Completely Overheated my Brakes!!!!

Jim_Chow · 07-05-05, 05:14 PM

Cary, I know that grade and have used it in the past! It's super steep, but cuts off a lot of distance, puts you very close to the Yosemite entrance! I only use that short-cut on the uphill...always the main highway on the way down since the grade and curves are more gradual. I'd guess your pads fried, or maybe the rotors are too thin to dissipate the heat.

cary · 07-05-05, 05:21 PM

Jim,

I sent you a PM, but figured I would ask here. I saw you had the porterfield R4-S pads and wondered how you feel about them after a few years. They are the only company that makes pad upgrades front and rear. I saw you mention so-so cold weather performance. When you say that do you mean less effective when dead cold, or like the old Metal Masters that when it is 40f and you hit the brakes nothing happens for about 100 feet?

Thanks

Cary

lovetoski · 07-05-05, 11:23 PM

Cary,

Glad that you and your family are safe. Intersting though that you brought up bikes. I've been racing and riding for 30 years, and long steep descents are still a problem for racers (road more than mtn). While I am not as much a "motorhead" as I am a cyclist, I still know enough about cars/trucks to know that brake fade isn't that unusual. I've experienced it twice - once in a Ford Country Squire station wagon, once in a BMW 320.

I'm no engineer, but I understand enough of physics to appreciate the energy (heat) involved in fighting gravity...the lesson I've learned is that wheel brakes stop faster, but have a limit in terms of energy dissapation. Engine braking cannot produce as much force, but tolerates much more accumulated energy...but there's not much disscussion on this difference.

All mechanical devices have a failure point - and one of the best parts of this forum is the discussion of how to push the failure point out further. Brakes are not a common failure point on 4X4 vehicles, though I suspect that it's a more common thread on "high-performance" BBs.

My point being...we think of traction, torque, clearance, etc as primary performance vectors...yet can forget that brakes are essential. Like Doug's post a few months ago about his brothers accident, it's good to get a real world reminder of the things we need to look out for.

cpg · 07-06-05, 08:53 AM

I had the same exact thing happen
Too steep, Too Heavy, and too long for second gear.
After that I got a center diff lock switch and put the truck in low to go down that grade no problems much better engine breaking. I never had a problem there until the 35's went on. Even stock a lot depends on how you drive that grade. Low range really made it a lot safer and less stressful with the larger tires.

IdahoDoug · 07-06-05, 11:34 PM

Cary,

What size tires are you running?

DougM

cary · 07-07-05, 09:18 AM

Doug,

Huge Tires.

Actually, they are 265/75/16, or 32". Not significantly oversized so shouldn't be overwhelming.

My theory on the problem is that there is insufficient airflow to cool the brakes at the speed I was traveling. As you know from vehicle design, airflow basically increases at the square of the speed you are traveling. Given I was traveling at 25mph, I think there was insufficient airflow to cool the brakes for that distance. I think if I was going down the same type of grade that allowed for higher speeds, the additional airflow would have cooled the brakes.

My plan is to upgrade the brake pads from OEM. I have been looking at the Hawk Pads, Performance Friction Z- Carbon-Metalic, and Portorfield. I am leaning toward the Performance Friction or the Hawk pads. While this doesn't solve the heat problem, it will at least keep the brakes functional if I should get them that hot again. That and knowing the issue exists will make me be a little more cautious about how I use the brakes in the future on slow long downhills.

Funny aside. My wifes answer to the problem is she wants an X-5. I told here if we get an X-5, I am keeping the 80 and selling her 525i. She said, "I though you wanted a sports car." I said, yes, I want one, and the 525i isn't it, I want a 911. She says buy a cheap 911, I explain, there is no such thing.

Rich · 07-07-05, 11:47 AM

Cary, I think the root problem is just that you used too much brake, aggravated by an out of adjustment proportioning valve.

I've been on a number of steep grades where 1st gear high range, or higher gears in the low range, were the only gears that provided sufficient engine braking to eliminate the need to ride the brakes.

I drove that specific grade years ago while visiting California on vacation. I had no idea of where it lead. I love backroads. Reading the sign "Old Priest Grade" was all it took to divert my route. To the best of my knowledge, I was driving a rental Mustang, which, of course, is much lighter than a FZJ80. No excitement with the brakes ocurred.

Thinking back, I seem to recall driving that same rental Mustang through a few dry washes in Arizona & New Mexico. Sure seemed like they were roads when I first got on! Must have been bad signage!

Tools R Us · 07-07-05, 01:05 PM

Quote:

Thinking back, I seem to recall driving that same rental Mustang through a few dry washes in Arizona & New Mexico. Sure seemed like they were roads when I first got on! Must have been bad signage!

Washes are roads here!

Rich · 07-07-05, 02:13 PM

That's what I thought, until the tops of the washes got higher than the car and the wash widths got narrower than the car. Forced to backtrack!

IdahoDoug · 07-07-05, 10:02 PM

Cary,

I'll be curious what you choose for pads, but would suggest you carefully research a "performance" pad's cold performance well. A very high percentage of emergency brake applications occur with cold brakes, so that should be one of the highest considerations in your choice.

I think you could easily have handled that grade with a properly proportioned brake split, and definitely with 1st gear in use. It's worth noting that if the O/D button is OFF, you also get more effective engine braking so if you were in 2nd with the O/D on you weren't using the 80's capacity fully. I base this on my own experiences crawling down 7-8% grades at around 25 in 1st gear weighing 11,500 (trailer) with only a few touches of the brakes required. Don't at all worry about overheating the tranny in this situation - the engine's loafing/likely cooling down along with the rad which can then handle more tranny heat. But the tranny heat is all about power generated heat (in either direction - drag or powered by engine torque) and the drag torque is nowhere near engine output plus no shifting or torque converter slippage (if above tip is used).

That sounds like some seriously steep stuff for a public roadway!

On the cheap 911s, the only ones I've ever seen were crushed into balls - heh. Personally, I'd take a Honda S2000 (sunny days) and a WRX STI (rainy days) for the same mony instead.....

DougM

cary · 07-07-05, 11:02 PM

I'm having a hard time with the pads, as I can find very little good data on any of the three manufactures. Performance Friction has not responded to my e-mail (that will probably rule them out), the guy from Hawk was an idiot that could do nothing more than repeat the very limited information they have on their website, and Porterfield was very nice, but still limited information.

Jim Chow PM'd me back about his porterfields and said they were great, but when he lived in LA in colder weather they were not so good on that first stop. Being I have lived long enough to have experience the old Metal Masters in another car in 30f weather (basically no brakes for the first 100 feet), I am very sensitive to that issue. I wish Pagid made some pads for the LC, then I would just be done with it.

My mechanic suggested the porterfields saying in his experience the Hawks were to agressive on rotors, even their street pads. He uses their race pads on his track car so he has no axe to grind with them. When I told him about the problem, he responded that he had gone down it in is e30 325i, punching it out of the corners and hard braking for the next corner with no problems and was suprised that I had the overheating problem.

The overheating really caught me off guard as I was in second and was doing moderate engine braking. I was on and off them them all the way down, so they weren't being drug constantly and didn't feel any signs of fading until the bottom when I needed to stop. As I posted earlier, I went down it again the next day in 1st and just let the engine rev to 3500rpm (I wasn't concerned about anything because as you said, I am putting less torque into the tranny engine braking than under heavy throttle) and just played it like we used to with old cars that had drums. That time, I only had to tap the brakes a few times with no fade.

A honda S2000 woudn't cut it for me. I don't like convertables and they don't have enough punch on the top end (I got into a race with one on the freeway in an 89 911 cab and kept walking away from it from 80-120mph, we went back and forth about 4 times, he wasn't happy). I have driven a WRX and thought it was a pig. Turn in wasn't good, suspension was to soft, and it wasn't all that fast. My mechanic agreed, and then a few months later he told me he instructed a guy with an STI (my mechanic is a NASA instructor) and it was an entirely different car and well worth checking out. The problem is that the STI is to much of a boy racer and would go over about like a lead brick with the wife. Part of the love of 911's for me is the challange of driving them, they are a lot of work to drive fast, but very rewarding when done right. The only other cars that are on my list would be an e36 M3 or e46 330i. That said, we just had a client that gave us an S500 benz in trade for writing off his bill and I am considering buying it from one of the partners ($20,000 or so for a 2001 with 100k).

Cary

IdahoDoug · 07-07-05, 11:13 PM

Ooh, that S is a LOT of car.

Yep the STI is remarkably changed vs the regular WRX. Basically track ready for an enthusiast, a couple grand away from serious track ready for someone wanting more.

Agree on the 911's capabilities. My issue with it would be as you mention - it's tough to wring out that last 15% where other cars you will only have problems wringing out the last 5%. And the downside of the 911 is that you're playing with fire experimenting with its limits. They've done a lot with the car's layout, but at the end of the day it's still a rear engine car with all the issues that come along for the ride. And yes, I've been a victim of the dreaded drop throttle oversteer as well - but on a track. I was quite surprised by it as I was reasonably good and it was on a track where the consistent surface let me probe the limits safely. Dunno. They're rewarding to drive briskly, too. But on a daily driver basis that rear engine design also brings a lot of negative ride qualities to the table that would bother me.

DougM

Tools R Us · 07-08-05, 09:25 AM

The EBC Green Stuff 7000 Series pads on my truck have performed very well. They are Kevlar based, the small amount of dust they make rinses off with water. When I bought the truck it had bad "warped rotor" judder, changed to the EBC's and did an aggressive bed-in and it's been smooth as silk. They have about 14K miles on them and have about 40% life left.

http://www.ebcbrakes.com/Automotive.html

MaddBaggins · 07-08-05, 12:29 PM

Quote:

Originally Posted by Tools R Us

The EBC Green Stuff 7000 Series pads on my truck have performed very well. They are Kevlar based, the small amount of dust they make rinses off with water. When I bought the truck it had bad "warped rotor" judder, changed to the EBC's and did an aggressive bed-in and it's been smooth as silk. They have about 14K miles on them and have about 40% life left.

http://www.ebcbrakes.com/Automotive.html

Kevin, where are you buying those? Are you ordering or does anybody here in AZ stock them?

cary · 07-08-05, 01:22 PM

Well at this point I am going with the Porterfield R4-s pads. FYI, I did not look into the EBC pads because it seems to many people have trouble with them and the 7000 series are an organic pad, so no real upgrade from stock.

The reasons for porterfield:

1) I can't reach anyone at PF. I spoke to Hawk again and they are worthless. The guy told me about 10 times, their pads are just better, but could give me no objective data. When I asked about how they compare to porterfield, PF, he said they never compared them. He actually asked me if my vehicle weighed more or less than 1/2 ton, to which I asked him to name one vehicle sold in the US that weighs less than 1/2 ton that isn't a motorcycle. He couldn't. I asked to speak to an engineer and was told that they don't speak to customers.

I spoke to Porterfield again and the lady was pretty honest (note that porterfield sell Hawk and PF). She said all three are very similar in terms of performance. She said in comparison to the Hawk pads, the R4-s has better cold bite and less dust. This agreed with most of the info I found on th net.

2) Porterfield is the only company of the three that makes front and rear pads for the LC. It seems strange to me to replace the front pads with a grippier pad, but leave the rear alone. It will unbalance the braking system. So that pretty much pushed me over.

I will order in the next week or so and then get them on when I can.

Cary

hoser · 07-08-05, 01:32 PM

Cary, Have you consider Axxis Ultimate brake pads? I believe they make it for both the front and rear for the 80 and 100.

Tools R Us · 07-08-05, 01:42 PM

Quote:

Kevin, where are you buying those? Are you ordering or does anybody here in AZ stock them?

Pep Boys had them in stock for ~ $60.

cary · 07-08-05, 02:01 PM

Quote:

Originally Posted by hoser

Cary, Have you consider Axxis Ultimate brake pads? I believe they make it for both the front and rear for the 80 and 100.

I didn't realize that. Anyone tried them?

MaddBaggins · 07-08-05, 02:25 PM

I've been using the Hawk HPS for a year now, and I don't see them being to aggressive. Maybe they are too aggressive for ford or gm rotors, but they are just fine with my OEM's. My .02

cary · 07-08-05, 02:38 PM

Quote:

Originally Posted by MaddBaggins

I've been using the Hawk HPS for a year now, and I don't see them being to aggressive. Maybe they are too aggressive for ford or gm rotors, but they are just fine with my OEM's. My .02

How would you compare them to the stock pads in terms of cold bite, dust, and noise (squealing)?

Thanks

Cary