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Allison HT 740 No reverse

This is a public forum to discuss Eagle related technical issues. If you are having a problem with your Eagle, this is the place to find help.
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beltguy
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Posts: 2663
Joined: Wed Oct 08, 2008 4:39 am
FMCA #: F246286
Bus Model: 1985 Eagle 10 with Series 60 and Eaton AutoShift 10 speed transmission (SOLD)
Location: Evergreen, CO
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Re: Allison HT 740 No reverse

Post by beltguy »

I know zip about the mechanical details of the Allison

However, building on Clifford's comments, if this is a sticking situation, I have to wonder what condition the transmission fluid is in. If it has not been changed in the past year or two (or?) I would consider changing it and the filter as a preventative measure.

The question becomes what fluid would you use if you decide to change it. Some folks go full bore and buy Transcend. I think Clifford has said in the past that Transcend is not necessary in an HT740. I had heard that Dextron and engine oil are acceptable.

I looked at an online owners manual for the HT740 (and other versions): http://manuals.chudov.com/M939-Series-T ... Manual.pdf
Hydraulic fluids (oils) used in the transmission are important influences on
transmission performance, reliability, and durability.
• Transmission fluid types recommended for use in the AT, MT, and HT Series
transmissions are TranSynd™, DEXRON® -III, and C-4.
• TranSynd™ is a fully synthetic automatic transmission fluid that meets new
Allison specifications for Severe Duty and Extended Drain Interval
. Please note that the tables showing fluid and filter change intervals are for
TranSynd™, Non-TranSynd™, and mixed transmission fluids.
• Some DEXRON ® -III fluids are also qualified as Type C-4 fluids. To ensure the
fluid is qualified for use in Allison transmissions, check for a DEXRON® -III or
C-4 fluid license, or approval numbers on the container, or consult the lubricant
manufacturer. Consult your Allison Transmission dealer or distributor before
using other fluid types; fluid types such as Type F, and universal farm fluids
may or may not be properly qualified for use in your Allison transmission
It appears that C-4 used to describe diesel engine oil. It appears that the current ratings are CK-4 and CJ-4 but they describe diesel engine oil.

Clear as mud?

Jim
Jim Shepherd
Evergreen, CO
'85 Eagle 10 with Series 60 & Eaton AutoShift 10 speed transmission SOLD
2005 Dodge 2500 with 5.9 Cummins and 6 speed manual 2022 Sunset 28 foot trailer
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Clydes Barn
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Joined: Wed Dec 28, 2016 12:15 pm
FMCA #: 226731
Bus Model: 1982 Silver Eagle

Re: Allison HT 740 No reverse

Post by Clydes Barn »

W0W! Thx Jim for the solid info. I tried finding a manual and as the Forrest Gump of tech I struggle with that. But I serviced it 4500 miles ago and it's Dextron.
Mikes74eagle
Posts: 24
Joined: Wed Jun 14, 2017 9:59 pm
FMCA #: F474888
Bus Model: 1974 eagle http://www.eaglesinternational.net/test ... &mode=view
Location: Canada

Re: Allison HT 740 No reverse

Post by Mikes74eagle »

Just wondering if you got this issue fixed mine did the same on the way to
Sturgis last month
I have a stone Bennett shifter and it turned out to be some bad contact pins
Clydes Barn
Posts: 8
Joined: Wed Dec 28, 2016 12:15 pm
FMCA #: 226731
Bus Model: 1982 Silver Eagle

Re: Allison HT 740 No reverse

Post by Clydes Barn »

It sort of fixed itself. I never had another problem. Next time I have it serviced I am going to have them pull the pan and polish the valves.
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gpzzdrm
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Bus Model: 1978 - 05 / Cummins ISM 450 / Allison HT740
Location: Carson City, NV

Re: Allison HT 740 No reverse

Post by gpzzdrm »

Years ago, when I had a Stone Bennett shifter, I had the problem with reverse. I found the shift lever was not moving far enough to get into reverse. It was a simple adjustment. All I did was run the shifter through the gears and made sure each position was correct. Never had the problem again. I would bet the current cable shifter could have the same problem.
1978 05 Eagle with 450HP Cummins ISM / Allison HT740
Started in 1996 and still an in-progress hobby.
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