Pacific Torque might have some answers.

http://www.pacifictorque.com/aonht.html

Thanks Bill, these guys look experienced. Wish they had a branch in CA. I'll send an e-mail request and let you guys know what they say..

You know I have R&R'd engines, rebuilt them, done many different clutch jobs on a variety of vehicles and feel I have a reasonable apttitude...is this something I should attempt or leave for the experts? I don't have much if any experience with diesels or transmissions

Larry, if you have mechanical experience as you mention, changing out a trans shouldn't present that much of a challenge, The Allison MD3060 is very BIG and REALLY heavy, but the area around the trans is farly open. I think the biggest challenge for you would be the electrical, as I mentioned before, the trans cable is very large and the controller depends on signals from the engine. The throttle position sensor is another issue that would have to be addressed because this varies from engine to engine and application to application. I believe that my Barth is the first year that they used the MD3060 and the throttle position sensor is a real cobbled up mess. A couple of experienced Allison mechanics have commented on that and they have mentioned that is is common for that to be seen on the first year or so of the use of the MD3060. Better brackets and linkage were used in later years.

Have you verified what ratio diff you have? It should be listed on a tag or name plate on the housing.

If I may help with this change over let me know. Things have settled abit for me and all I have to do now is finish the LS6 engine installation in my BMW M6.

I have a trip planned to So CA sometime in December/January and will plan to stop by.

Hi Ed, got the engine serial number over the weekend but forgot the info at home..I'll have to look for that plate on the trans too. Leaving on a trip to the desert tomorrow night so I'll get back to you on this. Look forward to seeing you next month!

I am following this thread with a great deal of interest as I plan on installing a 3060 in our brakeaway.

I have quotes of $4500 for a used transmission with all the parts needed to make the conversion.

The only unkown is the parking brake. I currently have one attached to the drive train and it appears I need to keep the arangement. I might luck out and get a transmission with one already on it.

The 3060 is about 1-2" longer than the 542. This makes for an interesting drive shaft which is already just slightly over 1"

The spring operated parking brake and emergency brake is on a drum at the back of the MD3060 in my Breakaway. If anyone wants I can measure anything and take pictures for your future reference.

I think you will find that the MD3060 is also lower then the other transmissions, Mine seems to "hang down" which is normal because of the 4 inch sump pan.

HTH

I posted a copy of the MD3060 transmission data sheet for those who are interested.

Allison Brochure

Will post pictures of the installation in my Barth tomorrow.

HTH

I'd like the 6 speed in mine also, just have a hard time with running 2500 on the tach so much. Have wondered about a gear vendor ,any body know anything about them? Also thought of ratio or bigger tires but tires would make it set higher and then I would garage door problems

Probably should have started a new thread, but does anyone know the rear end ratio. The best I have come up with is 3.73. That assumes 65 mph at 2500 rpm and 8R19.5 tires at 619 revs per mile.

On my Breakaway it is 4.11 but with the 6 speed Allison that has a 0.65:1 overdrive in 6th. At 60 MPH in 4th (1:1) I run 2550 +/- RPM, I hit top of the governor just shy of 65 in 4th. In 6th I am at 60 MPH at about 1650 RPM. Tires are rated for 75 MPH max so that is where I draw the limit, I am still accelerating at 75 (in 6th) if I keep my foot in it.

I'm totally with MWrench here. Any diesel engine shuld be happiest at the RPM which put it a bit ahead of the torque curve. Because the Cummins is a long-stroke engine, max torque is at a much lower speed than the GM 6.5 TD in mine, a short-stroke diesel which hits max torque at around 2350 RPM. Mine runs 2450 RPM at 60 mph; the Cummins should be run at a much lower RPM, because it's designed to do so. It sounds like the Cummins is redlined at around 2700RPM. My 6.5 GM redlines at 4000.

If the transmission swap isn't practical, I'd surely look at changing the differential gear ratio down a notch. I just don't think that the final drive ratios were chosen as wisely as they could have been for the Cummins/Allison drivetrain, based on Ed's experience. OTOH, the diffy ratio for Barths with the Cummins and 4-speed Allison may have a taller rear end ratio than the 5- or 6-speed...but your experience would indicate they weren't.

So, Creepy, I think you have a very valid issue - it's fine for my GM 6.5L TD to run at 2500 RPM at cruise - it's supposed to. The Cummins should run at a much lower RPM, maybe in the 1800-1900 RPM range (a WAG on my part).

I'm going to get under and look at the tag on the rearend and see just what the ratio is. I was looking at some of the electric diagrams that came with my coach and I see that they must have even offered 2 speed rears,(that takes me back a long way) The last one of thowe a had was in a 1962 HI V-225 with a 549 cu. V-8. About 2 million miles back!

I looked at the tag on the rearend housing and couldn't find any numbers that look like a gear ratio. Looked at the book and it looks like you have to call Spartan with the numbers on the code tag and get the ratio.

Or jack up one side and count the ratio.