| Author | Message | ||
| Dan (Cintrepd)
Registered Member Username: Cintrepd Post Number: 13 Registered: 8-2008 Posted From: 70.54.51.206 Rating: N/A |
Apologize if this has been asked before: Any special things to do to a 6V92TA MUI crankcase to accept an HT740/750 transmission? | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 868 Registered: 8-2006 Posted From: 74.32.83.4 Rating: N/A |
nope | ||
| Bill Gerrie (Bill_gerrie)
Registered Member Username: Bill_gerrie Post Number: 352 Registered: 3-2006 Posted From: 216.198.139.38  Rating: N/A |
Dan Make sure when you get the transmission you also get the proper flywheel. You might want to have the transmission tested before you go to all the work of installing it only to find out it is burned out just like a friend of mine did. He wasn't very happy when he had to remove it. Bill | ||
| Larry Baird (Airhog)
Registered Member Username: Airhog Post Number: 187 Registered: 1-2001 Posted From: 108.0.48.25  Rating: N/A |
I have a rebuilt 740 if your looking. | ||
| Justin Burie (Justinb)
Registered Member Username: Justinb Post Number: 14 Registered: 1-2010 Posted From: 209.254.23.194 Rating: N/A |
Most Allison rebuilders have a Tranny Dyno. Make sure that any Allison bought has been run, tested & passed prior to installation. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1249 Registered: 12-2000 Posted From: 68.26.211.71  Rating: N/A |
When we had our 740 repaired (new front seal, hub and torque converter housing), they put it on their transmission dyno for about 1 hour. They checked shift points, lock-up and for leaks. Dyno charge was $250 and I considered it priceless. | ||
| Floyd Lillies (Flois)
Registered Member Username: Flois Post Number: 8 Registered: 1-2006 Posted From: 64.114.143.93  Rating: N/A |
I want to replace my 5-speed manual with a 750 auto (1984 MC9 with 6V92) but was told it will be a nightmare .... need a cradle?? ... no driveshaft room?? .... any comments from experience? | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 962 Registered: 8-2006 Posted From: 99.39.13.50 Rating: |
One thing to think about, a 750 Allison is a 740 with a compound low, which isn't necessary in a bus. Speeds 2 thru 5 are the EXACT same as a 740. A 754 has five different speeds, with 1st being a little lower than 1st in a 740, and all of the other speeds are a little closer together, with 5th being direct in the 754, as 4th is in the 740. The type of stick trans you have will determine whether or not you will have to change the flywheel. Then you have to add a shifter, a trans cooler, and modulating throttle linkage to the auto. Your cradle stays, with modifications to hold up the auto. Cooling can be done with a dual oil cooler, which puts the trans heat load on the radiators, aka oil to water, or an oil to air cooler, with electric fans. Definitely room for a 740, there are thousands of them out there, a 754 is almost 4 inches longer. Good luck, and welcome! G | ||
| Tom Christman (Tchristman)
Registered Member Username: Tchristman Post Number: 197 Registered: 1-2006 Posted From: 66.218.33.156 Rating: N/A |
1st and 2nd gear are the same on the HT740 and the HT754CR, with the final gear being direct drive in both. The HT754CR has two close ratio gears (3rd and 4th) in place of just the one gear (3rd) for the HT740. A bit better on the highway, but in my opinion not worth the extra money and the fact that the HT740 is a more robust transmission (the extra gear on the HT754CR is bolted to the rear of the transmission). As said before-use the HT740-it will give you great performance and many years of faithful service. Good Luck, TomC | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 105 Registered: 3-2004 Posted From: 75.245.169.229 Rating: |
For the money do a air oil cooler with a thermostat (vairable 160-220f under $30.00) and also a manual overide switch,for the fans or fan. Keep the heat out of the engine. My fans are 12V.,used from old Subies. If you plan on the change, it can be done, they came with auto trans. | ||
| George M. Todd (George_todd)
Registered Member Username: George_todd Post Number: 963 Registered: 8-2006 Posted From: 99.172.180.138 Rating: N/A |
Tom, I beg to differ with you, please look closely at an Allison spec sheet for both transmissions. These will show that ratios 2-5 on a 750 are the same as 1-4 on a 740. A 754 has 4 entirely different ratios, with first being lower than first in a 740, second is a little higher than 1st in a 740, and so on, the only thing the same is 5th, which is direct. Both transmissions have the same FACTORY horsepower rating. G | ||
| Dan (Cintrepd)
Registered Member Username: Cintrepd Post Number: 14 Registered: 8-2008 Posted From: 70.51.239.27 Rating: N/A |
Thanks to all for the kind replys. Can anyone tell me what a flexplate is for/does? Thanks again | ||
| Luvrbus (Luvrbus)
Registered Member Username: Luvrbus Post Number: 869 Registered: 8-2006 Posted From: 74.32.83.4 Rating: N/A |
A flex plate goes on the crankshaft to connect the 740 too and is made to flex with the heat build up from the torque converter good luck | ||
| joe padberg (Joemc7ab)
Registered Member Username: Joemc7ab Post Number: 394 Registered: 6-2004 Posted From: 66.38.159.33 Rating: N/A |
There might be 740 in my life sometime down the road. In my particular situation the transmission output flange would be 9 inches closer to the rear end, or in otherwords the drive shaft would be 9 inches shorter and the angle of inclination would be greater than what it was prior. My question is could this be ignored or would the engine rear have to be lowered somewhat in order to compensate? I know Mark Renner has done this on a MC9 in a previous life and I am sure others have also. Waiting for the collected wisdom of this fine board for answers. Joe. | ||
| Kyle Brandt (Kyle4501)
Registered Member Username: Kyle4501 Post Number: 583 Registered: 9-2004 Posted From: 72.147.34.235  Rating: N/A |
I picked up my new (to me) HT754CRD today. It came with a manual. For what it matters, this transmission is as TomC described & starts in 1st. It has a 1980 build date. Now, all I need is a nice MUI8V92 to round out the package.  |
