| Author |
Message |
Peter Broadribb (Madbrit) (65.37.90.158)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Thursday, August 28, 2003 - 1:36 pm: | |
I found an Allison transmission for sale, still installed in a fire truck. I asked the seller to confirm it is a 5 speed HT 750 as advertised. This is what I got as a reply......
"The tag reads HT740-750 heavy duty, shift selector rears 1-2-3-D-N-R."
Is this for real? A 740-750 tranny? I thought a 750 would have 1-2-3-4-D on the shifter? Or is this a 5 speed with a first that you can't mechanically select?
Help needed or the location of a good used 750 tranny. Thanks. |
Henry R. Bergman, Jr. (Henryofcj) (63.164.175.175)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 29, 2003 - 6:24 pm: | |
The Triple's tranny is a 4 speed. Should be sound as fire service service does not run up the road mileage but would have many many cold full power starts. Good luck. |
smoky (12.222.48.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 29, 2003 - 6:58 pm: | |
personaly I would rather have a 740 4 speed. I think that they shift better and seem to last longer. The only thing you gain with the 5 speed is a creeper low gear that is almost worthless in a bus.
Smoky, |
Peter Broadribb (Madbrit) (65.37.90.158)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Friday, August 29, 2003 - 10:13 pm: | |
Smoky,
There are two 5 speeds, the 750DR with a 7,97 low forst, the 750CR has the same 3.69 first as the 4 speed only more gears in between.
Peter. |
Smoky (12.222.48.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 30, 2003 - 2:05 pm: | |
Peter,
I've never seen the 750CR most of the larger Allison transmissions I work on are out of cement mixers, dump trucks or fire trucks. And if they have a 5 speed its always the one with the low first gear. Sorry for sharing my opinion without knowing all the facts.
Smoky, |
Peter Broadribb (Madbrit) (65.73.177.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 31, 2003 - 10:44 am: | |
Smoky,
No problem. When I first looked at the possibilities of installing an automatic, I found the same info as you, just the 750DR.
Unfortunately, whilst Allison may support all these older trannys, they don't have much info on their website unless you want to buy books from them. So making a decision on whether to install a 740 or a 750 can be difficult if all the specs are not available.
I have found a couple of websites that carry things like gear ratios, torque ratings, etc. But it would have been nicer if this was all still available on the Allison site in one place.
I nearly bought an HT-70, which is an early overdrive 6 speed, I eventually found out that its torque rating was only 800 ft/lbs and my Series 60 can put out 1350 ft/lbs. It would have been fine behind an 8v71 or even an 8v92, but too much difference to gamble on its suitability for me.
Peter. |
smoky (12.222.48.5)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 31, 2003 - 11:18 pm: | |
Peter,
Have you considered an Allison world transmission.
I drove a sterling with one last week, man is that one sweet slush box. But maybe a little expensive.
Smoky, |
Peter Broadribb (Madbrit) (65.73.177.4)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Monday, September 01, 2003 - 1:53 am: | |
Smoky,
Yes, I did price out a World, but at about $12-14K for the tranny including core charge, then we add the ECM at $2300-4000 and then the shifter at $1000. Add to these parts, the hours of labor reprogramming the whole vehicle, especially as mine is a DDEC II which has to be rewired, etc and the average quoted cost is somewhere around $23K.
A rebuilt 740 or 750 will cost me no more than $5000, including core charge and installation is a much simpler thing as all I need is to install a throttle position sensor to tell it when to shift. In fact it is a job we could probably do in my workshop fairly easily.
I am still not sure whether to actually go for the extra gear in the 5 speed or go for the more plentiful 740 Series tranny.
Peter. |
Gary Carter (68.24.253.255)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Tuesday, September 02, 2003 - 5:34 pm: | |
I may be wrong, but I thought the 750 was also a longer transmission than the 740.
BTW: My 8V92 DDEC puts out 1470 ft pounds of torque which is as much or more than most S60s |