| Author | Message | ||
| Pat Bartlett (Muddog16)
Rating: |
I'm replacing my Allison Automatic HT 750 CR/DR, can anyone tell me the difference between the 750CR/DR and a Ht 740, I know that the 750 is a five speed automatic and that the 740 is a 4 speed, other than that what are the differences? | ||
| T. (Bluegrass)
Rating: N/A |
Hello Pat What Is wrong with your HT-750? the difference between your 750CR/DR and a HT 740 Is HT-740 Is 3.69:1 First...................................3.69:1 Second..................................2.00:1 Third...................................1.58:1 Fourth..................................1.25:1 Fifth...................................1.00:1 ____________________________ HT 750DR Range Ratios* First..(manually selected).............7.97:1 Second.................................3.19:1 Third..................................2.02:1 Fourth.................................1.38:1 Fifth..................................1.00:1 Reverse..(17.22 optional)..............4.72:1 This Is about the best I can do Tony | ||
| James Maxwell (Jmaxwell)
Rating: N/A |
Is it a typo or have we now added a 5th range to a 4 spd. | ||
| T. (Bluegrass)
Rating: N/A |
No James I believe It Is a typo, how about If we go with this one. HT-740 Range Ratios*: First...................................3.69:1 Second..................................2.02:1 Third...................................1.38:1 Fourth..................................1.00:1 Reverse.................................6.04:1 * Gear ratio does not include torque converter ratio. Power takeoff provision Converter driven (SAE 6-bolt) Location................10 o'clock position (as viewed from rear) Drive gear ratio............................1.00 x turbine speed Drive gear rating.................300 lb ft (407 N·m) continuous; 400 lb ft (543 N·m) intermittent Engine driven (optional) (SAE 8-bolt) Location....converter housing: one at 1 o'clock position and one at 8 o'clock position (as viewed from rear) Drive gear ratio.......1 o'clock position – 1.35 x turbine speed; 8 o'clock position – 0.84 x turbine speed Drive gear rating.................200 lb ft (149 N·m) continuous; 260 lb ft (194 N·m) intermittent Oil system Oil type..........................................Dexron II®, C4 Capacity (excluding external circuit)...7.5 U.S. gals (28.5 liters) (w/std. oil pan) Filter..................................External, remote mounted Cooler............................................Remote mounted (Filter and Cooler not furnished on transmission assembly but is supplied by vehicle manufacturer.) Size Length..........................................37.4 in (950 mm) Width...........................................21.7 in (552 mm) Height..........................................26.6 in (675 mm) Weight (dry)..........................840 lbs (381 kg) (approx.) +NOTE: Vocational ratings may vary by vocation. Transmission Cross-section (go to top) Design Features & Benefits (go to top) Designed for use with diesel engines up to 445 nhp (332 kW). Four forward ranges and one reverse. This transmission model is best suited for medium- and heavy-duty trucks and buses. Clutches are multidisc design, oil-cooled, hydraulically-operated, and self-compensating for normal wear. Spur-type planetary gears are designed for strength, quietness, and long life. Automatic lockup clutch, throttle-modulated for maximized fuel economy and enhanced engine braking. Automatic upshifting and downshifting within each drive range. Built-in inhibitors prevent downshifts or shifts into reverse unless vehicle speed is within an acceptable range. The Allison three-element torque converter provides smooth, shock-free operation. A choice of converters permits matching the HT 740 to a wide variety of engines. Converter-driven power takeoff drive on right side of transmission (as viewed from the rear) is standard. Design is SAE 6-bolt. Optional engine-driven power takeoff is available in two locations - upper right and lower left sides, as viewed from rear. Design is SAE 8-bolt. Provisions for neutral start switch, reverse signal switch, SAE regular-duty thread-type speedometer drive, electronic speedometer drive, and parking brake. 7.0 inch oil pan is standard. Optional 6.0, 4.5 and 8.5 inch pans are available when ground clearance or heavy duty operation dictates their use. Typical Applications (go to top) Dump Truck Refuse Hauler Lowboy Truck Hook & Ladder Truck Transit Mixer Fire Truck Logging Truck Rear Loader (Refuse) Agricultural Motorhome Construction Equipment Hauler Wrecker (Tandem Axle) Public Utility (All Wheel Drive Tandem Axle) Other applications are available. SCAAN Specification Assistance (go to top) To be sure that you get the most efficient engine/transmission package for your operation in your territory with your preferred vehicle, your local Allison Transmission distributor offers SCAAN. SCAAN stands for System for Computerized Application ANalysis and helps take the guesswork out of vehicle-buying decisions. What's more, it does so quickly and accurately through computer terminals located at all distributor outlets. This means rapid analysis of your vehicle needs on the spot. | ||
| Pat Bartlett (Muddog16)
Rating: N/A |
Thanks Tony, my Ht 750 is 20 years old as is the 8V71N, and i decided to replace both of them while i was doing my conversion, when i was driving it home the shifts were not crisp and what i thought smooth, the shifts weren't the same each and everytime, for reliability while on the road i wanted to replace both engine and transmission, for lack of a better explanation "peace of mind" and they were 20 years old, with the new remanufactured 8V71TA,and HT750 or HT740 would give me this, if i'm lucky, that should out last me. Thanks for the great information Tony, one last question would you prefer the 750 or 740? | ||
| T. (Bluegrass)
Rating: N/A |
Pat There has been many people that have wondered the same thing and to tell you the truth I don't know which one that Is the best, I will say this MCI,and Eagle Bus manufacturing spent millions of dollars on the design of these vehicles, who am I to say which one Is better than the other. If It was me I would probably go with what come out of the unit. even though we both know that you don't need the extra gear after all it is not like you was running around with a Bus load of People. Tony | ||
| RJ Long (Rjlong)
Rating: N/A |
Pat - Another transmission you might want to consider is the HT-754, a later version of the HT-750, and a lot more similar to the HT-740. Look for a CR model, not a DR, as the DR had the stump-puller lower gearing. If you're staying with the two-stroke Detroit, the extra gear of the 754 is well worth it. Both the HT-740 and the HT-754 are virtually bullet-proof in RV service, it's just a matter of personal preference. I like the extra gear of the 754. . . FWIW, RJ PD4106-2784 Fresno CA | ||
| MC - Iv Rating: N/A |
I always thought I had a 740 in my coach.(83 NJT 6V92) However, on acceleration the tranny shifts 5 gears, although the first is very quick to change. I have been told that the first is just a "granny gear"? The shifter only shows 1-2-3-4-R. How can I tell for sure? Thanks , Iver. | ||
| FAST FRED Rating: N/A |
You could be mistaking the torque converter lock up for the first shift. FAST FRED | ||
| Gary McFarland (Gearheadgary)
Rating: N/A |
Yeah, the TQ locking up feels (And Acts) just like a gear. Gary | ||
| Pat Bartlett (Muddog16)
Rating: N/A |
One more question i'm pretty sure this bus sat for quite awhile, there were enough wasp and mud daubers nests on the bus to prove this, I've got a 8V71TA coming, its a remanufactured one, with a warranty, lol......yeah i know those aren't much good anymore. But while i had both engine and transmission out my thinking was replace them both, i have a maintenance manual for the transmission but its pretty slim on information, is there anything i can do besides replace it? Filter, torque converter, oil, cooler, any recommendations? |
