Is there anyone of you modified a second gen Z28 rear end to fit Third Gen
F-Body including torque arm and parking brake.
Second Gen rear end are they the same length as the third gen ?
How mutch money it will cost ?

Thank for any advice

 

I had a 2nd gen rear end with the mounts cut off and was ready to make all the third gen mounts when we found a bearing cap bolt broken off, that was a heartbreaker. You are right they're the same width, and have the same lug pattern. It would've been a pretty trick setup had I got it in there, then I wouldn't be pulling 1 wheel out of my 9 bolt.

 

I can be done , and is almost as good as a 12 bolt. But it is a lot of work. Doesn't cost alot if you do it yourself. So if you have some tools and a little know how, it is a worth while project. I have one in a 88 irock. Street driven and runs 11.7 at 116 with 1.58 60ft. with 9 by 29 slicks. You have to clamp around the snout ,as you can't weld to the diff, it will crack. The clamp has to be a very very good fit. If not it will bind the bearing. It is easier if you fab up a torque arm at the same time.

 

im confused as to how a 10 bolt from a second gen can be almost as good as a 12 bolt.... My 79 Z's rear is about the same strength as my 10 bolt in my car.

 

Check this out 87ciz Posi 10-Bolt Upgrade Install - Tech Article - Chevy High Performance Magazine

 

The second gen 10bolt uses an 8.5” ring gear and the 12 bolt uses a 8.75” ring gear, and otherwise they’re very similar. Built up with similar parts the 10 bolt isn’t much weaker then the 12 bolt. If you want a surprise, compare the ford 8.8 to the 12 bolt, I’d bet that without the back cover on them most people couldn’t tell them apart.

 

Link is dead, any way we can get a re-link?

 

[quote=Brian Weatherbe;3097715]Check this out 87ciz Posi 10-Bolt Upgrade Install - Tech Article - Chevy High Performance Magazine

 

wow no wonder i havent broken it yet... i've been waiting for it to grenade like the 10 bolts in the 3rd gens lol

 

I'd like to see a pic of how you did that. I'm not sure what you mean by "clamp to the snout", but your setup intrigues me. I like the idea of a 2nd gen rear end, and i'm curious if a 2nd gen F-body rear is the right length? Shortening the tubes would make this kinda difficult. Then again, there are many sources of a 8.5" 10 bolt, says that article you linked, so i'm wondering which ones would fit the 3rd gen best.
2nd gens wheel bolt pattern is set up right, i'm using 2nd gen wheels right now actually.

 

2nd gen rear ends are exactly the same length, I believe it was 55 1/4 from the backing plate to the other plate. Plus they have the same lug pattern.

 

The housing we used was out of a 2nd gen. It actually was 1/4" narrower and fit better with our wheels. I will try to get some pics in the next little while. I wish I had before we put it in the car. I try and get some good light under there and see what I can get. I used 2 peices of alum. 4 by 6 by 2 wide bolted together with 4 1/2" bolts torqued to 70 lbs. But it has to be cut to fit around the snot very good. I made a cardboard template and sawed it out on a band saw. Then used blueing and a die grinder to get to fit as good as I could. It can not bind the pinion bearing when you tighten it . I will get some pics ,that will help. The control arm and spring brackets are easy, I welded the old diff down to a plate by the brackets and ground the weld of at the tubes . Then just set the new diff on the brackets ,centered it up , got the pinion angle right (masure that before you take the old diff off) and weld. I hope this helps .

 

Yep, that clears things up. I'll need to see a pic of how your did the torque arm mount. 4x6x2" aluminum is some THICK plate alright. I'm just having trouble visualizing it, if you can get a pic sometime, i'd greatly appreciate it.
Weld the diff to a plate on the floor to hold it still eh?

hmm, good idea, I had a tough time positioning my 10 bolt on sawhorses, it kept falling pinion down, and clamps didn't work well. Was decent enough to sand and paint, but that's it.

 

I agree, i need to visualize it !
Thanks

 

i would very much like to see this too, i have a spare 2nd gen and gutted 7.5 10 bolt. the only thing keeping me from getting going on this is the TA mount.

 

I talked to a friend about getting another 2nd gen Z28 rear end today. I really hope it has 3.08's in it with a posi. Hook us up with those pics that'll be awesome.

 

I will get some pics in the next week or so. I'm a little busy with work these days but I will do my best.

 

Same thing for me, I got the opportunity to purchase a use 81 Z28 rear end
and the torque arm mount are the big problem for me since welding onto
the diff is not a good idea.

 

Glad to find this thread. Finding a 2nd gen rear around here is easy. I didnt know that they are the same width.

What about brakes? Parking brake cable?

 

Why not just make the torque arm longer and attach it to the rearend tub and not the housing? With some kind of bracket or extension piece? Almost like a vette as from engine to rear end its all one solid piece.

Though if your gonna be fabin stuff
Should measure up a 78-79-80 buick electra or other rear end, not gonna be posi but it will be the strong one and they come set up factory for a 4 link / 4 bar setup. Mucho better then our LCA panhard bar setup.

 

Stock from GM the Torque Arm was attach to the diff. probably for a good reason (GM engineer knows about that), somebody knows about that ?

 

I don't know about that...

Yea, some people have affixed to the rear axle tubes, that just requires more bracketry, to bring the mounting point more in center, therefore more strength, gussets, etc.
I'd just make sure to weld up the tubes as well if you're doing any mods like this.

 

when welding on a rear end do you have to worry about warping the tubes at all?

 

yeah. just do small stitches then let it cool off so the heat doesnt build up.

 

ok, thanks.

 

My only hold back would be the torque arm mount..... Would like to see some pictures of some mounts.

Ray

 

The Ford 8.8" guys that have fitted them in to our cars weld to the housings for a torque arm mount. It can be done, just by a good welded with the right rod etc... I've got a 9 bolt beefed up in my ride but would go with the 8.5" 10 bolt if I ever needed something stronger..
Regarding the TA to the pinion housing..it is your pinion that wants to walk up the ring gear, this is the purpose of the torque arm, to stop this rotation. Wit the TA right on the housing it is in the best location as it will stop the housing from rotating. If the TA is on the axle tubes the housing will want to rotate upward and the joint between the axle tubes and housing needs to be strong enough to resist the rotation.. make sense?
I'd be suprised to hear of someone with a torque arm on the the pinion housing spinning an axle tube..ever!

 

We need pics!!!!!!!!!!!!!!!!!!!!!!

 

The 8.8 guys are using axle housings that have mounting holes/bosses around the pinion for mounting a heavy damper/weight that ford uses to quite down the driveline. The aftermarket TA’s for the mustangs bolt to that location and around the axle tubes or at the cover flange. Neither weld to the housing.

That’s not to say that you can’t weld to the housing, but that’s not how people have done it. My $.02, I know how to weld to a casting and I’m not sure that I would trust a TA mount entirely welded to a casting, I would want at least some bracing attached another way. Actually, let me rephrase that, that is not the way that I would do it. I’d probably just make an adaptor plate that bolted to the cover flange and the TA mount would work roughly like GM did it on the GNX but with the flange rather then the cover.

 

I will try to post some pics, new to this

 

I have some pics , how do I post them. I am doing something wrong.

 

See this thread;

https://www.thirdgen.org/forums/faq-...load-file.html

The link JT posted is to another thread showing the same thing. I think his is better, more clear pictures.
Give'r up!

 

Thanks

 

Here are some pis time I hope, torque arm mount from the front

 

After a year on the street and some high 11 sec passes nothing has come loose or broke. But next time I would build the torque arm heaver. Thicker wall tube and more ladder braces.

 

A few more. The clamp is aluminum and the plate is 3/8 steel. There was a small problem when we tried to tighten the clamp. It would cause the pinion bearing to bind. So the fix (don't laugh) was JB weld. After we got the clamp fitting as good as we could, that took two days of grinding with a die grinder. We searmed JB weld over the snout and clamp and bolted it together as tight as we could without causing drag on the pinion bearing then let it set up for 24 hours. Next day we torques the 1/2 inch bolts up to 70 f/lb without causing any drag on the bearing. The casting is so uneven and odd shape it hard to get an even fit. The JB weld acted as a filler to allow the clamp to be tighten with out any tight spots . Anyway it was a lot of work , but it worked and was cheap.

 

Thanks for the pics, well done realy nice job! do you use the stock bracket
on the transmission side to attach the torque arm?

 

Yeah, great pics!!!!

 

Sweet pics, I'm going to take these to my suspension guy and see if I can't pick up another 2nd gen rear.

 

Sent you a pm, Brian

 

Does anyone have pictures of a GNX torque arm mount?

Ray

 

Not bad Brian, do you have more pictures of the TA? What size/thickness tubing did you use?

JB weld is a fine solution for that problem. About the only thing that I see that isn’t quite right is that where you have the rod ends connecting the TA to your adaptor it should really be in double shear, even 2, 1/8” plates in double shear should be stronger then your single 3/8” plate in single…, and I probably would have used 3/16 or ¼” in double shear there.

 

Might as well show a link to the other page, since its pretty related, an alternate solution to fitting a 2nd gen rear in a 3rd gen is pictured:
https://www.thirdgen.org/forums/fabr...arend-fab.html


Brian, you're going to have to give up more info on this car of yours, i'm now more and more interested;

-year, car?
-Engine?? Runs high elevens, and is street driven, that's a nice combo right there. I also see side pipes
-what other suspension bits have you home made? Looks like LCA's, and SFC's ?
-A picture tells a thousand words, got any glory pictures of the car?

 

Hi all. car is 88 IROC, a little rough ,no show car, 700r trany , 4.56 gears with C-clip elliminators. Stock bore 350 out of a 92 truck with cast pistons stock bottom end , 180CC ProTop line cast iron heads home ported, but we did have them flowed and they flowed pretty good for the size. 9.5 compression, performer rpm intake ,CompCams 276hr cam, stock roller lifters, 1.6 rockers. We had some trouble getting it to rev past 5800 at first. Those CompCams HR cams need a lot of spring so we installed Comps 977 at 155lbs on the seat. On the track we run Hossier 29x9 slicks and front runners with Welds drag lites. And open headers. We have a B&M governor kit set at 6500. We just leave it in drive.
As far as suspension goes the front is stock worn out with the bar removed
the rear is stock with spacers over the springs to raise the car and home made LCA brackets. Moved the torque arm off the trany to a home made cross member and bolt in SFC. Everything on the car we got used, local or on ebay, except the valve springs and the gas. This is a low budget project. We wanted to see if we can build a cheap back yard car , drive it to the track , run a high 10 , and hopefully drive home. Just not sure how much spray it will take yet. Our best so far is 11.71 at 116mph with a 100 shot. But that was not a good run, rev limiter too low,was on it hard before both shifts. Next year we will install a 383 rotating kit ,if we can find a cheap one. With the 383 it will go high 11's on the motor and should go 10's with a 150 shot. We drive about 1 1/2 hour to the track one way. On the highway the motor is turning about 2500rpm at 65MPH . Love that overdrive and lock up torque. The side pipes were a quick way of getting mufflers on the thing as we had them sitting around and we were running out of time. I have a video but don't know how or where to post it. You don't have to spend a lot of money to go fast. You just have to have a good combination and work at it.

 

I agree with you crossfire, If I were to do it again I would too. I don't like single shear either. But I used 3/4 bolts if I remember, the tabs only come out just far enough to get the bolts in. Seems to be holding up so far. A lot of the stock car stuff is single shear as well. Seems to work , But it looks weak if you ask me.

 

I found this thread on welding axle tubes on a 8.5 10 bolt. I think this could be applied to fabing up a TA mount on the diff. alot of good info on weling steel to nodular cast iron.


How to weld axle tubes on GM 8.5" 10-bolt - NastyZ28.com

 

Stock car stuff done single shear is usually stuff that doesn’t have to be super strong and needs to be adjustable, like the serrated height adjustment for a PHR.

 

Thanks superirocz very good info. on this thread..., i'm not a welder, every
information on welding diff is welcome..., Thanks again !