Share your thoughts?

[SergntMac]

Okay...To y'all high HP and drag racin' MM owners, how about sharing some thoughts about welding up the rear end housing? The axle tubes are press-fit/sweated in, and hard launching will eventually take it's toll.

How about it...Where to weld?

[Breadfan]

I'm sure there are others with more detailed info than me, however, I do know welding the axle tubes on the 8.8" seems to be a common practice.

I believe the tubes are welded fully where they enter the "pumpkin" or differential housing. As you said, that's where they are just press fit.

The tubes are basically welded to the housing all the way around, a full bead.

Also, I seem to recall a few other places where tack welds or partial welds exist that folks would weld fully.

Also, I've heard of some using some plate steel to create a triangulating piece that is welded on the axle tube to the diff housing to increase the strength.

I could be wrong on the last too, just going off things I have heard, I've never done an 8.8 buildup past gear changes...

[magindat]

Not 8.8 rear specific, but....

In order to avoid warping, I would heavy tack weld at 4 spots, let it cool, then, in between for 8, cool, then in between, etc. After cooling for the last, I would run a quick 'sealing' bead at the axle, cool, then at the housing.

Swamp buggy building: Gusset the housing and tube at the 3 directions (Up, down, yoke) on both sides with triangular, shape formed gussets and follow the same slow, careful welding technique.

Disclaimer: I have built stuff like this, so it won't break and leave me stranded in the woods. Up to you if it applies to racing. But, it's worth repeating since strength is strength.

[Breadfan]

Not 8.8 rear specific, but....

In order to avoid warping, I would heavy tack weld at 4 spots, let it cool, then, in between for 8, cool, then in between, etc. After cooling for the last, I would run a quick 'sealing' bead at the axle, cool, then at the housing.

Swamp buggy building: Gusset the housing and tube at the 3 directions (Up, down, yoke) on both sides with triangular, shape formed gussets and follow the same slow, careful welding technique.

Disclaimer: I have built stuff like this, so it won't break and leave me stranded in the woods. Up to you if it applies to racing. But, it's worth repeating since strength is strength.

Much of what you just described (well aside from the stranded in the woods part) I've heard in discussions on building rear's for cars destined for the strip, or really powerful street cars.

[magindat]

I guess I should add that 'cool' means wait until cooler, but still warm, not 'throw water on it'. The idea would be to keep the metal warm, but not super hot and not flash cool to avoid cracking.

The tacks heat the metal up slower and distribute the heat applied. But, unlike tacking for fitting, tack it like you mean it. After all the (deep) tacking, it should be warm enough to run a quicker, shallower bead all the way around without warping.

I'm sure it wouldn't be hard to cut and fit your own gussets, then take the 6 pieces and the axle to a decent weld shop and any competent welder should know how to control the heat.

[TooManyFords]

Mac,

My guy is welding my tubes on when he back-halves the car. He wanted me to go buy a special kit from Moser that includes the bars out to the axle ends but I couldn't find it on their site.

It takes an awful lot of stress to bend a tube in our cars. The tires typically break loose first. Me, on the other hand, will have more than your average traction and stress involved. I guess that unless you hear others reporting them bending or cracking that is is probably a "non-issue".

Cheers

John

[martyo]

I will look and see what we did on mine. It has been so long since this was done.

[Marauderjack]

JB WELD = NO HEAT WARPING!!!:shake: :lol:

I'm with John.....On our "Street Cars" welding should not be necessary??:shake:

If you are making "Jugundo (sp?) Power" running "Giant Tires" for racing.....well....IMHO it ain't a "street car" anymore and anything you do toward overbuilding is a GOOD thing!!:bows:

Marauderjack:beer:

[Joe Walsh]

I've talked to both these guys about weldiing my axle tubes to the pumpkin:

(I think that it is a good idea on a HEAVY car with STICKY tires that is making LOTS of HP)

www.markwilliams.com

www.drivetrainspecialists.com

I'm going to send one of them a junkyard CV/GM/MM 8.8 rear and have them do the full treatment to it....

> Check the axle tubes for straightness with an 8 foot round bar inserted through the axle bearings,
> True the axle tubes and then weld them to the center housing,
> Install billet differential caps w/ARP studs, 4.10 gears, Truetrac differential, rear cover with preload bolts,
> Install my Moser 31 spline axles.
I might even have them weld on 9" rear tube ends with the bigger axle bearings if it will work with the ABS sensors and Moser axles.

Then I won't worry about the 8.8 handling ANYTHING I throw at it.

[SergntMac]

Yeah...It's something from my youth, when I destroyed a 12 bolt housing in my '69 Camaro. Ripped that sucker into three pieces. Can't say it's necessary today, but I thought I would throw it out for discussion.

I know I'm not the only one who has fortified the U-joints, ring and pinion, differential, stud kit and girdle, axles and control arms, and all of this tells me there is now one last area to consider. I don't think there is a problem with the OEM setup, but I don't want to learn this lesson the hard way.

Laying in a bead where the axle tubes meet the pumpkin sounds like inexpensive insurance, I'm not sold on adding any more structure to it, just may lead to another weak spot. Thanks again, guys, and I'm still open for suggestions. Keep the suggestions coming?

[fastblackmerc]

How about these guys?

http://www.currieenterprises.com/cestore/default_rearend.aspx

[Krytin]

Laying in a bead where the axle tubes meet the pumpkin sounds like inexpensive insurance, I'm not sold on adding any more structure to it, just may lead to another weak spot. Thanks again, guys, and I'm still open for suggestions. Keep the suggestions coming?

I do a lot of welding/fabrication at work.
One pass where the axle meets the center section would be good cheap (inexpensive) insurance. Not a bad idea on forced induction cars.

The method(s) described above are about right - four beads about a half inch long each and 90 degrees apart. Then fill in the spaces in between. I would not wait for much cooling to occur - especially not when laying the four beads. As each bead cools it actually shrinks and can, in some cases, pull the two pieces you are joining together out of alignment. It's a good idea to allow cooling for thinner materials but the axle tubes and center section are heavy enough that you may even want to do a little preheating with a gas torch/rosebud to prevent uneven cooling and to help insure even penetration.

Just my two cents.

[Rider90]

how about sharing some thoughts about welding up the rear end housing?
I am having problem with my pant seams, too, thank you. Subscribed!

[magindat]

I am having problem with my pant seams, too, thank you. Subscribed!

Preheat them with a torch!

Krytin is prolly right. I have never seen how thick our axle tube is. Preheating evenlywould be helpful.

[GreekGod]

Can and should is the caution when welding a rear axle housing. Sure, many have gotten away with stitch welding 8.8 and 9" housings but the right way is with a solid bar and housing/bearing adapters keeping everything aligned.

At the very least, alignment should be checked after welding, so the fixture is needed for welding and checking.

Welding puts extreme distortion into steel and castings, especially circular shapes. If the housing on a 8.8" is cast-iron, choosing the correct proceedure and welding rod or (filler/wire) is even trickier. It is possible to make it even weaker and/or prone to cracking.

The best solution might be a bolt-in 9" housing conversion, like Moser makes for the Camaro and Mustangs.

[Krytin]

Can and should is the caution when welding a rear axle housing. Sure, many have gotten away with stitch welding 8.8 and 9" housings but the right way is with a solid bar and housing/bearing adapters keeping everything aligned.

At the very least, alignment should be checked after welding, so the fixture is needed for welding and checking.

Welding puts extreme distortion into steel and castings, especially circular shapes. If the housing on a 8.8" is cast-iron, choosing the correct proceedure and welding rod or (filler/wire) is even trickier. It is possible to make it even weaker and/or prone to cracking.

The best solution might be a bolt-in 9" housing conversion, like Moser makes for the Camaro and Mustangs.

Very true on all points!