Allison Transmission Questions

[cobra54]

Allison Man,

I just bought a 1986 Diplomat by Executive (now Monarch). It has a 454 / 400. I noticed that an Allison 4 speed was available as on option and am curious as to whether it would be like an "overdrive" unit or one that gave me more grunt (don't need more..). What model would it have been? The p-30 chassis is an 85, the motorhome an 86. Are they still available? New/used? Expensive? Just curious about what I can do to lower rpm when driving over 55. Vehicle weighs 16000 and as near as I can research has a gross vehicle tow rate of 19000.

Thanks.

[AllisonMan]

Hi Cobra54,
I think I understand your question. If you have an 85 or 86 coach, the option would have been the Allison AT545. If you have not replaced your transmission yet, I would say you made the right decision. The combo of Allison AT545 married with a GMC454 was not the best of marriages. Your top gear ratio is 1:1 on the AT545. This transmission does not have a lockup feature like the bigger Allison or even the replacement of the AT, that being the LCT 1000, 2000 or 2400. These are all electronic and do have the lock-up feature which would help with high rpm down the road. Unfortunatly you cannot buy these transmissions yet for re-gearing.So I would say, enjoy the setup you have now, it has been good all these years. Sometimes change can be a big headache. I hope this answers your questions. Thank you and have a great day!

[cobra54]

Thank you AllisonMan. Yea, I'll stay with what I have - I just thought...you know, the other grass IS always greener. Appreciate your insight.
Greg

[denny]

Hey Allison Man,

I have a 3500 Chevy 4x4 with a duramax and of course the allison tranny. I also have a 2500 with the 8100 Vartec and the allison. The 2500 will really slow you down if you just tap the brake. The tranny cuts in and you'd have to add fuel going down hill to keep going. The 3500 with the duramax doesn't seem to work that way. Do I have a problem?

[Ken Powell]

My local Allison dealer told me not to use synthetic (sic) oil, stay wit Dex. III in my 95 MD3060 any comment????

[AllisonMan]

Hello Denny,
The one thing that comes to mind is that your engine ECM may be giving a signal to the Allison for an exhaust brake. If it is, the transmission will be fooled thru J1939 communication interface into thinking "you want exhaust brakes" and thru autodetect of your transmission, it downshifts to lower preselected gear everytime you let off the throttle. I hope this is it. Please keep me informed as to what your local GMC dealer finds out. I would contact your local Allison dealer to find out which GMC dealer in the area is best trained to diagnose your Allison. I know around the Portland/Vancouver area, there is only one dealer I would take a pickup to. The others are car dealers and only started working on Allisons 2 years ago which is not enough training.Have you logged on to allisontransmission.com and looked at pickups "most asked questions?" This may also have an answer. I also have to ask a question, Have you put bigger tires on either truck? If you have, this may be the problem. Not the fault of Allison but GM for only having one calibration for all pickups and if you change tire size, it really messes up shifts and eventually will fail transmission premature. Thanks for the question and have a great day!

[AllisonMan]

Hi Ken Powell,
I kind of agree with your dealer. If I had a 95 and never had a problem, I ask "Is it worth the expense of transynde?" You may have very low miles, then I would consider it but if you are up around 50,000, I would stick with the dexron III. My reasoning is if you use Dexron, you have to have the fluid changed every 2 years or 18,0000 miles whichever is first. This would give you a chance to have your transmission checked out for any problems. Remember, Allison came out with the World Transmission in 92 so a 95 still has had many updates to it, thus keep driving it the way you have been since you have not had a problem yet but having a 95, I would feel better giving you advise to stick with 2 year Dexron services.Thanks and Have a great day!

[Ken Powell]

Thanks for the info.

[ByronK]

Hi AllisonMan;

Did I understand you to say you folks will do all the required maintenance on motor homes? I have a '91 Dynasty which is due for its 80,000 maintenance. That amounts to just about everything that needs to be done is scheduled to be done bumper to bumper. Can you give me a ball park figure of cost to perform all this work?

Cummins C6AT8.3 with an Allison 5 speed I believe.

[n8rt]

Hello Allison Man,
I have a 03 Kountry Star, purchased April 2003 have 1300 miles on it at this time! Configured with an Freightliner XC Chassis, 330 Cat 3126E Engine, and 3000MH Allsion transmission!

I read the owners manual and it says to change the 2 filters no matter what fluid at 5,000 miles or 200 hours, Filters are the Main and the Aux/Lube!
I read on the Allison web site that I only have to change One Filter!
What do you think!

Also I have called Newmar, and Allison, and no one can tell me what type of fluid is in the transmission? I do not have a sticker on the tranny dip stick either!

I have not been able to get in touch with Freightliner yet to see if they can solve my mystery!
Since the type of fluid, dictates the future Servicing for the transmission I need to know exactly what I have!
thanks for your thoughts!
Rob
03 KS DP