I just returned from our biggest RV adventure - by far. We drove 11 states, from home in MI out to the Northern US Rockies. What a great time, the family loved every bit of it.
When I was coming down from Big Sky Mountain Resort in MT, I used the brakes with the transmission in OD (4). Right at the bottom I smelled the brake smoke for the first time. What hurts is having to pull over, bringing her to a near or dead stop down the hill to let cars pass. I figured that I would begin to use lower gears to augment the brakes on the next big descent.
So the next big pass descended into Ashton after West Yellowstone. It seemed pretty straight but steep at about 8%, and long, so I shifted into D (3). This held the speed at about 60 mph, plus we had a nice headwind that helped to prevent runaway speeds and I used almost no brakes which was nice.
Next up a few days later was the mighty Teton Pass. I have driven a lot of passes (in cars) and I thought this pass takes the cake. It seems to me that it's more extreme than even Loveland Pass. It's much lower in elevation however I think it's longer and it's a full 10% both sides and I think it has more switchbacks. Anyway, I felt that I climbed it alright but not great because 10% is so steep. We took a quick break, and the coolant stayed cool on most of the climb but in the last couple minutes warmed a little and then came back down during a couple minute break. I let traffic clear, shifted into 1st and descended. I kept it in 1st but the engine screamed (valve train sounds) and at times I was going 30 mph. It sounded like I was doing bad things to the engine. I have no tach and it would be useful for that. So I applied more brake and I tried to keep it at 20 or 25 mph but it took a lot of brake to keep the lid on the speed.
I have a 1996 P30 Chevy 454.
I made it all the way back home and it doesnt use oil, it didnt use oil before and it didnt burn oil on the descent, nor on the drive home. So I can assume the engine can happily take this kind of abuse.
Would you recommend using more brakes, or not worry about the engine taching out...how do you play the descent? thanks sorry about my verbiosity
Well you've tried BOTH incorrect extremes so now you need to find something right in the middle. Nothing wrong with using your brakes if they're used correctly. Slow down quickly so you are ON the brakes as little as short a time as possible and slow down BELOW the ideal speed by about 10 MPH. Then you get off of the brakes completely and use the transmission (now low gear but something like third and let the vehicle gain speed again until it's going about 10 MPH faster than you'd prefer and then you just repeat the procedure. The worst thing you can do is use the brake constantly and lightly because that will CERTAINLY overheat your pads. Using that method you're not revving high with the engine in low OR using up your brakes. You will usually get to the bottom of the mountain with only mildly warm brakes and NO excessive wear on your engine. Your engine may be able to stand up to the abuse but that doesn't mean it should be abused unnecessarily.
Good luck / Skip
2011 F-150 HD Ecoboost 3.5 V6. 2550 payload, 17,100 GCVWR - 2004 F-150 HD (Traded after 80,000 towing miles) 2007 Rockwood 8314SS 34' travel trailer
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Another big mistake many make is stopping at the bottom of the hill to let the brakes cool. You are at the bottom and do not need brakes anymore. Keep going at a slower pace until the brakes cool. Do not stop as the brake rotors will warp. This is because the area under the brake pads can not cool at the same rate as the rest of the rotor. Also if you are moving air can circulate through the rotors better.
It sounds like you've learned to use the gear that holds the coach the best with no brake application. That's my plan as well. As you've seen though, you still start hearing that engine turning up into the "worry" range on occasion. That's when I brake, kind hard to get the speed back under control, then backing off the brakes completely until/if necessary to do that again.
I try and shift down (and slow down) until I can descend using only the engine braking to maintain a constant speed. Of course, I have a tach to monitor engine speed, but the engine does scream at high, but safe, revs. As others have posted, if you can't quite hold it with the engine braking, then an occasional stab at the brakes to slow down is OK.
Note that while many engines have a rev limiter, it only works when you are accelerating, and will not work when the engine is being driven by a downhill run. So it might be a good idea to add a tach or devise some way to determine when you're at the safe RPM limit.
Ed
I go down mountains in 3rd or 2nd gear at around 40 mph.
When my RPMs get to 4,000 I mash on the brakes hard for less than 5 seconds, which usually drops me about 10 mph and down to 3,000 RPMs
I never start down mountains above 50 mph.
Many years ago I lost brakes in a pickup going down a mountain too fast and riding the brakes. I was able to get stopped when it leveled out but I NEVER went down a mountain fast again and always use engine braking.
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Took mfgs a few years but just recently they finnally figured out how to make tranny's effective at braking down hill. It's a little button called tow/haul. My 04 F150 did not have it but my 2010 Ram 2500, 2011 Jeep Grand Cherokee and now my 2011 Winne all have excellent down hill tranny brakes. I have towed 6000lbs behind all of them on some pretty serious grades with excellent results and rarely need to use the brakes.
In addition, I would suggest staying off of grades of more than 6% and 7% for short runs. Boiling brake fluid is a strong concern here if you don't do it just right and for sure, no stopping to let your brakes cool, if you can help it.
Change brake fluid frequently and especially before planning trips over these kinds of mountains.
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Next time you decide to head on our west, here's a good 5000 rpm tach in a small configuration for mounting on your steering column. You will need both the Tach and a thing they call the Mounting Cup to hold the actual gauge. You'd also have to fabricate a mounting bracket from bent metal, too. Or with some other arrangement depending on your rig.
I like the tach so I can keep the rpm around the torque peak (about 3200) when climbing. And coming down grades you can watch to see how high you are allowing the revs to climb.
Don't know that I'd worry about 5000 rpm coming down grades since my understanding is that these 454s are used on power cruisers and run all day up near 5000 (assuming there is an occasional fuel pump along the way).
Final comment. You might want to do a complete tranny flush after pulling all those grades out west.
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