Kfxguy

iTrader: (1)

I bet you're thinking I broke my **** again. Well not yet. Lol. But I thought this was funny. My buddy text me some pics last night of his transmission. He has a avalanche with a heads and cam 6.0 with a LSA blower. I built this trans for him years ago and it was in a 9 second car. And then he put it in the truck. I think he's gone through it a couple times because he kept breaking the 2-4 band ancor. Too much line pressure I think. Anyways. My damage.




His damage







Crazy huh?

sjsingle1

iTrader: (1)

is that a GM 5 pinion or a china clone ?

vorteciroc

I WILL NOT use the GM 5 pinion planets in any of the THM700-R4/ 4L60, 4L60E, 4L65E, or 4L70E Units in my shop...

The metallurgy report I had completed on both the original 4 pinion planets and 5 pinion planets, shows tremendously better materials in the 4 pinion planets.

I actually like the design of the rear planet better on the 5 pinion piece, but will not use it, do the inferior metallurgy.

I can not imagine how bad the aftermarket 5 pinion pieces are!

vorteciroc

I see output shaft failures as such, mostly on four wheel drive units... NOT so much in two wheel drive vehicles.

Many of us builders have had very good luck with Cryo treatment of OEM shafts.

Kfxguy

iTrader: (1)

Both are factory GM

Kfxguy

iTrader: (1)

I put sonnax input and output in mine since

Kfxguy

iTrader: (1)

Good to know. I have a rear 5 pinion and front 4 pinion currently.

sjsingle1

iTrader: (1)

looks like its time for sonnax or someone to step up and make a stronger pinion

MaroonMonsterLS1

I've said it before and I'll say it again.
4 pinion planets are the only planets you should use.

The 5 pinion planets are powder metal and has less meat around the carrier to make room for the 5th gear. Not a fan.
I've NEVER seen a 4 pinion break from too much power.
Some of them break from lube issues...even a 6 pinion will have issues here.
Alot of them break from thrust issues. The trapped needle bearing explodes then the needles go through the gear and its all down hill from there
A small percentage break from shock that comes from the output...such as a driveshaft or u joint going out, a horrible vibration, or a broken diff.
None of these issues are the fault of the 4 pinion planets.

I doubt the issue in this case was the 4 pinion planet. a spiral fracture of a shaft like seen here. in both shafts, it can be seen that the fracture started at the lower spline area. Right at the "shelf" between the two splines. There is a weak undercut here and it is where the stress concentration will be the highest. The fracture starts here, moves its way up the shaft in a split second, and where it reaches the upper spline area, it all lets go. The planet is merely collateral damage and the chunks have to go somewhere...so they go through the edge of the planet spline interface.

I have a theory/guess on why this is happening...but if you could share some details on how/when this is happening (during an upshift, during a downshift, tire hop, cruising down the highway, pulling a trailer up a hill, etc) and be specific for both cases...I can think on it a little more before I go spouting off.

Kfxguy

iTrader: (1)

I don't know what he was doing. When mine broke I was:

1) at the dragstrip
2) on sticky tires
3) in first gear, when the boost hit it broke

My theory is the massive amount of tq from the turbo, sticky tires and heavy car coupled with the fact that it's a cast steel shaft, the holes drilled and machined cuts are not designed with extra power in mind, the sonnax shaft is, however. Plus the fatigue life of it was probably up from all the blasts I've made since I had the car and the guy before me treated it like a red headed step child.

vorteciroc

Was it while in first gear?

Or was it really ON the 1-2 shift?

Kfxguy

iTrader: (1)

In first just as the boost hit. Never made it to second.