8 1/4 rear end strength?

[aris_unlimited]

Well long story short I finally checked my rear end and found it was an 8 1/4 and not an 8 3/4 like I assumed it would be. Pure laziness on my part lol, but there it is. Anyways I decided to keep that rear in the car, because I really don't feel like putting the money into an upgrade (and lets face it, if I'm going to upgrade I might as well go dana 60 and that will cost me). So I figured I could spend less money and do some strengthening on this rear end.

So it had me thinking what kind of power limits it could handle? I've seen on some places where people claimed to be running 600 hp for years and theirs hadn't broken. And I've heard that it was an upgrade from the 8 3/4 and that's why they stopped making the 8 3/4. Now I've also heard that they are weak and completely garbage, which I don't know if it is just my optimistic side but I don't think anything is really garbage so long as it is built right and you understand it's reasonable limitations.

Anyways it will be used behind a small block with at least 400 hp. I've been considering possibly pushing that up to 500 hp with forced induction. I never go to the track, although I might a couple of times after the build to just see how it does. So it will be 99% street car and I doubt it will ever see slicks on it. But I do have plans for fairly wide tires (12ish inches, can't remember the exact width). So combo would be a 318 stroker 904 trans 8 1/4 rear. Do you think it will handle it? And if so what should I do to the rear for durability? Keep in mind that the supercharger is just a passing idea right now, and I would stick with the 400 (crank) hp build if I thought that adding the supercharger would grenade my rear end lol.

[HP2]

Should live on a street cruiser that never sees track time and slicks. Avoid any neutral drops or heavy shocking of the drivetrain and you can make it live until you get to the Dana.

Anything can live with high power it is handled judiciously. Its the "drop the hammer and drive it like you stole it" mentality that tends to break things. If you want to drive it that way, then you should plan on drive line upgrades.

[Denison636]

I like to see that 318. A 400 hp 318 is hard to do. I got a lot of money in a 340 to get them power levels.
But on a another note. The 8-1/4 will work great. I bet it has highway gears so it will be a one wheel tire frier. I would start watching Craig's list for a 8-3/4", or if you don't want to ever have to worry go for the Dana 60. If you don't mind cutting you can get these all day in a junk yard.

[rockymopar]

The best thing about this rear is that 3.55 or 3.91 suregrips are in every bone yard

['Cuda Hunter]

I run an 8 1/4 with 410's and a 383.  Soon to be a 400.  Hasn't exploded yet.  And it gets driven like it's stolen.  You shouldn't have any problems.

[aris_unlimited]

I like to see that 318. A 400 hp 318 is hard to do. I got a lot of money in a 340 to get them power levels.
But on a another note. The 8-1/4 will work great. I bet it has highway gears so it will be a one wheel tire frier. I would start watching Craig's list for a 8-3/4", or if you don't want to ever have to worry go for the Dana 60. If you don't mind cutting you can get these all day in a junk yard.

I'll post a copy of the dyno sheet when I get the engine built. Might be a bit though. I am basically following a build I found in a magazine about 400 hp 318. The only differences I am planning is a mild stroker (thinking 349, 318 bored .030 and 360 crank). Also changed the cam a tiny bit. From what I understand the big benefits come from the more aggressive cam coupled with magnum heads.

[Chryco Psycho]

If you actually compare things the 8 1/4 is about as tough as the 12 bolt GM , it is overlooked mostly because Mopar had far better diffs available , the other factor here is even a 400 HP 318 will not build a ton of torque which is the killer so I doubt you will have a problem for a while

[aris_unlimited]

So what I've been thinking of doing for upgrades on the 8.25 is:
convert it to 29 spline axles, harder axles as well
truetrac lsd
stronger housing cover
and a complete rebuild

Thinking that should enable it to hang well enough. And it will cost me a lot less than building a dana 60 for it.

Sound good to you guys?

[Katfish]

You priced that yet? Tru track, axles and complete rebuild sounds expensive.
Can't you get a complete Dana ready to bolt in for under $2k?

[aris_unlimited]

From what I've researched swapping to a dana 60, I would have to:

Make it fit, means cutting tubes or adding longer tubes
swap in gears I want
Convert to higher spline axles
replace braking components
Add a truetrac
new axles
complete rebuild

By the time I'd be done it would be closer to $4k. Unless I could find a dana 60 that was originally in a 71-74 b body, that would save some money.

Heck I was even contemplating a Ford 9 inch if it would be cheap enough. But once you build it up, it gets pricey as well.

Also take into consideration that I have to pay someone to do all the work and custom fabbing rear ends suddenly becomes much more expensive.

[brads70]

From what I've researched swapping to a dana 60, I would have to:

Make it fit, means cutting tubes or adding longer tubes
swap in gears I want
Convert to higher spline axles
replace braking components
Add a truetrac
new axles
complete rebuild

By the time I'd be done it would be closer to $4k. Unless I could find a dana 60 that was originally in a 71-74 b body, that would save some money.

Heck I was even contemplating a Ford 9 inch if it would be cheap enough. But once you build it up, it gets pricey as well.

Also take into consideration that I have to pay someone to do all the work and custom fabbing rear ends suddenly becomes much more expensive.

Go talk to/research Cass from DrDiff . I got my Dana from him with the trutrac upgrade and a few other upgrades. No regrets! Get the popular B-Body width and be done with it.
 http://www.doctordiff.com/strange-60.html
http://www.doctordiff.com/drivetrain/dana-60/

[aris_unlimited]

Go talk to/research Cass from DrDiff . I got my Dana from him with the trutrac upgrade and a few other upgrades. No regrets! Get the popular B-Body width and be done with it.
 http://www.doctordiff.com/strange-60.html
http://www.doctordiff.com/drivetrain/dana-60/

And what did that cost you?

Looking at the website it appears to be pretty close to $3k all in. I don't want to spend more than $2k.

[brads70]

And what did that cost you?

Looking at the website it appears to be pretty close to $3k all in. I don't want to spend more than $2k.

I don't remember exactly but ya most likely around 3K . Prices have gone up since I bought mine too. If you have an unexpected issue with what your planning that extra 1K might not seem to bad? 

[aris_unlimited]

Considering it will probably take me 2 years to scrounge together $3k vs 1 year for $2k...

Seems like a big deal to me.

[HP2]

With a 400 hp small block, even force inducted, I think your Dana 60 plan is overkill, especially on a street car. The stock Dana axles and sure grip will be plenty strong. If your a street car, there also is little reason to change out brakes as well.  I'd think with initial purchase, size to fit and basic rebuild, you could come in under $2k for a conversion.