Which is stronger

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ronw

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Just curious, if you were building a rear by narrowing it and putting together the gears would you use an 8.75 or a 9.25? Which would be stronger? Or which would you choose and why? I just happened to have the parts for both. Thanks Ron
 
Actually, I'd probably pick a Ford 9". Way more parts available. So far as that goes, I would think a 9 1/4 would be lean on parts on the market
 
67Dart273 said:
Actually, I'd probably pick a Ford 9". Way more parts available. So far as that goes, I would think a 9 1/4 would be lean on parts on the market
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Was thinking that exact same thing.
 
I have heard the ford 9 inch has much more friction and is a bit of a power robber if you want to split hairs
 
8.250 will be easy to find and more affordable.
 
What 9-1/4" do you have? The recent 2005-ish area corporate LSD's have had some issues.
I've heard of narrowing issues due to the tube style that changes diameter.
 
I have a Ford 9" behind my 600+ HP 493 stroker in my 65 Belvedere. No issues whatsoever. Although, it is a spool!!
 
ronw said:
Just curious, if you were building a rear by narrowing it and putting together the gears would you use an 8.75 or a 9.25? Which would be stronger? Or which would you choose and why? I just happened to have the parts for both. Thanks Ron
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What's it going in? HP and weight? Stick or auto?
 
Daves69 said:
What 9-1/4" do you have? The recent 2005-ish area corporate LSD's have had some issues.
I've heard of narrowing issues due to the tube style that changes diameter.
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My dads 2004 ram has a 9 1/4 rear and at 125000 miles the rear locked up. Turs out the axle seals leaked gear oil and locked it up, it was a fairly easy rebuild though.

I say go 8 3/4 or dana
 
Automatics did sometimes get the 8-3/4. There fine for 600 level.
The DANA would be the best way to go. Period!
 
Cudafever said:
Really? I thought 440 4 speed and ALL Hemis here DANA 60's
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Only about 66? 67? or so and later. I don't think "all" 440s were 60s, either. In fact 440-6 autos were 8 3/4 unless ordered as a 60
 
I thought some of the super stock guys swapped their dana's for 8.75's due to weight and parasitic loss.
 
The 9.25 is out of a later 80's police car. I haven't had it apart but I'm thinking it has a posi. I just have the rears with no plans right now to do anything with them. Just thought I would get everyone's thoughts. Ron
 
johnnymac2k6 said:
I thought some of the super stock guys swapped their dana's for 8.75's due to weight and parasitic loss.
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talk to guys who raced back in the day and the two things that were common
..remove the Dana and replace with 8 3/4
..remove the Hemi and replace with 440
 
johnnymac2k6 said:
I thought some of the super stock guys swapped their dana's for 8.75's due to weight and parasitic loss.
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The opposite is true for parasitic loss I believe.
Weight wise, it's really not a big change. While every pound counts, it shouldn't count if longevity comes into play. Look up threads on the 8-3/4 vs a DANA or Ford 9.

ir3333 said:
talk to guys who raced back in the day and the two things that were common
..remove the Dana and replace with 8 3/4
..remove the Hemi and replace with 440
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Yep, it is true, stupid people in every decade existed.

Ronw, the 9-1/4 should be stronger. The pinion size is nice and large. However, as mentioned, parts maybe of an issue. I'm not sure how that narrowing vs. axle taper issue would play out. I myself have never seen a 9-1/4 narrowed.

If you ever narrow it, do so document it all and keep recorded prices. Thanks
 
I have no experience with a 9 1/4 so I can't comment on their strength. If your car is light weight, auto and doesn't hit the tires hard the 8 3/4 may be fine. Mine broke on the second pass after installing the 408 in my 3260# Dart. It couldn't take the 1.38 60'. After removing and disassembling the 727 to check the sprag I rebuilt the 8 3/4 and promptly sold the complete rear end. My Dart now has a Strange S-60 in it.

You can find 9" parts pretty cheap and IMO it's a better option than either rear you have for a car with decent HP.

As far as parasitic drag goes I don't think anyone on this board with a street or street/strip car would notice it.
 
justinp61 said:
I have no experience with a 9 1/4 so I can't comment on their strength. If your car is light weight, auto and doesn't hit the tires hard the 8 3/4 may be fine. Mine broke on the second pass after installing the 408 in my 3260# Dart. It couldn't take the 1.38 60'. After removing and disassembling the 727 to check the sprag I rebuilt the 8 3/4 and promptly sold the complete rear end. My Dart now has a Strange S-60 in it.

You can find 9" parts pretty cheap and IMO it's a better option than either rear you have for a car with decent HP.

As far as parasitic drag goes I don't think anyone on this board with a street or street/strip car would notice it.
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Just the guy I was thinking of! Did you post up on the Strange installation?
I don't think I would recommend the 8-3/4 for anything over 3000 while doing race duty.
Sure, you can brace them and swap to discs for lighter weight and .....
As the been there and done that crew here always states, do the DANA over the 8-3/4. Cheaper out right IIRC over a modified 8-3/4.

I have a 9-1/4 in my Magnum. But I'm not pushing it at all.
 
I think I'd rather use the 8 3/4. It's a welded case and easier to brace and won't have the issues of partially welded tubes or trying to weld to cast iron. Assuming you have to add strength to it for whatever reason.
 
i thought the Dana was nearly 100 lbs heavier.
Didn't Didduck replace the Dana with an 8 3/4 in his 9 sec. Hemi RR?
 
Rumble I don't think I posted anything when I installed my Dana, it's been in about six years.
 
If you have the parts, build the 9.25 it is one of mopars rears that I have not been able to break.
I have blew 8.75 out with a slant six, one owner car gave to me by my grandpa.

Beat a stock 9.25 hard in this Ram charger running 44" tires and a 4-speed, no issues.
Probably more stress on that rear jumping around in the mud, rocks than a street car would see, plus I wheeled in 2wd most of the time.

pWiJ2g.jpg
 
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