Engine Brake from 4th to 6th Gear

[Michael Marcocchio]

Hello all I was Canyonville and went to a seminar and heard a member tell us about having his Engine Brake reprogramed from 4th to 6th gear. I thought is was interesting so on my way back to Canada I stopped off at a allision dearer and had my done as well. Here is what I found before when your engine brake came on the trans went from 6th right into 4th to slow you down the trans took a big hit now the trans just stays in 6th with very low engine brake slow down pressure which in turn doesn't slow your coach down quite a fast and in a very hilly terrain which could be very dangerious so you must be aware you must manually shift your trans via your push buttoms from 6th to 5th to 4th to get your required engine brake slow down requirment.Your trans doesn't get the big hit but you also don't get the big stopping power until you manully shift the trans to lower gears (the Allision Dealer said that trucks right from the factory are also set to go into 6th instead of the big hit into 4th)I  just wanted to let you know to all in case you wanted your reprogramed as well.I do beleive it will be easier on the trans.Thankyou.

[Joel Weiss]

The braking effect of a compression brake increases dramatically as the engine revs approach redline.  There is a document on the Jacobs website that discusses this. So by having the Jake come on with the transmission staying in 6th means that you have less transmission braking and reduced engine braking.  This has been a concern to me and I appreciate you posting your impressions.

What I do to avoid repeated downshifting when driving in an environment in which the Jake is continuously being applied and released is to downshift to 4th which means that the application of the Jake doesn't result in a transmission downshift.  My coach can safely go to 65 in 4th and rarely is that speed possible in such a hilly environment, anyway.  Furthermore, my MH is extremely responsive when driven in 4th at speeds of 40-60 so driving in 4th is easy.  At most, I'm probably giving up a bit in fuel economy, but usually it's only for a few miles and can't have that much of an effect.

[Edward Buker]

If you do a lot of interstate travel you will find the 6th gear with the Jake to be a good option for gentle slope hills. It matches the braking need to hold speed quite well on a lot of interstate grades. Sometimes you will invoke 5th as needed. If your on secondary roads with curves and steep slopes choosing 5th or 4th to drive in as Joel discussed is an excellent way to be in the right braking range for the expected slopes and curves. Every driver is different and many of us take different paths when it comes to our travels. One of these options, 6th, 5th, or 4th being invoked with the Jake will best match your driving habits and gearing.

I am still one who would want to be able to engage the Jake at any speed without worry up to my maximum expected interstate speed. That is the 6th or 5th gear Jake option for me, going to 4th automatically and over revving is out.

Later Ed

[Steve Huber Co-Admin]

I use the Jake when I want to de-celerate quickly. Dropping from 6th to 4th is not a problem (IMHO). I've discussed this with both Allison and Cat and have gotten the same answer; Slightly exceeding the "max" rpm is not a problem unless the engine is loaded and pulling. Deceleration does not present this situation. So, if you are uncomforatable with the sudden deceleration and the jump on the tach, get the tranny re-programmed. Otherwise  be comfortable in your ability to decelerate rapidly.
Steve

[Glenn Perkins]

I'm with Steve.  160K miles and (knock on wood) no transmission issues.  Jake is my friend and I use him regularly to keep DW from developing white knuckle syndrome.

[Michael Marcocchio]

Hello all I was only sharing my views on what I did to my unit I know how a jake works and how much more powerful it is in 4th.I was making people awear of what would happen and what you need to do to get big power stopping power of 4th gear.Not saying whats right or wrong just my views. Thankyou.

[Roy C Tyler]

Mike, you are not supposed to be doing 80 MPH when you top the hill and start down the other side. If your DW was like mine, you would only be doing 40 MPH or less and the down shift to 4th would not be as severe.....lol

[Joel Weiss]

Hello all I was only sharing my views on what I did to my unit I know how a jake works and how much more powerful it is in 4th.I was making people awear of what would happen and what you need to do to get big power stopping power of 4th gear.Not saying whats right or wrong just my views. Thankyou.

I appreciated your post.  It confirmed what I figured the change would feel like.  Thanks

[Steve Huber Co-Admin]

Mike,
This topic ALWAYS gets a discussion going. I know of at least 3 threads on this in the past few years. Suspect there is no "right" answer, just what each of us feels comfortable with.
Steve

[John Harris]

Just a ball park figure, what does it cost to  reprogram the trans?

[Gerald Farris]

John,
It takes about 10 minutes to change the transmission default gear from 4th to 5th or 6th when the Jake brake is engaged, but most Allison shops will charge you for one hour of labor at the shop rate for the reprograming.  

Gerald

[Michael Marcocchio]

Hello your right about the cost Gerald but I had mine swithed for free as I worked for Detroit Diesel and the service manger is a friend of mine lol.He says they do the switch for others as well  for free also good customer service.

[Andy Clark]

Are you guys with the 4th gear program saying that your programming only invokes 4th gear ("4" shows up on the "target" side of the trans keypad), and the trans does not shift down past 4th? Maybe I'm confused. I had mine reprogrammed to invoke 2nd gear ("2" appears in the target window). The trans then shifts, within RPM limits all the way down to 2nd gear as the coach slows down. The PacBrake stays on until about 6 or 7 MPH, so I rarely have to touch the service brakes until the final few feet. The trans never goes straight from 6th to 4th, but goes down throught the gears in order. The 5th to 4th change can be a bit "urgent", though, if slowing down quickly.

The only thing I would do to improve the way the Pac Brake works would be to install the system that allows the coach to coast in whatever gear you are in and does not engage the Pac Brake until you touch the service brake treadle and turn on the brake lights momentarily.

Just wondering what you all have for a shift program.

Andy

[Roy C Tyler]

Andy... If you are talking about the BrakeSwitch that only comes on when you touch the brake pedal and then goes off when you touch the throttle, you had better order one soon.  I just installed mine last week and love it but Homer, the owner said he only had six BrakeSwitches left and then he was out of business.  I guess the newer Beavers and Monacos came out with the Allison programmed with that type of operation and basically put BrakeSwitch out of business.  I was going to check to see if mine could be reprogrammed but the BrakeSwitch only cost $85.

[Andy Clark]

Thanks, Chuck. Yep, the Brakeswitch is what I was referring to. Had momentary CRS and couldn't come up with the name at the time.

I had an e-mail exchange with Homer and it appears that I need the 4-wire system. The only problem I see is that my brake pedal has to move quite a bit before the brakes (and brake lights) activate. So it's more than just "touch the brake pedal". I'll need to somehow shorten the throw, when I discover how to.

Any insight into the shift patterns I mentioned?

Regards