Background - for the Berlinetta #2, LS1/T56.

Considered 12-bolt, so don't start on me already.

Starting with disk rear that spent time in the Rust Belt. Guts were in good shape, but the exterior wasn't very pretty. Guts doesn't matter, since Eaton posi, Sierra 4.10 gears & 28 spline axles, all new bearings, crush sleeve eliminator went back in. Summit support cover to top it off. I'm having a shop do it, as I don't have the tools, and not much time or patience to figure it out myself. The shop is full of a bunch of drag racers, and they've done a bunch of 7.5" rears in their day (mostly 4th gens).

When I dropped the rear off at the shop, we talked about welding the tubes. I figured I could do it myself; they recommended welding while the rear is disassembled after being cleaned up and before final set-up. I talked to them today, they said the rust was making it difficult to get a bead going, so they decided not to do that.

So, question is, how big a deal is it to have the tubes welded vs. not? If all the other stuff is done, has anyone seen failure because the tubes weren't welded? I understand the real "weak link" is the small ring/pinion. They said if the unwelded tubes turned out to be a problem, they'd work with me (but most 7.5's they work on don't go out with welded tubes).

Side note: Could be an interesting comparison with Berlinetta #1 - I'm doing 4th gen posi & 3.42 gears, Moser axles, Summit support cover, crush sleeve eliminator on a drum rear for it. Having the same shop set it up as well, but I welded the tubes myself before dropping it off. I'm no "master" welder, but I've seen worse beads that I've paid money for.

 

I'd take it all back apart and find another welder. That has to be one of the lamest excuses I've heard for half-assing something like that. Nothing a little wire-brush work couldn't take care of. In fact, hitting it with a reducing flame FIRST, might be all it takes.

All that's holding the tubes in, is 2 little spot welds. The ENTIRE FORCE of accelerating the car, is busily trying to lever those tubes sideways out of the housing, by breaking the welds. You can tell if they're already broken, by whether they leak. If they do, they need attention.

 

I did mine, but it was completely cheesy. Learning to weld and trying that - figured it couldn't hurt.

Here's a fantastic site about a guy TIG welding his 8.5", goes into great detail. Not sure if you're willing to do this work all yourself though. I think some naval jelly or something would dissolve the rust, or use a reducing flame, but a bit of surface rust shouldn't be a deal breaker. I would think they wouldn't just be trying to weld *over* rust...?

http://www.nastyz28.com/forum/showthread.php?t=18890
and one more
http://www.nastyz28.com/forum/showth...ing+axle+tubes

I think I used a 99% nickel rod myself, with a stick welder.

 

There was no leakage. It was more than a little surface rust - to the scaly phase.

I was willing to do the welding myself. Question is, how important is it to set up the gears after the welding has been done? Seems a bit of a stretch that welding out there would affect the caps.

 

ahh, for what it`s worth I welded the old ten bolt I had in mine, for the ten minutes it takes why not? My plug weld were leaking and the little baby 7.5 was going behind the 477 BBC, it held, I sold it to a member here and he has had it to mid 11,`s I believe, I had it to 10.80`s my self with a transbrake.. I want to tell you a story of my first F Body....

it was 1987 and I had a 76 Black trans am...455 4 speed close ratio with a 3.23 gear, bolted on some firestone slicks and went out to play one friday night, 20+ miles from home I decide to run this nova, I knew it well it was a 13.0 car and my car had not been to the track to guage it`s performance but I knew it was a screamer. Grand river and 8 mile we line up...light goes green, I slip out the clutch and leave on him...grab 2nd and BANG! bada bada bada clunkity clunk.....

after utimately stopping in the curb lane and accessing the car, the 8.5 10 bolts pig had broke loose from the tubes, the pig was pointed up into the floor pan, amazingly though the driveshaft was still in the splines of the M21 RockCrusher....after consideration and a drive by of the nova to express their sympathy, I stunned the driveline in reverse with a quick snap of the clutch @ 3000rpm, it lowered the pigs position to VERY negative pinion angle, one small nudge of the clutch @ 2000 did it, it was centered again.....nurseing it home I welded the snot out of it at 2am so no eyebrows were raised the next morning at home if I were to crawl under the bird with the welder.

 

I don't think I'll be topping that story. . .

Interesting, I've been running the 8.2" in the '57 since 1998 with unwelded tubes.

I need to do some welding of brackets on the axle after I mock it up in the car, guess I'll weld the tubes then. I can put a wire wheel on the drill motor.

 

Hey five7, hope you don't mind if I jump in your post with a quick question. I've got a 7.5 rear that I'm going to be upgrading soon, and I was considering welding the tubes. Is this something that can be accomplished with a standard MIG welder, or does it require oxy-acetylene or an arc with a special rod? I was just contemplating this and noticed your post. Any advice on what type of welds would be greatly appreciated! Hmmm, just read the links that Sonix posted. Looks like a MIG would be adequate if you preheat the housing/tube and use a stainless, fluxcore type wire.

 

If you have access to TIG or stick I think that's your best bet. You can just buy a handful of rods from a welding shop and do it up. PRE-HEAT IT!!! Cast iron is nasty to weld.
Wire feed i'd get some nickel wire if that exists. You'd have to buy a big roll though, that's why i'd recommend non-mig.

You can probably get by with a propane torch to preheat. If you have a BBQ bottle, then buy/rent a tiger torch, bigger output flame on that vs the 1lb'er bottles that you get in the parts stores.

 

I didn't have any particular problem with stick welder and 6013 rod. Guess time will tell.

 

Yeah Sonix, I was thinking the same thing, that I'd have to buy a big roll of wire with the MIG. Boss has got a stick welder, so I'll pick up some nickel rods and go that route. He's also got an acetylene torch, so preheating shouldn't be a problem either.