8 3/4 rear end not strong enough?

[msbaugh]

Hey guys,
I have a question for all you who know your stuff with rear ends.
I just bought a 70 chally, and have only had a couple of weeks with it. So far everything looks pretty good with the car, the motor runs strong and everything is working alright... The engine is a 440 magnum with a 750 carb, and almost 7k worth of head work. It's a very powerful motor... whoever had it before me set it up like drag car. I have already replaced the carb with another 750 with larger primaries and a choke just so it would idle better and start no probelm. I have not really gotten to drive it on the road yet, but will soon.

When i first put it up on the lift I noticed something a bit discouraging... The rear end is a 8.75 but seems to be a "741" according to the casting. It also doesn't have a cover on the front side of the housing revealing the gears. I know that this rear is the weakest of the 8.75, which is the problem.
My question is, will this rear end hold up with such a powerful set up? I dont know exactly if the've tweaked it at all, but im pretty sure it doesn't have the sure grip, which is a no no in my book.
Any advice?

 

[DetMatt1]

Drive it till you wear it out and have your replacement 742 or 489 waiting for the swap. None of them are to difficult to find or terribly expensive. What makes you think the 741 that you have is not a sure grip?, a 741 that is in good shape will take a hell of a beating, but I could see wanting to swap it out if it is not a sure grip.

 

[msbaugh]

Not totally sure yet. I have not had much time with the car lately mostly because i've been so busy. That's most likely what I will end up doing though. Running it until it busts and then switching to a 742

 

[burntorange70]

Don't do any burnouts with it if it does not have a sure grip. That will kill it quick. But ya I would just run it till it gives up on you.

 

[msbaugh]

no burn outs?! haha I don't know how long i can handle that

 

[6packcuda]

I wouldn't be too worried about the rear holding up. The tires will give long before the rear does. If you were running huge horsepower and slicks I'd be concerned.

 

[burntorange70]

I think it should hold up well. But if it does go I don't think another 8 3/4 will do any better. May as well go with a Dana 60 and be done with it.

Jack the back of the car up then turn one of the tires. If the other tire turns the same way it has a sure grip. If it turnes the opposit way it is an open diff and you need to be carful about doing one leg burnouts.

 

[Rob C]

A buddy of mine has run as quick as 9.20 in a all steel 69 Dart with a Indy headed 500 cid wedge. This car has seen many many street miles for a long time. The 8-3/4 held up fine, but did brakein the end.

I think the rear preety strong after watching yearly abuse in the street and at the track. The 741 case should be replaced with the above mentioned 742 or 489 for the bigger pinion gear. Though, if your going to run slicks and hit the track in a powerful engine, I beileve a DANA would be well suited for the job and problem/worry free.

 

[71Plym]

Its all good until you get traction