The only thing that needs to be changed is the speedometer gear. The manual has a chart that matches the speedometer gear with the gear ratio and tire diameter. The gear Vendors unit uses turbo 400 speedometer gears which are readily available on ebay.

The 9" is a great option for many of us, I had one in my 9 second DartSport. They are durable, have a drain plug in the bottom, a removable center section carrier, and a much wider variety of gear ratios, especially for highway type gears.
I also had a Dana in my '69 Dart and I liked the 9" alot better.

I love my Mopars and Mopar engines but I could care less where the tranny or rearend came from. A turbo400 and a 9" is a perfect combo.

What was so much better about the 9" over the D60?

Here are a list of things that I know make the 9" better.

Lighter weight

More gear options. I don't believe you can go under a 3.55 with a Dana 60

Able to lower your car easier because 9" pinion is lower on the pumpkin than a dana 60.

easier to set up ring and pinion on a 9"

Possiblily cheaper to set up.

Larger pinion shaft diameter.


Dana 60 pluses are
More efficient transfer of power due to placement of pinion gear to ring gear. Not sure of the HP loss but there is a bit with a 9"

Looks cooler to me at least.

Looks more factory on a Mopar.

You missed one of the biggies, easy swap of center section between rounds and races.

I have a Dana with 4:30s and a GV. The GV is life altering. I've been very happy with mine. They do add some extra weight to the car though if you care about that sort of thing. The GV is bullet proof. I'm throwing decent HP at it and it's holding up fine. I've raced with it and driven on long cruises with zero problems.

I mentioned my favorite reasons in the paragraph you quoted ^^^

First of all, the 9" is NOT lighter. In order to gain equal strength, the 9" and D60 are equal in weight.

There are options all the way down to 3.08 gears for the D60. If you need taller than 3.08 gears you need an over drive, because you have compromised low (1st) gear.

I have no idea why you think ride height is compromised by pinion height.

It takes me the same time to set up a D60 as it does a 9". I'm sure anyone who has done them would agree.

It is the same money to set up either diff. The 9" is FAR more expensive than the D60.

I would have to look up pinion diameters but I've never broken a D60 pinion.
The D60 takes LESS HP to drive with LOWER gears (higher numerically) than the 9". This is NOT linear. As you go to lower gears the 9" starts to eat power like mad. The push is 3.90. At that ratio, they both take the same power to turn. By the time you get to 4.56, the 9" is wasting power. For years I ran 5.57 gears in my drag car. The gentleman who taught me how to set up diffs told me, in his personal testing, at that ratio, the 9" was eating 35-40 HP. And he actually tested them. That's why I used the D60. It was cheaper, just as strong, and took less HP to drive.


As for ease of replacement, that is the biggest bag of bullcrap I have ever heard. I can't hardly get a racer to pull all 8 spark plugs, let alone drop a 3rd member to change gears. And what about cost? You want me to think guys that [censored] about the cost of synthetic oils are going to front for 2 9" 3rd members? A Comp guy probably. A fast bracket guy maybe. But the rest of us? Fat chance.


In the end, I really don't care what diff anyone uses in their car. It's their stuff and their money. But what eats my draws is the general lack of knowledge about this stuff out there. It's sad that for DECADES the same crap has been passed around as truth.


And if Dr. Diff sees this, I would love his input and thoughts.

If you really looked at what I wrote down you would have found that I said you lose more HP running through a 9" than a 60

The pinion in the 9" is set lower coming out of the axle which allows you to lower the car over the driveshaft EASIER without cutting the driveshaft tunnel.
This is done mostly with very fast cars which start getting very low.

It is my experience that the 9" is lighter if you compare stock axle to stock axle. Even with the 9" gussetted.

The 9" ring and pinion can be set in the 3rd member on a bench without removing the rear axle.

The Dana 60 requires you set it up under the car if you don't want to remove the whole axle. Which, if you don't have a lift is a bit harder.

Plus I forgot to mention what others have said. It's easy to change 9" gears if you have extra 3 members around.

All that being said I would still prefer a Dana 60 under a mopar.

9"=Ford=

Chebby didn't have any real choices when it came to differentials so they may benefit from some Phord parts. But Mopar has always had enough superior diff choices that you don't have to resort to running Phord parts.

If you like putting Phord parts on your Mopar, it's yours, go ahead. But it is not necessary.

I'd still take the 9", I like being able to swap out the 3rd member, definitely not from a lack of knowledge. It's all personal preference, just like all the other threads about rearend ratios, overdrives, etc.

My thinking has always been that if your engine has enough torque to light up your rear tires,,,particularly with an auto trans and the torque multiplication they provide,,,that going to a lower rear end ratio buys you zip in performance.

In other words if you got a 3:08 and your motor will light your tires when you stand on it, going to a 4:10 helps not a wit. However if your plan might include some drag racing with some traction oriented tires to be swapped in as part of the deal, then yes a lower gear will usually pay dividends. I did not note what your current ratio is,,,however if slicks are not part of the plan,,,a 3:23 or even a 3:08(or whatever is close in the Mopar world) could be just the ticket,,,great on the highway and at the stoplight.

Build you motor,,,I suspect it will be a torque monster,,,keep your current gears,,,if you can light up your tires,,,save your rear end budget and spend it on something else. If the car is a slug,,,with the engine you are building, likely not,,,than think about overdrives and lower rear end ratios.

Some years back I replaced the stock 3:54's in my 3 speed push button torqueflite equipped 300 B with a 2:92 rear axle. With 3:54's at 80 mph sounded like the solid lifters were swapping holes. With 2:92's sounds like a Bentley. The torque laden dual 4 barrel 354 Hemi cares not a wit about the swap when leaving a stoplight.

When does the ground war begin?

Please tell me where I can get a new D60 3.08 gear!? Everything I have seen so far shows 3.54 is the closest that's currently available.

Same here, never see anything below a 3.54 for a Dana.


Nice car Sxrxrnr!!

Probably referring to the D61 3.07 gear that came in some Ford trucks and all 1st Gen Cummins 3 spd equipped Rams. I think I've read that a D61 gear can be put in a 60 housing with a spacer? Or it might be the other way around, 60 gear in a 61 housing with a spacer

While I have never owned a ford 9" rear end, summit sure shows a wealth of attractively priced components with gears going from 3.00 and up.



The other way around, the 61 will accept 60 r&p with a spacer from what I've read. In any event, I don't think anyone makes D61 gears at all.

Except Dana/Spicer, right?

One thing about the Chrysler vs Ford debate. As there were many many more Ford trucks built with Dana 60s than any Mopar. or probably all of them added together, it would be equally as (im)proper to call a Dana 60 a Ford rearend.

In theory, the larger the gear ratio in a hypoid gearset, the more power is eaten by friction. So it'd be a better choice to run a 1:1 Top gear and have deeper gears in the transmission. That's what the Doug Nash 5-speed was all about.

Also, in any gearset the larger the gear ratio, the weaker the gearset. Right around the 3.00 mark is when it gets tricky. To get a pinion gear strong enough for a 3+ gear ratio the transmission designer increases the distance between mainshaft and countershaft and the transmission gets bigger and heavier. All of the gears increase in diameter plus there's more case.

It's my opinion that around 10:1 total gear ratio is necessary to start a street car in any street situation. That'd be a 3.09 First and a 3.23 rear gear. My first car had a 3.09 First and a 3.08 rear gear and that was okay but I didn't live in hilly territory. Even so I could have made it work.

R.

Agree with above.

Another thing to consider is that for
durability and low noise
gears that have a
"Prime Number"
of teeth are better.

Actually, I have not seen a set of 3.08's for a 60 since 1983 when I bought the 5.57's for my car. I remember thinking who would use that gear? It's worthless to me. If they don't make it today, it's because no one wanted it.

I will never understand how people calculate gear ratio, especially the auto guys. They gear too tall and force the converter to slip and then say the engine rev's too high. Obviously, I don't care for automatics either.

I can't think of a single use for a 3.54 gear for a muscle car oriented set up. It's not a camry.

Please let all the manufacturer's know which parts you don't approve of so they can stop production immediately! And feel free to make a list of how you want us to build our cars, you crack me up.
Hopefully you'll be cruising around my neighborhood so I can show you how well 3.23 gears work with a stroked big block.
Not to mention the maroon colored Dart here on Moparts that runs 9.50's with a 3.54 gear. I hope he built the rest of his car to your expectations. Are you running less than 318 cubes with your 557 gears?