Red Horse Posted October 8, 2009 Share Posted October 8, 2009 Guys,My B has a Maxidyne that someone installed with a Duplex. (Truck was originally a B-60X). Also 9.05 Gears in a 29,000 rear. I'm thinking I'd like to put a 6 speed in to really take advantage of the Maxidyne.Any words of wisdom out there from those that have done it? I would also probably change the rear to a 4.60. Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/ Share on other sites More sharing options...
Lmackattack Posted October 8, 2009 Share Posted October 8, 2009 the 6 speed is Direct transmission in top gear. with 4.90s you will have a hard time doing 55MPH. you might consider an Overdrive trans or 3.87-4.17s for a play truck.Trent Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41598 Share on other sites More sharing options...
Red Horse Posted October 9, 2009 Author Share Posted October 9, 2009 the 6 speed is Direct transmission in top gear. with 4.90s you will have a hard time doing 55MPH. you might consider an Overdrive trans or 3.87-4.17s for a play truck.TrentTrent- 4.60, not 4.90 The truck has 11:00 x 24's so as I do the math, with 4.60 gears at 2100 its good for 61.9 vs about 68.4 for 4.17's The 4.17's would probably be better because at say 1950, I would be doing about 63- and if I saw a "large car" bearing down on me in the mirror, it should do 68! The issue is I can find a 4.60 CRD 62's or CRD 118's are tough to find. My bigger question is are all the mounts different and am I into drilling new holes etc?? Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41604 Share on other sites More sharing options...
Rob Posted October 9, 2009 Share Posted October 9, 2009 Trent- 4.60, not 4.90 The truck has 11:00 x 24's so as I do the math, with 4.60 gears at 2100 its good for 61.9 vs about 68.4 for 4.17's The 4.17's would probably be better because at say 1950, I would be doing about 63- and if I saw a "large car" bearing down on me in the mirror, it should do 68! The issue is I can find a 4.60 CRD 62's or CRD 118's are tough to find. My bigger question is are all the mounts different and am I into drilling new holes etc??You will most likely be fabricating your mounts to the frame. I would obtain from a yard the mounts on the transmission. You can utilize the original frame bracket mounting holes in that scenario.Fabricating the mounts is not difficult with patience.Very few Maxidyne series drivetrains were put into B models. Those that were were a "test bed" as I understand for the concept. Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41606 Share on other sites More sharing options...
maxidyne237 Posted October 9, 2009 Share Posted October 9, 2009 It would be interesting to see if you could find those taller gears for the 29 rear in your truck. I always wanted to find a B61x with the 35,000 rear and give it a little bit taller ratio so it would do more than 50mph Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41623 Share on other sites More sharing options...
HK Trucking Posted October 10, 2009 Share Posted October 10, 2009 My bigger question is are all the mounts different and am I into drilling new holes etc??When you go transmission shopping, also get the trans mounts that bolt to the bellhousing and the mounts that bolt to the inside of the frame.The frame width at the transmission mounting area may or may not be the same on your B model as on the "donor" truck, but having those frame brackets will still save you some work even if you have to modify them to fit.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41672 Share on other sites More sharing options...
Rob Posted October 10, 2009 Share Posted October 10, 2009 When you go transmission shopping, also get the trans mounts that bolt to the bellhousing and the mounts that bolt to the inside of the frame.The frame width at the transmission mounting area may or may not be the same on your B model as on the "donor" truck, but having those frame brackets will still save you some work even if you have to modify them to fit..Hi Herb, did the later "Maxitorque" transmissions use SAE flywheel housing mounts and get away from the transmission case boss mounts? I've never seen a Mack trans use the flywheel housing to mount to, only seen the SAE mounts used with Spicer, and Fuller transmissions. I've not been around anything newer than 1985 though.Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41695 Share on other sites More sharing options...
HK Trucking Posted October 10, 2009 Share Posted October 10, 2009 Hi Herb, did the later "Maxitorque" transmissions use SAE flywheel housing mounts and get away from the transmission case boss mounts? I've never seen a Mack trans use the flywheel housing to mount to, only seen the SAE mounts used with Spicer, and Fuller transmissions. I've not been around anything newer than 1985 though.RobHi Rob.When I said "bellhousing" I was referring to the transmission half of the bellhousing,with the mounts on it, just like what's on your 107 series transmissions. On the later T200 & T300 series Mack transmissions the trans. bellhousing is integral with the main case, and the mounts are still on the trans, just rear of the bellhousing to flywheel housing interface. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41697 Share on other sites More sharing options...
Rob Posted October 10, 2009 Share Posted October 10, 2009 Hi Rob.When I said "bellhousing" I was referring to the transmission half of the bellhousing,with the mounts on it, just like what's on your 107 series transmissions. On the later T200 & T300 series Mack transmissions the trans. bellhousing is integral with the main case, and the mounts are still on the trans, just rear of the bellhousing to flywheel housing interface.Hi Herb, now I follow. I was thinking the housing and main case did not separate although I should have known because I've physically unbolted them in the past. The memory I retain is slipping I guess. Thanks,Rob Quote Plodding along with no job nor practical application for my existence, but still trying to fix what's broke. Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41698 Share on other sites More sharing options...
Red Horse Posted October 11, 2009 Author Share Posted October 11, 2009 Guys, thank you all for taking the time to respond Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41720 Share on other sites More sharing options...
HK Trucking Posted October 11, 2009 Share Posted October 11, 2009 I got to thinking some more about this during a bout of insomnia last night.Your duplex is undoubtedly set up for a push type clutch (either single or double disc), so the flywheel & clutch from the original Thermodyne engine was bolted onto the Maxidyne to accomodate the duplex transmission.The Maxitorque transmission will be set up for a Spicer angle spring pull type clutch, so you'll have to get the correct flywheel & clutch and stick it on your engine in order to install the Maxitorque transmission.Since the original clutch was push type and you're switching to a pull type, you'll have to re work the clutch linkage to pull instead of push. You might want to consider adapting a suspended under dash clutch pedal &clutch actuating cable from a DM or R model.Also, you'll have to use the correct speedometer drive gear or adapter for your truck's rear axle ratio.. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41741 Share on other sites More sharing options...
Red Horse Posted October 12, 2009 Author Share Posted October 12, 2009 I got to thinking some more about this during a bout of insomnia last night.Your duplex is undoubtedly set up for a push type clutch (either single or double disc), so the flywheel & clutch from the original Thermodyne engine was bolted onto the Maxidyne to accomodate the duplex transmission.The Maxitorque transmission will be set up for a Spicer angle spring pull type clutch, so you'll have to get the correct flywheel & clutch and stick it on your engine in order to install the Maxitorque transmission.Since the original clutch was push type and you're switching to a pull type, you'll have to re work the clutch linkage to pull instead of push. You might want to consider adapting a suspended under dash clutch pedal &clutch actuating cable from a DM or R model.Also, you'll have to use the correct speedometer drive gear or adapter for your truck's rear axle ratio..HK (Herb?) Thx- I would bet you are correct. the truck is a 56 B-60X and I'm told the maxidyne was installed in around 79. My bet is the gas job was gone long before 79 when a 673/Duplex was installed. Maybe I should just live with it. The truck was in use up until a couple of years ago- not a lot on road miles but it does work- I drive it like a six speed- either upshifting while in first or any gear in between. No split shifting though- I had too many old timers tell me it is very easy to vblow the back of a Duplex out with all that torque. Quote Link to comment https://www.bigmacktrucks.com/topic/10978-duplex-to-maxitorque/#findComment-41812 Share on other sites More sharing options...
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