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Author Topic: V730 third gear lock up  (Read 1043 times)
Barn Owl
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PD4106-1063 "Wheezy Bus"




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« on: June 06, 2007, 09:30:16 PM »

Those of you who have a V730 at what speed does your tranny hit third gear?

Mine will go into third at 55mph and drop out at 50mph. The shift down can be rather harsh at times. Traveling the back roads at 45mph would lower the fuel mileage a good bit wouldn't it?
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L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
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« Reply #1 on: June 06, 2007, 11:45:06 PM »

You must have 4.11 gears.  With my 4.625 gears and 11R-24.5, the trans shifts into 3rd at 42 and down shifts at 38.  If I hold it in second, I can get 48mph out of it.  46mph is the highest the trans will shift from 3rd to 2nd on a hill climb, with the down shift being much smoother than letting it get down to its' automatic down shift.  With my gearing, at 65 mph I'm turning 2100rpm.  At my 2350rpm governor setting, I can get 72.5mph out of it-which is fast enough for me, plus I still have decent startability since my bus with towing car weighs in at 34,750lb.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
donnreeves
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« Reply #2 on: June 07, 2007, 04:28:43 AM »

I have 4:11 gears in my RTS and it shifts into 3rd at 55 mph @2350 rpm. It holds 3rd down to around 50. All the shifts are very smooth. The shift between 2nd and third is the harshest, but still very smooth. 1st,2nd and converter lockup are almost unnoticeable.   Donn
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gm4106
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« Reply #3 on: June 07, 2007, 01:30:52 PM »

V-730 transmission which is actually a
three-speed with a lock-up torque converter. Is the last shift you speaking of" actually when the torque converter locks up
If not what speed does it lock up at?
Whats the different in the rmp before and after?
 
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GM PD4106-1689 8V71TA  V730
Mount Holly,NC
Buffalo SpaceShip
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« Reply #4 on: June 07, 2007, 02:01:03 PM »

Hey Laryn (yes, I'm still alive! Cool), the speeds you and Donn mention sound about right for third lock-up with my V730. The 35' parlors from GMC have 4-1/8 rears.

You could check and see if your coach had an air modulator installed with the tranny. Since the '06 had a cable accelerator, unless yours has been upgraded to air throttle, I doubt if you could have an air modulator. Anyways, these sense throttle position and speed of throttle application and send it to the tranny shifter... and might remove some of the harshness (speculating).

The only shift I'd consider harsh on my V730 is when I force it into first gear lockup... which isn't supposed to happen, according to the manual, but most certainly does happen... and is a Godsend on those slow downgrades where the Jakes are ineffective. It's also nice when going up grades (like you see out here in the West), but isn't as reliable for me to engage.

Tom C. taught me how to do this... I'll look up his postings on the subject, but involves sensing the second gear lockup and then lifting the throttle while dropping the tanny manually into first gear. IIRC, Brian Diehl actually built a device to force the tranny into lockup with the bush of a button on his Allison. Ingenious!

Russ Long taught me to shift the V730 manually when on grades (up and down), and it makes a huge difference on tranny temps.

HTH,
Brian Brown

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Brian Brown
4108-216 w/ V730
Longmont, CO
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« Reply #5 on: June 07, 2007, 02:07:44 PM »

Uh.. For lack of better info, I heard that you can have the modulator assembly readjusted to better suit
the new gear ratio. I once heard that but can't remember where I heard it.

I think there is an Allison Tech tip that covers that process...

It's been a while since I fooled around with a V-730 however.

Maybe Pete (Daytona) remembers where that info was found...

Dave....
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JimC
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« Reply #6 on: June 07, 2007, 07:50:49 PM »

Under normal acceleration, about 3/4 throttle mine will shift into 3rd at 52MPH and shift down at 48MPH, hope this helps.
JimCallaghan
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4106 - 8-71/730
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« Reply #7 on: June 07, 2007, 08:00:09 PM »

Larn, the best thing I ever did for my Atec tranny was put some Lucas Auto Trans Additive in it. It went from rough shifts to smooth and flawless with about a quart. I don't sell additives but that one must have been made for our trannys, they love it.
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Barn Owl
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« Reply #8 on: June 09, 2007, 08:05:36 PM »

I have spent the last two nights at my Grandmothers and needless to say she doesnít have a computer. That is why there is a delayed response. Thanks everyone for your replies.

The only time I would consider the shift harsh is when climbing a hill, and it shifts from third lock up to second lock up? I donít remember the shift sequence for the V730 so someone will have to refresh my memory. I do have an air throttle, and I guess the airline in the photo is going to the modulator? Not having anyone else to compare rides with makes it difficult to know sometimes if things are just normal.

At 45mph what state would the transmission be in? I am guessing 2nd lock up?
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L. Christley - W3EYE Amateur Extra
Blue Ridge Mountains, S.W. Virginia
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Have fun, be great, that way you have Great Fun!
TomC
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« Reply #9 on: June 09, 2007, 11:34:16 PM »

The shift sequence of the V730 mechanical (V731 electronic has adaptive technology that varies shift sequence, whereas the V730 is predictable) is 1C-2C-2L-3L.  1st and 2nd are modulated by the throttle modulator (in your case an air one just like mine) and 2nd to 3rd is strictly speed controlled no matter what the throttle position is (at least on mine) so 2nd to 3rd and back to 2nd happen at specific speeds.  I have a R-N-3-2-1 shifter that allows me full control (as much as you can get out of a 3 speed trans).  Hopefully you have the same since then you can pull it down to 1st and get lockup in first.  Good Luck, TomC
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Tom & Donna Christman. '77 AMGeneral 10240B; 8V-71TATAIC V730.
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