Jretal

Clicked 2 more things off the list this week on the 4000... she's almost road ready again! lol

Over the course of the past month+ I've been planning this swap out and getting things organized. During some free time, I took the time to tear apart the V8 rear diff I picked up mid summer from the local pick and pull ($65 rear diff anyone??? ).

<img src="http://lh6.ggpht.com/_4dSd8RzzFyI/SUXW_QenYCI/AAAAAAAAAgw/hpTe1zX0Xss/s800/IMG_3705.JPG">

axle cups out waiting for some machine work

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SUXXA-ZQ_NI/AAAAAAAAAg0/E8aLOqjQpqY/s800/IMG_3706.JPG">

and sweet sweet torsen goodness:

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SUXXDvS9rRI/AAAAAAAAAg8/fyKHuzwfwk4/s800/IMG_3708.JPG">

Getting to this point wasn't too hard, obviously... Unfortunately, the V8 rear axle cups are bigger than the 4000 inner CVs, (as shown here:

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SUXXGltxQNI/AAAAAAAAAhE/czFf28440-Y/s800/IMG_3710.JPG">

In addition, I couldn't use the 4000 axle cups because they are too short to fit in the V8 rear diff, so there isn't enough spline engagement to work... so the V8 Axle cups needed to get machined.

After doing some research, I finally got the info that I needed as to what machining needed to be done to get this to work, but I also heard that there might be interferences b/n the cups and the 4000 diff, so I held off bringing these to the machinest until I got the rear diff out to confirm fitment.

So the next logical step was to get the rear diff out of the 4000 and start playing around with it. After getting the motor and such in the car, I went right at getting the rear diff down and out of the car...

Hoping to dismantle as little as possible, I was able to drop the rear subframe enough so that I could just shimmy the rear diff out from the car and not touch the rest of the suspension... thankfully, this worked out as I hoped!

Pulling rear diff from the 4000:

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And sitting waiting to get violated:

<img src="http://lh3.ggpht.com/_4dSd8RzzFyI/SYEltL-h-7I/AAAAAAAAAug/4Agv5dI7q5Y/s800/IMG_3917.JPG">

Last week I spent a very cold and late night on Thursday tearing apart the old locker rear diff on the 4000 so it could accept the V8 rear torsen diff.

Up and ready to get torn down:

<img src="http://lh3.ggpht.com/_4dSd8RzzFyI/SYphxpEGNqI/AAAAAAAAAuk/92-qdunzABw/s800/IMG_3918.JPG">

And the locker unit out to clear room for the torsen:

<img src="http://lh3.ggpht.com/_4dSd8RzzFyI/SYphydUfvkI/AAAAAAAAAuo/UlBQzcpKNAs/s800/IMG_3919.JPG">

<img src="http://lh6.ggpht.com/_4dSd8RzzFyI/SYphzWLu0ZI/AAAAAAAAAus/N7BNpfANSlY/s800/IMG_3920.JPG">

Next on the list was to start making room for the torsen. Since I'll be using the V8 rear axle cups, there's no need for the old 4000 seal... so out it comes:

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SYph0GRauJI/AAAAAAAAAuw/vr7_EMiZass/s800/IMG_3921.JPG">

In order to get the lock collar out, I had to remove three bolts:

<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYph2hTfWbI/AAAAAAAAAvA/HZr-uHQ-TX0/s800/IMG_3927.JPG">

They were located here:

<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYph1Wf0rWI/AAAAAAAAAu4/DnNcplkk-kc/s800/IMG_3923.JPG">

and here:

<img src="http://lh6.ggpht.com/_4dSd8RzzFyI/SYph2IFHQYI/AAAAAAAAAu8/k3JdGm0n-yw/s800/IMG_3925.JPG">

This will allow you to lift the gears out of the rear diff. Make sure you put these bolts back into the housing after everything is out, otherwise it'll leak! These bolts thankfully do not interfere at all w/ the torsen unit, so I didn't need to shorten them at all... which was a plus.

Next on the list was to swap the ring gears on the diffs. The V8 ring/pinion is different than the 4000. This was a little tricky as these pieces are interference fits, so even after the bolts are removed, it's not coming off w/o a fight!

I started off by buzzing off all the bolts w/ my impact gun. I then realized that no matter how I hit the edge of the ring w/ my deadblow hammer, it wasn't moving. So I threaded a few screws in at choice locations and started hammering (while the diff was on a piece of wood mind you!). This gave me a bit of a gap, but the screws weren't long enough to fully disengage the ring from the diff. So I then took a large piece of 3/16" AL I had laying around and stuck it in the gap, and with the other side of the plate resting on my knees I started hammering away. Eventually I was able to free the gear... and success!

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I then repeated the same thing w/ the V8 rear diff. It was def easier the 2nd time around w/o a doubt!

Next was reassembly, and it's times like these that I fully realize I'm still a bachelor living in my own house :-P. Since this is an interference fit, the way you're suppose to reassemble it is to heat the ring to ~212* (according to Bentley). So since it was below freezing outside, I left the diff out in the garage and brought the ring inside and started to bake it (WARNING: do not attempt if your wife/gf is in the house watching, as she might try to mame you!)

<img src="http://lh3.ggpht.com/_4dSd8RzzFyI/SYph4H_sl_I/AAAAAAAAAvI/KJbBhYENZC8/s800/IMG_3930.JPG">

After baking it for about 20 min (wanted to make sure it was good'n hot) I brought the diff into the house and set it up on the stove top. I then tossed on my welding gloves and pulled the ring out and popped 'em together. To my surprise, it literally slipped together! No pushing necessary what so ever! I twisted it until the holes lined up and then ran a couple bolts into it to hold it in place:

<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYph5CNJ3zI/AAAAAAAAAvM/dVlgN7yNiLE/s800/IMG_3931.JPG">

Again, do not attempt to do this w/ wife/gf watching you :-P

I then torqued down all the bolts to the recommended 66 ftlbs and tossed her in her new home

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And the other side where the locker used to live:

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SYph6ols1fI/AAAAAAAAAvY/hCBZ29fzkmE/s640/IMG_3933.JPG">

At this point, I was now waiting on my machinist to finish off the V8 axle cups so I could bolt everything together. After a few day wait, I finally got the call yesterday morning that everything was done!

This is what needs to be machined into a V8 axle cup to accept the smaller 4000 inner CV joint:

<img src="http://lh6.ggpht.com/_4dSd8RzzFyI/SYph7foqqCI/AAAAAAAAAvc/E0BmdgsH6aI/s800/IMG_3944.JPG">

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SYph8HXysGI/AAAAAAAAAvg/LqMRbd2_MB8/s800/IMG_3947.JPG">

and with CV bolted in place:

<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYph9A1lp2I/AAAAAAAAAvk/vpfwCKsB6bQ/s800/IMG_3948.JPG">

*Special thanks to Bernie again for providing me the inner CV joint! Couldn't have done it w/o it, so thank you sir!!!*

Basically what needs to be done is to machine a lip into the flange to help center the CV joint, and then drill/tap new holes into the material. This isn't nearly as strong as the OEM location, so be careful when torquing down or you're going to strip 'em! I torqued the bolts down a few ftlbs less than recommended to prevent that from happening.

Before finishing off, one more thing to do is to plug the hole where the actuator arm stuck out of the rear diff. I had thought about putting a bolt in there, but that just seemed... ghetto. So instead, I hacked up the arm to the locker.

It started like this:
<img src="http://lh3.ggpht.com/_4dSd8RzzFyI/SYph9ksSUKI/AAAAAAAAAvo/HcWkILgcuuA/s800/IMG_3949.JPG">

and ended up like this:
<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYph-74GhJI/AAAAAAAAAvs/DLfgPaF_KdU/s800/IMG_3950.JPG">

once installed, no one is the wiser... minus the zip tie of course (I ran out of hose clamps, and it was 9-930 before I got this far so everything was closed)
<img src="http://lh6.ggpht.com/_4dSd8RzzFyI/SYph_kZB5RI/AAAAAAAAAvw/cIBTopxtvVE/s800/IMG_3951.JPG">

Once that was done, in went the flanges:

<img src="http://lh5.ggpht.com/_4dSd8RzzFyI/SYpiAa6hisI/AAAAAAAAAv0/xLa6A79Z0js/s800/IMG_3952.JPG">

and into the car it went! Things bolted up just like normal. Because the lip on the axle flange wasn't as big as OEM, it was a little more difficult getting the inner CVs to center and stay centered until you put enough bolts in, but def not the end of the world. I'm real happy with the outcome, and can't wait to get this on the ground and ready to go!

Also, during the course of the week I managed to make a new heat shield for the motor mount. My previous plans of using AL plate failed miserably, as there just wasn't the room to do what I wanted to do, and the AL plate wasn't really buying me anything. I ended up just using the AL/Fiberglass insulation I bought and formed it to fit and bolted it to the car... took a helluva lot longer than it should of (won't go into details of what I had to go through before getting to this point), but rest assured it was excessive and had me throwing a few tools.

And the final product:
<img src="http://lh4.ggpht.com/_4dSd8RzzFyI/SYpiBLk58RI/AAAAAAAAAv4/aFoa_CtQuS8/s800/IMG_3934.JPG">

This should protect the mount. The insulation material is rated to 1750*, so that should be MORE than enough to block the radiant heat off the turbo/exhaust manifold.

So that's about it for now! Next step is to refill the fluids and finish up the mounts for the 6 point harnesses and I can finally put the interior back!!! Hopefully in the next 2 weeks the car will be road bound once again!

SCarGo02

...driving it!

Jretal

hopefully this will help fight some of the wheel hop/spin I was getting w/ the open diffs when hitting turns on the track! :-P

SCarGo02

Eh, the urS guys seem to love'm...and that's on a big pig of a car...should do wonders for the 4kq!

teach

A second WOW. Very impressive.

Supercoupe

Nice job..but one quick "did you try" question.

The V8 cup looks to use bigger diameter bolts for attaching the inner joint, which gives the cup a larger outer diameter, but, rather than machine the V8 cups,did you investigate changing the inner spline and rollers from the 4Kq joint into the V8 joint housing?

AudiSport4000

Awesome work! I have never been able to take one of those diff's apart, so its cool to see the guts of them

Keep up the good work!

Jretal

you talking about the inner CV joint?

From what I'm told, you could also use the older 4000 (i think) axles that use the bigger inner CV joint. I didn't keep the inner CV joints from the V8 when I took it apart, so I'm not sure if they would have slipped onto the 4000 axle. Something tells me they wouldn't have worked, but I didn't confirm this.

Jretal

kinda cool to see all the gears and what not and see how they work! But then again, I'm an engineer at heart, so this stuff easily intrigues me :-P

reddiamond

dont want to ruin your day but there is an easy fix for axle problem, just use v8 cups with 84 4kq axles. ps you will love it with torsen in the back