Author Topic: 7 speed transmission to suit Detroit 6V92  (Read 12092 times)

Offline Tim Strommen

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Re: 7 speed transmission to suit Detroit 6V92
« Reply #15 on: August 17, 2010, 08:03:15 PM »
I saw this thread and though of my wife's home state Ohio... and a supplier I like out there (Adelman's).

I'm not affiliated with them or compensated - but if you're looking for pulls or remans that can be shipped worldwide, Adelman's has a bunch of stuff, might be worth a phone call.  This is a link to their latest ad (direct pull from their website, but it is hosted by

They have a few 7-speed Spicers listed: ES-66-7-B, ES-56-7-B.

Fremont, CA
1984 Gillig Phantom 40/102
DD 6V92TA (MUI, 275HP) - Allison HT740
Conversion Progress: 10% (9-years invested, 30 to go :))

Offline denning

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  • 1979 Denning 40ft 6V92 5 speed Fuller 4.11
Re: 7 speed transmission to suit Detroit 6V92
« Reply #16 on: September 08, 2010, 05:50:28 AM »
Fellow "bus-brothers",
I've now put photos of our rig on photopage. Check it out.

Thanks for so much useful information, especially to Dr Steve, Jim & Tim.
Usbusin (Gary D) - another "Gary", the ratios you mention are almost the same as the transmission I've now got.

A used engine/transmission importer in Melbourne located the exact box I needed in USA, and I now have it here in Oz ready to be changed over. It is a Spicer 1372 A. 1300 ft-lbs torque, 7 speed non-synchro. Any way who needs synchro - I don't use the clutch going up, only to start from stationary & change down. I'm very lucky, as you never can be sure with an import what the condition is like inside, but the gearbox reconditioners just lifted the top cover & resealed it. All I need is a new clutch & can of oil! Just waiting for my diesel mechanic to have time to help me with the changeover.

Tom C, This Spicer is still only 1:1 in 7th, and with 12R-22.5 tires I'm doing 100kph @ 2050rpm. (Governed @ 2100rpm) Would like to get my revs down to 1750-1800 @ 100kph. Diff is currently 4.11. What should I change it to - 3.9?

Denning (Gary J) :)

Offline bevans6

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Re: 7 speed transmission to suit Detroit 6V92
« Reply #17 on: September 08, 2010, 06:12:25 AM » is one of about a million differential ratio calculators out there.  My 12R-22.5 Firestone FS-560 Plus tires have a static loaded radius of 19.8", so you could use 40" as the diameter and probably be close.  A diff ratio around 3.4:1 will be close, calling 100 KM/H = 62 MPH.

My bus has a 3.7:1 diff ratio and I have the same governed rpm, near as I can tell, and a top speed around 72 mph.  Slightly shorter than you might want, but I may see more hills than you do.

1980 MCI MC-5C, 8V-71T from a M-110 self propelled howitzer
Allison MT-647
Tatamagouche, Nova Scotia

Offline TomC

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Re: 7 speed transmission to suit Detroit 6V92
« Reply #18 on: September 09, 2010, 08:15:10 AM »
Gary J- I would go down to a 3.55 gear ratio. Then with 485 rpm tires (12R-22.5) you'd be at 1779rpm @ 100KM/H.  Since you have a good couple of low gears with the direct 7spd, even going to a 3.42 or 3.36 wouldn't be out of line.  With the 3.36 you'd be at 1683rpm.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.