8 3/4 Diff strengths?

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I am just saying that in any instance a larger diameter shaft is alway stiffer and stronger all other things being equal. If you are trying to keep precision machined gears precisely aligned under extreme load, that larger diameter deflects less.

That's not true n this case. .....and once again this is splitting hairs, but let's split them completely, shall we? The 489 is not the strongest, because it uses a crush sleeve. That in itself is a weak point. With a crush sleeve eliminator, it's a different story, but stock for stock, the 742 wins out of the three.........even if just barely. You really need to understand the 8.75 as a whole in order to make a statement about them, because their strengths are so close, that any of the three could fail under the exact same circumstances.

In short, it's simply not a difference worth arguing over. Yet here we are.
 
Personally I like the 742 housing the best, because it has the largest inner pinion bearing And has no crush sleeve.

Exactly. But again.......and I know you agree, splittin hairs.
 
Street/tires racing dont matter what so ever. If your trans brakin or clutch droppin above 4000rpm with not low enough gear with slicks Regardless of HP. Then you should be concerned...........
 
all that and no mention of HP capability, isn't it around 800 horses with street tires and less with drag slicks?

The 8.75? I think 800 is well beyond the 8.75's capacity. That's Dana territory.
 
It's a hell of a lot more than a 7 1/4 (250 HP) and the 8 1/4 (450 HP) 8 3/4 (750 plus). Those are the figures I have and they are supposedly right but any nut can break a 350 HP rear end with a stuck truck and have only 150 HP.
 
I am not trying to argue, but I do not believe any stock 8.75 can withstand 700 plus HP. Maybe 700 FLYWHEEL HP, but not 700 at the rear axle. Ain't happenin, IMO. At least not for very long.
 
I know of a couple high 9 sec A-bodies running 8-3/4s at the track, but I've also seen a couple break in high 11 sec cars though too. Waaaayyy too many variables to put a HP limit on them.

Hell, I know it's apples to oranges, but my late uncles 7.60 FED ran an 8-3/4. Many old FEDs and fuel altereds did back in the day. Of course they don't weight anything though. Like I said- waaayyy too many variables.
 
That's not true n this case. .....and once again this is splitting hairs, but let's split them completely, shall we? The 489 is not the strongest, because it uses a crush sleeve. That in itself is a weak point. With a crush sleeve eliminator, it's a different story, but stock for stock, the 742 wins out of the three.........even if just barely. You really need to understand the 8.75 as a whole in order to make a statement about them, because their strengths are so close, that any of the three could fail under the exact same circumstances.

In short, it's simply not a difference worth arguing over. Yet here we are.
You missed the part where I said all other things being equal.
A crushed sleeve versus solid spacer is not equal.
I do not consider this an argument, but a discussion or debate.
No ill will intended on my part.
 
You missed the part where I said all other things being equal.
A crushed sleeve versus solid spacer is not equal.
I do not consider this an argument, but a discussion or debate.
No ill will intended on my part.

Nor mine. Yes, I saw where you talked about eliminating the crush sleeve. Without that however, it's a pretty level playing field.
 
489's and 742's break in the same places as 741's do. Been there, done that and seen it many times.

BTW, it was a good design for it's intended use.
Agreed. Good design for its intended use, which was not launching off a transbrake, but it's ability to last for 100,000 miles. IMHO the larger diameter would help achieve that.
 
I'm a big 8 3/4 fan but I'll tell ya this. 600 Real horsepower, nicely prepped track, great hook, 4500 clutch dump and say bye bye. And were talking good innards, too. Mark Williams stuff.

I think a little wheel spin is definitely a good thing.
 
I am not trying to argue, but I do not believe any stock 8.75 can withstand 700 plus HP. Maybe 700 FLYWHEEL HP, but not 700 at the rear axle. Ain't happenin, IMO. At least not for very long.


Sorry to say but my buddy with the 750 flywheel HP blown 340 Demon has been running his with a 8 3/4 rear end for 13 years and no problems and that is with sticky street tires...he is not the easiest guy on the gas pedal.
 
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