Diff ID

[aussiewannabee69]

Hi i have a 440 6 pack in my 69 coronet. not a original setup, i think it had a 318 in it previous.
I wanna know if this diff will be able to hold up with the setup i have now or will i have to upgrade to something stronger

 

[Bb70charger500]

That rear is good for up to around 450-500 h.p.
There good rears people up grade to the 742 but if your motor is stock leave it be

 

[4mayhemi]

Sure Grip or not? What have you done to the 440? Do you like to swap for races or just want bulletproof? Don't get em started again (have a lookee here)!
http://www.forbbodiesonly.com/moparforum/threads/8-3-4-or-dana-60.131528/

 

[aussiewannabee69]

That rear is good for up to around 450-500 h.p.
There good rears people up grade to the 742 but if your motor is stock leave it be

ok sweet, yeah its only a street driven car with a cam but thats it.

Thanks!

 

[Bb70charger500]

Yeah leave it be I've been contemplating the same but you know what I'll leave it in there till it quits then I'll upgrade!
Good luck

 

[aussiewannabee69]

Sure Grip or not? What have you done to the 440? Do you like to swap for races or just want bulletproof? Don't get em started again (have a lookee here)!
http://www.forbbodiesonly.com/moparforum/threads/8-3-4-or-dana-60.131528/

i was just worried because the info that i have found says its for the 6 cylinders or small v8s being the 741 case.

 

[BeepBeepRR]

I heard those were also in Max Wedge cars too. Not sure about that but something to think about.

But here is a shitton of info on the 8.75 rear ends. http://www.mymopar.com/Mopar8_75RearEndGuide.htm

 

[beanhead]

i was just worried because the info that i have found says its for the 6 cylinders or small v8s being the 741 case.

The 741 casting uses a smaller pinion gear and u-joints, yes it's what the factory used for some /6s & the lo-po v8 cars...it can live with your setup, but it's generally not recommended...you're going to be making lots of torque, the best long-term solution is find a 742 or 489, all the cases interchange with the housing & axles on the 8-3/4

 

[aussiewannabee69]

The 741 casting uses a smaller pinion gear hand u-joints, yes it's what the factory used for some /6s & the lo-po v8 cars...it can live with your setup, but it's generally not recommended...you're going to be making lots of torque, the best long-term solution is find a 742 or 489, all the cases interchange with the housing & axles on the 8-3/4

Yeah thats what i was worried about. Especially since i live in Australia, finding something like that gets hard.

 

[66Satellite47]

For a street car with limited traction the 741 probably works OK for a while. If you get traction with a big block it won't last very long especially in a heavy car. The bigger pinion (489 or 742) setups are much stronger. Chrysler knew what they were doing back in the day with big blocks. Many of the 6 Paks (4 spd or auto) came with the "Super Trak Pak" Dana 60 rear axle. That is probably overkill for a street mild 440.

 

[aussiewannabee69]

I have found a few 489s on ebay. What are the axles i should look for to go with it?

 

[PurpleBeeper]

I have found a few 489s on ebay. What are the axles i should look for to go with it?

I think your current rear end is just fine & should last a long time. If you do go with a different center section, I think your existing axles will fit. However, I just heard something about spline count on '70 & up or something like that being different ???? So, I guess double check that. Someone else here probably knows for sure. Your axles will be the correct length for sure.

 

[AMX364]

Input yoke spline is different, axles same. 7 1/4 is the weak rear end, not the 8 3/4.

 

[1967coronet440]

If you have the funds to upgrade I would do it just for peace of mind. Every one of us gets a heavy foot from time to time wether it's a stock motor or heads cam etc... every time your foot goes to the floor there's potential for a failure.

 

[Fran Blacker]

What u-joints are in the car? May need an adapter u-joint if you go to a 742 or a 489. If it's a 318 driveshaft it would have 7260 u-joint.

http://www.actionmachineinc.com/ujointmeasuringguide.aspx

 

[aussiewannabee69]

I have found a few diffs on ebay all with different ratios. What would be a good ratio for it. Street driven car, 3 spd trans 3000 stall. 18"rims

 

[Daves69]

Some info here on 8.75"....................
http://www.bigblockdart.com/techpages/875axle.shtml

 

[Fran Blacker]

Guys need to know what kind of driving your going to do. How far you will travel, city, wide open spaces or a mix.
I put a 4.10 in my car as a tryout. 25 miles was enough to convince me way to much. Had 3.55's and 3.23's in the car also. Drove 350 miles with 3.55's at no more than 70 mph at 3100 rpm, no problem with 26" tires. Bigger tires less rpm. smaller more rpm. There are, many variables.

Edit: Re-read your post that 3000 stall convertor I think need more gear than a regular one. I have no experience with them. I lean to 3.55's.

 

[beanhead]

Ditto what Fran said...It's not so much the rim size but overall tire height that affects final drive ratio/rpm. You mentioned street car but with 3000 stall I'd go with no less than a 3.55 on 28" tire (that's low profiles on an 18" rim) personally I'd do a little taller tire and at minimum 3.91s to utilize your converter, which hopefully matches your camshaft

 

[aussiewannabee69]

Ditto what Fran said...It's not so much the rim size but overall tire height that affects final drive ratio/rpm. You mentioned street car but with 3000 stall I'd go with no less than a 3.55 on 28" tire (that's low profiles on an 18" rim) personally I'd do a little taller tire and at minimum 3.91s to utilize your converter, which hopefully matches your camshaft

Well i didnt put the T/C in, prev owner has told me it was a 3000 stall. since ive imported it, i havent driven it as i knew it wasnt that safe. so its pulled apart. engine and trans will be coming out at some stage so i will be able to check the stall then. but i was leaning towards 3.91s