Am I doing it wrong

[steve R]

I have a 07 Winnebago 35J on a Workhorse chassis. Today I was driving down a long windy grade with my grade brake on. When i started to slow down it jumped from 6th gear to 4th gear and the RPM climbed to over four thousand. I started to apply the brake again to drop the RPM a little bit but then it drooped to 3rd gear just what i didn't want it to do. I gave it a little throttle and it jumped to 5th gear. Is this how the grade brake supposed to work. I know when you are in over drive it will jump from 6th to 4th. But I cant seem to find that sweet spot.

[edgray]

steve R: There are certain conditions that must be met before the GB will cause a downshift, but basically speaking....it sends a downshift command to the tranny each time you press the brake pedal. So essentially each brake application will increase the RPM (assuming the ecm will allow it), but both the higher RPMs and the brake application will slow the coach, and that is a good thing if you're going downhill. Ed

[DriVer]

Quote:

Originally Posted by Steve R Is this how the grade brake supposed to work. I know when you are in over drive it will jump from 6th to 4th. But I cant seem to find that sweet spot.

I am not sure how much seat time you have with the Transmission Grade Brake (TGB) however depending on the drivetrain load and RPM your TCM may just call for lower shift positions and it will want to hold it at that RPM level until the road conditions change.

The elevated RPM that you were seeing are not all the bad. If you need to moderate the speed of the vehicle while the grade brake is engaged just tap the brake pedal really hard for about 2 seconds and let it go. You will find that you will have scrubbed off enough speed to lower the RPM. Apply the brake in a similar manner if you need to scrub off additional speed. You should not exceed the maximum safe descent speed that is posted for the grade.

When you are in compression and the TGB is engaged, stepping on the gas pedal is telling the TCM that there is no further load on the drivetrain and to up-shift. Now if you find yourself going too fast and get back on the brake the TCM is going to want to go back down into the gears.

Trust your equipment to do the right thing, stab the brake pedal to scrub speed and lay off the gas. If you do not trust the TGB (I do) then turn it OFF and grab the shift lever and yank it down to 2nd gear and start there. Up shift if you find yourself going too slow. Again stab your brakes to scrub speed. Do not keep you foot on the brake pedal for any period of time.

[UFO Pilot]

When using the grade brake, I regularly see RPM's in the 4000 range. Am I in danger of damaging the engine? With the engine in the rear I don't hear the noise like I did in the W24 so I don't think about the RPM's as much.

[DriVer]

Quote:

Originally Posted by wthomas1 When using the grade brake, I regularly see RPM's in the 4000 range. Am I in danger of damaging the engine?

No sir that's fine. Just watch your speed and if your descending at a safe rate of speed that meets the conditions you'll be just fine. Again like any other rig, just stab your brakes to scrub speed.

[UFO Pilot]

Thanx Driver

I have always been more concerned with the speed than the RPM's.

[steve R]

Thanks everybody for your input. I just wanted to make sure that bit was working right and it sounds like it is.

[Mr JP]

I just went down a 6% grade for about 20 miles (kingman to Bullhead city) and the grade brake worked very well. If i got on the brake and dropped speed below 60 it would drop down to 3rd gear and over 4000 rpm. I agree it is enough to raise the hair on your back but it handled it great. Back on the gas a little to just over 60 and up to 4th gear a lot quieter and only around 3500 rpm. I am very happy with this grade brake. Then up the other side crossing the river at Laughlin and 6%+ up hill 3rd & 4th Gear 4500 rpm engine temp at 200 trans temp at 178. 50mph ran well. at the higher rpm discovered an exhaust leak very minor but could hear at high rpm only. got home and i could look theough the passenger wheel well and see thr black line on header flange on #2 cylinder. It must be time to re-torque the header bolts. I was very happy with the performance of the grade brake and the 8.1. Good Luck all JP

[DriVer]

Whether you own a vehicle with a TGB or not, you do have the opportunity to get that functionality installed on your 2001 to 2004 motorhome and it works as advertised!

The UAGB works and I am very pleased to have it on my rig. What makes is so good is that it accomplishes everything it needs to do without any input from the driver other than normally stepping on the brake.

If you are really a proactive driver and have driven a stick all your life, you know when to grab a gear and going low doesn't bother you. Some folks are very apprehensive to pull the shift lever down because they feel that its gonna hurt something. The most at times that you can get some folks do is toggle their OD switch.

The UAGB/TGB takes those perceptions out of the picture if you just allow the system to do what it does best. Since I have installed the system, I have left the system ON, have not had to toggle the OD switch and except for downshifting on flats exiting the Interstate, I have not had to grab a gear.

[Nap&Joe]

I have a question about my just installed Grade Brake. My grade brake switch is on the right of my instument cluster (oposite the Overdrive switch on the left side). Is the GB turned "on" when the top of the switch is depressed (like when the OD switch is activated)? I have only just picked up the RV from the shop (Auto Truck Services in Colorado Springs....a GREAT authorized Workhorse Center) to home so do not have much experience with the GB as of yet. Thanks!!