03' Big Red Posted October 18, 2018 Share Posted October 18, 2018 (edited) I want to swap in a Allison 750DRD in my 2003 RD688S i run the Eaton 8LL now... no computer on trans my question is how will my ECM be effected ? amd what year donor chassis would work to get all the pieces needed? i am looking at a MR for the donor chassis Edited October 18, 2018 by 03' Big Red Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/ Share on other sites More sharing options...
03' Big Red Posted October 19, 2018 Author Share Posted October 19, 2018 I talked to my local Mack dealer, they contacted Mack engineering who wouldn’t release any info. i did find several 2001 LE donor chassis with the 4500 series trans, would the mounts and such from the LE work in my RD ? i would appreciate any information in regard to what I may have to change in my ECM, and if any changes are needed can a competent shop make those changes? Or would I have to find a dealership that would make things happen? Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-408140 Share on other sites More sharing options...
jkruss82 Posted October 19, 2018 Share Posted October 19, 2018 Pretty big undertaking. Special transmission wire harness, and engine wire harnesses needed. Does the donor chassis have the same engine type as your RD, then maybe you could just pull the donor ECM. Not sure about component shop flashing new software. Flywheel housing should be the same, but flywheel needs swapped out and you need the spacer ring. Allisons are very heavy and require rear buggy spring mounts at the rear of the transmission, so you probably need to fabricate brackets on your frame. I'm not familiar with where the RD rear engine mounts are located (Flywheel Housing or Side of transmission) in either case they will not likely be the same. There would probably be more headaches along the way, that I'm not thinking of. Hate to say this, but I'd recommend trading your truck to get the transmission you want. Pic of buggy spring 1 Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-408142 Share on other sites More sharing options...
03' Big Red Posted October 19, 2018 Author Share Posted October 19, 2018 Thanks for the info, I did find a RD single axle that would work much better. Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-408148 Share on other sites More sharing options...
03' Big Red Posted October 19, 2018 Author Share Posted October 19, 2018 I would really like to keep this truck since I know what I have and to find a RD with a automatic set up like I need is fairly difficult. i did find a 2003 RD on the internet with a Allison VIN # 1M2P296C23M066900 this should help me create a parts list if I can’t find a suitable donor truck, my guess sticking with a RD would be my best bet for a donor truck. Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-408152 Share on other sites More sharing options...
03' Big Red Posted December 27, 2018 Author Share Posted December 27, 2018 Ok folks i am still working on the details of this swap, I have a vin From a 2000 rd with a Allison, can anyone tell me which Allison this unit has and 1st gear ratio and also the axle ratio ? Vin 054124 also talked to another Mack tech and he says all that’s needed for the engine computer is to change the top gear ratio and change it to A designation for the automatic.. i would appreciate any other input in this swap, I plan to use to 750DRD for simplicity I also need to know what bell housing,flexplate and mounts to use. Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412015 Share on other sites More sharing options...
AZB755V8 Posted December 27, 2018 Share Posted December 27, 2018 I have looked into doing an Allison for a 1985 MH with an E9-V8. The big issue is to get the trans to bolt up to the engine. The bellhousing that you have should work as it is a SAE #1 or something of that sort. From what I know most trans have the same housing diameter and flange, but I am no expert. There is a 13/16 inch spacer available to set back the trans. As for flex-plates there are several different ways to get the starter gear and torque converter to bolt up, maybe gear on torque converter. I have no choice but to make a custom steel "flexplate/flywheel" as the E9 is counterbalanced in the flywheel. Still working on that. The rear of the trans does need supported like in the previous illustration and not solid mounted. Trans I am going with is a HT754CR, 5 speed without deep reduction. What is going to make this all work is a cable shifted trans, no electronics. My truck does not have any electronics and the early Allison's were cable shifted before they had the brain. Actual RPM shift points are set in the valve body with spring pressures, that is old school as well and having someone do that setting is hard to find these days. As for help from Mack there really is no one there that could tell you much about older "Mack" trucks as they are focused on new Volvo stuff, just plain forgot or retired. Retrofitting is going to be all on the guy (you) that wants it bad enough to figure it out to make it work. Torque capacity for that HT750 is 1450 ft/lbs but can do that load all day long, is that matched to your engine torque rating? I am just playing with this E9 and will never be fully loaded. Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412018 Share on other sites More sharing options...
fullfuel01 Posted December 27, 2018 Share Posted December 27, 2018 I don't think mack fitted any Allison to their E9, but I have somewhere a book with all the adapter p/n from Allison to fit on mack engines. You will probably be done before I put my hand on it again.. You might have better luck asking the guy who did the Bandag Titan in Australia (I believe) they made it for sure and might have spare parts Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412020 Share on other sites More sharing options...
03' Big Red Posted December 27, 2018 Author Share Posted December 27, 2018 (edited) Is that HT754CR going to hold up to a E9 ? I thought the torque rating was much lower than the 750DRD Am I correct the 1st gear ratio is 8.0 ? Or something like that on the 754 my truck has the AMI 370 and I would be pushing the torque limits. It’s around 1480 ftlb Edited December 27, 2018 by 03' Big Red Bad spelling Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412021 Share on other sites More sharing options...
AZB755V8 Posted December 27, 2018 Share Posted December 27, 2018 50 minutes ago, fullfuel01 said: I don't think mack fitted any Allison to their E9, but I have somewhere a book with all the adapter p/n from Allison to fit on mack engines. You will probably be done before I put my hand on it again.. You might have better luck asking the guy who did the Bandag Titan in Australia (I believe) they made it for sure and might have spare parts Well you are close to being 100% correct. Mack did do 5 Superliner tractors with E9's for the military to move aircraft. Wish I could find one now... The same Mack engineer that did the 5 military E9 Allison's did the Australian Bandag drag truck, he did the 2500hp engine in that truck as well. Super nice guy but as I said has forgotten most of what was done so long ago. I can say that all the parts were custom made by or for Mack but the blue prints have been long gone. He did give me a few pointers and wished me good luck, saying it can be done. It would be great if I could get any of that Allison info from you!! Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412022 Share on other sites More sharing options...
AZB755V8 Posted December 27, 2018 Share Posted December 27, 2018 Just now, 03' Big Red said: Is that HT754CR going to hold up to a E9 ? I thought the torque rating was much lower than the 750DRD Am I correct the 1st gear ratio is 8.0 ? Or something like that on the 754 my truck has the AMI 370 and I would be pushing the torque limits. It’s around 1480 ftlb The MH is just a play truck now, not a money maker. The HT754CR has around a 3.8 first gear not a 7.2 or so as in the deep reduction as you are talking about. Torque capacity is basically the same at 1450 ft/lbs for all the HT700 series. That Bandag drag truck had a 2500hp E9 with a HT700 trans and it did OK with no load and just drag racing. The MH should be OK for just bobtailing and an occasional trailer on it. If not the 18 speed will go back in. Quote Link to comment https://www.bigmacktrucks.com/topic/54588-allison-conversion/#findComment-412023 Share on other sites More sharing options...
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