8 3/4 center section - What is the best?

[lucascosta21]

Hi everybody,

I recently read an article about rear differentials and it says that the 741 center section (2070741) is the weakest available.

I just purchased a 68 Charger powered by a 440 high compression and I will swap the auto trans by a 4-speed Spline 23 and I checked my center section and it is a 741. I am worried because I will invest in a 4spd trans and in the future I want to upgrade it to a 6-pack carburator and I'm not sure anymore if my rear axle will be able to support this.

Follow the link I read:

http://www.mopar1.us/875.html

Please, help me with suggestion. I don't have budget to buy a new differential, I've been checked in Ebay and some guys ask more than $1000 for a rebuild.

Thanks a lot.

Lucas

[Sublime/Sixpack]

The 742 and 489 third members are stronger than the 741. But with that said I think you'd be hard pressed to break the 741 with a relatively mild 440 unless you're running big sticky meats in the back and constantly hammering it from a dead stop over and over again. 

[Kern Dog]

That factory put a Dana 60 behind 440 4 speed cars but I wonder if that was to cover themselves against warranty claims?
The 741 is still a strong unit. The 1 3/8" pinion is the "least" strong of the three most common center sections. It is still adequate.

[birdsandbees]

This belongs in the drive train section, but my '69 Bee has a 741 in it from a '66 Charger. 2.94 gears. Was put in when the original rear axle fell apart in 1978 and this one has been beaten hard and put away wet since I was 16 years old. Clutch dumped daily, drag raced on Sundays, run flat out on the highways and considering I just had it apart in the last few months to inspect, I can say it has ZERO issues some 39 years later. Center section wiped clean and put back in the housing, other than a new pinion yoke seal. New axle bearings and seals... and only because it needed seals. Bearings still fine at 51 years old!

[lucascosta21]

Thank you, guys.

If I make an upgrade for 6-pack, 741 still keeps adequate?

A sure grip is a great idea for it?

[Sublime/Sixpack]

Thank you, guys.

If I make an upgrade for 6-pack, 741 still keeps adequate?

A sure grip is a great idea for it?

Yes, you'll definitely want Sure-grip! Rather than buy/install a Limited-slip unit into your 741 third member I'd check the "You Pull It" type wrecking yards in your area. Sometimes you can pick up a 489 Sure-grip unit with 3.23 gears for little cash. Granted they are getting harder to find but they do show up once in a while. FWIW The 489 third member will have a larger yoke on it. There's a special u-joint you car buy and install to make your existing driveshaft work with the 489 yoke.

[1974dodgecharger]

you wont bust any of them.....unless your a hardcore racer....

[cdr]

I would not waist one DIME on any 8 3/4 rear end hot rod 4 speed car period.  dana 60 all the way.

[Lennard]

I would not waist one DIME on any 8 3/4 rear end hot rod 4 speed car period.  dana 60 all the way.

I know quite a few guys that drag race with an 8 3/4 axle behind +- 600 hp engines for years now without any problems. They are automatics though.

[cdr]

I would not waist one DIME on any 8 3/4 rear end hot rod 4 speed car period.  dana 60 all the way.

I know quite a few guys that drag race with an 8 3/4 axle behind +- 600 hp engines for years now without any problems. They are automatics though.

I did say 4 speed 

[1974dodgecharger]

I would not waist one DIME on any 8 3/4 rear end hot rod 4 speed car period.  dana 60 all the way.

I know quite a few guys that drag race with an 8 3/4 axle behind +- 600 hp engines for years now without any problems. They are automatics though.

just how much abuse you put it through its the torque that's gonna kill that rear end.....

[Bronzedodge]

I'd check the "You Pull It" type wrecking yards in your area. Sometimes you can pick up a 489 Sure-grip unit with 3.23 gears for little cash. Granted they are getting harder to find but they do show up once in a while.

I want to visit whatever area you're in!  The few good yards left in the mid Atlantic area are disappearing quickly.

Like others have said, you'll be hard pressed to break a 741 carrier unless you have sticky tires. 

[fastmark]

I build a lot of rear ends for customers. Yes a Dana 60 is the best but not necessary on a street car. I've bought good third members at swap meets for a fair price. You have to be able to tell the good stuff from the junk.  The ratios for the 741 are not available as easily as the better 489 or 742.  Scrap yards will sell you any third member for the same price so get a 742 or 489 as a core. You'll be lucky to find a cheap sure grip at a salvage yard. Doctor diff sells the best deal on a  suregrip with the improved 1968.5 sidegear design. Other suregrips can be hard on the axle splines because they have two piece side gears. This is not a cheap hobby anymore.

[68 RT]

Just use what you have till it breaks since you have no budget for it. Save up if it does break you can buy a 742 or 489. If its tight and not making noise you should be good for a while.

[c00nhunterjoe]

Save the money, build a dana. I built mine for under a grand. Or buy the strange s60 unit if you dont have the tools and k owledge to build it yourself.

[John_Kunkel]

If you're gonna run ordinary street tires, chances are you won't break any of the 8 3/4's. When you get some tires that really bite, you starting busting rear ends.

[Sublime/Sixpack]

I'd check the "You Pull It" type wrecking yards in your area. Sometimes you can pick up a 489 Sure-grip unit with 3.23 gears for little cash. Granted they are getting harder to find but they do show up once in a while.

I want to visit whatever area you're in!  The few good yards left in the mid Atlantic area are disappearing quickly.

Like others have said, you'll be hard pressed to break a 741 carrier unless you have sticky tires. 

I did say "sometimes", and that "they are getting harder to find".

But if you're in the right spot at the right time they do occasionally pop up. Some people walk right past the C-body cars and vans without checking them.

[lucascosta21]

I will probably set it with 275/60/R15 tires in the rear and 255/70/R15 in the front. Does this set is a lot for my 741?

The car will be projected to the streets but I want to let it with 3.55 as minimun rate. Probably higher because I like short gears/more tork instead of long gears (road way drive).

What do you think, guys?

[Dino]

It's fine, I beat on my 741 and it doesn't budge. Sure that's with an auto but even with a 4 speed you'd have to go pretty nuts all day every day to break one of these.

Besides, what's the harm? IF it breaks you replace it with something else. No loss except maybe a tow ride home.

[c00nhunterjoe]

I twisted stock 8 3/4 axle shafts with a mild 440, 11" converter 3.91s and 255/60 street tires.

[Kern Dog]

The stock ones or a discount pair from Harbor Freight?   

[c00nhunterjoe]

The stock ones or a discount pair from Harbor Freight?   

The factory origonals, then a replacement pair. Neither broke, but i could feel them twist on launches. Pulled to inspect and verified. 

Broke several sets on my little 383. Stock and upgrades. Went to dana- no more problems.

[Kern Dog]

You must be pretty skilled to be able to know that. Sort of like being "One with the machine".

[c00nhunterjoe]

When one twists vs the other it can kindof feel like a suregrip that opens. The car just doesnt feel right. Sometimes it will even pull to one side.... or worse when one breaks. Lol. I saved the one out of my plymouth that twisted. I will have to look for it.