Hi folks,
I'm hoping for some more detailed responses here than I got over on the CF. I have a 94 a4 with 2.59 dana 36. I bought a second pumpkin and I'm having some 3.54 s installed in it. I figured I could probably do the swap, but I've never been under the car. It would seem that I should just be able to remove the the six bolts on the 3 u joints attached to the unit, and the bolts that make the seal to the batwing (10 on a d36 correct?) The one response I got over on the cf spoke about a c-beam. would it really need to be removed to do this? I can use a wrench, just never got under the vet and want to know what i'm in for. Anyone have a pic series? Any help would be greatly appreciated.

Thanks guys.
Alan

Same thing you were told on the other place - drop the rear.

I think it would be a huge PITA to swap a pumpkin in-situ, and much more likely to f things up. Maybe if you had a lift, but for us mere mortals, drop the rear.

Here's the pictorial for you:

http://www.corvetteforum.com/techtips ... TopicID=218&TopicID=2

They just dropped the pumpkin+batwing. I would (and did) drop the whole thing. You probably need new u-joints anyway, so don't waste time doing it twice.

Hmmm. I had a thread with pics of my swap on the original DM website, but it seems to be inaccessible. I'll see if I can hunt them down.

Did you happen to look at the new diff before you sent it out? Did you notice the two, three inch long (approx) vertical bolt holes to the right of the pinion? Those are for the bolts that bolt the "C" beam to the differential. You will have trouble removing the diff from the car if you don't remove those "C" beam bolts.

Also, I think you would have trouble accessing all 10 of the diff cover (batwing) to diff bolts with the batwing still in the car.

RACE ON!!!

I would drop the entire rear, too...

It just seem easier to me... besides, you can use this op to clean up the rear of the chassis and install bushings.

I'll have to chime in as the voice of dissent here. I see no reason to remove anything beyond the third member itself unless you have other reasons for doing so. Remove the driveshaft/C-beam and support the rear of the transmission in the meantime. Unbolt the halfshafts from the output yokes of the diff. Remove the two nuts/bolts on either side that hold the camber arm brackets to the diff. on either side near the bottom. DO NOT disturb the bolts that hold the camber arms to these brackets and you'll have no alignment issues upon reassembly. Now simply remove the rest of the bolts that go through the batwing and secure the differential to it. After dropping the differential, clean the mating surface on the batwing and on your replacement diff. Seal it with The Right Stuff or Permatex's Ultra-Gray RTV at minimum. If using the RTV, let it set up overnight before adding your gear oil. If using The Right Stuff, this is not necessary. It's a non-RTV formula that requires no wait time for "skinning" and then assembly, nor before adding oil and putting into service.

Thank you very much for the replies (and link Vis). I did notice the large through holes cfi, I guess I have to deal with at least that. I'll feel my way through it. I'd still like to try it w/o dropping the entire assembly, but good points have been made for both schools of thought. If its too tight under the car, I'll drop it.

Thanks very much for the great replies. Sean at the Vette shop in Warminser has the rear right now. As soon as I get it back I'll give this a try.

Looking forward to Spring!
Alan

Quote:I am not sure what is meant by "dropping the entire assembly". The only thing I would do differently than Notorious described, would be to leave the 10, carrier to cover bolts alone, until after the two batwing to frame bracket bolts were removed and the diff with cover were lowered out of the car. Whatever works best for you.

RACE ON!!!

Hi Aquavet, good to see you here!! I'm the one you bought the diff. from. I swapped it out and put in a diff. I bought from another forum member with 3.07's. Musical rears!!!

Anyway, I took my car to a trans shop nearby and had it installed. I'll work on the motor all day happily, but I hate working under these cars for any more than about 20 mins. He installed the rear for $300, and at the same time installed a torque converter for $250. That is labor. He did remove the cover (batwing) and all from the car, swap the batwing to the new diff, and reinstall it as a unit.

Don't forget to change the speedometer gear also. BE CAREFUL when removing the VSS to get to the gear, pry gently going back and forth from 1 side to the other if it sticks.

Hey Dan! How are ya?

How's your new combo working? what stall?

I dont think I have to change the gear for the speedo....On the 94 its all done by reprogramming. I'll need to p/u a hypertech unit or get tunercat I guess. Case the Corvetteman hangs out here too he's helped out a bunch of guys with this situation, mabey he'll send me a tune too if I ask real nicely

Alan

Ooh, I forgot yours is newer than mine, you are probably right about the programming. I'm not sure as my '89 is the only vette (only Chevy car, for that matter) I ever messed with. I haven't gotten into tuning yet, I have pcmforless do it. I do want to get into datalogging so I can see if I need a tune adjustment or timing adjustment for fuel pressure adjustment.

I ended up with a 2800 stall converter. It's great, but it's not for a daily driver. I'd go 2000 for a daily driver. MPG goes down the tubes as stall goes up, but I didn't get it for mpg so I'm fine. My car is all back together except for the intake, which I am still waiting on. Should be here today or tomorrow. While waiting I did about 100 little odds and ends like sanding, priming and painting the windshield trim, mirror wind spoilers, door handles, trunk rack, etc., polished wheels, painted wheel cutouts, and a bunch of little stuff inside and out I've been meaning to do. As soon as I can get it out of the garage I'll post some pics, I'm proud of it. Not sure if my sig is showing up or not but my combo is listed there.

Quote:

I don't quite get the entire assembly part of the question either. I wouldn't pull the batwing off either as posi additive stinks like hell and you'll make a mess. Great to see CFI on here !!!