WTR388

Well, after seeing what 83rdracr is up to, I decided to follow suit, mind you on a way less cool build... But this is going in to a stock chassis car behind an LS1 and T56.

So why this axle? I was planning on an 8.8 build from a ranger or mustang, which all in all is pretty simple to do... However, I assumed I had 28 spline axles, turns out my 87 has 26 splines so I started to look at different options (keeping things cheap here).
The ZR2 has 3.73 gears, an 8.5 ring gear and a "locking" diff, better axles, and the same bolt pattern (with same lug size) as our cars, and is only slightly wider at 3/4" according to Mr. 83rdracr.
I will be eventually getting a trutrac for this thing, and I'm installing ls1 rear brakes that I got for $25 (backing plates, rotors, calipers etc)... Which adds to the project a bit.
For parking brake cables I'll end up using Lokar universal cables, for the torque arm I'm going to use an aftermarket arm to use in my proposed mount... See how that one goes over.

So, here is my $150 rear axle:


She ain't pretty yet.

Here is the only issue with putting the F-body brakes on the rear. The mounting flange on the ZR2 is further in than on the F-body:
truck:


4thgen:


So, in order to use the F-body brakes, I need to move the mounting point out, somewhere in the order of 0.67" for the caliper to center over the rotor.
I'll likely be getting a piece of steel machined to act as a spacer, I'll weld it to the zr2 axle and brake plate... I'll mess around with the exact measurements a bit later.

I pulled the diff cover out and the gears look good... Side note; the bolt that holds the retaining pin in place is 5/16", NOT 8mm like the 10 bolts (I rounded the bolt off not paying attention, just threw the 8mm on there and rounded the corners off assuming... Lucky I got it out)


Started grinding off the ZR2 suspension mounting locations but ran out of time, so tomorrow I'll be back at it once our hobby club here on base opens up again.
Tomorrow's goal is to get the zr2 rear cleared from the mounting points and to measure and get angles from my 4th gen rear housing I snagged for $50, since our mounting points are the exact same, it was better than destroying my current rear.

So far I'm in to this thing $225 Canadian, so something like $5.78 For you southerners.

big gear head

I'm guessing that you already know that the Gov Lock in that rear end is junk since you said you are going to install a Truetrac. That's a smart move.

WTR388

Yep, I've never been impressed with any of my GM's "locking" rears... Except the one in my 04 Canyon seemed to work pretty good out on the trail.

Once I've got it in and functioning, I'll swap it out.

I'll need the drive shaft shortened up a bit so I'll have to find a local shop for that.

83RDRACR

WTR388, I just came across this thread. Hope you like the ZR2 axle. except for the gov loc posi its a pretty good deal. I will be sollowing along to see what you do for a torque arm mount.

jkris53406

iTrader: (5)

Any progress on this? Very interested to see how you do the mounts.

WTR388

It's slow... I'm on course at the moment (aircraft structural stuff), living in the barracks (essentially a dorm) and the garage is the base auto hobby club, makes it difficult to get everything all set up, get some work done and then pull it apart, especially while working with making sure it is all level, even and square... However, I haven't given up, I'm hopefully buying a garage (and I guess a house unfortunately) when I'm posted sometime next month, so I'll be able to get back to it in my own environment... I actually came up with a different T/A mount today that should work great.
Since I'm moving provinces, the car has to pass another inspection so I have to do some work (floors) and I figure I'll fix my 4th gear issue (syncros) in the spring, so I have a list of to do items.

I'm about to do my LS brake swap on the front end in the next couple weeks, so at least there is some progress in that department.

All is not lost, this will be completed! I'll also have access to a lathe at my next unit so I can make up a weld-in spacer so I can use F-body LS rear brakes instead of the ZR2 stuff (which I'm sure work just fine, I just want to do things this way for some reason)

WTR388

Ran in to a bit of an issue... My parts were at the base auto hobby club, and someone decided to clean up the storage area, I guess my "junk" suspension mounts that I had cut off the f-body axle ended up in the metal bin, which I dug through but came up empty handed.

So, I still have my ZR2 rear, but I got to thinking, that since the ZR2 tubes are narrowed down to the same diameter as the f-body tubes, that the axle bearings are likely the same between the f-body and the ZR2.
If this is the case, I'm considering doing the build in the same way more 8.8 builds are done, with cutting the tubes apart, and welding the 3rd gen tube ends on. If so, this could be a bit easier than the way I was planning to do it. I can likely make a sleeve at work to go over the seam and keep it the stock ZR2 width to use the Zr2 axles in the F-body tubes.

Move is in a couple weeks, have my own garage finally so maybe I can dig back in to this over the summer.

WTR388

I would assume that this means I'm in luck:

https://www.yukongear.com/productdet...px?ProdID=4743

I know there is lots of talk with no action... But I will get this to work at some point. Either I need to go find another F-body axle for mounts or to cut the tubes out, unless I blow apart my 10bolt this summer.

big gear head

I'm not completely sure, but I think the ZR2 rear end uses larger axle bearings. If this is true then the ZR2 axles will not work in the F body tubes.

WTR388

I don't think it will work anyways, to maintain the ZR2 width for the axles, the suspension mount points also move out.

Maybe I'll play with the idea of making my own suspension mounts.

cosmick

Still lighter and easier to just get a '71-'81 Camaro 8.5", they're nearly the correct width also, but without the multiple sizes of axle tubes. Much cleaner look, too.