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Old 12-08-2011, 05:48 PM   #1
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Suburban: Long Down Grade - Tow Mode - Brakes

TV: 2007 Sub 5.3L, 4WD, Auto, 4.10 gears

I am towing my old trailer today up to Eugene to trade in on my new AS. This was my first time towing anything with the new (to me) Suburban. I used the Tow Haul mode all the way. Here's what I didn't like: On long downgrades on I5 it seems like 3rd gear doesn't provide any engine braking and 2nd gear is way too low for 50-55MPH or so. This means using brakes all the way down. With my previous TV (Kia) I had 5-speed and 3rd gear was perfect for that same down grade and same trailer -no brakes touched at all.

Maybe I am too concerned, but I am worried that this will be nasty for brake wear. The trailer I had hitched today was only 3000#. I am thinking when I get 6500# behind me those brakes are going to burn up! Over thinking it?
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Old 12-08-2011, 06:05 PM   #2
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Do not use tow haul unless the trailer weighs at least 75% of the tow rating of the TV. Your owner manual explains this.

And yes, you're over thinking it....IMO.
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Old 12-08-2011, 08:14 PM   #3
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When you are towing a trailer, you have to drive the same way big trucks do.

If you have to frequently or continuously brake going down a hill, you are going too fast. 50-55 is often going to be too fast. Slow down until you can shift into a lower gear. If you don't you will overheat the brakes. There is a reason that semis go down hill so slowly.

Ken
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Old 12-08-2011, 08:44 PM   #4
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Hi redwoodguy,

I have a question for you. ( In normal driving around and without using tow mode, and or towing anything, does the coast condition still exist when descending long grades in third gear as you have stated? )

Personally, I wouldn't own any vehicle that didn't keep the converter engaged with the drive train to the rear wheels, and or all four in 4 wheel drive.

I totally agree with you that there should be an natural engine compression braking feeling when descending a grade when you take your foot off the gas. More control, and saves on your brakes as well!

Now, to put you within your comfort zone, there are alternatives available. just watch this video.
Banks Power | BankspowerTV - Banks Brake on TrucksTV

Best of luck to you,
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Old 12-08-2011, 08:48 PM   #5
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Agree Ken, I just keep shifting down until the engine will provide the braking, and this could be quite slow, but that is no problem.

But always approach the top of the grade at lower speed rather than trying to slow down after you are moving to fast. You will learn to judge this with experience, but start on the slow side.

doug k
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Old 12-08-2011, 08:57 PM   #6
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Somewhere on here I saw what I believe to be excellent advice... Never go down a hill faster than you went up it..... works for me
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Old 12-08-2011, 10:58 PM   #7
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Funny, How I Remember Working For The Largest And

Oldest Truck Dealership in the City of Boston, MA. way back in the day!
We sold an pretty impressive number of different brands of trucks and among the list were Mercedes-Benz. So, guess what was the most popular pick for our salesmen to drive around town?
Mercedes-Benz, was the choice of the day. From 350s to 450s, The auto versions that is!. Not the trucks!

The automatic transmissions in the car versions disengaged the converter when you let off the throttle so as to put you into an sort of a free fall, to conserve fuel efficiency. However, they were and chewed up four wheel disc brakes in a heartbeat! The moral of my drift is to convey that you could buy two Chevy's for what it cost for a brake job on one of these four wheeled disc brake models.

What Do Shop Foreman's know?
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Old 12-08-2011, 11:14 PM   #8
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Quote:
Originally Posted by w7ts View Post
When you are towing a trailer, you have to drive the same way big trucks do.

If you have to frequently or continuously brake going down a hill, you are going too fast. 50-55 is often going to be too fast. Slow down until you can shift into a lower gear. If you don't you will overheat the brakes. There is a reason that semis go down hill so slowly.

Ken
I went up the grade at 55. When going down the tv was in third and wanted to gain speed. I wouldnt say it was "coasting". From previous climbs on tight road i know that second gear peaks out about 40-45. I thought that would be too slow for the Interstate which was pretty busy. In other words i was needing gear between second and third.
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Old 12-09-2011, 12:31 AM   #9
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Rivet I Was Trying To Be Helpful...

Quote:
Originally Posted by redwoodguy View Post
I went up the grade at 55. When going down the tv was in third and wanted to gain speed. I wouldnt say it was "coasting". From previous climbs on tight road i know that second gear peaks out about 40-45. I thought that would be too slow for the Interstate which was pretty busy. In other words i was needing gear between second and third.
Maybe you need to find an extra gear using what you already have... ??

Again, best of luck to you...
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Old 12-09-2011, 08:58 AM   #10
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Hi all, Previous advice to go downhill at the same speed you went up, however valid, should be taken lightly. These new pickups with the hi-torque diesels can blow you away on the uphill grade. I took the Wolf Creek Pass west side uphill grade at an easy 55mph with my Dodge diesel. I could have gone faster too. Could make for a hairy downhill on the other side so take that advice the way it was intended. Back off at the crest of the hill and slow down to begin the downhill grade. Also mentioned earlier it's easier to maintain a proper downhill speed than having to slow down from a higher speed. A bit of caution at approaching the crest will ease the downhill stresses.

Drive carefully, see ya on the road sometime.
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Old 12-09-2011, 09:40 AM   #11
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Originally Posted by polarlyse View Post
Hi all, Previous advice to go downhill at the same speed you went up, however valid, should be taken lightly. These new pickups with the hi-torque diesels can blow you away on the uphill grade. I took the Wolf Creek Pass west side uphill grade at an easy 55mph with my Dodge diesel. I could have gone faster too. Could make for a hairy downhill on the other side so take that advice the way it was intended. Back off at the crest of the hill and slow down to begin the downhill grade. Also mentioned earlier it's easier to maintain a proper downhill speed than having to slow down from a higher speed. A bit of caution at approaching the crest will ease the downhill stresses.

Drive carefully, see ya on the road sometime.

Good point. I guess I assume, incorrectly, that with gas prices and towing mileage, the temptation to try to go up hills at 70 mph is one that most would avoid. So your advice makes perfect sense and a bit more universal.

Thanks for clarifying
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Old 12-09-2011, 11:43 AM   #12
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I remember the adage as "Go down the hill in the same gear you need to climb it." On my diesel, this isn't quite enough on very steep hills (10+ %) due to the minimal compression braking, but it's close.

If you do find yourself needing to use the brakes intermittently to control your descent, use them in cycles: allow the rig to slowly increase speed until your limit say 55 mph, then apply the brakes sufficiently to slow you to 48 or so... and repeat.

Also, if your truck would descend the grade by itself at an acceptable speed, you can just apply a little trailer brake with the controller to hold things back. I put disc brakes on our Tradewind and they don't mind doing this at all - and pads for the trailer would be a cheaper fix than the truck as it likes to eat rotors for some reason.

If I lived in Colorado or similar, I'd get an exhaust brake.

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Old 12-09-2011, 11:44 AM   #13
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The 4L80e and 4L60e transmissions have an overrunning clutch on 3rd gear. It has nothing to do with the torque converter.

What's the problem with using 2nd gear? Would you be over redline or is it just that you don't like the noise it makes?
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Old 12-09-2011, 08:48 PM   #14
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Quote:
Originally Posted by Jammer View Post
The 4L80e and 4L60e transmissions have an overrunning clutch on 3rd gear. It has nothing to do with the torque converter.

What's the problem with using 2nd gear? Would you be over redline or is it just that you don't like the noise it makes?
Ok, I picked up the trailer today, and towed it back 90 miles on the same I5. I don't go over 55MPH. I try to maintain 55 up and 55 down the grades. It feels like 3rd doesn't quite hold the speed on a 6% downgrade. It tends to creep up to 60. I was a bit leery of using 2nd, because the revs would be up around 4700RPM. I am not used to driving with the engine roaring like that for say 4 miles. Is that OK? It's just a bit foreign to me.

What does overrunning clutch mean?
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