8 3/4 axle strength

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Duane

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Went to Toronto motorsports park this past weekend to watch some of the street car nationals event.
Saw a 72 dart with a new style hemi in it that ran a best of 8.93 et at 147 mph with an 8 3/4 axle. Car weight without driver was 2850. Power glide trans 1.36 60 ft.
Guy says he has never broke the rear end. He just changes the gears after every 300 passes.
I asked him what's in there that the axle hold that kind of power and he says Two mark Williams axles caps and a back brace. 3.23 gears moser 30 spline axles
Engine also had a turbo. There is a video of the car on you tube. Look for turbo dart.
Go figure

Duane
 
Duane said:
Went to Toronto motorsports park this past weekend to watch some of the street car nationals event.
Saw a 72 dart with a new style hemi in it that ran a best of 8.93 et at 147 mph with an 8 3/4 axle. Car weight without driver was 2850. Power glide trans 1.36 60 ft.
Guy says he has never broke the rear end. He just changes the gears after every 300 passes.
I asked him what's in there that the axle hold that kind of power and he says Two mark Williams axles caps and a back brace. 3.23 gears moser 30 spline axles
Engine also had a turbo. There is a video of the car on you tube. Look for turbo dart.
Go figure

Duane
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he`s pushin it. we started blowing them everyother week-end. went to a dana 60, end of problem. 3:23 have more tooth contact, and the turbo probably isn't shocking the tires like a gen 2 hemi would.
 
I'll bet the car leaves pretty soft. He has several things going for him, fairly light, power glide and 3.23 gears. Mine with 4.30 gears lasted two passes after I built the 408, 3240 pounds with radials.
 
8 3/4 is a LOT stronger then some people think been running one for 6 seasons now,behind my 416 and 360 no issues to speak of using Moser axles 4.30 with spool,have seen more then a few dana 60's grenade though:D:D
 
stroked340 said:
8 3/4 is a LOT stronger then some people think been running one for 6 seasons now,behind my 416 and 360 no issues to speak of using Moser axles 4.30 with spool,have seen more then a few dana 60's grenade though:D:D
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What is your 60 ft time and weight of car. My Demon did fine with 8 3/4 until I started getting 60 ft. times in the 130's then it broke a ring gear then later broke the cap. My car probably weighed 3400+ with me in it. Stock interior with bench seat , fiberglass hood only.
 
High 1.30s is what my Dart ran when the 408 was fresh, the 8 3/4 broke on the second pass it hooked.

Anything that will break a 30 spline Dana will destroy an 8 3/4.
 
If you're breaking a Dana, you don't need to be around cars. Might wanna try 4 wheeling in trucks/jeeps with Rockwell axles (front and rear) in them. You might have better luck that way. If by some astronomical chance you do break a Rockwell axle, you might wanna find a different hobby. Just sayin :twisted:
 
A rear will last until it's load capacity is met. It is not the amount of HP but the amount of torque. The things that push the rears limits are a short list. Avoid the things you can and the others that can't be avoided don't worry about.
Take a look at the drag racers and hot street cars to take note of the cars (and drivers) weight as raced, tires style, suspension, weight transfer ability, and then the power the engine puts out. Since the rear will fail under extreme torque and/or load, this is the area you have to search on.

Ask the racers how they launch and there '60 times.
Street cars are easier on fears since there's more tire slip/spin.

My buddy had an 8-3/4 live 2 (IIRC) seasons under a all steel '69 Dart with an Indy headed 500 wedge. He was in the 9's. The Dana was next. No issues. And that's is what you would want (The Dana) if your pumping out some power. The track or not.

If your lookin for a number for safe operation of the 8-3/4, limit torque to 500 ft. lbs. & less. While I have seen them live under more power, there also not raced or abused.
 
once we went trans brakes, we went D60 in both cars. we ran the Duster for a bit with the 8.75, but it was twisting the axles pretty good.
 
D-50394 said:
What is your 60 ft time and weight of car. My Demon did fine with 8 3/4 until I started getting 60 ft. times in the 130's then it broke a ring gear then later broke the cap. My car probably weighed 3400+ with me in it. Stock interior with bench seat , fiberglass hood only.
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Was 1.42-1.45..car with me is 3450..
 
justinp61 said:
I'll bet the car leaves pretty soft. He has several things going for him, fairly light, power glide and 3.23 gears. Mine with 4.30 gears lasted two passes after I built the 408, 3240 pounds with radials.
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You call a 1.36 60 ft time a soft leave? He gotta be puttin some torque to it to get that kinda 60 ft no? He gets over 300 passes out of a set of gears and just changes them as Maintainance.

Duane
 
Duane said:
You call a 1.36 60 ft time a soft leave? He gotta be puttin some torque to it to get that kinda 60 ft no? He gets over 300 passes out of a set of gears and just changes them as Maintainance.

Duane
Click to expand...

Yes for an 8.93 a 1.36 60' is pretty soft. My small block steet/strip car pulled a bunch of 1.38s and it ran no where near 8.93.
 
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