Hello all, I've searched to find no answer on the internet for the specs On my 1949 Chevy Dually axle. Anyone interested in chiming in? I may run it for a year or two with the old drum brakes. Just want to know what I have. I appreciate any help offered. Attached are a few pics.
If you have specific questions, post them in the appropriate forum. In each new thread/question, give the make, year, model truck you are referring-to/working on.
Hy BignScar, welcome, your rear axle is a vacuum shifted Timken double reduction two speed, that was the factory two speed differential in that era, hope that helps.
Hy BignScar, further research has identified two possible ratio options, one is 6.13 to 1 in high gear, 8.10 to 1 in low gear, or 6.70 to 1 in high gear, 8.86 to 1 in low gear, hope that helps.
Bignscar My 51 6400 has that same 2-speed axle works fine !
That's good to hear, I'd really like to keep the rear axle. What's your power train set-up? My goal is to be able to drive it a lot Have a smooth ride on the freeway Pull a 5th wheel camper Add 4wd Possibly go big block, like 427 or 454 eventually I have a 5.3 4wd powertrain I can use now though Brought it home today.
Nice truck. 4wd front axle gets sort of high off the ground because stock frame does not have enough arch to allow for front driven axle to clear. Can be done OK, just have to allow for that. Look at factory late ‘50’s 4wd conversions.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
Hy BignScar, further research has identified two possible ratio options, one is 6.13 to 1 in high gear, 8.10 to 1 in low gear, or 6.70 to 1 in high gear, 8.86 to 1 in low gear, hope that helps.
So if I want this to be capable of freeway driving one day, and I keep this stock Differential, hook it up to; let's say.. a 4L80e, what do you believe top speed in overdrive will be?
You have to figure out what size tires you are running. Once you have that, you need to know the circumference. Many tires have specs you can look up on line. The number you are looking for is revolutions per mile. Once you have that number it is easy to translate that to RPM at 60mph. in drive. Multiply that by the overdrive ratio, .i.e. .87 x rpm@60 in 1:1 = overdrive rpm.
You have to figure out what size tires you are running. Once you have that, you need to know the circumference. Many tires have specs you can look up on line. The number you are looking for is revolutions per mile. Once you have that number it is easy to translate that to RPM at 60mph. in drive. Multiply that by the overdrive ratio, .i.e. .87 x rpm@60 in 1:1 = overdrive rpm.
If you ever plan to load your truck up, the 4L80E might not have a low enough 1st gear to get you moving...something to think about and you'll need a lot more HP/Torque to do it. You may need to think about using an Allison Truck Transmission.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
If you ever plan to load your truck up, the 4L80E might not have a low enough 1st gear to get you moving...something to think about and you'll need a lot more HP/Torque to do it. You may need to think about using an Allison Truck Transmission.
Mike B
Mike B thank you so much sir.
Just confirmed it's a two ton 6100 (unless it was a typo ment to say 6400?) Sticker says 16,000 GVW
I belive you are correct needing an Allison Truck tranny Which is an exciting new realm for me to look into
Definitely want something around 600 Hp for an engine
Suggestions on what Model Allison Trans to start searching for? I'm also interested to hear motor Suggestions
Other than suggesting the Allison trans I'm of no further use in this discussion...putting a 600 HP engine in a AD Dually is not something I've ever thought about doing and I have no idea if there's even an Allison that would be up for that much HP.
I had a 1977 Kenworth W900A with a Cummins NTA-400 and a 13-speed RR with OD and 3.90 rears that would run 85 mph, but your front axle would be flattened if that engine and trans were set on top of it.
The 6100 has a 137" wheel base while the 6400 is 161".
Keep us posted with your project, I'd like to hear more about it!
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
Other than suggesting the Allison trans I'm of no further use in this discussion...putting a 600 HP engine in a AD Dually is not something I've ever thought about doing and I have no idea if there's even an Allison that would be up for that much HP.
I had a 1977 Kenworth W900A with a Cummins NTA-400 and a 13-speed RR with OD and 3.90 rears that would run 85 mph, but your front axle would be flattened if that engine and trans were set on top of it.
The 6100 has a 137" wheel base while the 6400 is 161".
Keep us posted with your project, I'd like to hear more about it!
Mike B
Input is appreciated Mike, been looking at possibilities all day. It's going to take a while for a final decision. 600hp is up there at the Max of the spectrum. In reality, ill most likely end up at 350-400. Tons more research to do That's for sure.
Getting back on topic, one thing about the 4l80 transmission that I do not like is the ratio in 2nd gear. I have two 3/4 ton suburbans. One is an 86 454 THM 400 w/3:73 rear ratio. The other is a 2001 6liter 4L80 w/4:10 rear ratio. The 86 actually has a little taller tire that reduces the effect of the ratio some. I have a vintage 31' Airstream trailer. There is no doubt that the 2001 would pull faster and probably win a drag from the stop light, but when you try crossing independence pass, the 454 truck will March up in 2nd gear at 45 MPH., without feeling like you are thrashing it. With the 6l truck, I have to run in 1st gear at 25- 30. The ratio in 2nd gear is too tall even with the lower final drive. The 454 makes torque, the 6l makes horsepower. (There is a photo of my 86 in the new gallery section.)
Getting back on topic, one thing about the 4l80 transmission that I do not like is the ratio in 2nd gear. I have two 3/4 ton suburbans. One is an 86 454 THM 400 w/3:73 rear ratio. The other is a 2001 6liter 4L80 w/4:10 rear ratio. The 86 actually has a little taller tire that reduces the effect of the ratio some. I have a vintage 31' Airstream trailer. There is no doubt that the 2001 would pull faster and probably win a drag from the stop light, but when you try crossing independence pass, the 454 truck will March up in 2nd gear at 45 MPH., without feeling like you are thrashing it. With the 6l truck, I have to run in 1st gear at 25- 30. The ratio in 2nd gear is too tall even with the lower final drive. The 454 makes torque, the 6l makes horsepower. (There is a photo of my 86 in the new gallery section.)
Just something to think about.
Steve
Thank you Steve, good information; good to know. I tried to check Out the photo of your 1986, but couldn't find it. It's not much fun navigating a forum on a cell phone. I'm sure that section will pop out to me when I get on a pc with a normal monitor, 😄 Originally, I was thinking 427 or 454, but also looking at Cummins options. I've never owned a diesel, still like the idea of gas a little bit more. But the more research I do; the more it leans towards diesel. Hoping to find a donor truck in the next year or so. In the meantime I have tons of body work to keep me busy
What 600hp engine do you plan on fitting in an AD truck? If your rear ratios are 6 and 8 to one, probably can start out with an auto in the low ratio. Might consider fitting a Brownie trans in there, however a 6000 series is quite large. Original rear end might not stand up to that kind of HP or RPM.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
To do all the things you've talked about, highway speeds, pulling a 5th wheel trailer and all. Have you thought about moving your sheet metal onto a modern GM Medium Duty Truck chassis? You'd have to widen the front clip to cover the wider axle, but the complete drivetrain would already be engineered. And to try and fit a Cummins with an Allison into your existing chassis your already going to be doing a lot of custom sheet metal work to make it all fit...just a thought.
Mike B
Mike Boteler
1956 Chevy 3100 Resto Rod 1952 Willys M38 Army Jeep 1983 Jeep CJ7 Laredo 1984 Jeep CJ7 +++++ Silver Spring, MD
What 600hp engine do you plan on fitting in an AD truck? If your rear ratios are 6 and 8 to one, probably can start out with an auto in the low ratio. Might consider fitting a Brownie trans in there, however a 6000 series is quite large. Original rear end might not stand up to that kind of HP or RPM.
Ed
Doing a lot of research at the moment, 600 being at the top of the pipe dream, I've been looking at crate engines along with complete damaged vehicles as donors. I am doubtful the original rear end is going to make the cut, but still considering it. Long way to go, this is the beginning of a few years of hard work. Going to check out the brownie Trans stuff as you suggested. Thanks Ed!
To do all the things you've talked about, highway speeds, pulling a 5th wheel trailer and all. Have you thought about moving your sheet metal onto a modern GM Medium Duty Truck chassis? You'd have to widen the front clip to cover the wider axle, but the complete drivetrain would already be engineered. And to try and fit a Cummins with an Allison into your existing chassis your already going to be doing a lot of custom sheet metal work to make it all fit...just a thought.
Mike B
Considering this also Mike, Definitely would mean a lot less fab work, and the integrated engineering is highly appealing.
BignScar My driveline is 235 insert brg./sm 420 8.25 rubber happiest at about 48 MPH I live by a smooth class 3 truck route runs great on that. I think theratio's are 6.14 and 8.10
BignScar, I mounted my ‘37 GMC frame and all on Dana 80 rear axle, solid front axle, power steering and hydro boost brake system(4 wheel 10 lug discs) from a P3500 HD baby school bus. Works out well with modern running gear. Easy to get parts for. Engine is a Detroit diesel 4-53T(but Cummins 5.9 would also fit in there) with RR 10 speed and Brownie. Room in grille for large radiator and i’cooler.
P model GMC’s are getting hard to find but regular pickups also have 10 lug wheels, large engine bay.
Ed
Last edited by EdPruss; 03/02/20218:23 PM.
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
Finding a 4WD front axle to match the ratio of your rear axle sounds impossible to me. Which side of your two speed do you choose? 4WD is not practical with your original, or any two speed rear axle.
Most modern 4wd vehicles get by just fine, no matter what body is on the running gear, with being geared for cruise speed at say 70 or so, and get adequate reduction with their main trans, be it auto or manual OD plus gear reduction in two speed transfer cases.
Ed
'37 GMC T-18 w/ DD 4-53T, RTO-610, 6231 aux., '95 GMC running gear, full disc brakes, power steering, 22.5 wheels and tires. '47 GMC 1 ton w/ 302, NP-540, 4wd, full width Blazer front axle. '54 GMC 630 w/ 503 gasser, 5 speed, ex fire truck, shortened WB 4', install 8' bed. '55 GMC 370 w/270, 420 4 speed, grain, dump bed truck from ND. Works OK.
Ya guys, the original rear axle is not going to make the cut. Would of been cool and all but ehh whatta ya gonna do. Glad scrap Prices are up, doubt anyone on earth would be looking for it lmao Appreciate everyone's help and input!!
BignScar, I mounted my ‘37 GMC frame and all on Dana 80 rear axle, solid front axle, power steering and hydro boost brake system(4 wheel 10 lug discs) from a P3500 HD baby school bus. Works out well with modern running gear. Easy to get parts for. Engine is a Detroit diesel 4-53T(but Cummins 5.9 would also fit in there) with RR 10 speed and Brownie. Room in grille for large radiator and i’cooler.
P model GMC’s are getting hard to find but regular pickups also have 10 lug wheels, large engine bay.
Well my first battle was getting it in the barn, big thanks to my buddy Johnny for coming over with the v10 f-250 and giving it a push (yes it needed to be in 4wd 😄). And so it begins, taking it apart for metal prep and paint. Gonna need a new impact set, so many Big Bolts haha
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Martin '62 Chevy C-10 Stepside Shortbed (Restomod in progress) '47 Chevy 3100 5 Window (long term project) ‘65 Chevy Biscayne (Emily) ‘39 Dodge Business Coupe (Clarence) “I fought the law and the law won" now I are a retired one! Support those brave men/women who stand the "Thin Blue Line"! Hug a cop! USAF 1965-1969 Weather Observation Tech (I got paid to look at the clouds)
You can ask the forum Moderator to change the title for you, however he will have to change it in every single post. Very time consuming. My suggestion is to just start a new thread every time you change subjects and let this thread die. By doing that folks searching for subjects in the future won’t have to read through all the extraneous stuff. The Moderator will appreciate it.
Sounds good, do I have a 6100 or 6400? Anyone? Thanks!! ðŸ˜ðŸ¤“
Bignscar Have noticed when I go to high axle it seems a little out of balance.then downshift then go back up it smooths out. that is at about 50 MPH top end for me ! Maybe a little more in hot weather, I have a rare in illinois class 3 truck hiway you can really fly on it's smooth. Probably need to balance all six too !
The 6400 series has a number of sub models. Go to the GM Heritage website. it contains tons of information, spec's, stock and optional RPO's, dimensions, gear ratios, tire sizes, etc gmheritagecenter.com
Last edited by Chevy's till I d; 03/08/20216:28 PM.
