agreif

iTrader: (4)

OK guys. First ever time to the dyno today. I was the first one on there. With only a mail order tune I would have been ecstatic with 240, looking more for 225/230 realistically on my 01 4.8 (270/285 factory ratings). So I put it up on there, first guy of course. Get the dyno rolling and at 4100RPM/210 HP, KAPOW! It was like slow motion as I saw my driveshaft drop into view and rattle around underneath. Came completely loose. Shut it down.

Driveshaft broke into three pieces, long piece from the diff to about ½ way (pulled the bolts right off the pinion U joint deal – need a new one of those), 2nd piece about ¼ of the length, and the last ¼ up to the tranny pinion housing. At the end of the driveshaft, the housing that holds the pinion shaft and is welded to the driveshaft sheared completely off at the weld and then provided to crack and completely grenade the trans output shaft housing. Broken casing is hanging down by a sensor now with the rest of it (the flange) still bolted to the trans. You should see this driveshaft. I’m a long bed standard cab, so it’s a one piece AL driveshaft filled with foam. It hit so hard underneath it popped a hole in the floorboard so now I can see my carpeting!

I didn’t have my camera with me (the one time), so I’ll have to go get pics on Monday when I go back. It looks like that shaft coming out of the trans might be damaged, but I’m just not sure how much damage was done to the rest of the internals to the transmission. The owner of the shop was dumbfounded when all this happened. Gonna check on a core on Monday. I’m just not sure how much of a complete tranny I am going to need. Hopefully go over there Monday and get a little more figured out along with some pics.

Only thing that I have on the trans is the shift kit. I just have 0 idea what happened. The weld sheared clean off, but that could have been a result of the shaft letting go somehow.

Bummer of a day. Never had anything bust on this dyno yet, and the first thing that breaks is a weak little stock 4.8L. Friggen A. Puts the halt on the cam I was gonna get. Luckily the exhaust and headers are already on their way.

Andrew

P.S. On teh good side, I forgot to mention I was running rich, so there should be some more horsepower to grab off the table!

tdrumm

iTrader: (18)

Damn, that sucks. That fear is always in the back of my mind when I dyno. What gear were you dynoing in and what size are your tires?

unklej

iTrader: (1)

wow, that sucks... I have heard of others having problems with spinning the AL. shaft too fast and blowing it up. It may have something to do with resonance.

Tdrumm, you shouldn't have a problem since your/our shaft is steel.

Jeff

thunderwagen

iTrader: (3)

That sucks man. One of the places I have had my truck dynoed at has about half of an aluminum driveshaft out of a suburban with a radix on it sticking out of the wall about 15 feet up. I';m sure that was pretty hairy.

quicksilverado

iTrader: (8)

Its not the shaft itself. The problem is from the factory they are not balanced very well. I had mine balanced when doing the 4l80e swap. They spun it up and it was waving all over the place. I thought it was bad, but the guy at the shop said it was well within factory specs. After they balanced it, it was straight as an arrow.

CHEVY6000VHO

iTrader: (2)

looks like another poor quality item from GM.
I'm surprised a lot of you guys do not have driveshaft safety loops.
Who makes a bolt on driveshaft safety loop for our trucks?

Jim

agreif

iTrader: (4)

Heard summit makes em for ~20. Funny how I never caught any of the earlier posts about this. Looks like I'll be ordering up a Denny's Driveshaft here soon.

TouchOfEvil04

iTrader: (13)

So now i gotta worry about my driveshaft flying out from under my truck....great!
What kinda power are the storck DS's supposed to hold up to?
What kinda shaft should i look into getting if my fear becomes more and more far warning to me heh.

Coban

iTrader: (14)

While you're at it, get the pinion angle shims. When you put the shackles on it changed your pinion angle and that was probably what caused the vibration. I had them on my last truck and never had a vibration problem, but then again, I never drove it without them either.

CHEVY6000VHO

iTrader: (2)

This is the driveshaft that all of us need with high HP & TQ applications:
http://www.dennysdriveshaft.com/index.html

Jim