Posted by Malcolm [Boardmaster] on Friday, November 19, 2004 at 6:35PM :
Moderator
Ever since I've owned my 94 4x4 Ranger (purchased in 2000) I've been plagued with the rear tires
locking before the front under hard braking. Since I like to drive fast and
brake late this has been a huge problem for me. Even worse is in the rain.
Because then the rear tires would lock and slide just under firm braking
without me even screwing around.
If you're wounding what's the big deal you've probably never had your rear
brakes lock before the front. Trust me it's not fun. You have very little
control over where the vehicle's going and you usually have to let off the
brakes to gain control and then get back on them and so on and so forth.
This greatly increases your stopping distance.
So first I do the obvious. Replace all the brakes. New rotors and pads up
front and new brake shoes out back. I had the rear drums turned at a
machine shop instead of replaceing because they were like almost brand new.
Same Problem!
I tinkered with the adjustment on the rear brakes with no successes. I
tried bleeding the brakes but it didn't make much difference. I even went
as far as lowering the rear of my truck 2 1/2" after several close calls in
the rain. This would change the weight distribution and put more weight on
the rear tires. This is about the only thing I did that really helped any
but the problem still existed.
I tried bleeding the brakes again and noticed that it was very hard to get
fluid out, especially in the rear. But what really caught my attention is
that the fluid almost appeared to be black and dirty? Now I remember as a
kid my dad would change out his brake fluid every two or three years because
it's sensitive to moisture and would contaminate and loose it's properties
etc. That's supposed to be something of the past though. After some
searching on the net I found this is still true of vehicles today. It's
just the fluid we have today is much better and lasts longer but still needs
to be changed. So I bought a generic vacuum pump (works with a venturi
valve, powered by an air compressor) and rigged up a vacuum collection glass
bottle to pull all the fluid out the brake system.
Anyhow, long story short. The fluid was so contaminated and grungy I
couldn't get any out. Even with the pump pulling 28Hg of vacuum. I had to
spin the bleeder valves off and stick some wire in and use the air
compressor to break free all the gunk and crap. Finally I had fluid
draining out. It was pitch black like the dirtiest oil change you've ever
seen. Unbelievable. I kept feeding in fresh fluid until clear fluid was
running out.
What an amazing difference. Not only did it fix my problem but it's like
driving a different vehicle. The brakes are so different I had to get used
to them again like it was a new truck. The peddle is super sensitive now
and I can lock up the tires really easy. I have much shorter stopping
distances and the front tires will lock first too :)
So anyhow just something to watch out for on older vehicles. Change out
that brake fluid.
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