Duplex Shift Technique

[Red Horse]

How about some help. I have a Duplex behind a Maxidyne. I just got thr truck and have basically been driving it as a six speed. Any and all suggestions on properly shifting a Duplex would be aprreciated. I think the 1200-2100 rpm band makes splitting this a bit more difficult.

[Freightrain]

Sounds like you don't really need to split them with the Maxi motor. Typical shift pattern for Duplex 1 lo, 1 hi, 2 lo, 2 hi, etc thru the gears. Not sure how the straight or OD box compares, as the triplex and quad box have different shift patterns in 5th gear for single OD and double OD boxes.

Unless you get a load behind it, drive it like you are.

[ThaddeusW]

Wait, do you have the older single counter shaft TRT that sat behind the Thermodynes or the tripple countershaft Maxitorque series two stick six speed?

They are both very different gear boxes. What kind of truck is this setup in? I see you have B models but just making sure. To be honest the older TRT series is not a good transmission for the Maxidyne. Not only are they not as strong as the Maxitorque but they are not setup for the wide torque band making the gear splits kinda useless. If its a show truck that isn't loaded and you want an engine that's easier to find parts for, your okay as long as you are careful with the shifting. The torque of the Maxidyne can tear up the duplex/triplex/quad. If its a work truck then save the duplex for another truck and go with a 2 stick/air shift 6 speed or even a 5 speed if you dont need a low gear.

Some people have reported their TRT's are holding up behind the Maxi's but they don't make parts for them anymore. That right there is in itself a reason to not have an old duplex behind a Maxi.

[Freightrain]

Good point Thad. Didn't even think about possible newer tranny.

[Red Horse]

[attachm

nt=4183:B60XBolton_001.jpg]Guys,

I probably should get under this and read the numbers. the truck is a 56 and my guess is that somewhere along the line, someone yanked the gas motor and stuck a 673/Duplex in it. I have the build sheet but the original box could not have survived with the 673. I'm told that around 79, they put the Maxi in it. I believe it has a 10 speed- not a low hole six. And I agree that as the Maxi was designed to run from 1200 to 2100, the splits in the 10 speed were designed for a 400 rpm band- not 900.

Again, assuming I want to split as conditions dictate, what is smoothest way? move main first or compound?

And I intend to use this truck- with the respect a 53 year old truck is due.

[Freightrain]

Yes, the gas motor uses the smaller boxes, so definitely would be a big box now. Though it still is not rated for the low end torque of a Maxi. With the use you plan, it will likely survive fine.

This is my triplex, but it works the same way. The only difference is your sticks are changed position. The Duplex has the main closest to you, the compound away. They shift the same way other then I have three splits and you two.

[Mike]

RedHorse,

I'm trying to understand your question about the shifting. I also would like to know if your truck has the handbrake next to your right leg.? And are you having problems meshing with the gears?.....I'll back out of the post if it is something other than what i'm thinking. Also having the transmission #'s will help when discussing about your particular setup.

Thank You

mike

[theakerstwo]

Wait, do you have the older single counter shaft TRT that sat behind the Thermodynes or the tripple countershaft Maxitorque series two stick six speed?

They are both very different gear boxes. What kind of truck is this setup in? I see you have B models but just making sure. To be honest the older TRT series is not a good transmission for the Maxidyne. Not only are they not as strong as the Maxitorque but they are not setup for the wide torque band making the gear splits kinda useless. If its a show truck that isn't loaded and you want an engine that's easier to find parts for, your okay as long as you are careful with the shifting. The torquedulplex of the Maxidyne can tear up the duplex/triplex/quad. If its a work truck then save the duplex for another truck and go with a 2 stick/air shift 6 speed or even a 5 speed if you dont need a low gear.

Some people have reported their TRT's are holding up behind the Maxi's but they don't make parts for them anymore. That right there is in itself a reason to not have an old duplex behind a Maxi.

I agree a maxidyne can destoye a dulplex trans real easy. I have seen some tore up mfrom a thermodyne from being to hot and some one getting rough with them. The back box will split if you mash on it under a heavy load with a maxidyne. It that dont happen then the input shaft will twist at the oil pump hole.

[Red Horse]

Yes, the gas motor uses the smaller boxes, so definitely would be a big box now. Though it still is not rated for the low end torque of a Maxi. With the use you plan, it will likely survive fine.

This is my triplex, but it works the same way. The only difference is your sticks are changed position. The Duplex has the main closest to you, the compound away. They shift the same way other then I have three splits and you two.

Larry- this truck was used up until two years ago with that powertrain-again, owner operated and I'm sure that has something to do with it surviving.

[Red Horse]

RedHorse,

I'm trying to understand your question about the shifting. I also would like to know if your truck has the handbrake next to your right leg.? And are you having problems meshing with the gears?.....I'll back out of the post if it is something other than what i'm thinking. Also having the transmission #'s will help when discussing about your particular setup.

Thank You

mike

Mike, hand brake gone, has Maxi's. And my issue is trying to do a split shift without a lot of gear clash or a lot of lost momentum. And as it is a Maxidyne, it sure doesn't need 10 ratios but it is nice to have the option to split a gear or two.

[Red Horse]

I agree a maxidyne can destoye a dulplex trans real easy. I have seen some tore up mfrom a thermodyne from being to hot and some one getting rough with them. The back box will split if you mash on it under a heavy load with a maxidyne. It that dont happen then the input shaft will twist at the oil pump hole.

One other thing. The rear is a 9.05 ratio so that puts a lot less strain on the rest of the driveline vs. having a faster ratio.

[other dog]

[attachm

nt=4183:B60XBolton_001.jpg]Guys,

I probably should get under this and read the numbers. the truck is a 56 and my guess is that somewhere along the line, someone yanked the gas motor and stuck a 673/Duplex in it. I have the build sheet but the original box could not have survived with the 673. I'm told that around 79, they put the Maxi in it. I believe it has a 10 speed- not a low hole six. And I agree that as the Maxi was designed to run from 1200 to 2100, the splits in the 10 speed were designed for a 400 rpm band- not 900.

Again, assuming I want to split as conditions dictate, what is smoothest way? move main first or compound?

And I intend to use this truck- with the respect a 53 year old truck is due.

That sure is a good looking truck!

[HK Trucking]

[attachm

nt=4183:B60XBolton_001.jpg]Guys,

I probably should get under this and read the numbers. the truck is a 56 and my guess is that somewhere along the line, someone yanked the gas motor and stuck a 673/Duplex in it. I have the build sheet but the original box could not have survived with the 673. I'm told that around 79, they put the Maxi in it. I believe it has a 10 speed- not a low hole six. And I agree that as the Maxi was designed to run from 1200 to 2100, the splits in the 10 speed were designed for a 400 rpm band- not 900.

Again, assuming I want to split as conditions dictate, what is smoothest way? move main first or compound?

And I intend to use this truck- with the respect a 53 year old truck is due.

If the B model designation is an even number (B42, B62 etc) then your truck was originally equipped with a gas engine.

If it's an odd number ( B61, B63, etc), then it was always a diesel.

In the past I've swapped a ENDT 675, and an ENDT676 into trucks that had TRQ7220 quad boxes, and they worked just fine, it's just like anything else, if you drive it properly and shift it smoothly, it'll stay together.

Abuse it and shift it rough, and it'll come apart.

[b61fred]

Hello,

My b61 has a 237 with the old trd720 trans behind it, I have found that if I split the shifts the engine don't pull as hard. I think it will save the trans. I don't know for sure but it has worked well so far. As for your original question... The way I shift my truck is to start in 1st and lo, then hi. Then you should shift the main to 2nd, let the clutch out, this spins the input shaft of the auxiliery trans up to speed and then clutch and shift the aux. to lo. Repete this all the way through unless you have a overdrive then 4 th-hi, you shift to 5th and leave the aux in hi. To know if you have a overdrive front box, see if the number ends in 0, should be like trd7220 or 720 or if it still has the little trans trd670( i have seen these behind diesels) If you have any more problems maybe I could video my duplex like freightrain.

Fred

[Mike]

Hey Fred,

If you don't mind doing so, I bet there would be plenty of folks out there that would benefit from a video of your transmission setup. Tell what kind it is then drive it while someone video's the event. I think it would be great for the forum. That is if you have time to do so. I would do this, but mine is having gear clash at all speeds but starting off in 1st Lo and Hi. I always shutdown my truck with both trans. in neutral. It takes about 10 seconds for it to go into 1st Lo feeling the gears slowing down and stopping before I can shift into 1st Lo with clutch always too the floor. I've heard some people say that ya have to feel the gears. Maybe so, but if it's clashing at any speed and clutch distance off the floor then I feel my truck is having clutch issues. It looks as if the trans. is so covered in grease that I figure it has not had any adjustments in a bunch of years or it's time for a new something. I have the duplex I believe it's a TRD 67. with brake in the floor. Last owner said he did not have it set-up.

mike

[Red Horse]

Hello,

My b61 has a 237 with the old trd720 trans behind it, I have found that if I split the shifts the engine don't pull as hard. I think it will save the trans. I don't know for sure but it has worked well so far. As for your original question... The way I shift my truck is to start in 1st and lo, then hi. Then you should shift the main to 2nd, let the clutch out, this spins the input shaft of the auxiliery trans up to speed and then clutch and shift the aux. to lo. Repete this all the way through unless you have a overdrive then 4 th-hi, you shift to 5th and leave the aux in hi. To know if you have a overdrive front box, see if the number ends in 0, should be like trd7220 or 720 or if it still has the little trans trd670( i have seen these behind diesels) If you have any more problems maybe I could video my duplex like freightrain.

Fred

Thx Fred, bottom line, you are shifting the mainfirst and then the compound? None of this two handed stuff?

[Red Horse]

That sure is a good looking truck!

thx O'dog- and it works! did three loads this weekend.

[417mack]

Advice is normaly worth what you pay for it, and this may be the same because every truck is different. My 58 B61t is a 673 duplex I start in 1st lo then 1st hi then pull the aux box to neutral and then pull the mann to2nd then the aux to lo. this works until 4th then I leave the aux in hi mainto 5th aux to lo then to hi. mine is not od. To down shift I must drop the aux to lo then back to hi then drop the main a gear and so on. When pulling a load up a steep grade I normaly leave the aux in lo and downshift only the main box. Hope this will help a little.

[other dog]

Thx Fred, bottom line, you are shifting the mainfirst and then the compound? None of this two handed stuff?

you can do it either way, but one key thing Fred and 417mack are right on is make your upshifts first, which would be in the main first when upshifting, compound first when downshifting.

as in first high to second low-shift main first, then compound to low.

5th. low to 4th. high-shift compound back to high first, then downshift the main.

[Rob]

you can do it either way, but one key thing Fred and 417mack are right on is make your upshifts first, which would be in the main first when upshifting, compound first when downshifting.

as in first high to second low-shift main first, then compound to low.

5th. low to 4th. high-shift compound back to high first, then downshift the main.

I just grab dem dar sticks and push/pull as hard as I can and they slip right in after "break in".

I gotta agree with the other guys that have posted as that routine works for me. I never shift both at the same time as my mind does not process fast enough.

Rob

[b61fred]

Thx Fred, bottom line, you are shifting the mainfirst and then the compound? None of this two handed stuff?

Yep you have got it, as you go along you will find that you can speed the process up by using both hands. I find that the main will take a long time to "wind down" in RPM to be in the sweet spot to drop in to mesh with the next gear. The aux. will be ready to go into lo almost imediately. I have found as you are shifting the main into the next higher gear right about the time it is meshing into the gear you can slap that aux stick into lo and it will go in with a little practice. You have already noticed that it shifts different loaded and unloaded I bet.

I think that the duplex is a hard trans to learn on due to the long drops in rpm between gears. I learned on a duplex and then drove a triplex and thought this triplex is great.

Did I see your truck for sale in the WOT mag this last issue? I think it had a big brother b75 with it. I would like to have a b model dump truck myself. looking good and keep trying, in no time you will be an expert!

Fred

[b61fred]

Hey Fred,

If you don't mind doing so, I bet there would be plenty of folks out there that would benefit from a video of your transmission setup. Tell what kind it is then drive it while someone video's the event. I think it would be great for the forum. That is if you have time to do so. I would do this, but mine is having gear clash at all speeds but starting off in 1st Lo and Hi. I always shutdown my truck with both trans. in neutral. It takes about 10 seconds for it to go into 1st Lo feeling the gears slowing down and stopping before I can shift into 1st Lo with clutch always too the floor. I've heard some people say that ya have to feel the gears. Maybe so, but if it's clashing at any speed and clutch distance off the floor then I feel my truck is having clutch issues. It looks as if the trans. is so covered in grease that I figure it has not had any adjustments in a bunch of years or it's time for a new something. I have the duplex I believe it's a TRD 67. with brake in the floor. Last owner said he did not have it set-up.

mike

I will try and do a video, Rob is going to come over in a week or two. maybe I can talk him into playing camera man. That is if we can get both of our rageing fat-a$$es into the cab of a B model. I may need some pointers on how to load a video on to the site.

As for your grinding, Try shifting with out the clutch and see what happens, It sould go in whe the RPM is right, or it should I guess??

Fred

[Mike]

So he's saying that he's a real GRABBER. And can only play with one STICK at a time......POOR MOMMA!!!!........I hear the rust in someone's roof a callin.

mike

[Mike]

Fred,

I have tried that method and it definitly does not work. The shifter will not pull easily out of gear at any speed except at all STOP. Just like my SuperM's you have to stop before shifting into any gear.

mike

[Red Horse]

Yep you have got it, as you go along you will find that you can speed the process up by using both hands. I find that the main will take a long time to "wind down" in RPM to be in the sweet spot to drop in to mesh with the next gear. The aux. will be ready to go into lo almost imediately. I have found as you are shifting the main into the next higher gear right about the time it is meshing into the gear you can slap that aux stick into lo and it will go in with a little practice. You have already noticed that it shifts different loaded and unloaded I bet.

I think that the duplex is a hard trans to learn on due to the long drops in rpm between gears. I learned on a duplex and then drove a triplex and thought this triplex is great.

Did I see your truck for sale in the WOT mag this last issue? I think it had a big brother b75 with it. I would like to have a b model dump truck myself. looking good and keep trying, in no time you will be an expert!

Fred

Fred, thx for info- yes it does shift differently- and in particular going down, RPM's are very critical- 4th to 5th is much easier with the clutch and a quick shift. I remember a long time ago when the Maxidynes first came out, and guys were used to Roadrangers, our fleet instructor would tell them- "just like a waltz- slow and one, two"

And you are observant. Ive been trying to get a two other B's together and the WOT came out- I recognized the phone exchange and the barn in the background- 25 years ago I used to take my kids past the barn where this local contractor had a fleet of B's Same trucks! The B-75 sold the next day. Been 20 years since I lived there-some things you don't forget. These trucks were still working and well cared for by an owner (and his father before him) who cared about equipment.

Now the wife is leaning on me to get rid of the other two as I "have my truck"