6.4 Hemi Gear Swap

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wespentecost

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Wow that's not bad at all with that Steep of gearing to only be turning 2k at 70 mph. I'll have to play with the gear calculators. Id be fine turning 1800- 2k in 6th at 70 with my stock tires...but don't know what gear would put me there.

I know how much those 3.73s woke up an otherwise stock 5.0 mustang going from a 3.08 gear. It made it feel like a totally different vehicle. So i can only imagine what a 4.88 would feel like in my truck with stock tires. I bet i could surprise a few mustangs and cameros...at least off the line.
Same here on my 96 stang I had....3.08 on mine, buddies with 3.55 would pull almost a car length, 3.73 was almost 1.5 but that guy wasnt the best driver

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GsRAM

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Same here on my 96 stang I had....3.08 on mine, buddies with 3.55 would pull almost a car length, 3.73 was almost 1.5 but that guy wasnt the best driver

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Oh yeah! Good memories that's for sure. I may look for an older 5.0 mustang to play with in the next few years. Bring back a piece of my youth...lol. the 350 cameros were tough to beat, especially when the newer ones came out...I want to say late mid-late 90s? They would get me on the big end....no replacement for displacement.

The roller cam 302 sounded great and pulled hard and could take a ton of abuse. Great engine.
 

wespentecost

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Oh yeah! Good memories that's for sure. I may look for an older 5.0 mustang to play with in the next few years. Bring back a piece of my youth...lol. the 350 cameros were tough to beat, especially when the newer ones came out...I want to say late mid-late 90s? They would get me on the big end....no replacement for displacement.

The roller cam 302 sounded great and pulled hard and could take a ton of abuse. Great engine.
Funny you say that! I remember the first v8 maro I beat, I pulled half a car on him. Did it two more times...we met back in the plot of a place we would all meet. He wanted to know what i had under the hood....I laughed and said lots of determination! All I had was intake, h pipe with flows, and synthetic oil. That poor dude couldn't drive his Camaro to save his life, lol! But winning is winning!!

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GsRAM

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Lol good stuff man! Yep as Dom said in the original fast and furious..."winning is winning" lol

A friend of mine bought a 94 mustang boss and we ran. I had a mostly stock 86 mustang, off road h pipe, shifter, exhaust, 3.73 gears. I beat him. He claims he spun too much...lol. a win is a win and he hated it.

Also took down an early 90s firebird or Camaro. My brothers friend thought was super fast. Man I did so much street racing in those days (dumb) it's by God's grace I'm still here

I was never a huge mopar fan back then and unfortunately in those days besides for turbo 4s they had no rear drive v8 powered coupes to compete with Ford and Chevy.

The new chargers and challengers are awesome though. Chrysler really nailed the retro look with them.

Sorry to derail this thread for my trip down memory lane....lol
 

wespentecost

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Lol good stuff man! Yep as Dom said in the original fast and furious..."winning is winning" lol

A friend of mine bought a 94 mustang boss and we ran. I had a mostly stock 86 mustang, off road h pipe, shifter, exhaust, 3.73 gears. I beat him. He claims he spun too much...lol. a win is a win and he hated it.

Also took down an early 90s firebird or Camaro. My brothers friend thought was super fast. Man I did so much street racing in those days (dumb) it's by God's grace I'm still here

I was never a huge mopar fan back then and unfortunately in those days besides for turbo 4s they had no rear drive v8 powered coupes to compete with Ford and Chevy.

The new chargers and challengers are awesome though. Chrysler really nailed the retro look with them.

Sorry to derail this thread for my trip down memory lane....lol
Yeah...lots of stupid stuff for me too!

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BOB RAM 2500

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So I finally had my 456 gears installed. 75 mph on the highway at 2100 rpm’s with 34 1/2 inch tires and 15.5 miles per gallon according to the onboard computer. What a huge difference in the amount of power available to me now. Never downshifts going over simple Street bridges on I 95. Can’t wait to break it in for 500 miles to see how it does on my fifth wheel trailer. So far around town mileage seems to be about the same as it was between 10 and 11 MPG.
 

SuperBeeMike

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So I finally had my 456 gears installed. 75 mph on the highway at 2100 rpm’s with 34 1/2 inch tires and 15.5 miles per gallon according to the onboard computer. What a huge difference in the amount of power available to me now. Never downshifts going over simple Street bridges on I 95. Can’t wait to break it in for 500 miles to see how it does on my fifth wheel trailer. So far around town mileage seems to be about the same as it was between 10 and 11 MPG.


Break them in right and you will love having those 4:56's. I can't say enough good things about changing from my 3:73's to the 4:56's. My mileage is about 16/17 on the highway and 13/14 in the city.
 

BOB RAM 2500

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I really can not understand why the 373's were an option for this truck. The 456's seem to be a natural for every day driving ... and the power you get to the ground is just amazing. Can't wait to pick up my 5th wheel tomorrow and see how the towing improves.
 

BOB RAM 2500

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Well, picked up my 14,200lb 5th wheel 2019 FOREST RIVER CEDAR CREEK SILVERBACK 37RTH. I don't know what it would have been like with the 373's but I will tell you, the 456 will get this down the highway @ 65 MPH 2600 rpm with power to spare. You may not take off from a stop like you are at the drag strip, but a solid pull through the gears and getting up to speed. You should use the tow haul as it seemed like the transmission would slip sometimes between shifts. I am not smart on this stuff so any inputs about the trans are much appreciated. Oh did I forget? 65mph cruise control and getting 9.2 mpg on the flat land. I wasnt getting that with my truck camper and boat attached (approx 6400 lbs) with the 373's.
 

Ratket

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Definitely use tow haul when pulling a load, it changes more parameters in the transmission than we can prolly fathom
 

Ole 340

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Reading here you guys are doing the same thing I did with a 2WD 1985 F-150 straight 6. Been awhile so don't recall exactly the ratios but about 300 to 373. Truck ran rather better and better milage. Agreed on the 373 in the 6.4 being to high gearing. Between that 6th gear ratio and the anchor drop that leap from first to second is (ridiculous for a 6 speed) it feels similar my old 3 speed autos. Think about it. Truck probably hits the rev limiter at 80 in second and is governed at maybe 106. I don't pull enough or run mountains to justify doing the swap on this one, the motor has plenty snot to compensate my use, but I'd like the lower gearing for sure.

Someone commented way back their 410 whining at 60-65 mph. My 373 rear is quiet till 60 and full on whine with a touch of gas or more at 61. Comes on that sharp. Not that bad but clearly audible above the radio. Dealer says completely normal, nonsense. Great truck but I could do without that and I don't have a good setup guy close anymore, one a little over two hours away. I'd never trust a dealer on a gear swap or to reshim the pinion, what mine needs. Some can I'm sure but not many. Good gear guys are rare, always were.
 

BOB RAM 2500

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New picture of my rig after the 456 gears swap. 2019 forest river cedar creek silverback 37RTH. Time to go camping LOL
 

lharrell79

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Well, picked up my 14,200lb 5th wheel 2019 FOREST RIVER CEDAR CREEK SILVERBACK 37RTH. I don't know what it would have been like with the 373's but I will tell you, the 456 will get this down the highway @ 65 MPH 2600 rpm with power to spare. You may not take off from a stop like you are at the drag strip, but a solid pull through the gears and getting up to speed. You should use the tow haul as it seemed like the transmission would slip sometimes between shifts. I am not smart on this stuff so any inputs about the trans are much appreciated. Oh did I forget? 65mph cruise control and getting 9.2 mpg on the flat land. I wasnt getting that with my truck camper and boat attached (approx 6400 lbs) with the 373's.


Bob, what kind of mpg are you getting, while not towing? Also, what kind of range do you have per tank?

I'm currently shopping for new trucks, and it's between the new 4.30 6.2 F250, or Ram 2500 6.4. I really like the ram. However, it really does need 4.56 gears from the factory, to match the gear ratios of the Ford.
 

BOB RAM 2500

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So I am getting about 15 to 16 miles per gallon at 75 miles an hour on flat driving Highway. As for range it’s a fairly small gas tank I think. I do so much city driving that the range is not very good. Local mileage in town is between nine and 10 miles to the gallon. Towing 14,000 pounds at 65 mph I’m getting around 9 miles per gallon with the 456 gears. They only offer of 373 and 410 from the factory I do believe.
 

Ratket

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May be worth waiting to see if an 8 speed is released.
 

lharrell79

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May be worth waiting to see if an 8 speed is released.
The 2019 HD is supposed to debut today. The base engine is supposed to be the 6.4, mated to an 8HP75 (8 speed). The 8HP75 can have two different gear sets. No telling which gear set will be used, but either is a vast improvement over the 68RFE.

8HP75

First – 4.71/5.00
Second – 3.14/3.20
Third – 2.10/2.14
Fourth – 1.66/1.72
Fifth – 1.28/1.31
Sixth – 1.00/1.00
Seventh – 0.83/0.82
Eighth – 0.66/0.64
Reverse – 3.30/3.45

Ford Torqshift-G

First – 4.17
Second – 2.34
Third – 1.52
Fourth – 1.14
Fifth – 0.87
Sixth – 0.69
Reverse – 3.40

Even if Ram uses the taller gearing 1st 4.71, 2nd 3.14, etc. The final drive ratio will be on par with the Ford's Torqshift G transmission. Essentially, the 2019 Ram 2500 with 6.4, 3.73, 8HP75 will be the equivalent of the 2019 F250 6.2, 4.30, and Torqshift G. The 6.4 and 8HP75 combination could be the ticket.
 
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