[rooster]

Repowering my 79 36Ft Newell.  Replacing 555 with 6V92 Silver and 747HD Allison.  Need to know what model and Ratio Rear that I should be searching for, and any leads on where to look.  Thanks   Pete

[rooster]

I am repowering my 79 from 555 to 6V92.  I cannot find tag on drive axle.  I know I need to change ratio but don't know what axle I should be searching for.  Anyone know what axle it is.  I think someone said Rockwell SQRD but need to calculate ideal ratio for Allison 4 speed 747hd.  Thanks for any information you might have.

[Johnnyboy]

I have the 8V92, 4 speed. 3.55 gear

[Guy]

A little off the track here but, you are migrating to a 2 cycle engine. We have an original 8V92 and love it, but I am curious as to why you went that direction. 

Wishing you well in your repower, and hope you will post pictures along the way

[rooster]

This project has been an ongoing nightmare for 15 years or more. At the time, I purchased a rebuilt by GM 6V92 Silver with rebuilt 747 Allison. The "mechanic" in Missouri stole my money and never finished. I Had it towed to Ohio where it presently is stored with engine half in. I knew it would require taller gears but not sure what rear it is without any tags. I will probably pass on before I get to drive this thing, but need to keep thinking I will get it done.

[77newell]

The gear ratio can be determined by blocking one wheel, jacking the other and spinning it around 10 times while counting the the revolutions of the drive shaft. Double the count and divide by 10 and you will have your current ratio.

[rooster]

Thank You. My predicament is that I do not know what model rears I am looking for. I would like to change the ring and pinion but need to know model axle that Newell used that year. The metal tag on the axle is nowhere to be found so I cannot identify my axle. Someone said Rockwell QRD100, but I need someone with a similiar setup with the 555 cummins who can tell me what axle they have. Mine is a 79 36 foot with 4 spd allison. I think I have gears in the 5's and need something around 3:55.

[MPerry]

I would be curious to know the cruising RPMs for a 555 and a 6v92, that might help you determine if you need to change the current ratio. I believe top gear on a 747 is 1 to 1, and suspect the top gear on the 555 was also 1 to 1. So if the desire cruising RPM on the 6V92 is close to the 555 you may be ok as is.

My 903 runs about 1900 rpm at 60mph. (though not exact, using this and tire size i estimate my ratio at 3.82)

[rooster]

Thanks for your interest.  I have settled on 3:55.  Remember, I started this about 16 years ago and at that time, a bus company was phasing out their 2 stroke engines.  I purchased a GM rebuilt with transmission which was a spare for them.  I like the Detroits.  I had a 06 Bluebird 450 LXi that we bought new, but it had so many issues that we finally gave it up.  It was our 13th motorcoach, if that means anything. I now have a 1988 Newell 40 with single rear axle.  Like it a lot.  The ole 79 is like a burr beneath my saddle.  Want to get it done or pass it on.   Pete

[Guy]

Pete,

Good luck on getting rid of the problem coach. Huge undertaking doing a repower. I am sure someone would really enjoy completing a project like that
Happy to hear you have a nice coach to enjoy. Life is too short. 

Best regards,
Guy