Go Back   iRV2 Forums > MOTORHOME FORUMS > Class A Motorhome Discussions
Click Here to Login
Join iRV2 Today

Mission Statement: Supporting thoughtful exchange of knowledge, values and experience among RV enthusiasts.
Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on iRV2
 
Thread Tools Search this Thread Display Modes
 
Old 07-05-2012, 10:16 AM   #1
Junior Member
 
Join Date: Jun 2012
Location: Pryor, OK
Posts: 23
Changing how the engine braking works

I have a 1998 National Tradwinds equipped with a 3126 300HP Cat, Allison 6 speed tranny, and Jacobs Exhaust Brake.

Currently, when the exhaust break is armed "switch on" and you are in 2nd gear or above and lift your foot all the way off the accelerator pedal, the transmission will shift down "eventually to 2nd" and the exhaust break will engage.

Since I lift my foot off the accelerator and coast down most small grades, I often do not desire to have exhaust braking, so I usually manually control the exhaust brake using the arm switch. I would rather be able to leave my exhaust brake armed and not have it engage until you hit the brake pedal and quit braking when you hit the accelerator pedal.

Is this possible with my Jacobs exhaust brake on my rig?
__________________

__________________
1998 National Tradewinds with a 300 Cat...
mrjimbo is offline   Reply With Quote
Join the #1 RV Forum Today - It's Totally Free!

iRV2.com RV Community - Are you about to start a new improvement on your RV or need some help with some maintenance? Do you need advice on what products to buy? Or maybe you can give others some advice? No matter where you fit in you'll find that iRV2 is a great community to join. Best of all it's totally FREE!

You are currently viewing our boards as a guest so you have limited access to our community. Please take the time to register and you will gain a lot of great new features including; the ability to participate in discussions, network with other RV owners, see fewer ads, upload photographs, create an RV blog, send private messages and so much, much more!

Old 07-05-2012, 11:34 AM   #2
Senior Member
 
1ciderdog's Avatar


 
Join Date: Jun 2010
Posts: 4,325
I think this thread is about what your are looking for: Anyone have a BrakeSwitch besides me?
This is the website for that product: Brakeswitch, A better way to manage your diesel exhaust brake
I believe you can have Allison program the transmission to a mode that will do the same or similar.
I have the brake switch and use it all the time. I think it's a great device and makes hill country type traveling much more pleasant for the driver.
__________________

__________________
Bob, Sandi & Marmaduke the Big Pug
SW OREGON 2004 Journey 39K, 330 Cat
If towing: a 2006 Mini Cooper or 1995 Wrangler
1ciderdog is offline   Reply With Quote
Old 07-05-2012, 12:35 PM   #3
Senior Member
 
Tiffin Owners Club
Join Date: Jun 2008
Posts: 588
I didn't read the links above but I believe Allison service centers can reprogram the transmission so that it switches to 4th gear instead of 2nd when you lift.
__________________
michelb is offline   Reply With Quote
Old 07-05-2012, 01:01 PM   #4
Senior Member
 
dons2346's Avatar
 
Country Coach Owners Club
Join Date: Dec 2010
Posts: 4,488
I just keep light pressure on the throttle.
__________________
dons2346 is offline   Reply With Quote
Old 07-05-2012, 03:49 PM   #5
Senior Member
 
Join Date: Nov 2011
Posts: 204
Quote:
Originally Posted by mrjimbo View Post
I have a 1998 National Tradwinds equipped with a 3126 300HP Cat, Allison 6 speed tranny, and Jacobs Exhaust Brake.

Currently, when the exhaust break is armed "switch on" and you are in 2nd gear or above and lift your foot all the way off the accelerator pedal, the transmission will shift down "eventually to 2nd" and the exhaust break will engage.

Since I lift my foot off the accelerator and coast down most small grades, I often do not desire to have exhaust braking, so I usually manually control the exhaust brake using the arm switch. I would rather be able to leave my exhaust brake armed and not have it engage until you hit the brake pedal and quit braking when you hit the accelerator pedal.

Is this possible with my Jacobs exhaust brake on my rig?
Hi mrjimbo, I am a retired cross country trucker. If you have a Jacobs("Jake Brake") You will have a two position, hi and low switch. This brake holds the engine valves shut. The other system is a Pac Brake, which is a damper that restricts the exhaust. This brake only has an on and off position. I would rather think you have a Pac Brake. Maybe the trans codes can be changed, I am not sure. I have a Pac Brake, it does the same as yours. I just control it manualy. If the switch is on.. it is designed to engage with the reduction of pedal pressure, It down shifts to increase the engine RPM's, therefore creating more exhaust pressure necessary for deceleration. Your brake is doing all it is designed to do. Yes I understand that you do not always want it to down shift, but I would save the trouble and run it manualy. best wishes, old trucker
__________________
Old Trucker is offline   Reply With Quote
Old 07-05-2012, 03:56 PM   #6
Senior Member
 
Mr_D's Avatar
 
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 28,516
Quote:
Originally Posted by michelb View Post
I didn't read the links above but I believe Allison service centers can reprogram the transmission so that it switches to 4th gear instead of 2nd when you lift.
Yes, they can. Had it done to our 2000 DSDP, hated it ever after. Changed it by trading it for a new 2002 DSDP.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
Mr_D is online now   Reply With Quote
Old 07-05-2012, 03:58 PM   #7
Senior Member
 
Mr_D's Avatar
 
Solo Rvers Club
iRV2 No Limits Club
Join Date: May 2011
Location: Vancouver, WA
Posts: 28,516
Quote:
Originally Posted by Old Trucker View Post
Hi mrjimbo, I am a retired cross country trucker. If you have a Jacobs("Jake Brake") You will have a two position, hi and low switch. This brake holds the engine valves shut. The other system is a Pac Brake, which is a damper that restricts the exhaust. This brake only has an on and off position. I would rather think you have a Pac Brake. Maybe the trans codes can be changed, I am not sure. I have a Pac Brake, it does the same as yours. I just control it manualy. If the switch is on.. it is designed to engage with the reduction of pedal pressure, It down shifts to increase the engine RPM's, therefore creating more exhaust pressure necessary for deceleration. Your brake is doing all it is designed to do. Yes I understand that you do not always want it to down shift, but I would save the trouble and run it manualy. best wishes, old trucker
Jacobs makes an exhaust brake and some refer to it as a jake brake because of the manufacturers name, not how it functions.
__________________
2009 45' Magna 630 w/Cummins ISX 650 HP/1950 Lbs Ft
Charter Good Sam Lifetime Member, FMCA, SKP
RV'ing since 1957, NRA Benefactor Life, towing '14 CR-V
Mr_D is online now   Reply With Quote
Old 07-05-2012, 04:07 PM   #8
Senior Member
 
R2Home's Avatar
 
Join Date: Mar 2012
Location: Palmer Ak
Posts: 1,124
When I had my transmission serviced I had asked about re-programing the engine braking. They hooked a computor to it and changed the settings and had me try it out. I did not like the new settings so I had them change it back to what it was. As has already been said, I just keep a slight pressure on the throttle.
__________________
2009 38' Diplomat
CSM- retired, wife as co-pilot
Reka & Ali providing security (our 2 labs)
R2Home is offline   Reply With Quote
Old 07-05-2012, 04:17 PM   #9
Senior Member
 
Triker56's Avatar
 
Fleetwood Owners Club
Join Date: Jun 2009
Posts: 3,952
When you turn the exhaust bake on and the shift panel then says 2nd. That is the selected gear it will work down too. It doesn't automatic go to that gear right away. It may be in 5th when turned on and will work its way down to 2nd when the engine RPM speed & Allison talk to each other and say it is OK to move to 4th, then 3rd etc. Like others said, a slight pressure on the go pedal will turn the exhaust off, until you take the pressure off and it will return to exhaust braking.
__________________
99 Discovery 34Q ISB
2014 MKS AWD EcoBoost Toad
Fulltime Since "99"
Triker56 is offline   Reply With Quote
Old 07-05-2012, 06:18 PM   #10
Junior Member
 
Join Date: Jun 2012
Location: Pryor, OK
Posts: 23
Yes mine is indeed a Jacobs brand EXHAUST brake. It does choose 2nd gear when it's on and I remove my foot from the accelerator pedal at speed.

I really like the exhaust break and it works REALLY well, sometimes too well. I just would like to leave it activated and not have it engage until I hit the brakes. The rest of how it works is fine.

I will look into the brake switch mod listed in the link above, but it's not a big deal to use it as is.

I had a close call with a person pulling out in front of me shortly after purchasing and needed all the braking I could get. After barely stopping in time to avoid smashing into the side of them, I realized it would have been nice if the exhaust break would have been active. I didn't think to flip the switch.
__________________
1998 National Tradewinds with a 300 Cat...
mrjimbo is offline   Reply With Quote
Old 07-05-2012, 07:57 PM   #11
Senior Member
 
Join Date: Aug 2010
Posts: 1,898
Just have Allison reprogram your transmission. It will operate just as you described you wanted.
__________________
Terry & Alice
2006 Bounder 38L DP
2012 GMC Terrain
firedoc is online now   Reply With Quote
Old 07-05-2012, 08:18 PM   #12
Moderator Emeritus
 
Gary RVRoamer's Avatar


 
Join Date: Jan 2000
Location: Silver Springs, FL. USA
Posts: 18,096
The CAT ECM can be re-programmed to engage the exhaust brake in the way you wish. Any Cat dealer should be able to help. Tell him you do not want the exhaust brake to latch when the throttle lifts and that it should be controlled by the brake pedal.
__________________
Gary Brinck
Former owner of 2004 American Tradition
Home is in the Ocala Nat'l Forest near Ocala, FL
Summers in Black Mountain, NC
Gary RVRoamer is offline   Reply With Quote
Old 07-09-2012, 06:46 PM   #13
Senior Member
 
Pusherman's Avatar
 
Join Date: Oct 2006
Location: Rochester NY
Posts: 2,546
Quote:
Originally Posted by Gary RVRoamer View Post
The CAT ECM can be re-programmed to engage the exhaust brake in the way you wish. Any Cat dealer should be able to help. Tell him you do not want the exhaust brake to latch when the throttle lifts and that it should be controlled by the brake pedal.
That's what I did. It's called 'Latch' mode.


And then go to Allison and have the shift point changed to '4' instead of '2' when the engine/exhaust brake is engaged.

With the combination of those 2 program changes above, it's really sweet to drive. I keep my exhaust brake on all the time.
__________________

__________________
Don
'07 Winnebago Journey 34H - CAT C7, Koni's, MCU's, SS Bell Crank, Safe-T-Plus
'07 HHR Toad, SMI AFO, Blue OX
Pusherman is offline   Reply With Quote
Reply



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 12:25 PM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.