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M1070 HET Speed Improvement

simp5782

simp5782

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Mustangsud said:
Has anyone with a HET undertaken modifications to get the speed up? Replacing four pumpkins can't be fun, but just curious about any mods.

My 55 mph trucks I want to run 65, but I'd be happy getting the HET just up to 55.
Click to expand...
Swap to a 7 speed Allison 4560P or a 4700sp with a 6th .74 would give you 16 more mph and a 7th .64 OD would add an additional 27mph.

Or a CAT 7155 would give you a 9mph improvement with the .83 OD


Cat would be the easiest and cheapest swap

Or a Spicer 18 speed. They can be had for around 3500 rebuilt

Or Any 13 speed for that matter.

There were a few eaton 18 auto shifts that came behind the DDEC II 8v92 so that would mate with the computer
 
Mustangsud

Mustangsud

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simp5782 said:
Swap to a 7 speed Allison 4560P or a 4700sp with a 6th .74 would give you 16 more mph and a 7th .64 OD would add an additional 27mph.

Or a CAT 7155 would give you a 9mph improvement with the .83 OD


Cat would be the easiest and cheapest swap

Or a Spicer 18 speed. They can be had for around 3500 rebuilt

Or Any 13 speed for that matter.

There were a few eaton 18 auto shifts that came behind the DDEC II 8v92 so that would mate with the computer
Click to expand...
These are great ideas. Have you done or known someone who's done one of these conversions? I guess the mating of a new trans. isn't an issue since the 92 engine is very common. The Cat 7155 probably would be cheapest, but I have a 916 and all that air clanging and banging while shifting drives me nuts. Every time we take it somewhere people think that parts are about to start falling out underneath it as we go down the road.

I'll look into the Allisons. I've not ever done a trans. swap like this, so I'm not real sure what all it entails.
 
simp5782

simp5782

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It's on the drawing board to do. But with a repower as well.

The Allison from a garbage truck is what you want. They used 92 series

Cats aren't loud if you put a regulator on them and turn the air pressure down to about 85/90

HET uses an 1810 jackshaft. You will need a trans with an 1810 or 9c output yoke.
 
simp5782

simp5782

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Mustangsud said:
These are great ideas. Have you done or known someone who's done one of these conversions? I guess the mating of a new trans. isn't an issue since the 92 engine is very common. The Cat 7155 probably would be cheapest, but I have a 916 and all that air clanging and banging while shifting drives me nuts. Every time we take it somewhere people think that parts are about to start falling out underneath it as we go down the road.

I'll look into the Allisons. I've not ever done a trans. swap like this, so I'm not real sure what all it entails.
Click to expand...
Why does the cat bang and clang?

If you swap the vents for the metal bell type the air burst are much quieter.

You should only have to shift 3x for normal driving in that 916 from takeoff to max speed.

Start in 9th. 11th 13th 15th 16th
 
Mustangsud

Mustangsud

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Right now I’m first looking at replacing axle gears to improve speed, possibly even planetaries.
Initial estimate for putting in a 4700 rds transmission is about $50k. That’s a pretty steep hit for a little speed.
 
simp5782

simp5782

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Mustangsud said:
Right now I’m first looking at replacing axle gears to improve speed, possibly even planetaries.
Initial estimate for putting in a 4700 rds transmission is about $50k. That’s a pretty steep hit for a little speed.
Click to expand...
You can find a takeout from behind a 60 series detroit with harness and all that.

The 916s with the 7spd use a stand alone tcm and a a cable drawn tps for the 4700sp.

You could always but a parts truck mtvr and use that transmission and you have spare parts for yours.

A guy on here in Suriname did the PLS planets on his HET

Your could also just add auxiliary transmission behind the transfer case and leave it in OD. Moving the front axle engagement to it's own switch. So all rears could pull with the front freewheel while it's in OD. But you would need to shift it back to direct to use the front axle
 
Mustangsud

Mustangsud

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simp5782 said:
You can find a takeout from behind a 60 series detroit with harness and all that.

The 916s with the 7spd use a stand alone tcm and a a cable drawn tps for the 4700sp.

You could always but a parts truck mtvr and use that transmission and you have spare parts for yours.

A guy on here in Suriname did the PLS planets on his HET

Your could also just add auxiliary transmission behind the transfer case and leave it in OD. Moving the front axle engagement to it's own switch. So all rears could pull with the front freewheel while it's in OD. But you would need to shift it back to direct to use the front axle
Click to expand...
Thanks for the great ideas! I will add them to my list of possible solutions. I’m hoping to not have to go far down the list for a solution. The guys I have looking at it just did a job for FEMA changing out pumpkins on new trucks somebody ordered that would only run 45, so I’m hoping they find some gears!
 
Gunzy

Gunzy

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Has anyone looked at doing away with the planetaries in all the hubs and going to a direct drive? I would think that would increase speed albeit at the cost of low end torque.
 
C

crazyalaskan

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simp5782 said:
You can find a takeout from behind a 60 series detroit with harness and all that.

The 916s with the 7spd use a stand alone tcm and a a cable drawn tps for the 4700sp.

You could always but a parts truck mtvr and use that transmission and you have spare parts for yours.

A guy on here in Suriname did the PLS planets on his HET

Your could also just add auxiliary transmission behind the transfer case and leave it in OD. Moving the front axle engagement to it's own switch. So all rears could pull with the front freewheel while it's in OD. But you would need to shift it back to direct to use the front axle
Click to expand...
Can I swap the transmission out on the M1070 HET that has the 8V92 and use a Allison HT-755 CR? I have a fresh rebuilt transmission sitting in my yard and I am eyeballing a HET in JBLM but I'm shy of the 45MPH speed. If I can get 55MPH I can manage.
 
simp5782

simp5782

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crazyalaskan said:
Can I swap the transmission out on the M1070 HET that has the 8V92 and use a Allison HT-755 CR? I have a fresh rebuilt transmission sitting in my yard and I am eyeballing a HET in JBLM but I'm shy of the 45MPH speed. If I can get 55MPH I can manage.
Click to expand...
Yes. I have a source for a 7spd Allison 4700 that can handle 600hp. Has harness and all the applicable parts.
 
DeMilitarized

DeMilitarized

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simp5782 said:
Swap to a 7 speed Allison 4560P or a 4700sp with a 6th .74 would give you 16 more mph and a 7th .64 OD would add an additional 27mph.

Or a CAT 7155 would give you a 9mph improvement with the .83 OD


Cat would be the easiest and cheapest swap

Or a Spicer 18 speed. They can be had for around 3500 rebuilt

Or Any 13 speed for that matter.

There were a few eaton 18 auto shifts that came behind the DDEC II 8v92 so that would mate with the computer
Click to expand...
@Elijah95
 
1994M1

1994M1

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simp5782 said:
Yes. I have a source for a 7spd Allison 4700 that can handle 600hp. Has harness and all the applicable parts.
Click to expand...
Hey @simp5782 - I'd love to hear more about this 4700 Alison + harness + parts. I've been doing a lot of research on this and I can't find anyone thats as confident as you. If you're sure this combination adds the speed gains, I'm about ready to pull the trigger.
 
1994M1

1994M1

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1994M1 said:
Hey @simp5782 - I'd love to hear more about this 4700 Alison + harness + parts. I've been doing a lot of research on this and I can't find anyone thats as confident as you. If you're sure this combination adds the speed gains, I'm about ready to pull the trigger.
Click to expand...
simp5782 said:
Yes. I have a source for a 7spd Allison 4700 that can handle 600hp. Has harness and all the applicable parts.
Click to expand...
Let me know how to get ahold of you and lets make it happen!
 
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