8 3/4 or Dana 60?

[moparnation74]

Money pit is putting it lightly but yeah...........

That was my sarcasm indeed. My current build all the invoice/receipts has filled a 5" binder.....and I am not done yet, lol...

 

[EngineerDoug]

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.

 

[moparnation74]

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.

If you were closer my buddy here could build you a dana from a truck...He has been building them for years....Maybe in your area there is a Mopar aficionado that can do that....Contact a local Mopar club if you have one...

For an 8 3/4 I got my stuff from Dr Diff and his recommendations based on application and the same goes for parts for a dana. Opinions will vary but I have not had a bad experience with DD....

 

[1967coronet440]

What do we have to do to get dr diff on this forum, I think he's on moparts

 

[big_shmoop]

Sure he could spend that anywhere but why not just get what you want? The ultimate decision is his to.make to decide what makes him happier with his car.

My vote is obvious Dana all the way....get what you want you only live once and you cannot take it with you the grave...

I have had both rears....and after having 4 spd cars with Dana's I have never ever looked back...

For the record, I agree with everything you said here.

The fact that you reference a 4 speed car I can see why you feel so strongly about the Dana...I would too.

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.

As @moparnation74 and @1967coronet440 have already said...call Cass over at Dr. Diff. Tell him your plans and your budget and he'll get you setup with the everything you need.

 

[EngineerDoug]

I did call Dr Diff this AM; he suggested that the longevity of an 8 3/4 would really depend upon how the vehicle is driven. He also stated that a fully built Dana would be just under $3K shipped.

 

[1967coronet440]

Doug,

The fact that longevity even came up in your discussion with cass tells you which route you need to go.

 

[68 HEMI GTS]

Here's some food for thought. You mentioned street tires, 500 cubes, alum heads, roller cam. That's an absolute waste, and the car will probably be dangerously out of control every time you wack the gas with street tires. Even with good sticky tires, a proper running 500ci motor is still a hand full (I know from experience). So now your adding sticky tires to what I assume to be a relatively heavy street b body. the 8 3/4 will probably survive for a while given good parts, including axle's. There's plenty of guys that do it. I don't personally fall into that camp. Over kill is a good thing, and I really don't think a Dana is overkill for a 500 incher in a heavy car. Insurance is more how I see it.

 

[PurpleBeeper]

For whatever it's worth, I've used an 8-3/4" posi rear in my '70 440 4spd nitrous car for over 30 yrs. (no slicks) and it's never failed. I use the "happy button" regularly. Stock axles, stock center section. I've considered adding a back brace to the 8-3/4". If I ever run slicks, I'd planned to put in hardened axles & the backing plate. If it breaks, I'll go Dana.

FYI- if you do go Dana, you can cut the axle housing ends of your 8-3/4" and use the axles too I believe (in many cases....didn't know about the spline number differences)

 

[moparnation74]

For the record, I agree with everything you said here.

The fact that you reference a 4 speed car I can see why you feel so strongly about the Dana...I would too.



As @moparnation74 and @1967coronet440 have already said...call Cass over at Dr. Diff. Tell him your plans and your budget and he'll get you setup with the everything you need.

Appreciate that! I also appreciate your input and knowledge!

 

[4mayhemi]

If it was a numbers OEM 6pack that came with 8 3/4, well, if ma said so, ok. But you'll have some money and thought in a stroker, well-breathing alum heads and intake, purring and looking nicely. Even if an 8 3/4 can handle it depending on "how the vehicle is driven" (quote DrDiff), if I saw it I would think of the showy weightlifters who bench press freight trains and curl refrigerators, but walk on little chicken legs.

 

[coloradodave]

Did they not use 8 3/4 's on the old dragsters?

Sonny doesn't want to sound like a dumb-*** but...

Most of the front engine dragsters used Olds or Pontiac rearends in the 60s. Imagine sitting behind the rearend with your legs over the axle tubes and only a 1/2" thick piece of metal shielding your family jewels from a potential disaster...

 

[EngineerDoug]

Well, after reviewing your inputs and mulling it over my vote will probably go to the Dana 60. It just sounds like the 8 3/4 will have little or no safety margin with the powerplant I have in mind.

I don't mind building in some overkill factor, but I also weigh the expense. The decision is many months in the future, but there are a couple of avenues open to me as far as the Dana goes. I drive past Magnum Force Racing everyday on my way to work, as I live in mountains bordering Silicon Valley. They offer a Dana 60 package for a good price, and I would not have to pay shipping.

There is also an outfit in the South Bay Area that specializes in rear axle work. I intend to spend some time talking to them about the cost of modifying a truck Dana to suit my needs. I do like the idea of finding a truck Dana with 3.54 gears and a Sure grip - that would cut my costs considerably. I see these pop up in Craigslist once in a while, typically for $500 or less.

Anyway, I appreciate the viewpoints and the benefit of your experiences.

 

[Bill Monk]

Well, after reviewing your inputs and mulling it over my vote will probably go to the Dana 60. It just sounds like the 8 3/4 will have little or no safety margin with the powerplant I have in mind.

I don't mind building in some overkill factor, but I also weigh the expense. The decision is many months in the future, but there are a couple of avenues open to me as far as the Dana goes. I drive past Magnum Force Racing everyday on my way to work, as I live in mountains bordering Silicon Valley. They offer a Dana 60 package for a good price, and I would not have to pay shipping.

There is also an outfit in the South Bay Area that specializes in rear axle work. I intend to spend some time talking to them about the cost of modifying a truck Dana to suit my needs. I do like the idea of finding a truck Dana with 3.54 gears and a Sure grip - that would cut my costs considerably. I see these pop up in Craigslist once in a while, typically for $500 or less.

Anyway, I appreciate the viewpoints and the benefit of your experiences.

You won't regret it

 

[moparnation74]

Well, after reviewing your inputs and mulling it over my vote will probably go to the Dana 60. It just sounds like the 8 3/4 will have little or no safety margin with the powerplant I have in mind.

I don't mind building in some overkill factor, but I also weigh the expense. The decision is many months in the future, but there are a couple of avenues open to me as far as the Dana goes. I drive past Magnum Force Racing everyday on my way to work, as I live in mountains bordering Silicon Valley. They offer a Dana 60 package for a good price, and I would not have to pay shipping.

There is also an outfit in the South Bay Area that specializes in rear axle work. I intend to spend some time talking to them about the cost of modifying a truck Dana to suit my needs. I do like the idea of finding a truck Dana with 3.54 gears and a Sure grip - that would cut my costs considerably. I see these pop up in Craigslist once in a while, typically for $500 or less.

Anyway, I appreciate the viewpoints and the benefit of your experiences.

Smart man Indeed!

 

[Fran Blacker]

Well, after reviewing your inputs and mulling it over my vote will probably go to the Dana 60. It just sounds like the 8 3/4 will have little or no safety margin with the powerplant I have in mind.

I don't mind building in some overkill factor, but I also weigh the expense. The decision is many months in the future, but there are a couple of avenues open to me as far as the Dana goes. I drive past Magnum Force Racing everyday on my way to work, as I live in mountains bordering Silicon Valley. They offer a Dana 60 package for a good price, and I would not have to pay shipping.

Around here hit the junkyards. Maybe construction company's have a crapped out vehicle with a Dana?
There is also an outfit in the South Bay Area that specializes in rear axle work. I intend to spend some time talking to them about the cost of modifying a truck Dana to suit my needs. I do like the idea of finding a truck Dana with 3.54 gears and a Sure grip - that would cut my costs considerably. I see these pop up in Craigslist once in a while, typically for $500 or less.

Anyway, I appreciate the viewpoints and the benefit of your experiences.

Maybe you can hit the junkyards, Dana's in trucks don't crap out often. Another place is construction company's, they might have a crapped out vehicle with a Dana. Just watch out that they aren't Dana 70's . The sure grip takes a larger ring gear but axles are the same. I bought a S/G on ebay went to put a 60 ring gear on it a year later didn't fit. Bought another Dana 60 S/G and switched the guts from the 70 to it. Other than the ring gear (10.25" dia. my guess) you could use that? Only question is gear availability and their cost. Rear covers look the same so to tell them apart, I don't know how. Looked on an I.D. of rear diff website, if there is a tag on cover maybe there. The Dana 80 is much taller.

 

[Cranky]

Yes, the 70 is bigger but uses the same rear cover. As for the truck 60....they do not have the machined area for a snubber. They also (most) have full floating axles but the newer ones that did not have limited slip units were semi floating most of the time. I'm not up on the ones after the late 90's. And some food for thought.....a SureGrip for a 60 vs an 8 3/4.

 

[cdr]

I have been setting up differentials for 30 years & built a 83/4 for my STREET strip 68 Charger,512,very mild set up, it was a handfull with street 295/50/15 tires, 60,70,mph it would BLOW the tires off, put some Drag radials on it& broke the 83/4, I wasted over 900.00 in parts, I knew better than go 83/4 but money was,is tight, called Dr diff & got me a S60,

 

[Sonny Black]

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.......

 

[Cranky]

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.