GEN1 Front wheels locking up

[chadzeilenga]

Hi All,
I have a bit of an issue that is eluding me. A few weeks ago I thought I felt a rear caliper dragging, so when home I let it cool and took everything apart, adjusted and cleaned. Been fine since.

Tonight I was driving home from work and noticed that after some time driving the Montero would not roll in gear with foot off brake. When driving it felt like someone was lightly pressing the brakes. I pulled in garage and lifted front axle and both front tires would not turn at all. Let cool and now they both will turn.

I can’t feel any grinding like a bad wheel bearing, no pulling right or left when driving.
If it were a stuck caliper I would think it would affect only 1 wheel.

I’ll have it apart tonight and report findings


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[JohnnyBfromPeoria]

Sticking caliper(s), collapsing brake hose(s) or malfunctioning brake master cylinder. Or wheel bearings. That's about all I could imagine.

John B.

 

[chadzeilenga]

Sticking caliper(s), collapsing brake hose(s) or malfunctioning brake master cylinder. Or wheel bearings. That's about all I could imagine.

John B.

Hey John,
I have a caliper rebuild kit on order and will take a look when it arrives. Hoses are all new as of last summer. Master cyl was done a few years ago, but could still be the culprit as I’m not aware of the quality used.

With wheel bearings I’d expect them to growl when spinning, could they be so bad to resist turning but also be quiet?


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[Salonika]

If it’s wheel bearings and they are that bad they will produce heat. You should be able to feel it with the back of your hand or measure it with an IR thermometer (the disc won’t get hot but the bearing housing / hub will). It would be odd to me if both front calipers were dragging at the same time but I guess it’s possible. I can usually diagnose dragging calipers with the IR gun since it will make the disc quite hot. If they are radiating a lot of heat after a short drive with minimal braking, that would be enough for me to tear them apart.

 

[chadzeilenga]

Yea, I felt both rims at the time and they were warm, but not hot. As usual, when I let it cool down everything spun freely. I pushed some fresh fluid through both calipers and was surprised at what came out.

This fluid was installed 6mo ago when I installed all my new hoses and rear cylinders. It was a fresh bottle at the time, so I’m surprised to see it so dark. When I bled back in June I ran a whole quart through the lines.


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[Oso]

its dark because its cooked. service your calipers. eventually they'll get so hot the fliud will boil and you'll end up with no brakes at all. ask me how i know. hth.

 

[chadzeilenga]

Thanks. The pads and slides on the calipers are clean with the high temp sylglide lube. The calipers really need a full teardown with new piston boots though.

Everything was turning smooth with the pads removed so I don’t have a bearing problem. The DR caliper piston was very hard to return. Also, the booster piston was misadjusted from previous owner to have some interference with the BMC. I adjusted per FSM and swapped BMC out with another 15/16” unit. Bled with fresh DOT3 all around. This should be ok until I can source all of the parts for my front disc upgrade.

Rotors, Calipers and large bore master cylinder, although I need to do my homework on the BMC/Booster upgrade still.

Thanks for all the insight.


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