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Author Topic: V730 Overdrive  (Read 4641 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" 6V92 V730  PS, Air shift  4:10
1996 MCI 102 D3
Barn Owl
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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
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TomC
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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
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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.
busfan
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« Reply #6 on: April 07, 2018, 08:51:42 AM »

Wow Did not know back in 2004 this VS-2 v730 transmission topic was so heated..
http://www.busnut.com/bbs/messages/233/6006.html?1083517264

I think I am going to go the 24.5 tire route with my 68 Fish bowl manual suburban with Allison 730 being considered for swap.

Any suggestions as to steer tires and drive tires brands and models?  No power steering on my bus.
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Brian Diehl
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« Reply #7 on: April 07, 2018, 08:59:01 AM »

I'm a fan of toyo tires.  My first set lasted 105,000 miles and 15 years.  YMV
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busfan
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« Reply #8 on: April 07, 2018, 02:51:55 PM »

Thanks for the suggestion Brian, that's alot of miles!  Guess that's why they cost so much..
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TomC
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« Reply #9 on: April 07, 2018, 02:53:47 PM »

I just put 6- 11R-24.5 Hankook AH37 tires on my bus. Very similar tread pattern and rating to the Michelin XZE I replaced (were 12 years old), but $1,200 less! Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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« Reply #10 on: April 07, 2018, 04:34:36 PM »

I just put 6- 11R-24.5 Hankook AH37 tires on my bus. Very similar tread pattern and rating to the Michelin XZE I replaced (were 12 years old), but $1,200 less! Good Luck, TomC

Thanks Tom those look like a pretty nice compromise!
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Bill Gerrie
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« Reply #11 on: April 07, 2018, 06:01:56 PM »

TomC
I have one of only three buses in existence that have the overdrive unit in them. You need parts that are almost obsolete now. You need the following parts to even start to do it.
8V71 flywheel from a VS2-8
V730 input shaft
VS2-8 planetary gear set as well as a VS2-6 planetary gear set.
VS2-8 input shaft
VS2-8 clutch packs
A lot of machining time on a lathe
I run a 4.56 rear end and once I reach 55 mph I engage the overdrive and I am able to do over 80 mph. I normally do 60 - 65 mph and the engine turns at approx 1500 rpm. My top speed without the overdrive unit is 68 mph at 2110 rpm. My engine is DDECIV so I can't up the rpm. 
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busfan
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« Reply #12 on: April 07, 2018, 10:53:03 PM »

TomC
I have one of only three buses in existence that have the overdrive unit in them. You need parts that are almost obsolete now. DDECIV so I can't up the rpm. 

Hi Bill! It's George, I got your your old A730!

Hope you might be able to shed more light on this mod, if it has not been documented before.  I would guess that the 3 buses that have this mod are still very reliable.

Is there a schematic somewhere or a general how to? Might be easier to manufacture these parts in the future.

Thank you!  George

 

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Bill Gerrie
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« Reply #13 on: April 08, 2018, 06:05:34 AM »

George
One bus was the original Bill Teal that developed the overdrive unit and the other was in FL on a 4106. Mine is the only other one. You have to get the parts I listed. They are still around but scarce. I originally bought the book from Bill Teal for $275 US. A lot of guys have tried but never completed the unit. I found a flaw and corrected it. The shaft from a V730 has to be welded to the shaft from a VS2-8. There is an oil hole that is welded off. My shaft broke about 3 years ago closing the Canada USA border for over 20 minutes. I wasn't very popular to say the least. I had the shaft remade eliminating the weak point and all is good now. The original shaft lasted 9 years but the torque of over 1000 ft lbs finally broke the shaft.
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Geoff
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« Reply #14 on: April 08, 2018, 06:18:02 AM »

With a 4.10 rear end you can go 80 mph with a stock V730 @ 2300 rpms and 12-22.5 tires, so you get the same results as the VS overdrive unit on top end.  Oh, this is on the RTS or FLX buses,  so I guess the VS overdrive benefits the GM coaches.  I don't know if the AM General uses the same rear end as the RTS/FLX.
« Last Edit: April 08, 2018, 06:35:30 AM by Geoff » Logged

Geoff
'82 RTS AZ
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