8 3/4 or Dana 60?

[1967coronet440]

A problem with letting a rear end blow up is other parts can get taken out also. Are ya willing to take that chance? If the rear goes and goes bad enough, the sprag in the auto will usually go and damage can be done to drive shaft and the car itself can also be damaged.

Blew the first rearend out of my coronet, took out the differential, sent the driveshaft through the floor, and trans. That 383 had some torque!

 

[Fran Blacker]

Sure can't sell a blown 8.75 to cut down cost of Dana.

 

[Cornpatch MO]

Why don't you explain why a Dana is overkill? Since you appear to have vast knowledge in this area...Do not include the obvious aka cost.....

Specifics....True specifics, not hearsay...

I would say : the time and research involved , the chance of doing something wrong, and having problems down the road, Being able to find the parts needed, And is it really neccessary for a street driven car? I don't often hear of 8 3/4 " blowing up all over the place. They are probably as strong as a 9" Ford. Don't subscribe to " because that is the "in" thing to do" JMO because I don't have money to burn.................................MO

 

[moparnation74]

I would say : the time and research involved , the chance of doing something wrong, and having problems down the road, Being able to find the parts needed, And is it really neccessary for a street driven car? I don't often hear of 8 3/4 " blowing up all over the place. They are probably as strong as a 9" Ford. Don't subscribe to " because that is the "in" thing to do" JMO because I don't have money to burn.................................MO

Yes it is necessary....even the factory thought so as well for higher horsepower and 4spd cars....I never once stated that an 8 3/4 would blow up....I will state that in long term performance and durability the added cost for a dana is money well spent....Yes, we chose where to burn our money at least I will burn mine with what has been proven, tested, and is historically known as a virtually indestructible rear end in comparison to other rear ends....JMHO...MN74

 

[Cranky]

In the early 80's I was helping a buddy run a 4 speed car and when we got it into the mid/low 11's, it started shaving teeth off the ring gear of the 8 3/4. After replacing 2 third members and with the 3rd starting to howl, we went looking for a 60 and stuck it in before the 3rd one gave up the ghost. After that, breakage stopped and we went on to running low 10.70's. We did waste a couple of 833's before sticking in a Doug Nash 5 speed....

 

[coloradodave]

checked with a few different sites and old timers, and was told... The 8 3/4 Mopar rear ends were used in the old top fuel dragsters w/ old 4.86 us pro gear....other wise not strong enough...

so sonny says DANA 60....(when I blow up my 8 3/4 ) Dana 60 or a 9" Ford.......

Sonny; I'm an old timer who lived and raced on the West Coast in the 60s, 70s and 80s. Like I said, our shop always used Olds or Pontiac rearends because they were cheap and plentiful. This was before there were specialty shops like Strange. And, like I also said, I used an 8.75 with a spool in one of my D/Gas Corvettes, mainly for the ease of maintenance and gear changes. We were a dealer for Zoom so that's whose gear sets I used. My current street car has a fabricated Moser 8.75" with a True Trac Helical gear limited slip. There were a ton of locally built front engine cars across our country and I'm sure both types were used.

 

[Cranky]

Sonny; I'm an old timer who lived and raced on the West Coast in the 60s, 70s and 80s. Like I said, our shop always used Olds or Pontiac rearends because they were cheap and plentiful. This was before there were specialty shops like Strange. And, like I also said, I used an 8.75 with a spool in one of my D/Gas Corvettes, mainly for the ease of maintenance and gear changes. We were a dealer for Zoom so that's whose gear sets I used. My current street car has a fabricated Moser 8.75" with a True Trac Helical gear limited slip. There were a ton of locally built front engine cars across our country and I'm sure both types were used.

View attachment 428324 View attachment 428325

What was the weight of the cars? The weight of the car I was helping with was 3100 lbs at first and it was soon down to 2900 without the driver. I know from experience that weight is a huge factor and so is launch rpm and the heavier the car and the higher the launch rpm, the more breakage happens.

 

[coloradodave]

I believe the Corvette weighed in right at 3,000 lbs. without driver. It had a 331" small block, 12.5:1 compression, severely ported 2.02 heads, Isky roller cam, Isky rockers and a tunnel ram with 660 Holleys. I launched it at 6500 and shifted at 9,600. It had a rock crusher 4 speed with Joe Liberty gears and 5:38s in the rear, which was supported by lift bars and the transverse spring. All that is so dated now...lol. It ran very low 10s, which, for the time was competitive. Now you can buy several cars off the show room floor and beat that by train lengths...

 

[Cranky]

I believe the Corvette weighed in right at 3,000 lbs. without driver. It had a 331" small block, 12.5:1 compression, severely ported 2.02 heads, Isky roller cam, Isky rockers and a tunnel ram with 660 Holleys. I launched it at 6500 and shifted at 9,600. It had a rock crusher 4 speed with Joe Liberty gears and 5:38s in the rear, which was supported by lift bars and the transverse spring. All that is so dated now...lol. It ran very low 10s, which, for the time was competitive. Now you can buy several cars off the show room floor and beat that by train lengths...

View attachment 428731

Yeah, the new cars are crazy but I'm not interested in spending that kind of money for a factory car that's not even legal to compete on the drag strip. And most of them are forced fed and electronically controlled. I dunno....just doesn't appeal to me and I still like to be able to say "I built it".....

 

[coloradodave]

I'm with you, Cranky.

 

[Chilsam]

Glad to see I sparked an interesting debate. You all make some good points - let me ask a couple of further key questions that would bear upon my decision:

1) Mention was made of "setting up an 8 3/4 the right way"....does that mean stronger axles? Or something additional?

2) Chilsam, you did what I thought might an option, especially finding a Dana that did not need gears or a sure grip unit. Can I ask you how you knew the truck unit would work for the conversion? If I tried to duplicate what you did, what rear axles should I look for?

Thanks - this is a good discussion.

I asked STRANGE ...all the D60's and S60's pretty much the same internally...I ordered 30 spline axles from STRANGE but seeing how the 8 3/4" uses the same ends and bearings+ the splines are 30 count the diameter is the same. I contacted another axle comp "moser"and asked about their 30 splines to which said we only have 35's why would we make 30's as 35's are the strongest,to which I replied a 30 spline behind a cummins towing a 5th wheel with a skidsteer and other stuff impressed me and I got such a good deal on the 4.10 T.L I couldn't pass it up.I was going to get a truck housing I seen on ebay that was mod'd for B body rides but the lack of pinion snubber holes changed my mind.Traction bars would fill the void tho....hope this helps

 

[Hosehead]

Interesting read here, for sure. Last summer I was getting back into drag racing with my 65 belvedere. Tired 440 auto, 8 3/4 with 3.23 sure grip and drag radials. Ran 12.90's.
I called Cass at dr.diff to order a set of 3.73 gears for my 8 3/4. Once he heard I was racing, he started in on me, telling me I should get a Dana. I didn't listen and a few weeks later the yoke let go on my 8 3/4 during my burnout at the track. The result: driveshaft repair, a very expensive tow, pulled trans for inspection and finally a DANA 60! Lol!
The car is getting a new engine now and boy am I glad the Dana is under my car. I look at it as insurance in case you want to go a more radical direction with your car in the future.
Plus, it looks badass under there!

 

[cdr]

 

[Chilsam]

My 30 spline..