Gear Ratio for 4107 GM bus

[luvrbus]

What is the tallest rear gear ratio you can find for a 4107 GM this one tops out at 64 mph @2100 rpm with the V730.it will have enough power to handle the higher gear so that is not a problem

[Runcutter]

Clifford, my 4107 manual only shows 4 1/8 to 1.  Parts Book shows 4 1/8 to 1; 4 3/8 to 1; and 4 5/7 to 1.  Also a 5 3/6 to 1, a ratio I've never heard of. 

I tried to attach copies of the two pertinent pages, hopefully they'll attach successfully.  If not, let me know ant I can email them.

Arthur

[Utahclaimjumper]

 Highest I've seen is 4 1/8,, to get more go to 24.5 wheels..>>>Dan
( Mikey has 4 1/8 with 24.5s + V730 and is happy.)

[luvrbus]

Highest I've seen is 4 1/8,, to get more go to 24.5 wheels..>>>Dan
( Mikey has 4 1/8 with 24.5s + V730 and is happy.)

a
It has 12rx22.5 tires now not much to gain with 24.5 wheels with 11rx 24.5 tires  best I can tell it has the 4-1/8 so I will be looking at different ratio torque converter I guess

[chessie4905]

about 4mph between the two ratios. 4:12 and 4:27. Mine would go about 74@ 2450. Has 4:27  in it. Have the 4:12's to install.
different ratio torqueconverter will effect starting out but no difference after locked up. Dont have Allison book handy, but they list 2 ratios for V730. I know the 740 have several ratios.

[RJ]

Cliff -

The stock rear axle ratio, like Arthur said, was 4.125:1.  Coupled with the four-speed manual's 0.808:1 bevel gear ratio, that gave an overall rear axle ratio of 3.333:1

Pulling the 4-spd and installing the V-730 changes the overall ratio because of the different bevel gears in the automatic. This equates to 4.125 x 0.875 = 3.609:1, not quite 10% lower than the 4-spd.

The 4905s came stock with a 4.375:1 rear axle ratio, which, combined with the 4-spd equaled a 3.535:1 overall ratio. (This equates to a 100 rpm difference in 4th gear at 60 mph between the 35' and 40' Buffalos.)

If somebody takes a stock 4905 and swaps in the V-730, they end up with an overall ratio of 3.828:1 (4.375 x 0.875)

Interestingly, if an operator ordered a late ('77 and later) model 4905 with the V-730, GM installed the 4.125 rear axle with this combination!

Finally, in all the research I've done over the years, installing 11R24.5 drive tires that turn 470 revs per mile on a coach with the V-730 and a 4.125 axle will provide an overall ratio of about 3.510:1, the closest compromise I've seen.

FWIW & HTH. . .

[luvrbus]

The v drive must be power hog for a light weight bus to be that low of a gear ratio you see old T drive with 8V71 NA engines  with 3:36 and 3:36 gears lol even some with 6v71

[Utahclaimjumper]

80MPH is the new 65..>>>Dan

[luvrbus]

80MPH is the new 65..>>>Dan

You. should be able.to run 65 mph at 1700 to 1800 rpm with a 2 stroke they do not like a steady diet of.2100 and 2300 rpm everyday of  their life
   

[Dave5Cs]

We were hitting 71 yesterday on I-10.....

[chessie4905]

8-71's are like a honey badger. they dont give a dam how long you run them at 2100 to 2300. 92's thats a different story.
coach still starts fine without a low gear.

[luvrbus]

8-71's are like a honey badger. they dont give a dam how long you run them at 2100 to 2300. 92's thats a different story.
coach still starts fine without a low gear.

.   They don't bleed as much at 1700 to 1800 rpm for sure

[RJ]

We were hitting 71 yesterday on I-10.....

Dave -

Did you see the message I sent you back in April???

RJ

[chessie4905]

Yeah, you pound one at 2100 all day long, youll see leaking getting worse. Funny nobody spends the money on a Walker Air Sep to eliminate the leaks. Used a lot in boats to keep the bilge clean and dry of oil. They are pricey though.
GM has used a smaller version on their diesels since 1981 on the 5.7. Really made a difference on leakage. Used clear up to today on at least on Duramaxes. CDR- crankcase depression regulator valve.

[TomC]

With 11R-24.5, V730, 4.56 rears, 60mph is right at 1,900-of which is my usual cruising speed. Good Luck, TomC