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Old 06-27-2007, 12:20 PM   #1
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Default 7" diff install

I have:
assembled diff, driveshaft, halfshafts, new diff bushings

Need anything else? Is the swap as "easy" to do as it appears to be? Looks like lots of cussing and beer drinkin--but relatively straight forward.
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Old 06-27-2007, 12:34 PM   #2
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It's incredibly easy IMO... unless there's corrosion. What about the half shaft seals? I highly recommend new ones.
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Old 06-27-2007, 12:35 PM   #3
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Check the castle nut size for the bolt through the half-shafts that go through the hubs. IIRC, the 1.6 and the 1.8's are different sizes. We have a "loaner" 3/4" breaker bar + a few sockets that get moved around depending on who's doing the diff swap. The torque on those nuts are stupid 150+ ft-lbs (it says 160-> 216 in my workshop manual), so... you need to make sure you put the car in 5th + parking brake + have the wheel and tire on the ground to get it to turn. We tried one time with just a jack under a tire, and it kept turning -- it was a bitch to do it that way. It might be worth it to crack the old one before you pick the car up.

Other than that, it's just a matter of getting all the other hardware loose. The ones through the "ears" of the diff are a little awkward to do... but shouldn't be too bad on a US car, with no rust....

Also.... the bolts on the PPF can be a bitch. They are at least 10" long, and I believe one of them likes to "spin" the top if you are not careful, because I believe they are welded on the top of the PPF.

Once you get in there, you'll be good, it's pretty straight forward, just depending on the car, the use of colourful metaphores goes up. <G>

Dave,
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Old 06-27-2007, 12:39 PM   #4
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The bolts that hold the driveshaft to the diff input flange are a different size for the 1.8 style diff, so you can't re-use your old ones. It's either M10 vs M8, or M12 vs M10, something like that. Measure and obtain four new bolts, nuts, lockwashers.

If you're going to be transferring the new shafts to the old hubs, new cotter pins and preferably new castle nuts.

Since you've got it all apart, it's a good time to install new seals on the diff sides and tranny output.

I found it easier to unbolt the PPF from the transmission and then get the whole Diff / PPF assembly out onto the garage floor for the purposes of separating the diff from the PPF. There's a pressed-in spacer on the bottom that you can chisel out with the assembly in the car, but the spacer assembly on top was far easier to drive out with a punch once the unit was on the floor than to try pulling out the way Mazda indicates in the book.

If you have the later-model one piece half axles, then getting them installed into the diff is simply going to be a pain in the ***. No way around this. Remove the bolt which holds the hub to the upper A-arm to gain some working space, but ultimately you just have to cuss at it until it submits. When I did it I was applying to much force sideways to the thing that I nearly pushed the car over off the jackstands. Put some old wheels or similar under the car to prevent death should this occur.
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Old 06-27-2007, 12:50 PM   #5
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nope it's easy, my biggest pain was getting the PPF adapter off to free it from the PPF.

just unbolt the driveshaft, unbolt the ppf, pull out of stubs, unbolt the two plates up top, unbolt the PPF adapter, unbolt the two top bolts and it will drop out.
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Old 06-27-2007, 12:59 PM   #6
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Thanks for the heads up on the input flange bolts. My dad has a large selection of SS hardware (in labeled bins like the hardware store) at his shop I'll raid.

Work will be done on a lift and with compressed air, and a tranny stand, which always helps. I'll get the diff seals, the tranny seal was done with the clutch maybe 1500 or so miles ago.

If Ben (atl93le) is back in town, I'll con him into helping....

Ben
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Old 06-27-2007, 02:16 PM   #7
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shouldn't take you guys more than 1-2hrs
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Old 06-27-2007, 03:41 PM   #8
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Is this a Torsen or a RX-7 Frankendiff?

I just bought a torsen and hopfully will have it in a couple of weeks!
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Old 06-27-2007, 03:42 PM   #9
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RX7
but it's a "hybrid". Frankendiff = chineese
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Old 06-27-2007, 04:48 PM   #10
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Frakendiff ... meaning being made up of parts from different sources. Like Frakenstein's monster. And I'm pretty sure he was German not Chinese.
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Old 06-27-2007, 04:55 PM   #11
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you canadians kill me
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Old 06-27-2007, 04:59 PM   #12
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I'm just saying ...
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Old 06-27-2007, 05:07 PM   #13
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let me know when your governemnt crushes your car for suspision of street racing
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Old 06-27-2007, 05:12 PM   #14
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Wtf?
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Old 06-28-2007, 12:39 AM   #15
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[complete thread hi-jack mode]

Jay's on the other side of the world from that.... he may not have heard all the bitching.

Actually for those who have lots of time on their hands... there was a very interesting thread on one of local autox boards....

http://www.casc.on.ca/forums/showthread.php?t=11668

[thread hi-jack off]

[continuation of Jay's hi-jack]

I thought Franken-parts would have been Transylvanian....? Or was that only for Dracula...?

Dave,
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Old 06-28-2007, 01:10 AM   #16
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No my WTF was directed towards randomness. I've heard all about this car crushing BS.
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Old 06-28-2007, 09:47 AM   #17
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The primary difficulty area:
-----Freeing axleshafts from hub, about 50% dont wish to come out.
As already indicated, drop diff & ppf together, takes only one minute to split them on the floor...in the car is a bitch!
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Old 06-28-2007, 10:16 AM   #18
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yeah a BFH for the hubs, and maybe a pnumatic press if it is to stuborn mine laughed at my air hammer. but not the 30 ton press WTF canadian cop wants to suspend peoples licences over 80 mph i hit that just out of my drive way geez WTF is wrong with that country i vote they need more guns. the lack of violent crime has skewed there priorities.
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Old 06-28-2007, 10:36 AM   #19
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haha my axles fell out of the hub after I unbolted them from the stubshaft.
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Old 06-28-2007, 11:37 AM   #20
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Quote:
Originally Posted by Ben View Post
If Ben (atl93le) is back in town, I'll con him into helping....
Ben
No conning necessary; I'd love to get some experience before doing mine. I'm not sure you want to wait until I'm back though...I don't arrive in Atlanta until July 13.
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