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

[dentnshell]

Maybe I should have been a little more clear. Power level is not the only factor the ZL1 and other positive displacement power adders create a significant amount of torque at very low rpms. With a turbo setup you may be just fine with upgraded axles, and some sort of locker or similar limited slip upgrade.

The problem tends to occur when the tires break loose and then find a way to hook up. Honestly for how I drive my car. I didn't "need" one. I am way less likely to break an axle, but hat just makes something else the weakest link.

[Infern0]

Originally Posted by dentnshell

That driver might work, but due to the lip I am not sure I would use it. I found the correct one on eBay. 30 bucks. Pretty much idiot proof. I did one successfully using 1/4" socket extension and being ginger around the perimeter. The second seal I tapped one too many times and dented it. It is a tight fit. To change the seal is $45. Plus $60 in fluid. Taking out the axle. Which is pulling the brake caliper. Tie rod trailing rod and hub. After messing one up. I am am glad I had the correct tool for the replacement.
My dealer offered a loaner if I left my first born child. Might be worth a trip to check.

I saw the ones you guys were mentioning but there haven't been any decent deals on them so far. All $100+.

I'm confused though why you don't think the installer set I got might not work. It looks very similar to the tool you used, but with more sizes available. Which diameter is needed?

Thanks for the heads up. If it doesn't look like it will work I can still return it. I got it just for this job.

[dentnshell]

If you look on page 3 of this thread I posted a picture of the WRONG driver on the correct seal.
Notice the lip on the seal... On the correct driver that seal lip will go into a recessed portion of the driver.
Also the driver tool's lip does not allow you to over "drive" the seal. It will stop it and prevent the metal from collapsing.
Look at that picture and imagine using the flat drivers that you have in your kit.
It may be that you can find the correct diameter of PVC pipe to improvise.
The correct driver also has an inner support that keeps everything centered and puts tension on the inner part of the seal. That little bit of tension helps keep the spring on the seal while driving.
I am not saying it can't be done without the tool... I, and many others have done it. But I have also messed up a seal. My dealer does not have them in stock, so if you mess one up you are waiting on UPS.

[dentnshell]

ebay is your friend.
http://www.ebay.com/itm/Kent-Moore-J...858268&vxp=mtr

J38869 - There are a couple of them. I am not sure what the "A" at the end of the recommended tool is for but the J-38869 is the one I used.

[Infern0]

Originally Posted by dentnshell

ebay is your friend.
http://www.ebay.com/itm/Kent-Moore-J...858268&vxp=mtr

J38869 - There are a couple of them. I am not sure what the "A" at the end of the recommended tool is for but the J-38869 is the one I used.

Would the manual 6-speed be the one you indicated was wrong? It looked like you said that was for auto.

[dentnshell]

Originally Posted by Infern0

Would the manual 6-speed be the one you indicated was wrong? It looked like you said that was for auto.

I don't think it matters for the differential. The one that was wrong was one that hammdo used for the SS.
the ebay auction talks about using it for the actual transmission. I went to the dealer and had them look up the tool - took a bit to get someone to let me go back to the service department where the guy looked up the seal replacement instructions on his computer.

If you are talking about just the differential seal, it should be the same tool for manual and auto. (same axles)

[HOU_TX_SS]

where are you guys picking up the Zl1 Differential? any good leads. Im running a 4L80 with a DSS driveshaft so that's something else Ill have to overcome for the swap but I think it will be worth it.

[cc-rider]

Look here in the classifieds...or on eBay to find used ZL1 diffs.

Or...you can buy the whole works brand new from Jegs or Summit for around $3800.

You can piece it together with used parts for around $2000-$3000. So the brand new option really isn't over priced.

[dreksnot]

Originally Posted by HOU_TX_SS

where are you guys picking up the Zl1 Differential? any good leads. Im running a 4L80 with a DSS driveshaft so that's something else Ill have to overcome for the swap but I think it will be worth it.

I'm peddling my 3.73 ZL1 diff, about 4,500miles on it, if interested. Just the differential. I do have most of the install hardware (nuts, bolts, etc).

[Infern0]

Originally Posted by dentnshell

If you look on page 3 of this thread I posted a picture of the WRONG driver on the correct seal.
Notice the lip on the seal... On the correct driver that seal lip will go into a recessed portion of the driver.
Also the driver tool's lip does not allow you to over "drive" the seal. It will stop it and prevent the metal from collapsing.
Look at that picture and imagine using the flat drivers that you have in your kit.
It may be that you can find the correct diameter of PVC pipe to improvise.
The correct driver also has an inner support that keeps everything centered and puts tension on the inner part of the seal. That little bit of tension helps keep the spring on the seal while driving.
I am not saying it can't be done without the tool... I, and many others have done it. But I have also messed up a seal. My dealer does not have them in stock, so if you mess one up you are waiting on UPS.

Thanks for the added information. I'm a complete rookie at this so I definitely need all the help I can get or I'd turn this in to a 3-month process and prob be near double the cost in repairs/replacements. So don't take this as doubting what you're saying, but trying to learn ahead of time - Would I not be able to use one of the seal installers from my kit that would fit inside the rubber lip and tap it in that way?

To confirm, I believe the consensus is the seals should be replaced any time the axles are removed? Is that right, or would visibly intact seals be reusable?

To confirm one more point, the stock LS3 Trans Flange isn't usable with the stock ZL1 diff, right?

And I've had to re-read this thread a bunch of times but I don't recall seeing trans or diff fluids. Any recommendations on these?

Thanks again!

[dentnshell]

Get your hands on a seal, it is rubber inside the lip. Nothing to drive. I am not sure in the flange for the ls3. But I think the bolt hole size is different. If the instructions state there is a flange for the manual. Then I would suggest getting one.
Fluids are spec'd in the instructions. I ended up using Mobil 1 ls. And the gm additive.
I was using a used diff. So the second time I filled it I only added an ounce of the friction modifier. Figures the clutch packs had all they needed especially with the LS fluid.

[cc-rider]

Originally Posted by Infern0

Thanks for the added information. I'm a complete rookie at this so I definitely need all the help I can get or I'd turn this in to a 3-month process and prob be near double the cost in repairs/replacements. So don't take this as doubting what you're saying, but trying to learn ahead of time - Would I not be able to use one of the seal installers from my kit that would fit inside the rubber lip and tap it in that way?

To confirm, I believe the consensus is the seals should be replaced any time the axles are removed? Is that right, or would visibly intact seals be reusable?

To confirm one more point, the stock LS3 Trans Flange isn't usable with the stock ZL1 diff, right?

And I've had to re-read this thread a bunch of times but I don't recall seeing trans or diff fluids. Any recommendations on these?

Thanks again!

For what it's worth...I did not replace the seals on my used ZL1 diff when I put it in. I inspected them...they looked good...in went the axles. Zero leaks. All is well. So in some ways, I think the whole axle seal discussion is being overthought a bit. Have a look at it, it's a rubber seal like so many we've seen before. Holds in the thick diff fluid...not designed to be a submarine driveshaft seal holding 25000 psi at the bottom of the abyss. Make a good logical mechanic determination on it and move on. Some will/should need to be replaced. Others will likely be just fine.

At the end of the day...it's always good to replace a seal I guess. Just do it right. But don't overthink it either.

[Infern0]

You guys using the GM stuff or something else for the axle splines?

https://www.amazon.com/gp/product/B0...=ATVPDKIKX0DER

And locktite on the bolts, right? Red or blue?

Thanks.

[ZX1truth]

I just bought a 2015 ZL1 3.73 diff from Canada with only 4500 miles on her. This thread is freaking GOLD! Thank you gentlemen......highly appreciated!!!

What hubs did you guys use??? ZL1 hubs??? Are their heavy duty hubs for the track?