gregrob

Who has made an old school 12 bolt, 9 inch, 8.8 etc work in a 4th gen?

I'm wondering what would be so hard about it.

Been thinkin about getting and old school 12 bolt and start working on adding the requisite suspension and tq arm mounts.

Would it also have to be narrowed, or would a stock width 12 bolt from a car work?

I'm not opposed to using an 8.8 either.

Let me know what you guys think. And before you bring up the welding part, yes I can definitely weld whatever needs to be welded on the rearend. Even if it's mild steel stuff to the cast housing and axle tubes, got that covered no problem and it will be strong.

So, what other challenges would I face by doing this?


edit: From posting this on another board I know of 2 guys using 8.8's, anyone using an old school 12 bolt, or 9"?

MikeGyver

dooo it.
If you can weld all the bracketry on right, it's just a matter of getting the right width, bolt pattern, u-joint size.
git yerself a duece and a half axle. and axle tubes aren't cast, they're mild steel.

gregrob

I dont care if the axle tubes are cast, I can weld cast no problem.

and I dont think a "deuce and a half axle" would fit, but thanks...

Actually the only "mount" you have to fab is the tq arm, the way I'm going to do it (and the way it's been done before by at least 1 person) is to use the center section of the desired rear diff, and weld the 10 bolt axle tubes onto it. That way the shock / spring mounts, etc all stay in place on the axle tubes.

Daniel6718

yep thats the way to do it...now just make a tq arm mount and make it strong!!!!

MikeGyver

The Deuce. lol


Just curious, whats your method for joining mild to cast?
3/4 ton axles usually have larger diameter axle tubes, if that's the case your idea won't work. You would also probably need custom machined axle shafts.
And if you plan on building a housing you need a centering jig.

gregrob

Using the proper, specialty alloy. The company I work for sells an alloy that does a great job at just this.

Actually yes it will, it has already been done. You make a collar that joins the two different axle shafts together, the inner diameter of the collar is larger on the carrier side, to accept the larger axle shafts.


That depends... If you get an 8.8 rear with a 28 spline carrier, the stock axles will slide right in

That's true, the stock 10 bolt would be put in a jig from the very start, the jig would secure the axle shafts after the center section is removed.

MikeGyver

You'd need to get an actual centering jig, like this.


Any misalignment whatsoever will cause the axle shafts to be very prone to breaking, especially in a high HP application.

If you did put a ~1/4" bushing around your axle tubes to make them fit into the Larger new housing (lol..) you'd have to truss the hell out of the axle for obvious reasons.
You'd want to truss the axle anyway since under hard acceleration the axle tubes tend to flex forward as the tires hook up. The small axle tubes with the subpar tube-to-housing joint in a high HP application sounds like 3 strikes to me.

Sounds like a hell of alot of unnecissary work. I would just get a complete axle that is appropriate, cut the mounts off and weld new or salvaged ones on.

paxtonLT1

Sounds like a hell of alot of unnecissary work. I would just get a complete axle that is appropriate, cut the mounts off and weld new or salvaged ones on.[/QUOTE]

ill second that.

gregrob

If only it were that easy.

Tell me, what "axle is appropriate" that I can just "ut the mounts off and weld new or salvaged ones on"?

12 Bolt? Not the right width from what I've found, it would be narrower than the 4th gen 10 bolt, not something I want.

gregrob

and who said anything about a 1/4" bushing? The collar would probably be in the neighborhood of 2.5-3 inches on each side, for a total of 5-6".

I agree about the trussing as well. Not as big a deal as you're making it sound. But there does need to be some added reinforcement for the joined axle tubes. Something I had planned on doing anyway.

JD311

I rememeber measuring my rear for the 1st time thinking "damn, this thing is as long as an old Impala rear " lol. I think the 4th gens are too long from the factory, unless you want to use wheels with stock offsets I guess. Lucky for me I got a moser 9 in housing, traded it for an old Honda I was gonna junk. I too did look into the different 'do it yourself" setups. I was at one time going to put a Chrysler 8 3/4 from an old Challenger in my car.