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Old 11-07-2004, 08:10 AM   #1
Montana_139
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Exaust Brakes

We have a 2001 Durmax/Allison GMC Sierra 3500. I am planning on having exhaust brakes installed. I have several questions and would appreciate any answers that you can provide.
1. Is the Pacbrake sold at Camping World a good brake and a good value? They want $929 for the brake and $337 for the installation.
2. Does anyone know if this affects the 100,000 mile GM warranty?
3. Are there other exhaust brakes that are better than the Pacbrake?
4. What experiences have you had with exhaust brakes?

Thank you very much for your help.

Glenn
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Old 11-07-2004, 09:10 AM   #2
stiles watson
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I have been toying with the exhaust brake decision myself. My limited research and a summary of anecdotal information received from exhaust brake users, indicate that the Banks Brake is highly touted as the best engineered of the lot. I don't know how it compares in price.
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Old 11-07-2004, 01:03 PM   #3
Glenn and Lorraine
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Last year when I first bought my 2500HD, I investigated the Banks Brake system and was told by the Banks sales rep that it is not necessary with the Chev/GM Durmax/Allison combination. The Tow/Haul is all that is needed.
After hauling my 5er from New York thru Pennsylvania and Virginia to Tennessee to Florida back up into North Carolina to Tennessee thru Virginia and Pennsylvania to New York over thru Ohio to Michigan to Indiana and back again to Florida. Up and down many many steep grades in the Adirondaks, Great Smokies, Blue Ridge and other mountains I have to agree with the Banks Rep. YOU DON"T NEED IT!! Use your Tow/Haul and save the $$$$$.
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Old 11-07-2004, 06:22 PM   #4
Northstar
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I agree with Glenn. All you should need is the tow/haul mode. Keep us posted. Happyrving......
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Old 11-07-2004, 09:18 PM   #5
Montana Sky
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I had asked about having the Banks exhaust brake installed and they said right up front that it will void all warranties on the truck. GM does not allow any modifications to the motor or powertrain. I have found that towing my 3400RL with the Duramax and Allison tranny does so well I dont see a need for an exhaust brake to be used. Agree with Glenn, save the money..
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Old 11-07-2004, 09:22 PM   #6
Montana_139
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Thanks for the responses. My problem is that going downhill in the Rockies the Tow/Haul downshift causes the engine to go over the red line unless I use a lot of braking. I am trying to correct this by getting more engine braking at lower RPM.

Glenn
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Old 11-08-2004, 01:42 AM   #7
sreigle
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Glenn, welcome back. Haven't seen you posting in a long time.
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Old 11-08-2004, 04:06 AM   #8
Bob Pasternak
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Glenn: Simple solution; use a lower gear. That's what the big boys do! I don't have an exhaust brake on mine but I've been over the Rockies, Canadian Rockies, Grand Tetons, Adirondacks and the Smokies with no problem. I've never had my brakes so hot I couldn't touch them, truck or trailer. There used to be an admonition to go down a hill in the same gear you go up in but with the advent of retarders, that's no longer true. The Jake brakes on the large trucks are most efficient at 2100 RPM but then most of them don't turn as fast as yours does. I used to tell drivers to start down a hill in a gear they're sure will hold it. If it slows down when they take their foot off, they can probably go one gear higher and try it. If you're in high gear and maxxed out on rpm, you'll not be able to down-shift without breaking something. And cooking your brakes is likely not covered by warranty. There's an old trucker's adage that says "you can go down a lot of hills too slow; You'll only go down one too fast!!"
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Old 11-08-2004, 09:23 PM   #9
Montana Sky
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Glenn,
I have had the same problem as you with touching the brake will cause the tranny to downshift sending the rpm's over 3,000. I had talked with the dealership about it and they said almost word for word what Bob had just said. Start out in 3rd going down, and if it is too much use your brakes to get you down to where you can use and hold second gear. The engine and tranny will try to send you back into the next gear as you continue down the mountain. I have found using second and third seems to work really well.
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Old 11-09-2004, 01:53 PM   #10
Native Tex
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Glenn - I can only speak from an older model Powestoke that does not have the new transmission changes. I have the Banks system as you can see below. I bought the entire set up and have pulled a large TT and now my 5er. I have used my exhaust brake with great success and with little or no brake heating or engine reving problems. I guess it depends upon your tow vehicle and its capabilities. I have found that I can leave my truck in high gear going down the mountains and it keeps me at a good steady speed. Of course, I have the transcommand too, so there is some added support/braking there as well. In my case, it has been worth the expense.
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Old 11-09-2004, 10:51 PM   #11
Montana_139
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Your replies have given me a lot to think about. I wonder why GM offers an exhaust brake on mid size trucks with the Duramax/Allison combination. And if simply downshifting (which the Allison Transmission does automatically) solves the problem, why do the big rigs use Jake brakes?

Thanks,

Glenn
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Old 11-10-2004, 02:41 AM   #12
Bob Pasternak
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Glenn: From what I've read on D/max, as soon as your foot is off the brake it will go back to OD or whatever it was in.(Somebody tell me if I'm wrong.) You must manually shift to a lower gear. The big ones use Jakes in conjunction with gearing down. We also had switches on the dash to use 2, 4 or 6 cylinder retarding. You DO NOT start down a severe grade (south bound I-15 Cajon, 22 miles of 3 to 9%, east bound I-40 from Barstow to Needles, northbound I-5 Grapevine and others too numerous to mention.) in high gear and rely solely on the Jake to hold it back. Read my other post again. Start down the grade in a gear you're sure will hold it. Then you can shift up...maybe. With a 4 or 5 speed automatic you'll not have quite the braking effort of a tranny with more gears. The newer Jakes will give about 90%+ of the engine horsepower to braking effort. And you do not use exhaust brakes or Jakes on slippery roads. Instant jack-knife because all the braking effort is applied to the drive wheels. My experience has been with engines of 300 to 500+ HP, transmissions with 9 to 18 speeds, and gross weights up to 80,000+ lbs. The premise is the same regardless of size and weight.
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Old 11-11-2004, 03:01 AM   #13
NJ Hillbilly
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THe shifting of the 1000 series Allison in T/H is speed dependant. It will not shift into 5th in T/H unless speed is over 60 mph. I know what You are saying about the upshifting to the highest gear. I have the same issue with the 6 speed Allison (I think it's a HD 4060P) it shifts to 6th when throttle is released, as soon as the Jake comes on it immediately downshifts to 4th. This truck does have a 505 Cat pulling it along . The smaller trans does not do this. It will hold the gear that fits the speen, when the brakes are applied it will downshift and grade brake to slow or maintain speed.

John
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Old 11-11-2004, 05:12 AM   #14
Virgil
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The large trucks are running 80,000 to 100,000 pounds loaded. That is part of the reason for a jake brake. I think the transmission would have a hard time holding that load back w/o a jake brake. Some of the descents in the Rockies are relatively steep and can be quite long.
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Old 11-11-2004, 10:22 AM   #15
Bob Pasternak
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Virgil; The engine brake works through the transmission to apply braking effort to the rear wheels. Going to a lower gear gives the engine more leverage, so to speak, to hold it back. All a Jake brake does is essentially make a large air compressor out of the engine. The Jake delays the opening of the exhaust vales until TDC or shortly after.
The "POP" you hear from them is the explosive release of compressed air similar to sticking a pin in a balloon. With the newer Jakes and engines, up to 97% of engine horsepower can be converted to braking effort. A 500 HP Cat will have 485 HP of braking effort at 2200RPM and that will be multiplied through the transmission proportionate to the gear you're in.
There are electronic retarders that are basically a dynamo. An armature is fastened to the drive shaft; a field coil is wrapped around it and secured to the frame of the vehicle. The control on the dash is nothing more than a rheostat that sets up an electric field in the armature and slows the vehicle. I used them on VanHool buses but they're not as efficient as Jakes.
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Old 11-11-2004, 10:34 AM   #16
Virgil
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Bob:
Thanks for the excellent description of the workings of a jake brake. Your explanation certainly tells the workings of the brake. I have been up and down some pretty steep inclines and declines and I approach them pretty conservatively as I have been scared in the past. If you drive defensively, I am of the opinion, if you need a jake brake to slow a camper, your camper is too big, your tow vehicle is too light or your just driving too fast. Oh,, and by the way Bob, good choice in tow vehicle.
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Old 11-11-2004, 01:02 PM   #17
Montana_381
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Just in case someone hadn't noticed it, there's a giant difference between the Jake Brake used on OTR Diesels and the exhaust brakes used on Diesel Pickups:

The OTR Jake works by changing the valve timing while the PU brake, essentially, acts like a potato in the tailpipe.

The biggest problem with putting an Exhaust Brake on a Diesel PU with an automatic transmission is, quite simply, the fact that the transmission wasn't designed to handle the stresses of trying to drive the engine that hard.

The Allison and the TorqShift are each supplied by a manufacturer who'd have a "perfect out" on any warranty repair to the tranny by simply pointing to the EB. The Dodge 48REs prior to the mid-year 2004 models likewise. (They started installing a redesigned $6 part that testing showed to fail and may, eventually, certify the later-production units for EB use.)

For the Ford people, Western Diesel makes/made an electronic box that utilizes the warm-up butterfly valve as a Ford-approved EB for the 7.3L and, perhaps, the 6.0L engines.

FWIW, If you look at my sig, you'll see why I've been keeping up with the warranty issues (from D/C, at least).
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Old 11-11-2004, 02:08 PM   #18
sreigle
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Thanks for the info, Bob. So far I've not seen the need for an EB but will keep that info in mind. So far the TorqShift and 6.0 do a super job of keeping things under control. I read somewhere the 6.0 will also close down the variable-pitch vanes in the turbo to create some additional backpressure but can't find where I read that. But since we do mountains I will keep the Western Diesel product in mind, just in case I change my mind.
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Old 11-11-2004, 02:31 PM   #19
Bob Pasternak
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Virgil: I was westbound on I-8 one night going down El Cajon towards San Diego grossing about 76000 on a set of pups when the micro-switch on the side of the pump that controls the Jake went south. That's when the "Pucker Factor" kicks in!!
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Old 11-12-2004, 12:30 PM   #20
Montana_2194
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Quote:
quote:Originally posted by sreigle

Thanks for the info, Bob. So far I've not seen the need for an EB but will keep that info in mind. So far the TorqShift and 6.0 do a super job of keeping things under control. I read somewhere the 6.0 will also close down the variable-pitch vanes in the turbo to create some additional backpressure but can't find where I read that. But since we do mountains I will keep the Western Diesel product in mind, just in case I change my mind.
Thanks Steve,

I feel like I stumbled into an engineering class. I'm concerned about my Ford 350 7.3 PSD going down long hills! Should I be buying additions if I hit the Rockeys or just be careful. You know that I'm a neophyte, but an motorcyclist and sailor, so I know how to improvise. My RV experience is presently zero!

Jack Hadley
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