Rear Axle Question ... 9 inch v 8.8 inch
Senior User
Joined: Apr 2015
Posts: 459
Likes: 5
From: Buffalo NY
Yes. Assuming your AOD has a .667 OD gear.
Senior User
Joined: Jun 2002
Posts: 291
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From: Ft Lauderdale USA
I have a Ford Racing 302 340/HP 350/TQ bolted up to a 302 with a AOD. Disc brake conversion up front, stock suspension (posies springs). My original Dana 44 with a 3.92 holds up well to ocasional beatings and burnouts. It I am on it hard it has a 1 -2 gear chrip. I did convert it to a posi. cruises 70 at just about 2100 rpm with 15x275x60 tires, 28 inches tall. I have been know to run it 80 for a couple hours on end at about 2400 RPM. Dana 44 is rebuilt all new bearings, seals etc. (no leaks) Posi unit was purchased from Randy's Ring and Pinion.
Hotshot
Joined: Oct 2009
Posts: 16,135
Likes: 4,735
From: Burbank, WA
Where is it leaking from? It would be a lot less expense and work to change 3 seals and a rear cover gasket, since any one of those 4 places is all that can leak unless something is broken, than to do a complete axle swap for no other good reason. The original rear is pretty tough and is probably the last thing to break on one of these trucks. Who are these people 'advising' you to replace it?
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Senior User
Joined: Jun 2014
Posts: 182
Likes: 3
From: Frisco, TX
Where is it leaking from? It would be a lot less expense and work to change 3 seals and a rear cover gasket, since any one of those 4 places is all that can leak unless something is broken, than to do a complete axle swap for no other good reason. The original rear is pretty tough and is probably the last thing to break on one of these trucks. Who are these people 'advising' you to replace it?
Understand your point about not fixing what's not broken, and seals are easier than a swap.
How can I tell what gear ratio is in it now? I don't have a tach. I know the transmission is a T-98, but i don't know anything about its internals (other than that I have bad synchros). I've looked for an external indication, but not sure where to look under the 60 years of crusted oil and grime.
If I could get some comfort that the gear ratio would meet my goals (in original post), or that swapping them out wouldn't be a bigger deal than the 9" swap, I'd love to consider the Dana.
As far as who's told me to replace it.... It just seems like 90% of the folks that I talk to (on-line and in local "Classic Car" shops) say something like "I assume you'll want to get that Dana out of there" To my discredit, I have not done alot of digging into the specific reasons... maybe they all thought I was going for 400+ HP... which I am not.
Thanks!
Cargo Master
Joined: Feb 2006
Posts: 2,292
Likes: 876
From: Lititz PA
To find out your rear ratio, leave one tire on the ground and jack up the other side. Mark your driveshaft with a chalk. Put it in neutral and rotate the wheel two full revolutions. Count the number of driveshaft revolutions. I got almost 4 revolutions out of the driveshaft. It's a 3.92 . Dennis
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Hotshot
Joined: Oct 2009
Posts: 16,135
Likes: 4,735
From: Burbank, WA
Wayne. I believe it is leaking from both the front seal and the cover. No leaks out at the end of the axles.
Understand your point about not fixing what's not broken, and seals are easier than a swap.
How can I tell what gear ratio is in it now? I don't have a tach. I know the transmission is a T-98, but i don't know anything about its internals (other than that I have bad synchros). I've looked for an external indication, but not sure where to look under the 60 years of crusted oil and grime.
If I could get some comfort that the gear ratio would meet my goals (in original post), or that swapping them out wouldn't be a bigger deal than the 9" swap, I'd love to consider the Dana.
As far as who's told me to replace it.... It just seems like 90% of the folks that I talk to (on-line and in local "Classic Car" shops) say something like "I assume you'll want to get that Dana out of there" To my discredit, I have not done alot of digging into the specific reasons... maybe they all thought I was going for 400+ HP... which I am not.
Thanks!
Understand your point about not fixing what's not broken, and seals are easier than a swap.
How can I tell what gear ratio is in it now? I don't have a tach. I know the transmission is a T-98, but i don't know anything about its internals (other than that I have bad synchros). I've looked for an external indication, but not sure where to look under the 60 years of crusted oil and grime.
If I could get some comfort that the gear ratio would meet my goals (in original post), or that swapping them out wouldn't be a bigger deal than the 9" swap, I'd love to consider the Dana.
As far as who's told me to replace it.... It just seems like 90% of the folks that I talk to (on-line and in local "Classic Car" shops) say something like "I assume you'll want to get that Dana out of there" To my discredit, I have not done alot of digging into the specific reasons... maybe they all thought I was going for 400+ HP... which I am not.
Thanks!
Thread Starter
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Senior User
Joined: Jun 2014
Posts: 182
Likes: 3
From: Frisco, TX
The gear tag is still there and says 47/11 ... I think that means 4.27, right?
I can turn the drive shaft slightly (maybe 1/4 inch +/-) with the tires firmly on the ground. Is this level of "slack" ok?
Based on the calculator I've been using, 4.27 gears, AOD (.677 Transmission Ratio), and 28.5 tires should get me to 70 MPH at under 2,400 RPM. I'm fine with an ave highway speed of 65-70 (for this truck).
The leak seems to be coming from the front (where the drive shaft enters housing).
So bottom line... If (a) I don't need posi, (b) don't care about easily being able to swap gear ratio in/out, and (c) will not exceed 400 HP (probably won't exceed 300) for this build....
Should I just replace the seals on the Dana, and use it with my new AOD/302? Would make the project easier/faster, and get me on the road sooner (big deal to me).
Really appreciate any opinions to consider.
Hotshot
Joined: Oct 2009
Posts: 16,135
Likes: 4,735
From: Burbank, WA
I'd say that would be my 'plan A'. You can always change out the rear later if you find you hate it or it isn't working for you. But for now, you can use it and save a bunch of money, time and hassle.
Elder User
Joined: Jun 2013
Posts: 949
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From: Metro Detroit-MI
I bought my 2002 Explorer 8.8 rear end for $200. I got a bit of a deal due to knowing the owner of the junk yard. Here is something to consider....
The 9 inch, great selection of gears and parts to make it bulletproof and to fit your exact taste. You will have drums so that can be good or bad depending on what you want.
I wanted the 8.8 for these reasons:
8.8 is stronger, the explorers come with trackloc (posi) and 31 spline (beefier) axles. I got the 3.73 rear gear and disc brakes.
If I were to but a 9 inch posi rear end I wouldve cost me more to have the same setup, even though It was closer to a direct fit.
The 9 inch, great selection of gears and parts to make it bulletproof and to fit your exact taste. You will have drums so that can be good or bad depending on what you want.
I wanted the 8.8 for these reasons:
8.8 is stronger, the explorers come with trackloc (posi) and 31 spline (beefier) axles. I got the 3.73 rear gear and disc brakes.
If I were to but a 9 inch posi rear end I wouldve cost me more to have the same setup, even though It was closer to a direct fit.
Senior User
Joined: Jul 2003
Posts: 322
Likes: 0
From: FL
No, it is not.
That said, they are very good rear ends. They are more than strong enough for all but the all-out race-style engines out there. They're about the same as a GM 12-bolt...But they're not stronger than a 9".
That said, they are very good rear ends. They are more than strong enough for all but the all-out race-style engines out there. They're about the same as a GM 12-bolt...But they're not stronger than a 9".
Elder User
Joined: Jun 2013
Posts: 949
Likes: 0
From: Metro Detroit-MI
The downfall of the 9 inch is the flex in the housing.
The upside of the 9 inch is the endless amount of parts available (at a $$ price)
The upside of the 8.8 is the standard Trackloc and disc brakes for a fraction of the cost.