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ZR2 Lockers Retrofit?

62K views 127 replies 42 participants last post by  Jacqson 
#1 ·
Excuse me if this has been asked elsewhere but I've not come across it... I also wasn't sure if this belonged in Suspension or Off-Road. Anyway...

Do we have confirmed backwards compatibility of the ZR2 front and rear lockers (I think yes)?
Can anyone find the p/n for the front and rear lockers?
What is the cost from GM?
 
#3 ·
I haven't found a parts diagram that lists a PN for the front locker. The back G80 is a tried and true device for me, so I wasn't looking for that one.

Since it's an Eaton E-locker, there will probably be a pinout or wiring diagram that will be necessary also.

I sent an email to Eaton requesting a standalone locker kit for the twins, and posted the link for others here, but got a tepid response on both counts.

Eaton Performance (Eaton Performance Support)
Jun 26, 10:37 ADT

Hello Thunderbear,
Thank you for your inquiry. The ELocker for the Colorado is an OEM product. Eaton does not offer an aftermarket ELocker for the Colorado. For further information please contact a GM dealership.

Thanks!
-Eaton Performance Support
 
#4 · (Edited)
I went down to my dealer parts department a few days ago and asked the exact same question. To this point in time they told me all that was available was the ZR2 complete front diff which included the E-Locker but they didn't show an exploded diagram of the diff. (I was afraid to ask how much because there wasn't a cushion on the floor I could fall on after I got an answer :laugh:). I was told to wait a little while longer until the parts info is available to the GM dealers parts departments as some of the ZR2 parts are relatively new.
 
#5 ·
I remember hearing/seeing something from GM interview that the Lockers would be backwards compatible if one were to wire their own switch. However, I don't think the part is readily available yet. Im sure they are still waiting on adequate supply.
 
#6 ·
Agreed, it would be no problem for Eaton to supply this E-Locker with their own switch setup. Plus if you could pick up one of these E-lockers from Eaton or even GM you wouldn't be stuck with only having it only available to lock in low range like how it works on the ZR2. I used Eaton E-lockers on some of my other trucks and they are a great product.
 
#7 ·
Just an update to my previous post. I contacted Eaton about offering the Front ZR2 E-locker into the aftermarket and was told it is a GM part only. So for now, I guess if anyone that wants to retrofit the ZR2 E-Locker into their Colorado/Canyon, you're going to have to buy it from the General, and I can imagine you'll pay dearly for it. Eaton has been making the G80 for GM since forever and has that unit ever been available in the aftermarket? Knowing the answer to that might give you an idea of whether the ZR2 E-locker will ever be made for sale from someone other than GM.
 
#8 ·
A newly engineered part designed for an OEM supplier can have an exclusivity agreement. Sometimes permanent, sometimes only for a couple years until a restriction is removed or r&d costs recouped through sales. Some of the GM ones doesn't even allow a supplier to confirm they produce it, I've seen that on their GMPP exhausts. I've had excellent luck getting OEM parts dirt cheap by looking them up by AC Delco replacement part numbers instead of GM part #. Unfortunately it can take a year or two for that to get updated. Brembo calipers and ferodo pads for example.

They came out with a helical posi for the camaro before GM realized they needed it for the Z/28 which helped make it available outside of GM channels. Unfortunately the aftermarket is still small due to market share for these trucks compared to full size models. Hopefully that changes as time goes on.
 
#13 ·
D32 and a D46, front and rear, match what you found goleee33?

Given that this is the only application I'm aware of for this axle, I'd be very surprised if any of the aftermarket even produces for it. Hell, I'm skeptical of the 4.56s until someone actually tries them and reports back.

Going forward, unless some other vehicle picks up this axle, I expect to see some axle and diff swaps to recapture the flexibility of aftermarket shafts, lockers and gears on the twins. A single application is just too expensive to produce for.
 
#14 ·
#15 ·
I'm awaiting parts availability for the front diff. As soon as I can get under a ZR2 to measure the unit width and mounting locations, and confirm they are the same, I'll try to get a front diff. I'm thinking very positively that this will work.
 
#18 ·
I might of missed something in the multiple mini-threads above; so please forgive me in advance.

The ZR2 rear lockers are the same as those in other GM vehicles, the only difference is that the ZR2 has a driver controlled switch which asks (not asks, not commands, not manual control) the computer to lock the differential, and leave it locked. There is a relay in the engine compartment fuse box which the computer triggers the locker.

Two options: (1) disconnect the relay from the computer control, and put a switch into control the relay. (2) try adding a switch to control the relay in parallel with the computer.

Both options will almost definitely void warranty. Either option may damage the computer.
 
#19 ·
Traditional G80s are based on wheelspeed differentials: at a 120RPM difference between the L/R sides, the locker is engaged via flyweight/clutch/cam actuation, which locks the axles together.

For the ZR2 rear, I'm having trouble figuring out where in that mechanical system a BCM-controlled electronic switch could engage. Perhaps the flyweights or clutch are actuated by a solenoid?

@bcuzucant are you considering an entire front diff swap? I'm just hoping the front locker unit and a relay setup will get me what I want.
 
#23 ·
I'm considering my order or purchase on a 2017 or 2018 now and like you guys am running into the exact same thoughts over the front locker, which I just posted about.

A good piece of info I think I just learned from reading here is when you lock the diffs up on the ZR2 models it also shifts you into 4 low, that is correct? Not sure I really care too much about that but it is kinda stupid, I wonder if it can or will be programmed out some day via a tune?

Also this same thread I see considerations on the gear ratio - my other "issue" - looking for a way around the 3.42 (was hoping a way to order around it but I guess not, although maybe w/ an 8 speed transmission they give you a 1st gear that's fairly low anyway?)..

The dumbest thing about the front locker, for such a cool feature, is they package it only with a bunch of luxury options - looks like you can only get it in the chevy ZR2, as if the person who wants a work truck and uses their Colorado to get around a farm where things get real deep and mushy, goes hunting on logging trails, ends up out on the road in the worst of blizzards or plows driveways with the truck, who is really going to appreciate the front lockers as an option, is also going to value and want to pay for leather heated seats and up level audio/electronics like navigation? :) durr. Whatever the case I'm still happy they added front lockers - just would sure be nice if you could get it in a work truck or the regular Z71.

Jon
 
#24 ·
I think they figure if you need to use the front locker your not going to be in anything that you'll be able to do 25mph or whatever the limit is lol.
 
#25 ·
No, engaging the lockers does not shift the transfer case. You can engage the rear locker in 4x2, 4x4, and 4x4 low range. It will automatically disengage at 28 mph, unless you have it in off road mode, then it will stay engaged forever. The front locker can only be engaged in 4x4 low range, and only if the rear is engaged.

Sent from my SM-G930V using Tapatalk
 
#26 ·
So, if it's switched only, does a rear wheel just spin with no input from the switch? There's no ramp/clutchpack to engage, since that space was taken for the electromagnet engagement if I understand right, so theoretically it could wheelspin forever until switched, correct?
 
#32 ·
Looks like the ZR2 front axle assembly finally made it to the parts diagram database.

AXLE ASSEMBLY - GM (84090640)
[FONT=&quot]Canyon, Colorado. With zr2[/FONT]



Let the retrofittings begin!
 

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#33 ·
Looks like the ZR2 front axle assembly finally made it to the parts diagram database.

AXLE ASSEMBLY - GM (84090640)
[FONT=&quot]Canyon, Colorado. With zr2[/FONT]



Let the retrofittings begin!

Actually the pricing on that front diff isn't bad, as all you would need is the diff itself, you wouldn't need to replace the axles as you could use your existing ones. The great thing about retrofitting this diff into a non ZR2 truck is that you could have complete control of when you want to lock it up. You wouldn't be just stuck having it only lock up in low range. The downside I guess is you would most likely have to wire up a separate switch which could bypass the computer control. The diff itself should be a direct bolt in, into the truck. I'm going to look into this as I have had two previous trucks with front e-lockers and they are the best thing since sliced bread, IMHO. Thanks for posting TB....
 
#35 ·
I don't think that will be an issue as I can see GM making the CV's longer for the ZR2 because of the wider track, but I can't see them changing the spline count because that would cost them a lot of extra money. I firmly believe that the front diffs are identical except for the E-Locker and the wheel hubs would be the same as well. That being said, I will check into it and see what I can find out. On a side note, if you lift, as in lift kit, not leveling kit, a non ZR2 truck, using the ZR2 CV's would be a good idea because as you lift the truck the CV's get stretched out the higher you go. I know lift companies supply spacers to compensate to a point but all they really accomplish is to increase your CV angles.
 
#36 · (Edited)
Here's a bit of an update. According to my dealer parts guys, acquiring a full front diff from GM is sort of hit and miss depending on whether GM needs the front diffs for production ZR2 trucks. I also checked about purchasing an E-locker from GM and apparently it is listed but has no availability as of yet. Also, the front diff carrier,( I'm guessing bearings as well, but the ring & pinion are the same throughout), is different on the ZR2 front diffs because of the E-locker, however the mounting points and diff housing are identical, so the front diff would be a direct bolt in on a non ZR2 truck.
According to my parts guy as well, GM is reluctant to sell them a complete diff if they can repair a damaged or defective unit with just some new parts. This info so far, is just my preliminary findings, however, I will keep on this and if I find anything else of interest, I will post it here. Basically, if you got deep pockets and you want to put a ZR2 front diff in your non ZR2 truck, then all you need is some green because from what I can see, it's just a diff swap and possibly some creative wiring for the E-Locker. I also tend to think GM doesn't really want to sell anyone one of these diffs for a diff swap, although that is JMHO. Thanks TB for the part numbers.......
 
#37 ·
Fabricator recommended buying the diff assembly outright based on his experience doing something similar with several Jeep Rubicons. Mentioned that the Rubicon locking diffs had wire channels, bearing reinforcement and oil wells different than the non locking diffs.

I don't have deep pockets, but I will be doing this at some point. Since GM did not allow me to configure the truck I wanted, I'll do it my damn self, and without the nanny state BCM bullshit, too.
 
#38 ·
Fabricator recommended buying the diff assembly outright based on his experience doing something similar with several Jeep Rubicons. Mentioned that the Rubicon locking diffs had wire channels, bearing reinforcement and oil wells different than the non locking diffs.

I don't have deep pockets, but I will be doing this at some point. Since GM did not allow me to configure the truck I wanted, I'll do it my damn self, and without the nanny state BCM bullshit, too.

I don't have deep pockets either but I'm kind of holding out and checking the wrecking yards for some unfortunate ZR2 that was in an accident...Also, I got 46 pages of GM listed axle parts from the dealer for the front diffs of the Regular and ZR2 front diffs on the 2015-2018 Colorado trucks. Parts for Jeep diffs are everywhere, Colorado's, not so much...
 
#40 ·
They should have a service that lets you put in a part number and/or item name from a make/model/trim that notifies you when said PN/part/make/model hits the salvage yards. I'd have several models waiting to pull parts from, a Denali, a ZR2, even some W/T parts.
 
#42 ·
Subscribed as I would like to know if/when someone has successfully installed a front locker in a Z71 as well as replacing potential weak components that may break as a result of the upgrade.
 
#44 ·
Looks like we got some part numbers now. Found this on the 2nd gen fb page.

"GM part Numbers for the ZR2 electric locking differentials front PT#23403917 Retail $785.68, Rear PT# 84366616 Retail $988.35 . Parts are av in just a few days from warehouse to dealers."



 
#47 ·
So who is going to put the ZR2 lockers in a Z71 first and let us know exactly what is needed and how we get it working without errors getting thrown? :) This project seems a bit more than I am usually comfortable doing, but if I can find enough time to do the research and unless a tested aftermarket kit comes out this year, I may need to give it a try.

I found the main locker part numbers listed earlier in this thread for a pretty good price here:

https://www.gmpartsgarage.com/oem-parts/gm-differential-ki-84366616

https://www.gmpartsgarage.com/oem-parts/gm-differential-ki-23403917

I am still concerned about the weak parts up front that the ZR2 reinforced that us Z71 guys do not have so ideally, I would need to create a plan to remedy that too.
 
#55 ·
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