How to piece together a ZL1 differential swap - lessons learned from the battle
 

Just finished my ZL1 diff swap. Did a lot of reading on a lot of different threads to try and figure out how to piece it together using used parts. Kind of wish there was a definitive thread laying out what is needed. So I guess that's what I'm hoping to do here.

First, you need the obvious:

• Differential. You can get the 3.73 manual...or the 3.23 auto. Only difference is the gear ratio inside. Everything else (dimensional) is identical.
• Axles. You can use the ZL1 axles. Or go aftermarket. Note that the aftermarket axles designed for SS diffs will not work with the ZL1 diff.
• Driveshaft. Again, you can go with the ZL1 driveshaft or aftermarket one pieces. This is where you need buy the right one for weather you are hooking up to an auto or a manual on the trans end. They are different lengths.

In addition to the diff/axles/driveshaft....you'll also need the following:

• Trans flange (GM part# 22960154) Qty 1 (note that you can get away with using the stock SS trans flange if you go with an aftermarket driveshaft. Just make sure you tell them to build it to hook up to an SS trans flange on the trans end...and a ZL1 diff flange on the other end)
• Axle Nuts (GM part# 11611234) Qty 2
• Axle Washers (GM part# 11611965) Qty 2
• Driveshaft to Trans Flange Bolts (GM part# 11611336) Qty 3
• Driveshaft to Trans Flange Nuts (GM part# 11611365) Qty 3
• Driveshaft to Diff Bolts (GM part# 11611335) Qty 3
• Differential cooler plugs (GM part# 22960153) Qty 2 (this plugs off the cooler lines on the bottom of the diff. The ZL1 has a diff cooler. The SS doesn't)

Here is a link to the GM instructions on how to do the swap:

http://www.chevrolet.com/content/dam...&-22959395.pdf

Note that on page 1, it shows the parts listed. Also note that the driveshaft bolts and nuts are mislabeled in these instructions (backwards). I have them correct in my description above.

Also note that at the time of me doing this swap...GM has a backorder on the 11611335 bolts and no estimated time to replace. After a ton of aggravating searching, I discovered that the 11611336 bolts can also be used out back to connect the DS to the diff as well. So just use these if you can't get the 335 bolts.

Some other useful tips:

• You'll need a 32mm socket to get the SS axle nuts off
• You'll need a 36mm socket to get the ZL1 axles torqued on
• You'll need a 30mm socket to get the trans flange bolt off/on
• When you take the trans flange bolt off, watch the orientation of the washer that comes off behind it. It is a concave washer.
• Torque spec for the trans flange nut is 100 ft lbs. This is not stated in the instructions.
• Once the trans flange nut is removed, you can get a rubber mallet and bang it off.
• You can remove and reinstall the differentials by only removing the passenger side knuckle assembly. Leave the driver's side all assembled. Then drop the diff and pull it out towards the passenger side and the driver's side axle will come out. But its tight, and you need to be careful or you may bend you axles or rip a boot. But this will save you some time. To reinstall the ZL1 diff, its a bit harder because its so much bigger. But you put the axle into the diff first, then angle the diff and slide the axle up into place will you lift and rotate the diff. Of course...the safe way to avoid all this is to disassemble the driver's side knuckle too. But this can save you a bit of time if you have some help.
• I used a floor jack to help get the diff in and out.

Hope that helps someone!!!!

Just saying that I believe you can use the back half of the ZL1 D/S and mate it to the front half of your SS D/S at the carrier. They are the same splines. This should keep you from having to buy the trans flange plus nuts and bolts.

Unfortunately, I can confirm that doesn't work. Tried it when I had my SS driveshaft out. The ZL1 shaft has a larger spline to mate the center section.

This would have been awesome two weeks ago! I just completed my swap this past weekend.

I will add that I went ahead and purchased
Two differential Rear Axle seals... Might as well do it just in case. P/N 20964013
I also needed to retainer clips for the aluminum plugs that you use to plug the differential coolant lines... The plugs just push in and should have wire spring retainer clips to hold them in place... mine did not. I used two "C" clips from the auto parts store, not perfect but it works.

Just about every bolt on this swap is supposedly a torque to yield. Do you own research and make your own decision on that, for me I simply used loctite on several of them.

If you replace the seals you will want a seal driver. I used a 1/4 socket extension and a hammer. I took my time, but still am nervous about a future leak. The instructions mention using an tool to install and remove the axles... Just be careful as you guide them in and out you should be fine.

Agreed probably a good idea to get new diff seals. Mine looked good so I just went with them.

And you are right about some clips to hold the rubber plugs in the coolant fittings. Can you let us know what specific clip you used?

Honestly I am still searching for a better wire spring clip, I sent my wife to O'Reillys to get c-clips. The guy at the counter tried a few until he found one that was close.... I still had to grind down the thickness to get it to slide in. I also had to squeeze it into place with vice grips....

I did at least paint them after hitting them with the grinder.

What would be better is a smaller version of the wire clip that is used at the front of the coolant lines on the LSA kit from ADM. Just a wire retention clip.

Looks like autozone may have them - I have not checked size - "Help" or "Doorman" 800-801

I think I found them ACDelco 24205103 - Clips
the inserts already present in the differential I "believe" are ACDelco 15226661

Yep. I think you got them there. Available for $4 apiece at summit:

https://m.summitracing.com/parts/nal...FQIKaQodPe0I1g

I just ordered a couple on ebay... I will report on how they work.

I just ordered some as well.

I just hope your plugs stayed in! (actually, I just hope mine stayed in!)

Ha! Yep. Will have to have a look tomorrow. I couldn't handle it anymore. Got it back together...and had to go lay down some 100' black marks ASAP. Don't care if they came out. I'll get some new ones. Winter is coming here in MN and it will be hibernated. Had to go romp on it while the weather was still good and no salt on the roads.

Here is the tool. I just upgraded my SS diff to an Eaton

http://accelerationtech.com/photos/d...20(Medium).jpg

http://www.camaro5.com/forums/showpo...&postcount=933

-Don