Check Out My Math On IH Pulling Gear December 29, 2018 07:53AM
I need something close to a 16 MPH pulling gear and heres what I have in the rear end plus a IH tranny that has all the good parts...

13-73 bull gear
13-51 ring and pinion
28-45 constant mesh
34-39 pulling gear (if one is available) that I would put in the 3rd gear slot which still has stock gears....I need direct plus 1 & 2 over to pull other classes several times a year with different tires..

3000 rpms
227 inch tire circumference

I came up with 15.88 MPH be I could be off a mile as it gets confusing...Math never was my specialty..I do have an all stock tranny except for a 1566 input shaft..
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 09:31AM
Anyone??? Heres the formula that I used after researching several old topics on here...

Bull Gears 13 divided in to 73 = 5.615 ratio
Ring and Pinion 13 divided in to 51 = 3.923 ratio
Constant Mesh 28 divided in to 45 =1.607 ratio
Pulling Gear 34 divided in to 39 = 1.147 ratio-will put it in the 3rd gear slot unless thats not advisable..
Multiplying all of them gives a 40.60 ratio..

3000 rpms divided by the 40.60 ratio =73.891 x 227 inch tire circumference =16773.398 x .0009469 =15.88 MPH..

Is this correct or am I off a mile?? I hate to buy some $800 gears if they won't give me 16 MPH..
I have no idea where the .0009469 comes from but thats what some on here use to figure MPH..
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:05PM
You may be correct in your calculations, however that's a perfect world calculation. You haven't considered that you are draggin a 40000 lb sled behind you, or that your tires are going to slip. I recommend having faster gears than you will need so that you can more precisely dial in your actual track speed in real world conditions. Best of luck in your adventure.
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:08PM
You won't be able to stay dead on 3000 rpm either. Just saying many variables in real world pulling.
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:15PM
Quote
Tire slip
You may be correct in your calculations, however that's a perfect world calculation. You haven't considered that you are draggin a 40000 lb sled behind you, or that your tires are going to slip. I recommend having faster gears than you will need so that you can more precisely dial in your actual track speed in real world conditions. Best of luck in your adventure.

I'll be pulling a 12.5 MPH class...
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:19PM
Been running 16 mph for a few yrs now... A gear that runs 16 mph at 3000 is way too slow..... Stock 3rd in an Ih (18.5) mph at 3000 is closer to what the majority of guys run around here... The sleds we pull are set up as being speed sensitive.... All things equall, the tractor closest to the speed limit wins 9-10 times. Not a big fan of these setups, just the way it is though... Good Luck
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:29PM
Lol, I see you responded to previous poster while I was typing....... That setup may work...... 3.5 mph over 12.5 may be tough to keep tractor lit... what weight class? Running 3.5 over 16 would be mighty tough to keep tractor lit at mid track and night light it and go over speed...... Don't ask me how I know.. Around here in the 10-12 mph classes, the sleds don't drop near as hard. Therefore , the speed is not such an issue. A lot depends on how heavy the class is..
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Re: Check Out My Math On IH Pulling Gear December 30, 2018 02:58PM
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Been there
Lol, I see you responded to previous poster while I was typing....... That setup may work...... 3.5 mph over 12.5 may be tough to keep tractor lit... what weight class? Running 3.5 over 16 would be mighty tough to keep tractor lit at mid track and night light it and go over speed...... Don't ask me how I know.. Around here in the 10-12 mph classes, the sleds don't drop near as hard. Therefore , the speed is not such an issue. A lot depends on how heavy the class is..

10,500 lbs with 570 cubes and should have plenty of horsepower.....Hopefully it will stay lit at 2400-2500 rpms until I can go full throttle...I have several different chargers to try...The tractor that usually wins loafs a long at around 2500 rpms and is probably full throttle the last 20-30 ft..
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