I have a few questions about my 440 Charger with an 8 3/4" that is my daily, but I plan to bring to the strip once in awhile (and of course have fun at stoplights) First, has anyone ever seen a 741 pinion shaft cause any problems? I hear alot about how the 742 and 489 have bigger shafts, but how much does that matter? Second, if I am running 550 hp max, would I need anything to strengthen the rearend, and if so what? Third, in general what else would I need to beef up the car.(sub frame connectors?) I already plan on getting at least torque boxes. (Also, I already know half of the responses will be "get a Dana 60 or 9" Ford. I would only get a Dana 60 if it is cheaper than all necessary rear end upgrades)

i have beat on several 741's, [3.91 & 4.10] that i got from /6 trucks and vans that had sure grips, without problem number one. all the pinions neck down to the same diameter at the flange, so not being a rear gear expert by any means, i really don't give it much thought.
also, i have only been at 425/435hp, so for an extra 100hp or so, maybe use a brace on the housing ? i never have done that, but if i would, i'd go clear to the backing plates, using inserted tubes for the u-bolts.
subframe connectors help at any level, tightening up the car a lot. don't know if this helps or not. i'm sure you will have other responses different than mine. luck to you !

Where the 8 3/4 fails is pinion gear deflection inside the housing. So diameter at the flange is irrelevant, it doesn't deflect there.

If you really have 550hp and excellent traction you might have a problem and no back brace will handle the pinion deflection. All a back brace does is add extra unsprung weight here, which is exactly what you do not want in a handler. Now if you want to clean up the housing and make sure the tubes are fully welded and straight then that's fine.

In my humble opinion, I think your rear end will be just fine as long as you are running street tires & NOT slicks of any type. (if you run slicks, you need hardened axles & a driveshaft safety loop + ?) If you use slicks, then an 8-3/4" can get maxed out in heavy cars....but I think 550hp would be just fine (no DANA needed).

If you plan to race (at all), then get a copy of the current NHRA rule book. See what safety upgrade requirements your car has & put them in.


In general, I personally love frame connectors & driveshaft safety loops are cheap & pretty easy to install, so I install those whether required by NHRA or not. For street-tire cars, you might want to consider an adjustable pinion snubber OR some old-school "slapper" traction bars....maybe an clamp or two on the front of the leaf springs. Then, just go race & see what your Charger does.

Nick,

Run the 741. It uses a smaller bearing at the pinion head, but not by much, and it's not likely to fail.
It also has the significant advantage over the 489 of not using the crush sleeve (they suck).

As always, set up is important, you want a healthy differential section (preferably good aftermarket or a power lock clutch type) and a ring and pinion that is not showing abnormal wear. As far as strengthening, the first area to look at would be the main caps (carrier) but you are very likely fine with stock.

I too would run the 741, never seen one break the pinion shaft, have seen teeth broke, but that's all 8 3/4's. Frame ties really stiffened my dart up and I would recommend them as one of the first mods to make.

That's the pinion deflecting. the 9" has a support bearing on the end of the pinion that prevents this.

Yes all 8 3/4's suffer from it, the case is big part of the problem. The 9" is a great desigm, just not super strong in stock configuration. I broke two in four wheel drives, one busted the internal housing around the tiny support bearing.

They all have their issues that's for sure.

As stated many times, all of the 10-spline pinions neck down to the same size at the spline so failures are normally somewhere else but there are exceptions.

Like said before, a backbrace on an 8.75 is a waste of time.
If the car is a 4 speed, you'll be a lot more likely to break it. If you never get traction, it'll live a long time.

I plan on it being a 5 speed (the TKO600) so would ur comment still stand with that?

The whole key to this is if the car hooks it will kill the 8 3/4. If you only run it with street tires it will spin or your launch will be so soft it won't be a problem. If you put slicks on it,save your money and get a Dana. I have killed 8 3/4 rears with considerably less than 550 hp in A body NHRA stockers.

All 4 speed 440s and hemis came from the factory with Dana 60s. I wouldn't expect an 8.75 to last very long in a 500+ hp stick b body.

All? Hmm wonder what they put in Hemi cars before they started using the Dana?

Wonder why they started using the Dana?

Not all 4 speed Gen II Hemi cars used a Dana.

But the point is, the 8 3/4 was failing in that application nd Chrysler went with the Dana.

Since everyone loves dana 60’s so much, has anyone bought a complete dana 60 (or 8 3/4 if that option is still open to some) from moser engineering?

I bought a Strange S-60 because it uses spanner nuts to adjust the backlash. If I ever need to change gears no case spreader will be needed.

Have bought 3 Dana 60 from Doc Diff...Strange Dana 60 make with adjusters makes swapping gears alot easier.

It has yet to be proven what exactly could be deflecting with a 8.75. I am not convinced the ring is not also a contributor here. On the pinion, it its double bearing widely spaced (relative to the 9" with no cantilever), although a small cantilever, the size/dia of the pinion shaft plays a role in deflection under load as its stiffness controls pinion off axis movement. Street tires I would be fine with 741, but any money invested is throwing it away, at least a 742 has resale value. I agree also on back brace is mainly cosmetic in this application. Might want to consider a DS safety loop if any of this advice is wrong.

I wasted $1200.00 on my 8.3/4 in my Charger, put Drag radials on it & killed the 8 3/4. NEVER will i spend money on 8 3/4 again. got a S60 from DR Diff with the S Trac carrier, it cost more but works AWESOME, I dont know my HP but car is heavy 4050 with me, so far 11.33 @ 121.1 1750 DA