My Wife & I am planning on taking a 6000+ mi trip this fall, we will be going to Yellowstone, Redwood Nat Park, Yosemite and G Canyon. I was told by a friend that did this same trip that I should look into purchasing an exhaust brake for my truck. I have a 2009 GMC 2500 with 365HP Allison/duramax that I bought new in 11-2009. I tow a 2010 34-foot Forrest River Blue Ridge “full-profile” 5th wheel. The truck and 5th wheel were weighed on CAT scales. The combined loaded weight was 19,080 lbs. The truck manual states that max GCWR weight should not exceed 22,000 lbs, so I should be OK on this end. I checked with local GM dealer, only to be told that there is no optional factory brake available for the 2009 model. She further stated that I will void my 100,000 mi factory warranty if I buy an aftermarket brake. Does anyone have this same year-model truck with a trailer of approx. same weight that has traversed this route? My truck weighs 7680, 5th wheel weighs 11,400. I have pulled this trailer all the way from east Texas to Wash DC with no issues of going up or down grades, however I know that the western side of US has long, steep mountains; (have already pulled a 27 foot 5th wheel to Estes Park Colorado from east Texas with a 2001 F-250 about 8 years ago). I am wondering how the “tow-haul mode” (along with manual shifting) works in practice on the really rough stuff. Main thing, I want to be able to stop this rig without any problems. Thanks in advance for any tips, help!!

....well remember, your trailer also has brakes...that too will help....Your under weight on your trucks specs...I'd say use your T/H option and down shift on the shifter when going down a steep hill..The allison with it's grade braking, along with the manual downshifting you can do along with the brakes on your trailer ought to be enough. "IF" you really want to add an exhaust brake, make sure you purchase one that is adaptable to your D/A combo...I know Banks use to make one for the D/A and I understand it was a pretty good one.But again, you're not overweight, you have T/H, manual downshifter, the Allison grade braking and you have the brakes on your trailer...unless you want to spend more money, I think you will be ok...but it's more an opinion thing with me...

The exhaust brake is really just one of those nice to have items. You really don't need it. As stated the Allison trans is your friend. Use the manual downshifts and engine braking. It one of the best combos on the road. There are thousands of D/A's out there taking on those grades every day....

Tow Haul Grade Braking is an awesome feature of the Allison. It will work just fine for you. You don't need to add an exhaust brake.Just don't be alarmed when the engine screams a little and the RPM's jump UP when Grade Brake engages.

My 5er weighs in right at 10K fully loaded, and my 08 Duramax weighs in about the same as yours. I too wanted a little extra for our trip west in September, so I purchased the BD Diesel VVT Turbo brake. Banks has a very similar product called the "Speed Brake". While MI does not have moutain grades, I did have the opportunity to test the unit on a fairly long (3/4 mi) 5-6% grade after the installation and I was impressed to say the least. The VVT brake does require some rpms to achieve max back pressure, from 2300-2800 rpms worked best, providing substantial retarding power. I`m happy so far. I would recommend checking it out.

You should be fine with the rig as it is. Our Carriage Carrilite scale weighs 12,840 including he pin weight loaded to go and the truck is Chevy D/A CC LB 4X4 and usually has our 106 gal aux tank in the bed. Almost the identical weight as yours. We have zero issues with the OEM engine brake and seldom ever have to use the truck brakes unless the decent is more than 6+% and long. You also can manually over apply the trailer brakes occasionally to slow the rig down as it pulls backward on the truck and eliminates any fishtailing or sway possibilities. I occasionally use the trailer brakes pushed manually just a little bid harder than it normally is along with the engine brake on steep decents before going into a sharp or sharper curve. Eliminates any push effort from the 5th wheel behind going into the curve. Be sure to tap the brake pedal once before starting down a long grade so the tranny is in a low enough gear to be effective before your rig has already gained lots of speed. Much harder to slow a speeding rig than to maintain the slower speed starting down from the top. You'll learn fast.

Will tow/haul & manual shift stop GMC 2500 & 5th Wheel?

NC_Hauler
Explorer
Jun 30, 2013
....well remember, your trailer also has brakes...that too will help....Your under weight on your trucks specs...I'd say use your T/H option and down shift on the shifter when going down a steep hill..The allison with it's grade braking, along with the manual downshifting you can do along with the brakes on your trailer ought to be enough. "IF" you really want to add an exhaust brake, make sure you purchase one that is adaptable to your D/A combo...I know Banks use to make one for the D/A and I understand it was a pretty good one.

But again, you're not overweight, you have T/H, manual downshifter, the Allison grade braking and you have the brakes on your trailer...unless you want to spend more money, I think you will be ok...but it's more an opinion thing with me...
sch911
Explorer
Jun 30, 2013
The exhaust brake is really just one of those nice to have items. You really don't need it. As stated the Allison trans is your friend. Use the manual downshifts and engine braking. It one of the best combos on the road. There are thousands of D/A's out there taking on those grades every day....
downtheroad
Explorer
Jun 30, 2013
Tow Haul Grade Braking is an awesome feature of the Allison. It will work just fine for you. You don't need to add an exhaust brake.

Just don't be alarmed when the engine screams a little and the RPM's jump UP when Grade Brake engages.
msjdbman
Explorer
Jun 30, 2013
My 5er weighs in right at 10K fully loaded, and my 08 Duramax weighs in about the same as yours. I too wanted a little extra for our trip west in September, so I purchased the BD Diesel VVT Turbo brake. Banks has a very similar product called the "Speed Brake". While MI does not have moutain grades, I did have the opportunity to test the unit on a fairly long (3/4 mi) 5-6% grade after the installation and I was impressed to say the least. The VVT brake does require some rpms to achieve max back pressure, from 2300-2800 rpms worked best, providing substantial retarding power. I`m happy so far. I would recommend checking it out.
travelnutz
Explorer II
Jun 30, 2013
You should be fine with the rig as it is. Our Carriage Carrilite scale weighs 12,840 including he pin weight loaded to go and the truck is Chevy D/A CC LB 4X4 and usually has our 106 gal aux tank in the bed. Almost the identical weight as yours. We have zero issues with the OEM engine brake and seldom ever have to use the truck brakes unless the decent is more than 6+% and long. You also can manually over apply the trailer brakes occasionally to slow the rig down as it pulls backward on the truck and eliminates any fishtailing or sway possibilities. I occasionally use the trailer brakes pushed manually just a little bid harder than it normally is along with the engine brake on steep decents before going into a sharp or sharper curve. Eliminates any push effort from the 5th wheel behind going into the curve.

Be sure to tap the brake pedal once before starting down a long grade so the tranny is in a low enough gear to be effective before your rig has already gained lots of speed. Much harder to slow a speeding rig than to maintain the slower speed starting down from the top. You'll learn fast.
6dot6
Explorer
Jun 30, 2013
if you want to void warranty than there are a good number of options. efi is the best option you can do for tuning and turbo brake setup. idaho rob and kory willis are one of the two best out there that make the tunes.
Charlie_D_
Explorer
Jun 30, 2013
Been to all those places with my previous rig and a 2006 D/A. Use Tow Haul, tap the brake to downshift and if you don't like the RPM, brake HARD to slow down and then get off brakes. Don't worry about slowing down too much, you will regain that speed as you descent. Some stay on their brakes too long and overheat them. If there is a pull over on the decline, pull over and check your brake temp. with a digital thermometer.

I never manual shifted. I let the transmission do what it is designed to do.
skipnchar
Explorer
Jul 01, 2013
Tow/haul changes the shift points and in order to do that it needs an automatic transmission. NO way it can MAKE you shift at a different point. You should be just fine with the manual shift. Likewise for downshifting. YOu just do manually what tow/haul would do automatically.
wintersun
Explorer II
Jul 01, 2013
With my 2011 using Manual defeats the "grade control" of the Allison transmission from working properly. With Tow Haul mode engaged when I hit the brakes the engine shifts into a mode where the transmission downshifts and there is no fuel fed to the engine to achieve maximum braking. I get an additional 25-30% engine braking by enabling the exhaust brake.

The Duramax has a maximum RPM that the computer will not allow to be exceeded so no worries if you see the engine at over 3000 RPM on a steep downgrade. It is operating as it was designed to do. The LMM engine produces maximum horsepower at 3200 RPM which is within its safe zone.

I would add a third-party brake controller regardless of the affect on the drivetrain warranty - what is your life worth? At least as of 2011 a brake controller was included as part of the tow package with the Duramax trucks and the exhaust brake is provided with all Duramax engines.
gat75
Explorer
Jul 01, 2013
Wow! never believed I would get so much feedback so fast. Thanks a thousand to all who stopped, took of their time and gave of their knowledge. For too long, I have been quilty of reading, but not contributing to these posts. Everyone has been kind & gave me plenty to think about before we make the big loop around the northwest.