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Car Forum / Ford / Ford Explorer / May 2008Brake puzzle
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 proportioning 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 downshift 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) Proportioning 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 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... > Hello All. Sorry for the length of this. > [quoted text clipped - 82 lines] > Anthony Giorgianni > For everyone's benefit, please post back to the group Hey Jim!!!! Great hearing from you. Hope all is well up in the muskeg!! Incidentally, this year, I did a piece for the Canadian version of April auto issue about whether (and how) Canadians should come down to the states to take advantage of the lower new car prices and the loonies' being on par with the greenback. Very interesting issues, and I can see why Canadian are angry about some manufacturers' non-export policies (though not Ford. Perhaps you have a dealer's perspective?) As far as the brakes, thanks for the explanation. I'm betting you're right, especially since I use the emergency brake so much, sometimes even when the truck starts to roll. So would you change the rears at this point at a 6/64ths (2 mm) over the rivet head? The rear shoes only dropped 2/64ths over the last two years, so if it remains the same, I'd hit 1/16th two years from now. But I don't want to take chances or have to keep pulling the drum out of nervousness. Does $189 seems fair? They're figuring at least an hour's work. ($189 is US of course, but it's so close now anyway.) And is it right to tell them not to turn 'em but sand them instead? Aluminum oxide or garnet paper medium grit? As far as the story, I am embarrassed to say I don't think they ever used it, and I have no idea why, since the auto editor assigned. But I was a freelancer at the time, and now I'm on staff (though as finance, not an auto writer). So I'm going to push it. I also did a piece about using forums to get computer tech advice, and that ran. So I should be able to update and at least blog the auto one. The more I use forums, Usenet or otherwise, the more convinced I am that it is the BEST way to get help, pretty much no matter what you're into. And when you get experts like you or the Microsoft MVPs, it makes it even better! I will let you know as soon as I can resurrect it! My 92 still remains near showroom. While I had my tires off, I just Rustoleum-ed the wheels wells and leaf springs, as a do every few years. Looks like a brand new truck under there. I so wish Ford would bring back the manual for the Explorer. Xterra seems like the only choice these days that is close to the Explorer though with a "manny" "Manny!" Hey I just made that up!! :O) Anyway, thanks again. I'll be in touch!!!! Anthony Giorgianni For everyone's benefit, please post back to the group > Long time, no see, Anthony... How's things going? > [quoted text clipped - 130 lines] >> Anthony Giorgianni >> For everyone's benefit, please post back to the group Reading this string, I think Ford dropped the manual transmission in the Explorer because it was just too good a vehicle and they just couldn't get owners to come back! My '97 has almost 250K miles and still runs well, burns no oil, and is a daily driver. I had to have the clutch repaired twice (at 160K and at 240K), both times because of problems with the slave cylinder, but each repair (dealer or private shop) was under $800. That really has been "it" for this truck, except it has developed rust coming through from inside the fender above the gas filler opening. Sad, that, but a result of lots of winter driving on snowy roads in the northeast where salt is applied liberally. Just this past month I rotated this truck to my son, who is using it to get to work since his SHO was sold, and I picked up a new Mustang GT for my travels. I still have the title for the Explorer and will continue to use it for all the practical stuff needed here on the farm, even after he gets a new car. =Vic= Bear Gap, PA > Hey Jim!!!! Great hearing from you. Hope all is well up in the muskeg!! > [quoted text clipped - 182 lines] >>> Anthony Giorgianni >>> For everyone's benefit, please post back to the group Thanks for that Vic. $800. Wow. No dealer I tried anywhere in NY or CT was close to that. I sure do wish they'd bring back the manual! I love driving it. When I drive auto trannys, I feel like I'm in a kiddy car :O)That 240K is amazine. Wish I would have gotten 160K out of that slave.Mine failed at about 95,000, when the vehicle was about 14 years old. Anthony Giorgianni For everyone's benefit, please post back to the group > Reading this string, I think Ford dropped the manual transmission in the > Explorer because it was just too good a vehicle and they just couldn't get [quoted text clipped - 15 lines] > =Vic= > Bear Gap, PA >Long time, no see, Anthony... How's things going? > [quoted text clipped - 3 lines] >people use the brake pedal often... Since the front brakes "come on" before >the rears, Is that how it works these days. In the old days they used a hold off valve to make sure the rear brakes came on before the fronts because it makes the car more stable to do it that way. 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 [quoted text clipped - 116 lines] >> Anthony Giorgianni >> For everyone's benefit, please post back to the group > Is that how it works these days. In the old days they used a hold off > valve to make sure the rear brakes came on before the fronts because > it makes the car more stable to do it that way. Your "hold off" valve was actually called a metering valve. This was required on vehicles with a combination of front disc/rear drum brakes. This was to keep the front brakes from applying before the rears.... This was accompl;ished by "metering" the amount of fluid sent to the front brakes - limiting it, if you will, the movement of the front calipers until the rear drums "caught up". What it never did was to cause the rear brakes to apply "first", rather, it's purpose was to have the brakes apply in unison. Which brings us to the proportioning valve.... The proprotioning valve was there to limit the pressure to the rear brakes. The harder we brake, the more weight is shifted to the front wheels... If we allow the rear brakes to lock up early, the car will swap ends... Notice we haven't mentioned the residual pressure valve. Some vehicles used a "combination valve". This was a metering valve plus proportioning valve combined into one unit. But the theory is still the same and it does not involve applying any one axles brakes "first". Something like that is going to be a nightmare from a stability standpoint. With the advent of 4WABs, all of these functions can be incorporated into the hydraulic control unit. Misunderstanding both vehicle systems as well as vehicle dynamics can lead to all kinds of problems... Things "these days" work the same as they did "in the old days" as far as dynamics are concerned... Depending on the system, technology may achieve these conditions in a mechanically different way... That's fascinating, Jim. Thanks for that. Anthony Giorgianni For everyone's benefit, please post back to the group > Your "hold off" valve was actually called a metering valve. This was > required on vehicles with a combination of front disc/rear drum brakes. [quoted text clipped - 26 lines] > system, technology may achieve these conditions in a mechanically > different way... "Anthony Giorgianni" wrote... > Hello All. Sorry for the length of this. > [quoted text clipped - 7 lines] > is the rear brake shoes are wearing out FASTER than the front disc brakes > pads, although both are wearing very slowly... > MY DRIVING HABITS: I think you can tell that I am EXTREMELY light on the > brakes... > So... has anyone seen this before, with rear brakes wearing out as fast or > more quickly than the fronts? Thanks so much for making me feel better and not think that I'm crazy. I have a '96 Explorer with about 128k miles on it. Like you, I'm not an aggressive driver although I won't say that "I am extremely light on the brakes" as you do. I definitely don't use my emergency brake as a substitute for the disk brakes as you do. My rear pads were replaced at about 90k miles and the front pads are still original. [Even better, I'm still on my first clutch--yes, I'm stick shift, like you, with the V-6 engine.] I have a cousin who runs a very successful auto repair shop in Chicago who told me this is impossible, but it's true. I do have my brakes serviced (pad thickness check, lube the rails, etc. at the prescribed intervals) and am still on my original factory front pads after almost 13 years. Based on my history, I'd agree with you and go ahead and get the rear pads replaced now. More than likely, the car will live out its useful life without ever having a front pad replacement. Craig in Northern AZ Thanks Craig. Very interesting that you're having the exact same experience. I DID replace the clutch ... but only because the slave cylinder went. So they changed the clutch they were in there anyway. I had the dealer do it, which cost a lot. But I was really impressed with the work. If you don't mind my asking, how much did it cost to replace the rear shoes? Thanks again for the great feedback. Oh, here's photos of my 92 back in 04. It still looks just like this! http://giorgianni.homestead.com/explorer.html Anthony Giorgianni For everyone's benefit, please post back to the group > "Anthony Giorgianni" wrote... > [quoted text clipped - 38 lines] > > Craig in Northern AZ Thanks Craig. Very interesting that you're having the exact same experience. I DID replace the clutch ... but only because the slave cylinder went. So they changed the clutch they were in there anyway. I had the dealer do it, which cost a lot. But I was really impressed with the work. If you don't mind my asking, how much did it cost to replace the rear shoes? Thanks again for the great feedback. Oh, here's photos of my 92 back in 04. It still looks just like this, including the underside! http://giorgianni.homestead.com/explorer.html Anthony Giorgianni For everyone's benefit, please post back to the group > "Anthony Giorgianni" wrote... > [quoted text clipped - 38 lines] > > Craig in Northern AZ "Anthony Giorgianni" wrote... > Thanks Craig. Very interesting that you're having the exact same > experience. > I DID replace the clutch ... but only because the slave cylinder went. So > they changed the clutch they were in there anyway. I had the dealer do it, > which cost a lot. But I was really impressed with the work. If you don't > mind my asking, how much did it cost to replace the rear shoes? My rear pads were replaced at a Ford dealer, too. Just remember that these are May 2001 prices! Labor: $65 (which looks to be 1-hr) Pads: $41.42 I suppose there'd be a small shop charge and tax in addition to the above. If easily accessible, what was the cost for your clutch replacement? Craig Interesting. They want two hours and $189 total. It wonder what a shop manual says. The clutch and slave cylinder was $1,239 with tax. I checked with other dealers around here - metro New York and Connecticut, and didn't get much better pricewise. I think I might have gotten a lot cheaper at an independent shop. But the last time I replaced a clutch on my old Ford Fairmont, I found lose clips and other indications of a sloppy job, and the clutch lasted only about three years.!!!! That was an independent. This dealer did an excellent job. I can't tell anything was done, other than a change in pedal feel of course. And they even adhesived in the those troublesome tranny plugs that keep falling out on people's manual Explorers (I got the metal plugs, but they were the wrong ones). I put so little money into this XLT because I baby it and do mostly everything myself that the $1200 wasn't a big issue. Thanks again for your help. Anthony Giorgianni For everyone's benefit, please post back to the group > "Anthony Giorgianni" wrote... > [quoted text clipped - 18 lines] > > Craig For what it's worth, here is my experience with a somewhat newer, 98 model. A great vehicle with just minor problems in ten years of service. I was never happy with its front brakes, but the pads just refused to wear down, and would go forever. At around 75,000, with 1/4" thickness still left, I finally decided that it was time. Installed Raybestos 'Brute Stop' instead of whatever the original were, and WOW, what a difference -- the thing actually stops when I want it to! Yes, they wear down fast, and even with my light foot don't last more than 30,000-40,000, but they are not that expensive and I can replace them in an hour or so. They also create a lot of dust, which, if you are very concerned about the looks of your ride, you'd need to clean from your beautiful magnesium rims at least once a week. They may even wear the rotors somewhat faster. Yet having to choose between longevity, esthetics and stopping on a dime in an emergency, I know what I'd take. Newer types of friction material, like ceramic may deliver the best of both worlds - no experience with those. Thanks for that. I must say that my truck stops pretty well with the factory pads. Though given your wear experience, sit seems to make sense that you're getting a stronger response. I drive in such a way that I avoid hard stops. But then I have to put up with the nuns who give me the finger as they go by because I'm going so slowly :O) Seriously, I go the speed limit plus five, almost always using cruise control. And I assume that if they can go through the red light or cut or run in front of me, they will. And I leave lots of space between me and the guy ahead, especially if someone gets up close behind me. I figure if I have to use my brakes, I didn't anticipate correctly.If I'm heading around a curve that has a traffic light (as we have on the Saw Mill Parkway in NY), I let cars get ahead of me, and I use their brake lights to let know whether the light ahead is red. Save brakes incredibly. I even stay off the brakes in stop and go traffic! Anthony Giorgianni For everyone's benefit, please post back to the group ----- Original Message ----- From: "Happy Traveler" <happy_traveler@abc.net> Newsgroups: rec.autos.makers.ford.explorer Sent: Wednesday, April 30, 2008 4:44 PM Subject: Re: Brake puzzle > For what it's worth, here is my experience with a somewhat newer, 98 > model. A great vehicle with just minor problems in ten years of service. I [quoted text clipped - 11 lines] > emergency, I know what I'd take. Newer types of friction material, like > ceramic may deliver the best of both worlds - no experience with those. > For what it's worth, here is my experience with a somewhat newer, 98 > model. A great vehicle with just minor problems in ten years of service. I [quoted text clipped - 11 lines] > emergency, I know what I'd take. Newer types of friction material, like > ceramic may deliver the best of both worlds - no experience with those.
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