Truck Conversion & Toterhome Community - View Single Post

madbrit · 12-18-2003, 06:25 AM

Bill,

My Freightliner has a Series 60 11.1 liter, set at 350/365hp and with the speed limiter at 65mph. When I get down there, I am going to have the Phoenix Detroit dealer run some tests and possibly reprogram it for max hp and torque, but I think it is pretty much there as far as I can find. I am purchasing a Pro-Link 9000 so I can read faults and reset any computer codes and also reset that speed limiter.

My present search is for a used transmission. They can be bought from around $1000 and up, but I am trying to find one in an old vehicle which is or at least was running recently. Will make locating some of those "also need" parts a lot easier. Wrecking yards are quoting around $2500 - $3000, or I have been offered one rebuilt for $3500 with shifter and cooler. Best to find one that has come off a Detroit to start with as I have been advised that other parts may need to be bought if it was originally on another motor.

We will install it ourselves, if it proves too heavier a job, then I will look at having only the trans installed at the local Detroit service center. They are far too busy to mess with my sort of project, too many breakdowns on the I-40 to attend to, so we would do all the connecting up of shifter and cooler, plus sorting out the modulator connection.

I had been warned off a few rebuilders, but it turns out it was more their "conversion" work that was not good and so since they are still in business, they must do a reasonable rebuild job. Still, a 740 is only a big Turbo 400 and we have rebuilt a few of them....... LOL.

The 55 mph was not a feature I wanted either and my 3.91 Rockwell rear end has the ability to be changed to a 2.80, even though I will probably have to purchase another carrier and the gears new. This was quoted at around $2,000 for the whole job including parts, but I will look for a used one first.

I did think of using the 5 speed HT 750 CR, but it was so hard to find one other than a rebuilt unit and they wanted a bunch for the core charge. The other problem was that people didn't know which 750 they had. The DR is the one with the low first and then similar ratios to the 740. The CR has the same first and top gears as the 740 but 3 intermediate gears instead of the 740's two. After looking at the SCAAN from Allison, it appeared that the 4 speed might actually have better ratios. Of course, only an actual road test will prove this one way or the other. The other thing to possibly avoid is the electronic transmissions such as the 741 and 748. They are controlled by solenoids and another computer. The guy at Allisons said he would avoid them, especially if you did not know which one was a "good" version, apparently there were some problems with early units, so best to stay with the mechanical/hydraulic 740.

I did find an old model Allison called an HT70 which is a 6 speed with overdrive, however it does not have the rating for the torque of a Series 60. That being said, I have seen it behind a 450hp 8v92. The HT70 was reckoned to be so tough that Allison discontinued it as it rarely broke.

That's where I am at the moment, if you need anymore info, feel free to ask as I may have already covered it.

Btw, how do I post pics on here? I would like to be able to post some as the conversion progresses if that is acceptible.

Peter.

12-18-2003, 06:25 AM	#8
madbrit Member Join Date: Nov 2002 Location: Kingman AZ. Posts: 59	Bill, My Freightliner has a Series 60 11.1 liter, set at 350/365hp and with the speed limiter at 65mph. When I get down there, I am going to have the Phoenix Detroit dealer run some tests and possibly reprogram it for max hp and torque, but I think it is pretty much there as far as I can find. I am purchasing a Pro-Link 9000 so I can read faults and reset any computer codes and also reset that speed limiter. My present search is for a used transmission. They can be bought from around $1000 and up, but I am trying to find one in an old vehicle which is or at least was running recently. Will make locating some of those "also need" parts a lot easier. Wrecking yards are quoting around $2500 - $3000, or I have been offered one rebuilt for $3500 with shifter and cooler. Best to find one that has come off a Detroit to start with as I have been advised that other parts may need to be bought if it was originally on another motor. We will install it ourselves, if it proves too heavier a job, then I will look at having only the trans installed at the local Detroit service center. They are far too busy to mess with my sort of project, too many breakdowns on the I-40 to attend to, so we would do all the connecting up of shifter and cooler, plus sorting out the modulator connection. I had been warned off a few rebuilders, but it turns out it was more their "conversion" work that was not good and so since they are still in business, they must do a reasonable rebuild job. Still, a 740 is only a big Turbo 400 and we have rebuilt a few of them....... LOL. The 55 mph was not a feature I wanted either and my 3.91 Rockwell rear end has the ability to be changed to a 2.80, even though I will probably have to purchase another carrier and the gears new. This was quoted at around $2,000 for the whole job including parts, but I will look for a used one first. I did think of using the 5 speed HT 750 CR, but it was so hard to find one other than a rebuilt unit and they wanted a bunch for the core charge. The other problem was that people didn't know which 750 they had. The DR is the one with the low first and then similar ratios to the 740. The CR has the same first and top gears as the 740 but 3 intermediate gears instead of the 740's two. After looking at the SCAAN from Allison, it appeared that the 4 speed might actually have better ratios. Of course, only an actual road test will prove this one way or the other. The other thing to possibly avoid is the electronic transmissions such as the 741 and 748. They are controlled by solenoids and another computer. The guy at Allisons said he would avoid them, especially if you did not know which one was a "good" version, apparently there were some problems with early units, so best to stay with the mechanical/hydraulic 740. I did find an old model Allison called an HT70 which is a 6 speed with overdrive, however it does not have the rating for the torque of a Series 60. That being said, I have seen it behind a 450hp 8v92. The HT70 was reckoned to be so tough that Allison discontinued it as it rarely broke. That's where I am at the moment, if you need anymore info, feel free to ask as I may have already covered it. Btw, how do I post pics on here? I would like to be able to post some as the conversion progresses if that is acceptible. Peter.