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Aux braking for the long down hills

Yahoo Message Number: 69974
I would like to add some type of aux braking to my 1997 Intrigue. After spending last summer in the Rocky Mountains the coach needs some additional braking for the long down hills. I have the Allison transmission with a PacBrake but on the long down hills this is not enough and I have to use a lot of service brake to keep the coach from speeding up. I've not had any real problems but the brakes do get hot and you can smell the hot brake linings. I've been lucky because I'm usually at the bottom of the hill when things start getting hot. I thought the transmission had a "retarded" but I had it inspected by the Allison service center and I don't have the right model transmission. Does anyone know of some type of retarded device that can be bolted on. I'm aware of some mining trucks using a magnetic retarded that is installed on the driveshaft. My legs are too short to reach the road so I can't drag my feet.
Mike Hergenrather #10313

Re: Aux braking for the long down hills

Reply #1 –
Yahoo Message Number: 69977
Mike, you can manually downshift the transmission to a lower gear to keep your speed down. This has to be done before you get a lot of speed built up such as at the crest of the hill. I use the "go down the hill in the same gear I went up the hill in". Even though the gear shift pad says you are in 4th gear, you really are not. This indicates the lowest gear the trans will downshift to when it gets a chance depending on speed. If you are slower, you can pick 3rd or even 2nd and the trans will hold those gears.
I don't know if the electromagnetic brake system can be fitted on on a coach with a short driveshaft. I have heard that the city busses use this system. I do know that the system runs around $10K, not cheap.

Don

'02 Intrigue #11427
'02 Intrigue #11427

Re: Aux braking for the long down hills

Reply #2 –
Yahoo Message Number: 69979
Are you towing? If so does the toad have brakes tied to the coach brakes?

Re: Aux braking for the long down hills

Reply #3 –
Yahoo Message Number: 69981
I'm surprised that your "PAC" brake is not working better. Maybe it's not working properly? I found that my JAKE engine brake was not working and had it fixed. It was hard to notice the defective JAKE brake because the transmission would automatically downshift to 4th when I took my foot off the pedal giving me the sensation that it was working, but the engine brake was not engaging and I too had to use a lot of service brakes in those mountains out west. We learned to downshift the transmission to 3rd or 2nd and go down REAL slow (25-35)occasionally tapping on the brakes to keep the speed from creeping up and causing the transmission to upshift. We finally got the engine brake fixed and the difference is like night and day.
Do you know if you have the JAKE engine brake, or the PAC/EXHAUST brake? Which engine do you have? We have the Cummins ISL 370.
You might want to verify that your "AUX" (?) BRAKE is working properly. I've never had an EXAUST brake but it seems to me they should work better than you describe. JMO.

Larry, 03 Allure 30856

Re: Aux braking for the long down hills

Reply #4 –
Yahoo Message Number: 69984
Mike

My PAC brake does a good job for me in the mountains. You need to be sure you keep it lubricated and don't let your speed get away from you initially.
PAC Brake has come out with an improved version but it is around $800 so I have passed.

Dan 2006 Allure 31348

Re: Aux braking for the long down hills

Reply #5 –
Yahoo Message Number: 69989
Google "electromagnetic retarder" and you will find out more than you ever wanted to know on the subject. They are called Tesla or Telma (trade name) retarders and are an elegant solution to provide driveline braking but relatively expensive so only very rarely seen on RV's usually high end bus conversions. As suggested by someone else, maybe you ought to try downshifting to an appropriate gear before heading down the long mountain passes. Those signs as you approach the downgrade suggesting max speed and/or downshifting are there for a reason and apply to all of us except maybe those who ridicule California's speed restrictions, not to mention your RV's and tire manufacturers' max speed suggestions, and expound about driving their rigs "aggressively" and at 80+ mph across Texas.
Warning about depending on downshifting alone. Depending on how your automatic trans is set up if your engine rpm exceeds the limit the trans may automatically disengage so you wind up in neutral just when you don't want to be so avoid downshifting too extremely while your speed is building up.
Take it easy and enjoy the scenery. That's part of the RV fun scene.

Jim M

'02 Intrigue #11410 ISL 400

Re: Aux braking for the long down hills

Reply #6 –
Yahoo Message Number: 69992
Do you pull a toad? If so, does the toad have a supplemental breaking system?

From: "mhergenrather@..." Sender: Country-Coach-Owners@yahoogroups.com Date: Sat, 09 Apr 2011 02:14:39 -0000 To:
ReplyTo: Country-Coach-Owners@yahoogroups.com Subject: [Country-Coach-Owners] Aux braking for the long down hills

I would like to add some type of aux braking to my 1997 Intrigue. After spending last summer in the Rocky Mountains the coach needs some additional braking for the long down hills. I have the Allison transmission with a PacBrake but on the long down hills this is not enough and I have to use a lot of service brake to keep the coach from speeding up. I've not had any real problems but the brakes do get hot and you can smell the hot brake linings. I've been lucky because I'm usually at the bottom of the hill when things start getting hot. I thought the transmission had a "retarded" but I had it inspected by the Allison service center and I don't have the right model transmission. Does anyone know of some type of retarded device that can be bolted on. I'm aware of some mining trucks using a magnetic retarded that is installed on the driveshaft. My legs are too short to reach the road so I can't drag my feet.
Mike Hergenrather #10313

Re: Aux braking for the long down hills

Reply #7 –
Yahoo Message Number: 69993
Mike- your coach has some age on it, and the PacBrake has maintenance req'd to keep it operating properly, basically consisting of lube & test to assure its doing its job when called on. some add a relay & switch to put 12V to the solenoid for a periodic check. If you haven't put annual lube on your to do list, you should to make sure you're getting the PacBrake action called for. There is a PacBrake PDF on the service process on their website (or at least was, and I believe it can be downloaded off the Alpine Coach Tech Library (google) if you can't find it otherwise). Mike

Re: Aux braking for the long down hills

Reply #8 –
Yahoo Message Number: 69997
Don't have an answer for aux Braking. In addition to the other comments, on my coach the PacBrake works when the cruse control is turned off. When the cc is on, the trans will down shift, which for most mtn driving is not enough braking. Aux braking on your tode in some states is a requirement. Let us know what you find out.

Gil Bourdon
'05 Inspire
51322

Re: Aux braking for the long down hills

Reply #9 –
Yahoo Message Number: 69998

Gil Thats interesting, on my coach the Pacbrake works in cruise mode, although of course, it only kicks in on downgrades. Don hit the nail on the head when he said to down-shift sufficiently for the hill. I have been on hills steep enough to require 1st gear, but the norm would be 3rd or 4th. Our coachs are programed to down-shift to 4th gear. My old SOB would go to 2nd gear, very effective although a bit over kill in a lot of hills.

Dave

aka Billy Byte (trusty hound)
2000 Allure #30443

Re: Aux braking for the long down hills

Reply #10 –
Yahoo Message Number: 69999
Boy, you guys must not have day jobs 'cause I got a ton of responses in no time. Thanks for all the information. My PacBrake is well maintained and functions correctly and my tow car has air activated brakes ( if I'm not braking the coach the car isn't braking either). My system has a three position switch. Off, PacBrake only and PacBrake plus the transmission automatically shifting to a lower gear. I've found that 4 gear just won't keep the Coach from accelerating on moderate down grades with a posted speed limit of 60 to 70 MPH. I'm not talking about 6+% downgrades, probably more like 4to 5 %. I'm not trying go that fast and the coach handles well on the downhill when I limit the speed to less than 50 MPH . The other issue occurs when I engage the transmission with the PacBrake switch. When I brake the coach on the downhill's with the transmission in 4 gear, if I slow and the RPM drops around 2100 the transmission downshifts into 3 and the RPM shoots up to 2600 which of course requires aggressive breaking to get the RPM under control. I've found it easier to manually shift into the gear I want and not interface with the transmission ECM. I'll look at the PacBrake valve and make sure its going full closed and I'll try the next down hill in a lower gear to start with. Thanks for all the responses Mike 10313

Re: Aux braking for the long down hills

Reply #11 –
Yahoo Message Number: 70003
You are allowed to wind the engine up to 2650 when used in the braking mode in any gear. But don't apply any fuel until the engine returns to the normal range below 2150. I think you have a 3060 tranny as I remember. if you have a 300 hp engine. If you have a 325 or 350 you have a 3066. They are not as sophisticated as the World 3000 used with the ISC and ISL engines, but I think they do communicate with the engine and shift up the tranny to prevent the engine from over revving. I put little white dots on the face of the speedometer marking the spots where I could shift to 4th, 3rd and second manually while going down hills. When I went to larger tires and had the speedometer re calibrated I had to add additional dots of a different color. This allowed me to know when to shift a my discretion and to know what speed I had to crest a hill at in order to be in the correct gear while descending the grade. It is Easy with a little practice. With my ISL AND 3000 TRANNY I had the transmission programming changed so to slow the coach seeking second gear while engaging the engine brake and not 4th gear. My current coach weighs 8000 lbs more than the Allure, so I really enjoy the engine brake tranny combo.

The six years I had the Allure and pulled my Saturn L 300 at 3300 lbs we didn't use auxiliary braking on the car, but with the heavier coach and the Odessey, 4600 lbs, I had M&G install a braking system as required in Texas when a coach weighs over 26,500 lbs. dry, The Allure squeaked under the limit and as CC is one of the few Coach manufactures with brakes rated for the GCWR, I didn't worry. The M&G system, as does the addition of the tag Axle brakes, makes it possible for the Intrigue to stop in a shorter distance than the 36' Allure from 55 mph.

Your right 5th gear isn't much good for slowing the coach on 4.5% + grades. I have to get below 62mph on my current coach before it will shift to 4th gear, which off the top of my head is about 2450 rpm with the cruise control off and my foot off the accelerator.

TWI 2004 42' Intrigue 11731

Re: Aux braking for the long down hills

Reply #12 –
Yahoo Message Number: 70022
Mike,

The trans downshifting is normal. The ECMs will not do anything to let damage occur. The Pac Braks as well as the rest of em are the most efficient at higher RPMs, this is why the ECMs try to keep the engine in the high RPM range. You might want to let it do its thing one time and see the difference.

Mikee
 

Re: Aux braking for the long down hills

Reply #13 –
Yahoo Message Number: 70032
Mike

I tow a 4000 lb jeep with a M&G braking system behind my 40 foot Allure and I let the PAC brake and transmission do its thing. If I let the speed build up too much 65-70 and engage the PAC brake then I do have to use the service brake to get the speed down to where the PAC brake engages. I also do a lot of Mountain driving and don't have as big an issue as you seem to be having. You make want to look at your toad braking system as well as the PAC brake to see if anything is amiss in those systems.

Dan 2006 Allure 31348