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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: Lin on September 25, 2008, 08:12:46 PM

Title: Mc5a rear end
Post by: Lin on September 25, 2008, 08:12:46 PM
I was having a "get to know your drive train day" and wanted to find my rear axle ratio.  The book says the 3.36 was standard and 3.70 was an available option.   Did Greyhound go with the standard or the option back in them there days?  I guess I could hunt for numbers on it tomorrow, but it is not tomorrow yet, so why not ask?
Title: Re: Mc5a rear end
Post by: TomC on September 25, 2008, 10:18:15 PM
If you have a tachometer and 12R-22.5 tires (485rpm) then at 60mph you'd be turning 1795rpm with the 3.70's and 1630rpm with the 3.36.  Good Luck, TomC
Title: Re: Mc5a rear end
Post by: jjrbus on September 26, 2008, 06:29:41 AM
lift both rear wheels, mark both tires, mark the driveshaft, slowly rotate the tires, trying to keep them both rotating the same, rotate them 1 full turn, count the turns of the driveshaft



over 3 turns, 3.36   
just under 4 turns, 3.70

With the age of our bus's the rear end could have been changed several times, so what came from the factory no longer applies.   Jim   
Title: Re: Mc5a rear end
Post by: Tom Y on September 26, 2008, 08:57:38 AM
Lin, I would think the 3.70 was the standard. My 5C had a 4.10.  Tom Y
Title: Re: Mc5a rear end
Post by: luvrbus on September 26, 2008, 09:05:08 AM
Tom, wasn't the reason for the 4.10 gear because of the option of the Allision that you had in the later models with the V671 my 5 had the 3.70 and I changed to 3.36 was my understanding on the older 5 it was 3.36 or 3.70 depending on the area the bus was in service  so said Sam   good luck
Title: Re: Mc5a rear end
Post by: Tom Y on September 26, 2008, 09:08:43 AM
My 5C had a 8v71 with a Spicer.   Tom Y
Title: Re: Mc5a rear end
Post by: makemineatwostroke on September 26, 2008, 09:23:49 AM
the 4.10 was the standard gearing for the 8v71 and the 6v71 for the 5C but had options, 5A and 5Bs were 3.36 or 3.70 as Greyhound purchased most of those

have a great day
Title: Re: Mc5a rear end
Post by: kyle4501 on September 26, 2008, 09:29:30 AM
Raise 1 side of the drive axle & turn it 2 revolutions while counting turns of the drivr shaft. There's your ratio.  ;D
Title: Re: Mc5a rear end
Post by: pvcces on September 26, 2008, 06:19:07 PM
And you only have to jack up one side; it's easier to get an accurate reading, too.

I can't think of any good reason to turn both rear wheels.

Tom Caffrey
Title: Re: Mc5a rear end
Post by: jjrbus on September 27, 2008, 07:08:14 AM
I thought we had jacked up both rear wheels. But I have no memory so am sure you gentlemen are right. My 5C with the 6V71 automatic has the 4.10 rear end. That I am sure of as I wrote it down!!  Jim