the gills with gear, custom cabinets etc and do not plan to lighten the load much so whatever mods I do will be done with the extra weight in mind
5) I am Running 33's
6) I do not have an LSPV
7) I did pump the brakes w/ the motor off and then started the motor w/ foot on brake and the pedal did move an inch or so.

Any Ideas, I was thinking about getting the Man-A-Fre sloted rotors and semi metalic pads. Or something similar that Marlin Crawler might cook - up for me.

Thanks


Mark

 

[mrlocksmith]

Thanks All..

I'll start with new Man-A-Fre Rotors and New Pads, and change the brake fluid, then I'll see what happens from there. On the way home from SNT I stopped at a truck stop and put my rig on the scale. It was 6400 LBS which is 1000LB over GVW !! I wonder how heavy some of the other expo builds are??


I'll think about putting in Floating Rear Axels with Disc Brakes too..


Mark

 

[ntsqd]

You can have too much braking power on one axle or the other, but you can never have too much balanced braking power. There simply isn't room in a 15" wheel to get there at a reasonable cost.

That you're always ~1k lbs over GVW explains why the front rotors are over-heating. While you're replacing them have a look at trying to duct some air into the center of the rotor. James Walker's "High Performance Brake Systems" is one good reference book. Typically 4X's don't address brakes very much, so there isn't anything of quality in print that I'm aware of specifically for 4WD brake system upgrades. We'll just have to interpolate from road racing oriented publications. The fundamentals are all the same, though the goals will be different.

If you use a floating caliper type design then the Full Float rear axle isn't a requirement. The floating caliper can 'follow' the rotor back and forth. The two GM's, the Explorer, and Supra calipers are perfect candidates. The Explorer rear discs are used on 8.8" axles, which are a C-Clip design. I've no idea if these systems are reasonably adaptable or not, but they use a drum type parking brake and have worked exceptionally well on shorter wheelbases than an FJ60.