what gears to run?
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Junior User
Joined: Jan 2003
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From: Louisiana
what gears to run?
Just need a little advice on what gears to buy for mud racing. I'm running a 1982 F-150 SWB with a 460 aluminum intake 750 crab and mild cam 204/214 dur@.5 479/504 lift, a C6 auto and NP208 transfer (planning to run in low range) with a 9" rear and Dana 44 strait axle in front turning 38" Swamper Bogger's. Stock gears are 3.50:1 any thoughts or ideas would be appreciated.
Thanks.
Thanks.
Postmaster
Joined: Jul 2001
Posts: 4,038
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From: South Kitsap County, WA
what gears to run?
If you can dyno the engine and find your peak torque and horsepower curves I might be able to give you an idea on what you should run. It'll depend on the friction coefficient of the tires and mud as well....
I know it sounds way out there, but all top racing teams (I'm talking about circle track, road course, and drag racing) hire engineers to figure this stuff out and those are the numbers they start with. Then they figure in spring rate, shock rebound and tire air pressure, and center of gravity.
-Kerry
I know it sounds way out there, but all top racing teams (I'm talking about circle track, road course, and drag racing) hire engineers to figure this stuff out and those are the numbers they start with. Then they figure in spring rate, shock rebound and tire air pressure, and center of gravity.
-Kerry
Senior User
Joined: Mar 2000
Posts: 448
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From: Chimacum/Jefferson County
what gears to run?
I have a 77 F250 highboy with a tired 400, C6 trans, NP205 transfer case, Dana 44 up front and a Dana 60 in the rear with 4.09 gearing and 38.5 TSL and run in 4 high all day in the mud or on trails. Works good for me.
Postmaster
Joined: Jul 2001
Posts: 4,038
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From: South Kitsap County, WA
what gears to run?
Ok... did some figuring-
If you leave the truck in 4LO and run the truck through sticky mud
you'll hit 2000rpm at around 7 mph so you'll be in your peak torque curve at launch (which may cause a problem if you mash the gas right off the bat and have a great deal of torque in that engine) if you run a 4.11-4.11 (D44-9")gear combination. You'll be through the max hp curve at 46 mph in third. I'll need definite numbers on your HP and torque curves and the TC stall speed to give you better info. I'm thinking 3.73's if you want to run in 4LO ir even leave the stock 3.55/3.54's just to take that edge off the launch. It'll allow a higher top end, but not by much...try 53 mph.
Maybe the 4.56's will be a better bet in 4HI, you'll be under the peak torque curve at launch so you won't be throwin' mud and goin' nowhere. The torque converter will make up for any short comings in the higher gearing (over the 7.10 you'd have in 1st with the truck in 4L). The 4.56's will give you a peak speed of 107mph at 4500rpm.
Hope it helps somewhat, the 4.10's will help marginally with top end, but may not hook up the same in the sticky stuff. They will also be more streetable, if you need to drive the truck on the highway.
-Kerry
If you leave the truck in 4LO and run the truck through sticky mud
you'll hit 2000rpm at around 7 mph so you'll be in your peak torque curve at launch (which may cause a problem if you mash the gas right off the bat and have a great deal of torque in that engine) if you run a 4.11-4.11 (D44-9")gear combination. You'll be through the max hp curve at 46 mph in third. I'll need definite numbers on your HP and torque curves and the TC stall speed to give you better info. I'm thinking 3.73's if you want to run in 4LO ir even leave the stock 3.55/3.54's just to take that edge off the launch. It'll allow a higher top end, but not by much...try 53 mph.
Maybe the 4.56's will be a better bet in 4HI, you'll be under the peak torque curve at launch so you won't be throwin' mud and goin' nowhere. The torque converter will make up for any short comings in the higher gearing (over the 7.10 you'd have in 1st with the truck in 4L). The 4.56's will give you a peak speed of 107mph at 4500rpm.
Hope it helps somewhat, the 4.10's will help marginally with top end, but may not hook up the same in the sticky stuff. They will also be more streetable, if you need to drive the truck on the highway.
-Kerry
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Joined: May 2002
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From: Southwestern Michigan
what gears to run?
I am using 40" tires and 5:13 gears in my mudtruck 429cid. D44 front and 9"rear.
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From: missouri
what gears to run?
first question is this a pure mudd truck or will you drive it to the mud runs??? if it a pure mud truck you can do more to it get deeeper gears I raced my bb dodge with 3:54's in 4 low with a 4 speed and got my butt whipped by my buddys sb dodge with 4:11's in 4 low we was both running 36 tires. but yes a auto will do better in my opinion also a good ideal I saw it at the mud pitt
was get a locked rearend and a locker for the front open diff's do good but if you have all 4 going it will do better and what I mean about a pur mud truck is you can weld the rearend spider gears together and the front spider gears also but will need locks out on the front you don't want to do this to a good daily driver this is how we do our stock cars a poor man locker as we call it.
was get a locked rearend and a locker for the front open diff's do good but if you have all 4 going it will do better and what I mean about a pur mud truck is you can weld the rearend spider gears together and the front spider gears also but will need locks out on the front you don't want to do this to a good daily driver this is how we do our stock cars a poor man locker as we call it.
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Junior User
Joined: Jan 2003
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From: Louisiana
what gears to run?
Pure race truck. It has a 9" rear and I cant get to the spider gears to install a Lincoln locker because it's a factory posi, the spider gears are almost completely hidden however I do have a Dana 60 that’s welded but I don’t know what gears it has. I haven’t had time to pull the cover and count them out yet.
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From: Marysville Wa
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