TexVette

iTrader: (2)

So my car is one of two that has a Dana 44 from a viper in it. Took my car apart for my build and discovered the Dana 44 had been significantly damaged.

This is 1/2 inch thick aluminum:

Onefast V

iTrader: (3)

wow that is right along the weld bead. makes you wonder about the quality of those welds...

jmargo

iTrader: (10)

I don't know if it would be weld quality. More like too much movement. It appears to be solid mounted so every time you drive the diff wanted to twist. If the mounts allowed any movement the repeated force eventually fatigues the metal. High durameter bushings on the ears may be the next option.

family-man

damn. sorry to hear.

STAGEUP

So it was bolted in without bushings??? If so, that is the problem. Drivetrain shock is too much for solid mounts. Especially when its aluminum

jmargo

iTrader: (10)

Not being an engineer I would suggest a design similar to the CS 8.8 swap that bolts to the cover and has bushings at each corner.

Onefast V

iTrader: (3)

i agree is should not be solidly mounted. But from an engineers perspective, the weld itself is the strongest part of that joint, the HAZ surrounding it is what is the weakest and where you would expect to find cracks/ crack propagation.

NOLAG05

looks like a dragon sneezed on it... what did you do to that?

TexVette

iTrader: (2)

This is what happened. It's bolted in with bushings, but the way the part was designed and fabbed caused it to break at the weakest point (Where the flat 1/2 in aluminum met the bolt sleeves. As you can see, this happened previously and was repaired.

I have an engineer designing CNC a piece that will allow V owners to use a Dana 44 in their setups and won't break/fail like this. It's going to be beautiful and cost a helluva lot less than current solutions.

I'm hoping the creative steel diff users won't encounter this problem down the road. Hopefully that's a steel setup and not aluminum.

chitown21y

iTrader: (6)

Keep us updated! I would be all over this if its less then a few grand like the other solutions.

jmargo

iTrader: (10)

I look forward to seeing your solution.

TexVette

iTrader: (2)

I want to be able to get it done for under 2k, but a lot of that depends on if I use 7075 or 6061. 7075 is about 2x stronger but probably not needed except in extreme applications like what I'm building now.

Big *** plates of Aluminum are freaking pricey. Will let you guys know how it goes. The CNC is just sitting unused and waiting.

Everything has a fatigue life under certain conditions/loads. The science of it gets very complex. I will have the engineer chime in if I can to explain why current design failed.

This diff was put in by Corvette Shop in San Diego many years ago. Got a lot of use out of it, but I could feel something wasn't right back there. Still held together at 120mph, so that counts for something, right?

Onefast V

iTrader: (3)

If your talking about fatigue strength. The ideal design would be one in which no area of the part is stressed near its endurance limit (stress level at which material has theoretically infinite fatigue life) a good safety factor would be allow no more than 75% max of that stress level. Obviously this will be figured out by your engineer through geometry, material selection and material thickness. Ferrous and titanium alloys are preferable in this situation due to a defined endurance limit where as aluminum has no fatigue limit.

TexVette

iTrader: (2)

Exactly, or find a design where the level is so negligable that it doesn't matter.

It's hard to know exactly how much stress this part is experiencing, but the damage shows us how small the ballpark isn't.

disco192

I am working on putting this together soon.

I am still determining the failure mode, but it is unlikely fatigue related. Fatigue issues typically are found under high loads and frequency. I dont see a high frequency loading here, just high loading. Typical fatigue loading below 50% yield is typically in the millions of cycles to failure. This leads me away from fatigue cracking. (note: I realize that it sees MANY cyclic loads induced during driving, but SN curves are determined by maximum loads. Small loads rarely induce any fatigue issues).

The welds are not stronger on 6000 series aluminum than the base material. Welding returns the weld and the HAZ region to the 0 temper. The 6061 will return its strength with age, but you will likely never recover a T6 temper from welded 6061. Steel on the other hand, you are correct.

That being said, it doesnt surprise much that it failed at the weld.

I would likely think that this could be a moment induced failure due to mounting too rigidly about the axle rotation. This is common when you restrict too many degrees of freedom. Designing support systems are almost always about finding moment loads and strategically reducing them.

The solution will either be in the area of strategic material placement using FEA or creative fastening, but likely both.

I will know more when I take full dimensions and get some notes on paper, but that is my quick assessment from afar.

I will keep you guys posted on what we work up. I should have a 3D PDF within the next few weeks to keep everyone interested (This is a side job and I work too many hours at my real job).

aurora40

iTrader: (1)

Wow, a D44 would be cool. I guess I like them though because they seem really reliable in C4's and Vipers.

serik21

Why don't you Cnc a back cover out of metal and than the weakest link would be the mouting bolts to the 44, kind of how they have a metal back for the aluminum 8.8.

jmargo

iTrader: (10)

What axles do you plan to use with this set-up ?

z28C4maro82z

iTrader: (33)

Very interested

TexVette

iTrader: (2)

I need to do more research. I think it will be just different CVs for the Dana. Not sure if my axles are stock.

Anyone know how to identify a stock axle?