June 23, 2018, 02:21:03 PM

Author Topic: V730 4 speed Automatic?  (Read 4493 times)

Offline bryanhes

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Re: V730 4 speed Automatic?
« Reply #15 on: April 04, 2010, 03:02:19 PM »
I thought I could possibly find a 4-1/8 rear end out of a 4108 and swap it out with my 4-3/8 to gain back the lost gear going to a 730?

Would this make up a bit of my loss?

I did send Bill Teal an email.

Bryan

Offline TomC

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Re: V730 4 speed Automatic?
« Reply #16 on: April 04, 2010, 03:50:24 PM »
That relatively little change in rear end ratio really is not worth the money and effort.  The change will bring your rpm at 65mph from 2022rpm with the 4.375 to 1907rpm with the 4.125.  Not quite like when I bought my transit that had 5.55 ratio and changed it to 4.56.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.

Offline bryanhes

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Re: V730 4 speed Automatic?
« Reply #17 on: April 04, 2010, 04:00:55 PM »
Whatever I need to do I want to be able to maintain 75 on the highway. Now with the 4 speed I can run over 80. Not that I drive that speed but have run over 80 not realizing it.

Bryan

Offline buswarrior

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Re: V730 4 speed Automatic?
« Reply #18 on: April 04, 2010, 04:28:36 PM »
just have a friend fiddle with your speedo, you'll never know a thing...

happy coaching!
buswarrior
Frozen North, Greater Toronto Area

Offline bryanhes

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Re: V730 4 speed Automatic?
« Reply #19 on: April 04, 2010, 04:43:08 PM »
BW,

Problem with that is I use my GPS speed, LOL.

Bryan

Offline buswarrior

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Re: V730 4 speed Automatic?
« Reply #20 on: April 04, 2010, 04:49:04 PM »
I'm sure some other friend will figure out a way to fiddle with that too... ;D

Blissfully ignorant and down the road I go!

happy coaching!
buswarrior
Frozen North, Greater Toronto Area

Offline TomC

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Re: V730 4 speed Automatic?
« Reply #21 on: April 05, 2010, 03:16:29 AM »
One of the problems of the V730, is that it is a HT740 without 1st gear.  So startability is limited.  If you have a 8V-71N with 65 injectors, then you have a 304hp with 800lb/ft torque engine.  Figuring that your bus weighs in at 30,000lbs, that 1st gear is 1.77, that the torque converter multiplication is 2.5, that your rear end ratio is 4.125, that your 12R-22.5 tires are 485rpm, that works out to be a startability of 22%-which is alright so long as you don't get onto any 2 lane mountain roads.  Last summer, we went over the Sierra Nevada on highway 4 which had a couple of 28% grades.  With my 4.56 gearing, 31,000lbs, 11R-24.5 at 476 rpm, and 1125 lb/ft torque on my turbo'd and air to air intercooled 8V-71, my startability works out to be 32.5%-and we were down to 10mph on those short but steep switch backs.  Just pointing out that too much gearing, and you may get stuck sometime.  Good Luck, TomC
Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.