8 3/4 or ford 9 in.

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trbodrt

trbodrt

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I need some technical advice, with an 8 3/4 and the right after market parts can i put a 1000 hp through it or would i be better off going with a 9 in.
 
Thats strange...you have 10 posts here, you come on a Mopar Board and ask if you should use a FORD differential over a Mopar..

A 741 8.75" carrier is proven to be stronger than a stock 9" Ford.
A 489 carrier will handle 600 hp.
A 742 carrier has the largest and strongest Pinion...and I have never heard of a 742 carrier being broken.

How much Hp are you making/building for?

You could always go the DANA 60 route and forget either of your choices completely if you intend to be putting 1000+hp through the rear....They are damn near indestructible.

IMO find a 742 SG carrier and forget about it till it breaks....you have to be getting some serious bite, and throwing a helluva lotta torque at one to get it to pop.

.02
 
No... An 8 3/4 will not hold up to 1000 hp. Questions like this tell me you shouldn't be thinking about a 1000 hp build.

I assume you have a large income if you are planning a build like that.

1000 hp builders normally have designers, engineers or pro builders in the mix, what have yours had to say?
 
First of all one guys says yes and one guy says no, so that tells me someone doesn't know what they're talking about, second many people i've talked to said an 8 3/4 will not hold up to that kind of power but I like to get as many different opinions and find out if anyone has ever tried to put that kind of hp through one.
 
I have one guy telling me if i don't know a certain rearend won't take the abuse i probably shouldn't be doing the build then i think it deserves that response.
 
Ok hears your answer.there is no rear stock that is going to hold up to 1000hp unless you have one costom made.the 8 3/4 is better then the 9"{my opinon}But if you are building a 1000hp car I would be talking to strange axle or someone like that. Mark
 
thank you for a kind opinion, whatever ends up going under the car would definetly not be stock of any kind
 
trbodrt said:
I have one guy telling me if i don't know a certain rearend won't take the abuse i probably shouldn't be doing the build then i think it deserves that response.
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I told you.... An 8 3/4 will not hold up to 1000 hp.

And yes... I do feel that if you are doing a so called 1000hp build and you need to ask bad questions, you shouldn't be doing a 1000hp build.

Why don't you start with a nice 400hp build learn and move up from there.
 
trbodrt said:
I need some technical advice, with an 8 3/4 and the right after market parts can i put a 1000 hp through it or would i be better off going with a 9 in.
Click to expand...

To be honest, I didn't see anything wrong with posing your question to the group. I have run a 9" in my '52 Dodge truck and I had one in the '35 Plymouth coupe I am building. I did remove it recently to run an 8 3/4 but it was soley because I wanted to keep this project all Mopar (except for the rear disc brake setup - which is another story).

I am going to second dartcuda1's reply. Neither of those rearends (especially in stock form) are going to come close to handling that kind of hp. I would be even leary running a dana in stock form thinking about the application and what kind of driving would take place with a car with a 1,000 hp motor. Any specialized car (but especially one with this kind of power) needs to be custom built with custom built sub-assemblies and parts.
 
If your going to be making(wishfull thinking)anywhere near a 1000 h.p. you should be talking to Moser about building you a dana 60.i believe they are getting $1600.00 complete and when or if my 8 3/4 finally gives up i'll be ordering one:thumrigh::thumrigh:
 
when i talk about either rear end i'm no way talking in stock form. I'm not that crazy.
 
I dunno' whether this fellow is actually building 1000 horsepower or not, but his question about what will hold up seems an honest and legitimate one to me, why stir up doubt?
I'd certainly want to know if it were me and I hadn't done it, which I haven't.

I do suspect that you are going to need a DANA 60, at the very least, for this build.

Also, the '489 case 8-3/4 Mopar is much stronger, with a thicker pinion shaft cross section than a '742, you just need to use the crush sleeve eliminator kit to get rid of the '489's weak point.
Add the power lock Sure Grip, or a good 35 spline spool and it's an excellent rear end.

A 9 inch, even with all the aftermarket parts, is a mediocre choice.
Even built with all the best, they pretty much can't take what an 8-3/4 can take with very little A/M vendor support.

Mark.
 
IMHO..........a 9". One of the reasons a ford 9" is pretty much bullet-proof is there are 3 pinion gear teeth in contact with the ring gear instead of 2.

My $.02 worth, however I run a Strange Dana 60.
 
Either one would hold up to 1000 hp............ provided you ran only temporary spare tires.
 
Yeah, so I confused the Tapered 489 Carrier with the 742 thick straight pinion shaft.

I posted misinformation...out of forgetfulness....I knew the tapered pinion was the stronger, I just don't mess with carriers enough to REALLY know ALL the details all the time.

Get a Custom built DANA 60 and forget about it.
 
I see I have stirred up some contoversy which was not my intention so let me explain myself, before I knew the amount of power i would be making I aquired an 8 3/4 housing that i pulled from a C body at the junk yard, another time out I found a 489 third member, I figured since I already had the parts it would be nice to hear if anyone was ever able (with the right after market parts) to put that kind of power through one or if anyone even ever tried to. I know for a fact a lot of drag racers use the 9 inch w/ after market internals and put a lot more than 1000hp through them.
 
I will arque that a 489 is stronger than a 742. The 489 stem diameter at the gear is 1.875 while the 742 is 1.750. The 742 bearing behind the yoke is much larger than the 489 which shares the same bearing as the 741. They are both good units but the 742 gets my nod for being the strongest.
 
I'm going to strongly suggest that you sell the 8 3/4 you have already. Or hold on to it. Whatever. But do not use it for this "1,000 HP" build. You will need at least a DANA 60 rear. They are really strong stock. But if you custom build one than your golden.
 
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