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Eaton HO72 Tech Thread

Absolutely guys are twisting them, imagine the weight of 1974 chevy station wagon sitting on top of your tire as you try to accelerate. Some guys are running over 500hp. Iv seen 40 spline semi floater mosers break in this sport.
 
Demoman said:
Absolutely guys are twisting them, imagine the weight of 1974 chevy station wagon sitting on top of your tire as you try to accelerate. Some guys are running over 500hp. Iv seen 40 spline semi floater mosers break in this sport.
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Yet guys beat on 14b shafts with 43 stickies, 500 hp and hopping up and down on dry rock with decent luck.:laughing:

Guys also get away with much smaller rearends in drag racing than rock crawling.

I have been to one very legit demo derby (border bash with a $10k grand prise) and I was pretty surprised at how much money some guys have into derby parts.:smokin:
 
Yeah i know guys who have 50k into a drivetrain and interior setup that transfers from car to car.. we also run tires inside of tires and skid steer and forklift tires that are heavy and stiff.. id imagine the rock crawler and drag guys have alot of tire flex that is forgiving on shafts
 
Demoman said:
Absolutely guys are twisting them, imagine the weight of 1974 chevy station wagon sitting on top of your tire as you try to accelerate. Some guys are running over 500hp. Iv seen 40 spline semi floater mosers break in this sport.
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500hp doesn't mean anything on a dirt arena with negligible weight to actually find traction.

A V6 F150 in low range and hooked to a pulling sled or a dumb yuppie trying to wheel hop their way up a ledge in their 4Runner is gonna abuse an axle far more because it actually has weight and therefore traction on the driven axle.
 
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arse_sidewards said:
500hp doesn't mean anything on a dirt arena with negligible weight to actually find traction.

A V6 F150 in low range and hooked to a pulling sled or a dumb yuppie trying to wheel hop their way up a ledge in their 4Runner is gonna abuse an axle far more because it actually has weight and therefore traction on the driven axle.
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yeah but 74 chebby wagon, 3/4 cam, sum bitch'll jump a coke can :laughing:
 
did i read a mini spool from 14 bolt will work? and by work does that mean pull spider gears and put mini spool in place and put in 14 bolt shafts?
 
chaplinfj60 said:
so if a mini spool is so easy is there a down fall. like the carrier still a weak spot?
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Some diffs, yes the carrier is a weak link. Most of them are usually OEM LS carriers that had beef removed to make room for clutches. On a HO72 I wouldn't worry.
 
Can anybody verify if a 5.89(ish) ratio truly exists for the HO72? I would hate to waste countless hours trying to find one if it is just an unfounded rumor they exist.
 
i can not confirm, but in my readings i only ever heard of 410 457 514 or there abouts. again this is just what i remember.
 
Defecater said:
Can anybody verify if a 5.89(ish) ratio truly exists for the HO72? I would hate to waste countless hours trying to find one if it is just an unfounded rumor they exist.
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5.89s are listed in GM literature, but have never seen one in person.
 
Tech Tim said:
5.89s are listed in GM literature, but have never seen one in person.
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Had to take a wild guess, I'd say your better off looking at old equipment (airport tugs, lifts) for that low of a gear.

5.89 seems low for transmissions that only had 1to1 final drive.
 
Gravy said:
Had to take a wild guess, I'd say your better off looking at old equipment (airport tugs, lifts) for that low of a gear.

5.89 seems low for transmissions that only had 1to1 final drive.
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It is, but thats how they made heavy stuff move back in the day. Nothing really had much more hp than anything else, just lower gears :laughing:

I mean this exact axle came in regular pickups with 5.14s and 31" tall tires.
 
YotaAtieToo said:
It is, but thats how they made heavy stuff move back in the day. Nothing really had much more hp than anything else, just lower gears :laughing:

I mean this exact axle came in regular pickups with 5.14s and 31" tall tires.
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And an SM410 trans with the granny low 1st gear.

Probably because the engine only had 150 hp(?)
 
06h3 said:
AlxJ64 said he had a 5.86 gear set back in the day but didnt even realize it
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Correct, and sold it to someone as a 5.14 and they got mad at first but then realized they could use it after all. This was about 6 years ago now. If I had realized what it was instead of just a rusty pile that was assumed as 5.14 (because it turned more times than the 4.57s so I assumed 5.14). I wish I had gotten pictures of it.
 
Do they have a ratio tag on them somewhere? Never noticed one on the few I have looked at so far
 
Was hoping for a tag on outside to save time identifying ratio
 
Ok I got this info from the 67-72 truck forum, and honestly, I haven't seen evidence that you can find the stuff in the actual SPID codes for the trucks, because I went down that rabbit hole last night, even in C20 and C30 trucks, but here is a list that shows codes for very deep gears in single speed rear ends that should be Eatons. Do with it what you will, and don't shoot the messenger, but there might be some nice unicorns out there.

67-72 option codes

outintheshop.com

Looking for 1970 K20 build sheets - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Looking for 1970 K20 build sheets The 1967 - 1972 Chevrolet & GMC Pickups Message Board
67-72chevytrucks.com

anyone know a place to see everything that could have been listed on a SPID - The 1947 - Present Chevrolet & GMC Truck Message Board Network

anyone know a place to see everything that could have been listed on a SPID The 1967 - 1972 Chevrolet & GMC Pickups Message Board
67-72chevytrucks.com
 
Drummer79 said:
Ok I got this info from the 67-72 truck forum, and honestly, I haven't seen evidence that you can find the stuff in the actual SPID codes for the trucks, because I went down that rabbit hole last night, even in C20 and C30 trucks, but here is a list that shows codes for very deep gears in single speed rear ends that should be Eatons. Do with it what you will, and don't shoot the messenger, but there might be some nice unicorns out there.

67-72 option codes

outintheshop.com

Looking for 1970 K20 build sheets - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Looking for 1970 K20 build sheets The 1967 - 1972 Chevrolet & GMC Pickups Message Board
67-72chevytrucks.com

anyone know a place to see everything that could have been listed on a SPID - The 1947 - Present Chevrolet & GMC Truck Message Board Network

anyone know a place to see everything that could have been listed on a SPID The 1967 - 1972 Chevrolet & GMC Pickups Message Board
67-72chevytrucks.com
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Judging by the weight ratings for those axles, I am going to bet those are medium and heavy duty axles
 
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