Alison Tranny Retarder vs Jake Brake

[Joe Cannarozzi]

I have a question about our trans, kinda unrelated but.

Our trans selector has 5 marked forward gears yet I can feel, without a doubt, 5 distinct shifts giving it 6 forward speeds. Would someone care to shed a little light.

Also while at TGO talking with Bill he mentioned that he cruises at 50something and I asked him if that speed kept him from high gear because our bus won't even shift into final gear till 60 minimum. His responce was no, it is in final gear at 50something?

One more note for anyone trying to answer. There is a wide range from 1st to 2nd and 5th to 6th but 3rd and 4th have short close ratios. Also the build sheet shows the rear end has a 3.32 ratio, or is it 3.23.

Its an older bus and really can't say if its the original trans or not. Are there defining visual charicteristics between the 2?

[Jon Wehrenberg]

The first "shift" you feel in your tranmission is actually the torque converter lock-up.

[Joe Cannarozzi]

That would explain the firmness of it as well, downshifting too. Thank you Jon.

[Ray Davis]

The first "shift" you feel in your tranmission is actually the torque converter lock-up.

Thanks for explaining that. I've had exactly the same "feeling" on mine, i.e. one more shift than expected gears!

[jonnie]

Regarding the shifts of the transmissions, and Jon is probably more up to speed than I am, I believe there are several gears where you go from converter to lockup. On the 6 speed the final 2 gears are really overdrives and I believe you are in lockup.

Jon, I also stopped at DDA today because I was curious about the manual down shifting when using the Jake Brake. The tech told me this can happen either manually or elctronically. In my case since I go from 6 to 4 immediately and automatically, it can be reprogrammed to go down thru the gears automatically and end at 2.

John

[Jon Wehrenberg]

I know the retarder downshifts can be programmed with the normal downshift from 6th on the World transmission being to 4th.

I think if the Jake activation triggers a downshift it must be on newer coaches with the 6 speed transmission because on my 5 speed transmission (which had DDEC and ATEC) all downshifts were manual.

[Gary & Peggy Stevens]

Gentelmen, I am back on for more information about my Jake Brake.

As I posted when I got my bus, back in March 08, I don't think my Jake Brake is SET properly? Can the Jake brake capability be adjusted somehow? I would like to have more braking power coming from the Jake when I release the accelerator.

Someone told me it should downshift the transmission, automatically if it is set up correctly, is this true? It seems to me, it has no way to do anything with the tranny.

I was told it could be adjusted or checked for proper adjustment? Anybody know if this is true, and which one of the many mfgs. is responsible for this.

Can it be looked at and adjusted by Prevost while in their shop?

Thanks

Gary S.

[jack14r]

I think that a Detroit Diesel and Allison shop can help you with the Jake and downshifting which it should do.Back to the earlier post in this thread,I have a retarder and my new coach has a huge trans.cooler and I haven't seen the fluid temps.rise more than 8 degrees even in the mountains of NC,VA,KY(not real mountains)Black mountain on I 40 in NC is the greatest grade that I have descended with this bus and the temps are very steady all the way down.

[Larry W]

My coach does not downshift when the jake comes on. I would not want it to downshift as I rarely turn the jake off. The jake works best with high engine RPM. As a rule I downshift at about 1400 rpm when slowing down for traffic lights, freeway exits and such. This requires less braking plus saving the brakes for a need to stop in a hurry when the XXXX pulls out in front of you.

[Kevin Erion]

I agree with Larry, I also know that they can be checked for adjustment and if they are out, when put back to proper specs will work better.