Retarder Settings/Allison Transmission

[truk4u]

Jon,

My CC would activate the Jake with the cruise on, it sucked. It also defaulted to 4th gear depending on speed.

[Jon Wehrenberg]

Your forth gear is one down. In the six speed as you know dropping from cruise in 6th to 4th would be like hitting a wall.

[Jon Wehrenberg]

Bruce, no sense looking. You must have a jake. Apparently as Truk pointed out the jake does function with the cruise on.

I still want to know how you can drop into 4th from 6th. Don't try to answer. Just thinking out loud about how pieces and parts will be falling from the rear if that could actually happen.

[truk4u]

Mine would go from 6th to 4th if the speed was at a certain point. If the rpm's in 6th were low enough, it would go directly to 4th, bypassing 5th completely.

Just ask Jamie, he can confirm that....

[MangoMike]

The Jake brake on my Marathon does engage while using the cruise control.

Mike

[Gary & Peggy Stevens]

The Jake brake on my Marathon does engage while using the cruise control.

Mike

Ditto, what MM said above. My Cruise works fine even with the rocker switches turned on to engage the Jake brake when I touch the brake.

My problem is I don't ( IMO ) have much braking assistance from my Jake?

Prevost is looking into this Jake Brake deficiency for me this week since it is still up in Ft. Worth?

Bruce you would know, now if you had a Retarder or Jake. I am pretty sure you have a Jake, cause like Jon said, if you have a retarder it operates on the right side of the steering column and looks like a turn signal indicator. You pull it down 1-6 clicks to get it to offer more braking power. I wish I had one, but hey it is all good!!!! The jake is just a 1-2 toggle button on the dash.

Gary S.

[adamdegraff]

I am sure that Bruce has a Jake brake. Incidentally, my Jake is still acting up. I replaced my Throttle Position Sensor and it made no difference. My wife, or "driver" as I call her, says we have a lazy Jake. Symptoms: in the first hour or two of driving, the jake holds strong on even the steepest downgrades. (For those of you who think you have a weak Jake, you might... or you might try to gear down to 5, 4, or even 3 depending on the grade.) Then, after we've been rolling for a while, the jake simply doesn't come on. Or it comes on for a second and then kicks back off. This can be quite a surprise when you are depending on it... which we no longer do. Actually, our driving has become much better now that we can't trust the Jake. Plus Joe yelled at me in a previous post and I figured that I didn't want him fearing for my life any more.

Now, for the kicker.... once the Jake stops working, it will not come back on again until you stop the bus for at least 20 minutes. (No, 5 minutes makes no difference.) At that point, it is back on in full force. So, you give 'er a rest and she is ready to work again. Thus the technical diagnosis by "driver" of Lazy Jake.

Of course, if I took it into Prevost or Detroit, they would charge me a fortune and tell that it was all fine.... cuz it is.... for the first two hours!

~A

[0533]

I think what happens is that the computer senses the pressure removed from the throttle and starts the process of downshifting in sequence to 4th, but rather quickly, it does end up in 4th. It is not that abrupt but is hugely better than the default 6th gear.

[JIM KELLER]

I just want to mention how dangerous it can be to manually force a downshift into a lower gear while driving in the mountians on any declining grade. As long as you know what you are doing and remain totally aware of rpm's you will be o.k. If not, the downside is a Motor that will self destruct. Pistons will hit valves,etc,etc. When manually downshifting your Governor is unable to limit your rpm's.

[adamdegraff]

I just want to mention how dangerous it can be to manually force a downshift into a lower gear while driving in the mountians on any declining grade. As long as you know what you are doing and remain totally aware of rpm's you will be o.k. If not, the downside is a Motor that will self destruct. Pistons will hit valves,etc,etc. When manually downshifting your Governor is unable to limit your rpm's.

Really? When I try to manually down shift, the transmission won't actually shift down until I have reached a certain RPM. It will let me set the gear I want to be in, but it won't go there until I slow down enough... either by Jake or regular braking.

~A