raybing Posted June 24, 2007 Share Posted June 24, 2007 Can I get some ideas on upgrades for my RD600, 92 EM7, T2080 trans (40%) OD, 5.55 rears. 290 hp to the ground. Dynoed. This is a tree spade truck and works well off road. On the road top speed 57 mph. Also too big of spaces between gears. Any ideas or parts for an aux. trans. Thanks Ray Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/ Share on other sites More sharing options...
Maxville Truck Posted June 24, 2007 Share Posted June 24, 2007 I know your problem!!! i've got an MR with the same engine but the T2070 and "tripple nickel" Ratio. Haul cow SH&$ with it, couldn't shift it in the fields. open your hood and make sure when you press the throttle down that your throttle linkage is fully opening your pump.. The bell crank arm that clamps to your fuel pump could be loose or just plain wore out. IF thats your problem, but still not enough RPM, then your alternative is to remove your pump and have the RPM's bumped to 2100. @2100 that truck will move along at over 70mph. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12755 Share on other sites More sharing options...
HK Trucking Posted June 24, 2007 Share Posted June 24, 2007 As Maxville said, check your throttle linkage first. Have someone hold the accelerator to the floor (with the engine off) and check to see that the throttle lever on the side of the governor is contacting the stop screw (wide open).If it is not, then find the problem with the linkage and fix it, could be worn ball joints , a bent rod, stop bolt under the pedal set too high, worn actuator arm at the governor etc.Once you're sure the throttle is opening all the way, check your high RPM setting. The EM7 engines were originally set at 1750, but they were completely gutless at that setting and just about everyone turned them up to 2100.You can raise the high RPM's yourself by loosening the jam nut on the high speed stop screw where the throttle shaft enters the governor, and turning the stop screw to allow the throttle shaft to go further in the high speed direction.If these hints don't work, then you'll have to pull the pump and have an injection shop set it up for 2100 RPM's.I had a couple of trucks with the EM7-300 and T2070 which also has the .60 to 1 overdrive. Mine both had 5.73 rears and with the RPM's @ 2100 in high gear they would get close to 70 MPH. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12759 Share on other sites More sharing options...
GearheadGrrrl Posted June 25, 2007 Share Posted June 25, 2007 The EM7 is a Maxidyne engine, and those that came with a wide ratio Maxitorque transmission like yours usually had the governor set for around 2100 RPM with peak torque around 1200 RPM. There was a rarer reduced RPM Maxidyne with the governor set for around 1800 RPM and peak torque at 1020 RPM. These were primarily installed in fleet trucks and UPS probably had hundreds of them, but a vocational truck usually came with the regular 2100 RPM Maxidyne. If your truck has the reduced RPM Maxidyne you can probably set the governor up, which will give you more flexibility but will cost some in fuel if you run it continuously at the higher RPM. Most Mack engines give the best full load fuel economy around 1500 RPM, and cruising them above 1800 RPM wastes a lot of fuel. The low RPM Maxidyne was developed so UPS and other fleets could save on fuel by cruising at 1600 instead of 2000 RPM at 65. The low RPM Maxidyne in an MH was a sweet combination- you could lug down to 40 mph in top gear, yet cruise at 65. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12762 Share on other sites More sharing options...
raybing Posted June 30, 2007 Author Share Posted June 30, 2007 Guys, At 57 mph it turns 1900 rpm. It will pull a few more revs but not much more. On the dyno the rpm will hit 2050. It drives comfortable at 52 mph. Seems to have good power and throttle goes all the way down. have checked all that stuff. so back to the original question about aux. trans. Thanks Ray Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12816 Share on other sites More sharing options...
raybing Posted June 30, 2007 Author Share Posted June 30, 2007 Maybe my rears are deper than 5.55, I will check this weekend. Ray Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12817 Share on other sites More sharing options...
HK Trucking Posted July 1, 2007 Share Posted July 1, 2007 ..... reduced RPM Maxidyne with the governor set for around 1800 RPM and peak torque at 1020 RPM. These were primarily installed in fleet trucks and UPS probably had hundreds of themOver the years I had 3 DM 690's here with that engine, they each had the T2070 7 speed and 5.73 rears.According to the Mack specs the operating range is 1020 to 1750 RPM'sIn a dump truck application those engines were useless @ their stock RPM limit of 1750.Each one of them got "adjusted" to run 2100 very soon after arriving here.I'm not disputing that they work well in a highway application, but I can say for sure that in a dump truck a 1750 RPM limit just doesn't cut it. Quote "If You Can't Shift It Smoothly, You Shouldn't Be Driving It" Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12820 Share on other sites More sharing options...
GearheadGrrrl Posted July 1, 2007 Share Posted July 1, 2007 I'm not disputing that they work well in a highway application, but I can say for sure that in a dump truck a 1750 RPM limit just doesn't cut it. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12821 Share on other sites More sharing options...
GearheadGrrrl Posted July 1, 2007 Share Posted July 1, 2007 I'm not disputing that they work well in a highway application, but I can say for sure that in a dump truck a 1750 RPM limit just doesn't cut it. I agree- upshifting on an uphill is the Maxidyne's weak point. Turning the governor up to 2100 or so shouldn't hurt the engine, won't hurt fuel economy unless you cruise it above 1800, and will make for a marvelously flexible engine. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12822 Share on other sites More sharing options...
raybing Posted July 2, 2007 Author Share Posted July 2, 2007 I agree- upshifting on an uphill is the Maxidyne's weak point. Turning the governor up to 2100 or so shouldn't hurt the engine, won't hurt fuel economy unless you cruise it above 1800, and will make for a marvelously flexible engine.Ok , I found the problem 7.00 gears. So anybody any ideas for an aux transmission to upgrade? Anybody with parts for sale? Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12838 Share on other sites More sharing options...
David Posted July 3, 2007 Share Posted July 3, 2007 It's easier, cheaper, and more driver friendly to just change the rear ends. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12850 Share on other sites More sharing options...
theakerstwo Posted July 3, 2007 Share Posted July 3, 2007 It's easier, cheaper, and more driver friendly to just change the rear ends.It is better to change rear ratio's to keep the drive line speed dowm because that truck was spec'ed with a certain lenth drive line for a give rpm and gear ratio and when you speed the drive line up to much you may have some problems and I know the cowboys will tell you dont worry but I have seen it done many times with everlast problems of virbraions and you can blance drive line and if they are too long for the speed then the lease thing with cause then to loosen yoke nuts and the you have problems with bearings and ujoints going down and with eaton trans then you will have snyonizer pins breaking and the list goes on.glenn Quote glenn akers Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12851 Share on other sites More sharing options...
GearheadGrrrl Posted July 3, 2007 Share Posted July 3, 2007 I agree- it's easier to change two sets of differential gears. Auxiliary trannies may add a certain exoticness to a truck, but there are good reasons you don't see many new trucks built with them anymore. To add an auxilairy you need to add two new driveshafts, mounts, linkage, and maybe move some center bearings and crossmembers around. It's much easier to send the diffs off to be rebuilt with your choice of ratios. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12853 Share on other sites More sharing options...
David Posted July 4, 2007 Share Posted July 4, 2007 7.00 rears with 1100X22.5 tires at 70 mph, the drive shaft is turning 4000 rpm. Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12861 Share on other sites More sharing options...
raybing Posted July 4, 2007 Author Share Posted July 4, 2007 7.00 rears with 1100X22.5 tires at 70 mph, the drive shaft is turning 4000 rpm.Ok Guys, What rears should I look for ? keep in mind the trans has a 40% OD. If I could drive comfortable at 65 , I would be happy. Ray Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12863 Share on other sites More sharing options...
David Posted July 5, 2007 Share Posted July 5, 2007 What size tires do you run? Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12871 Share on other sites More sharing options...
raybing Posted July 5, 2007 Author Share Posted July 5, 2007 What size tires do you run?1100-22.5 Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12875 Share on other sites More sharing options...
David Posted July 6, 2007 Share Posted July 6, 2007 1100 x 22.5 tires and .6 to 1 overdrivewith 5.73 rears: direct @ 2000 rpm = 42 mph overdrive @ 1287 rpm = 45 mph 1715 rpm = 60 mph 2000 rpm = 70 mphwith 5.55 rears: direct @ 2000 rpm = 43 mph overdrive @ 1246 rpm = 45 mph 1662 rpm = 60 mph 1938 rpm = 70 mph Quote Link to comment https://www.bigmacktrucks.com/topic/2612-auxillary-transmission/#findComment-12890 Share on other sites More sharing options...
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