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Author Topic: V730 Overdrive  (Read 1515 times)
TomC
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« on: June 29, 2006, 10:56:32 PM »

I have the most popular V730 with .88 overdrive final.  I remember reading on someone put a input shaft overdrive unit from a VS2-8 on the V730 and made a double overdrive out of it. Anyone know the site I can look at?  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
Paso One
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« Reply #1 on: June 30, 2006, 06:26:48 AM »

The guy that had the info is Bill Teal He was selling a info Package. The link I have wasn't working as I typed it. Try the MSN group as his site was a MSN group
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68 5303 Fishbowl 40' x 102"
6V71  V730 4:10
Barn Owl
Roanoke, VA
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« Reply #2 on: June 30, 2006, 10:56:42 PM »

How do you tell what type of final is in a V730? Does most popular mean most common, or most desirable? Mine seems to have plenty of top end but I do not know what my rpms are. I hope to have a tach sometime in the future.
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L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
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« Reply #3 on: June 30, 2006, 11:35:58 PM »

Barn owl- Mine has the .875 overdrive in it.  If you knew your rear end axle ratio and tire size, it's pretty easy to figure what rpm per mph is going.  For instance, I have 11R-24.5 (478rpm for my tire) 4.625 (sometimes called a 4 5/8 ratio) and the .875 overdrive.  So at 60 I'm turning 1934 and at 65 just about 2100rpm.  Does fine for me.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
RJ
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« Reply #4 on: July 01, 2006, 06:32:36 AM »

Some clarification is in order here!

First, the V-730 is NOT an "Overdrive" transmission.  The ratio in third gear is the same as an HT-740 - 1:1.

Where the misnomer of overdrive came from is in the bevel gearset's ratio, which in 99.9% of the V-730s is 0.875:1.  If you look at a cut-away drawing of the 730, you'll see that the bevel gears are located between the engine and the torque converter, actually before the transmission gearing.

This is the same set-up as the Manual transmission, except that the manual uses an 0.808:1 ratio.

Stock rear axle ratio for the 4106 is 4.125:1.  4.375:1 was optional, but very rare.

The effective final drive ratio is equal to the following formula: (transmission gear ratio) x (bevel gear ratio) x (final drive ratio). 

For a stick shift in 4th, this equals (1:1) x (0.808:1) x (4.125:1) = 3.333:1

For the V-730 in 3rd, it's (1:1) x (0.875:1) x (4.125:1) = 3.609:1

Supposedly there were V-730s built with a 1.04:1 bevel gearset, but I've only heard of one in over 25 years in the bus industry.  Rarer than hen's teeth.

Taller tires on V-730 coaches (11R24.5s, usually in the 470 - 475 rev/mile range), will bring the coach back to almost the same top speeds as a stock stick shift w/ stock rev/mile tires (495).

HTH. . .

How do you tell what type of final is in a V730? Does most popular mean most common, or most desirable? Mine seems to have plenty of top end but I do not know what my rpms are. I hope to have a tach sometime in the future.
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RJ Long
PD4106-2784 No More
S13406 Now
Fresno CA
TomC
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« Reply #5 on: July 01, 2006, 08:22:42 AM »

Russ- If you want to get scientific about transmissions, then many transmissions have some sort of gearing that changes the main box's ultimate ratio.  For instance, take a nine speed direct Fuller Roadranger transmission and put the overdrive end unit on and now you have a 13 speed.  Or take a recent Fuller Roadranger 9 speed overdrive transmission and put the underdrive end unit on and now you have either a 13 speed or an 18 speed "double overdrive" transmission.  Or take an HT740 Allison transmission, take out first gear so it is like having 2nd, 3rd, and 4th only, put a .875 bevel angle input gearing and now you have the V730. How a transmission is measured is the overall ratio gearing comparing what the input shaft does compared to the output shaft.  What happens inside to get that ratio really doesn't count.  One side note-the Allison World transmission series only has 3 planetary gear sets that gets up to 6 speeds out of it.  Just think it is very clever what they did. Previous Allisons had one planetary gear per reduction with final drive being direct.  Allison does make very large off road automatics (2200hp) that are essentially a three speed main box with a two speed splitter on the back working together.  Just some trivia.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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