Long time, no see, Anthony... How's things going?
First, I'm going to suspect that it is your driving style that has the
brakes wearing more evenly. Braking effort is *usually* about a 60/40
split
front to back... Under what would be considered "normal" driving style,
people use the brake pedal often... Since the front brakes "come on"
before
the rears, we will experience more front pad wear than you might... You
use
your brakes only when you have to... and this may have you applying the
brake with just enough force to keep the brake wear roughly even front to
rear.
Let's spend a minute discussing your rear brakes... In the industry, these
are known as a "duo-servo, self energizing drum brake"... The "front" (or
primary) brake shoes serve two purposes... First, they do help to slow the
car down, but their second purpose is to force the secondary brake shoe in
to the drum. We will sometimes see the primarry brake shoe made of a
different grade of friction material. The primary brake shoe lining is
often
a different length than the secondary and can even be a different
thickness
than the secondary.
One would think that the engineers would have it figured out by now, but
the
primary shoe always seems to wear much quicker than the secondary.
Where we live and where we drive will have a great influence on brake
lining
life. In our area, we are entering into the first of our two annual "mud
bowls"... Most of our customers spend a good deal of time "off road"
(Alberta oil patch, remember?) and it isn't uncommon to do rear brakes
several times before these guys are ready for fronts.... Hell, in a rainy
year, it isn't uncommon to do rear brakes a couple or four times in a
year... Mud can be a techs blessing.
Since you say that your brakes are more than up to the task, I can only
suggest that you are looking for a problem where there isn't going to be a
problem to be found (flip over enough rocks and you're bound to find a few
bugs)...
What ever became of that magazine article you were writing? I was waiting
with baited breath to see the final product....
Take care...
"Anthony Giorgianni" <pleasereply@[EMAIL PROTECTED]
> wrote in message
news:4814ccde$0$11596$607ed4bc@[EMAIL PROTECTED]
> Hello All. Sorry for the length of this.
>
> I'm hoping folks here might be able to come up with a theory - or
confirm
> one of my theories - about what is happening with my 92 Explorer brakes.
> Keep in mind that I'm an unusual in how I use the brakes; more on that
> later.
>
> ISSUE: I have about 97,000 miles and have never changed the pads. The
> thing
> is the rear brake shoes are wearing out FASTER than the front disc
brakes
> pads, although both are wearing very slowly. My Ford dealer says the
front
> pads should wear about about three times for every one time the rear
shoes
> wear out, which I've heard elsewhere as well. He says something is
wrong/
> The question is: Why are the rear brakes wearing first? The dealer, who
> will
> do my state inspection Monday 4/28/08, is hypothesizing that maybe there
> is
> a problem with the brake system pro****tioning valve? (All stops, even
> emergency ones, are secure, fast and straight!)
>
> This is where wear things stand:
>
> FRONT PADS: 11/64ths (slightly more than 5/32) Ford recommends changing
at
> 1/16. One side is very slightly more worn than the other. The outer and
> inner pads are worn about the same. They have worn very slightly since I
> checked at this time last year. I don't see a need to change these now.
>
> REAR PADS: The front shoe on both sides is worn more than the rear
shoes,
> down to about 6/64ths to 7/64ths over the rivet head (3/32nds) in the
most
> worn spots. (They were 8/64 to 9/64ths in 7/06) Ford I think recommends
> changing at 1/16 above rivet head, though NY State requires replacement
> at
> 1/32 over the rivet. I'm thinking I should change them soon just to sure
I
> don't get the rivets too close to the drum, ad it's getting close to the
> inspection limits. The dealer wants $189 to do both sides of the rear
> alone.
> I told him I want the drums sanded and not cut, per Ford's instructions.
> The
> drums are in very good shape.
>
> MY DRIVING HABITS: I think you can tell that I am EXTREMELY light on the
> brakes. I coast to stop signs and red lights and stay far behind the car
> in
> front so that I rarely use the brakes or only very lightly and briefly,
> except for occasional fast braking in emergencies. I also have a manual
> transmission, though I don't down****ft excessively. However, I DO use
the
> parking brake a lot, often at red lights, since I don't like keeping my
> foot
> on the brake if I'm on even the slightest hill. (I tap the brake pedal a
> lot
> of let cars behind me know I'm stopped or slowing, but not enough the
> engage
> the brakes)
>
> THEORIES ABOUT WHAT COULD BE HAPPENING:
>
> A) Pro****tioning valve problem as the dealer thinks? Is there one?
> B) My light use of the brakes but frequent use of the parking brake,
> though
> applying at a stop, is causing the rear brakes to wear as fast as the
> front
> ones
> C) I disassemble and grease the calipers with dielectric compound
annually
> .
> I have never disassembled or greased the rear pads. I'm wondering
whether
> they are dragging a bit. Maybe the return springs are old? The drums
come
> off fairly easily, though it seems like the pads may be in slight
contact
> with the drum when I remove it on both sides.
>
> So... has anyone seen this before, with rear brakes wearing out as fast
or
> more quickly than the fronts? Any ideas what's going on? Does replacing
> the
> brakes make sense now, and is $189 for the rear brakes alone too high?
I'm
> reluctant to use these cheap quickie places. (One Jiffy Lube manger told
> me
> that he didn't even know what torquing the lug nuts even means!!!!)
Also,
> I've never done rear brakes before, and the procedure in the manuals I
> have
> (Haynes and Ford shop manual) seem like it's a lot of work, especially
> when
> I comes to adjusting.
>
> Thanks for reading and for any advise or feedback.
>
>
> Anthony Giorgianni
> For everyone's benefit, please post back to the group
>
>
>
>
>
>
>
>
>
|
