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Switch out 1989 tranny for a 6-speed?

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Ted Couch:
We have a 1989 Beaver Marquis with about 69,000 miles. The tranny does its job but going up a hill of any magnatude we need a while to make it up. Wondering if anyone has done a 6-speed in an older Beaver? We live in the Vancouver WA Portland OR area. Would the cost and possible complications make it a bad idea?

Ted Couch

Gerald Farris:
Ted,
The transmission exchange that you suggested will be expensive, and it will not solve your problem by itself. In the 6-speed Allison, fifth and sixth gears are overdrive to reduce engine RPMs for less engine wear and better fuel economy. So a 6-speed will not pull a hill any better than a 4-speed. However the overdrives in the 6-speed will allow you to change to a lower gear ratio differential that will help your hill climbing some.

The main problem in hill climbing with a 90 Marquis is the 3208 engine. It produces about 1/2 of the torque that my C 12 does. So if you want to go uphill faster you may try better intercooling, more boost, or other engine modifications, but it would probably be cost effective to trade-up to a later model coach with a high torque engine. The C 12 first came out in the 97 Marquis.

Gerald

Ted Couch:
Thanks for your input Gerald. I appreciate it. Great food for thought... :-/

Ted

Bruce Benson:
Ted

I have a quote for a new Allison 4000 from Stuart and Stevenson (an Allison Distributer) for $36,000 installed, if that helps you at all with your thinking.  In agreement with Gerald, you would additionally be looking at some rear end changes as well.  

Edward Buker:
My understanding is that there were several older Beaver Marquis Coaches (1992 or so vintage) that had the engine and transmissons replaced with a more modern Cat engine and Allison transmission. As I understand it several of these upgrades were done by Beaver in Bend Oregon. I did see one of these coaches for sale in an ad several years back from California Coach Company. They may recall the coach and perhaps have some insight or the name of the owner. I'm sure it is an expensive proposition but the chassis and body condition and quality may warrant the investment in an upgrade. Depends on your attachment to the coach.

Without a more modern engine and a well coupled transmission my guess is that you would be less than satisfied that the expense was warrented by the very marginal improvement.

Regards Ed

http://www.californiacoachcompany.com/inventory_avail.asp

Found more info, coach is visible on the sold portion of the website.

Description: This top of the line Marquis has been fitted with a 330H.P. 3126 Caterpillar electronic diesel and an Allison 6 speed transmission. The installation was done by Beaver in Bend, Oregon. This wonderful Marquis had a list price of over $280K in 1988! This well made coach features solid walnut cabinetry, corian counters, a private bath area, an ice maker, a gas range, big refrigerator, and microwave, full Zip Dee awnings, This coach is in very nice condition throughout, and with a fresh modern engine and transmission how could you go wrong? Please contact us for more information on this fine, affordable coach.

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