I know it might be archived somewhere, but a lot of people think you've gotta drop the sub frame to remove the differential. I just want to completely clarify that you DO NOT have to. I just took mine out today, and I'll explain how...right about now.

First off, you might want to have some PBlaster handy. Soak the bolts you need to remove for a bit before you start to remove em, loosen some rust up. Also, I had access to a lift throughout this ordeal, which will definitely make things easier.

Draining the fluid is optional, it doesn't hold much, there isn't too much excess weight to worry about... and you can do it off the car.

First you've gotta remove the split air pipe, and entire catback. Then the heatshield that covers up the driveshaft.

Next you're gonna want to remove the driveshaft by taking out the four 14mm bolts on the u-joint, at the differential. Angle it downwards, and slide it out. Put the nuts/bolts back in the u-joint, where you took them out. Do not lose them. Also place marks on the flange of the driveshaft and the u-joint, just to put it back in the way it was originally...couldn't hurt.

I loosened the subframe bolts in the front, just to maybe get a bit of play in the subframe, I don't know how much I got, if any, but I didn't want to leave that out. Moving on.

Next you're going to want to disconnect both axles going to the differential. Place marks on both flanges here, too. It can't hurt to put them back in where you found them. I don't recall what size they were, probably a 14mm again. Remove the nuts and push toward the wheel, slide down/ hang from wire, whatever you want to do. It would probably be easier to drop the differential if the axles were out, cause they're slightly in the way, but I did it without them being removed.

So far you should have your cat-back, heat shield, and driveshaft out. The axles should be disconnected.

Next you're going to want to unbolt the rear differential mount/bushings, and drop it as far as you can. Leave the nuts from them on the ends of the bolts, you don't want that thing to fall on your face. Loosen it up a bit, it should come down about an inch and a half or so.

Next are the differential mount bolts. This is where it is definitely a pain in the ***. The two in the front, closest to the driveshaft, are cake. Get a 17mm wrench, or 16mm, I'm not 100% sure, and remove them. The rear differential mount bolt is a PAIN IN THE ***. That's for sure. A ratchet with a socket will not fit in there. Ratchet wrenches will not fit in there, at least the set I tried to use. I wound up taking a 16mm or 17mm wrench, (I have Snap-On's, they are long) and I started to loosen it as much as I could, while the pumpkin was in the way of every 1/16 turn I could do. I borrowed a buddy's wrench that was about an inch shorter, and the bolt wound up coming out pretty easily. There's a trick about this part though. I was able to use one of those spinning dealy's that raises/lowers itself when spun, and I jacked up the differential, at the pumpkin, as high as it could go. This gives you about an extra 1/2" or so of clearance, to get that wrench in there. This DEFINITELY helps.

All the diff mount bolts are out, and the diff bushings/mounts in the rear are out, too by now. Get a tranny jack and put it under the differential. Pull on the bushings/mounts in the rear until they clear their stud/bolt. Push from the u-joint in the front, DO NOT hit it with a hammer or anything. It'll take some coaxing to get that bitch out, but it will come out. Fiddle with it for a bit. I had a buddy of mine pushing from the front, while I pulled down from the rear and controlled the jack. After two minutes of fiddling with it, we were able to drop it and wheel it over to a table on the tranny jack.

That's it. Hope it helps anyone who plans on tackling this. I was originally going to drop my sub frame to do this job, but after closer inspection per the FSM and looking at it on the car, I decided to try it out with it on the car.

By the way, the reason I had to drop mine was because I have an SE, with an open differential, which sucks. I wound up finding a differential from a GXL (S4) in the junkyard, and I was able to get it for free. So I am going to be swapping the gears from my differential into the other, so I can still retain the 4.10's, and not sacrifice acceleration.

James

 

you don't have to remove the cat back...or the split air tube since it connects to the cat... not sure why you are saying that.

No need to remove the driveshaft either... if the cat back is still in there it will hold it up nicely. Just unbolt it from the diff, remembering to mark the order of the nuts so that the drive shaft is balanced when you put it back on.

I never drop the subframe, but I think you forgot to mention the verticle subframe link needs to be unbolted as well to get enough clearance to pull the diff out towards the rear without struggling.

 

thanks for heads-up.

If you can, please provide pictures so it's easier to understand.

 

I really found it easier to drop the sub-frame. It wasn't a big deal.

 

^ i agree

its kinda a pain to put it back in though lol...

 

thats why you just don't drop it completely... just to THE EDGE!!!... lol

 

Well, I removed my cat-back because it was one of the first things said in the FSM to take out, plus my exhaust is relatively new, and I don't have any problem with rusty bolts. I also took mine off at my presilencer, which connects to the split air tube, which freed up some space. That's why I said that.

And about removing the driveshaft, if it's unbolted from the u-joint, it takes about 3 seconds to take it completely out of the transmission. Plus reinstallation is a snap.

And I did forget about the vertical subframe links. I disconnected one, on the driver's side.

Anything else I wrote that isn't right please feel free to correct.

James

 

...will s5 diff mount up to the s4 drivetrain?

 

If it's a NA -> an NA, it will. It won't if it's from a Turbo to an NA, or from an NA to a turbo.

Also, I had to remove and reinstall it two or three more times, due to tearing the rear mounts. The rear sub-link doesn't have to be disconnected, either. And the sub-frame does not need to be lowered. It might make it a little easier, but I did it without lowering the sub-frame.

James

 

should you still mark the driveshaft if your swapping diff to keep it balanced?

I plan on swapping out my open diff for a 4.10 in the near future.

 

Yeah, couldn't hurt to mark the u-joint to drive shaft flanges. Although I've forgotten to a few times and it hasn't hurt anything.

You could also do what I did. Took a LSD from a GXL auto and swaped ring gears from my case to that one, set back lash and it was all good! Although it would be easier to find a LSD from a 5-spd, it might not be in too good of shape.

James

 

this diff swap isnt going to be fun

 

If you can get the car decently high in the air, or get access to a lift, it really isn't that bad. Make sure you get a small 11/16 or metric equivalent (small as in short) wrench to get those front diff mount bolts out. Also, if you've got shitty bushings on the case of your diff, the aluminum part, I'd recommend getting some polyurethane or the Mazdatrix competition bushings. I wound up ripping 3 mounts and breaking two axles due to dry-rotted bushings.

Good luck,
James

 

I have a huge snap on tool box, I wrench for a living, but no lift acsess for the time being, so I'm just gunna jack it up and put it on jackstands


well if that happens I might as well do my 5 lug swap, I got all the parts minus the wheel/tires.

the whole carrier seems rather large, when I see my car again I'm gunna look at it closer

I might as well get the bushings since the diff is from an 86 so 20 year old rubber is probably not in the greatest condition... heh

 

About the wrenching...me too

The case is pretty heavy. Probably around 40-50 lbs. It's really not too much, but it's such an awkward shape. You're gonna need a press to put the mounts in, and an air hammer to get the old ones out.

My suggestion... If you get the Mazdatrix mounts, take note of how the factory mounts were installed. The mount lip was mounted at the top, which really doesn't make any sense. Put them in the opposite way, with the lip on the bottom, essentially holding the arms of the case up when bolted to the chassis.

I made that mistake, and it cost me an axle. The case just slipped right out of the mounts, dropped the diff to the pavement, and blew up the bearing race in the axle.

Also... when you go to press em in... drain the fluid, it'll come pouring out the vent.

James

EDIT: Coming out, you're gonna want to get the rear part of the diff, the aluminum side, to angle down, while pushing from the front to kind of slide it out. Install is the reverse. To get the bolts in the front mount you might have to push or pull on the mount while trying to bolt em in.

 

yeah I'm gunna go about this like when I swapped the rear end in my 240sx, grab a friend for help lol.

althought this appears that the carrier just bolts to the car, the 240 has it setup where you remove some nuts and with some shimmiying and moving around till it came out frm where it bolts to the subframe.

 

Thanks james, good info, should be archived

 

Great thread... Archive please....

 

im in the middle of swapping mine. (its been four days) i got an s4 lsd from a non turbo s4 and am trying ot put it in MY non turbo s4 but the drive shaft is not lining up. why is that? seems like the holes for the driveshaft are slightly further apart...

 

Sorry for bumping an old thread, but its good advice. I thought i would update it for anyone else that is using this as a guide.

I swapped mine last night and the part i struggled with the most was the little plate that the two bolts run through that go from the diff mount to the subframe. The subframe has a little lip on it that doesn't let you tilt the diff up until the plate is removed. Mine was rusted in a bit and I thought the plate was just part of the subframe. Once i pulled the plate out, the diff came out in a minute. I messed with that for way too long.

I left my exhaust, axles, and driveshaft all on the car. I lowered the subframe to the end of the studs and unbolted the vertical subframe link.

 

Yes, unbolting the subframe on the drivers side works well (as the manual states). If you remove the rear driver side tire, you can get at the two nuts on the diff pretty easy with a couple of extensions, and a ratchet, or impact. What I found with the plate, was if I let the diff drop down, and then jack it back up, the plate usually loosens up.

Good to know about the catback. I have always removed mine, but never thought to look, to see if I even needed to.

 

If the holes on the driveshaft at slightly outward compared to the holes on the diff flange then you have a T2 driveshaft and need a N/A shaft. Ask me how i know.

EDIT: Is this the same driveshaft you were using before you tackled the lsd swap?