Truck going on dyno, should I fear for my driveshaft?
07-31-2007, 08:21 PM
#1
TECH Addict
Thread Starter
iTrader: (10)
Join Date: Nov 2005
Location: Way out there
Posts: 2,199
Likes: 0
Received 0 Likes
on
0 Posts
Truck going on dyno, should I fear for my driveshaft?
After seeing 1slowhoe's mishap on the dyno, I am a little nervous about running 6000+RPM in 3rd gear. I am going to build loops for my truck, but I don't want to rush them and I want to get on the dyno Friday. I have a 2500HD so the driveshaft is steel and U-joints are bigger. Should I worry?
07-31-2007, 08:37 PM
#2
I think the most problems come from the aluminum driveshafts. The steel is stronger and the resonant frequency is high enough IIRC that you would have to be going way faster than is possible to hit that frequency and bust the driveshaft. I'll see if I can find the thread I'm thinking of that talks about that.
07-31-2007, 08:42 PM
#3
Where are you going to dyno Henry?
I am always concerned but it has never been a problem and we take mine to 6500+ with 3.73's.
You can take your DS to the DS shop down in South San Jose for balance $75 if it makes you feel better
I wouldn't worry, you're stock height and suspension, you DS angles are good.
I am always concerned but it has never been a problem and we take mine to 6500+ with 3.73's.
You can take your DS to the DS shop down in South San Jose for balance $75 if it makes you feel better
I wouldn't worry, you're stock height and suspension, you DS angles are good.
07-31-2007, 08:53 PM
#5
I would only sweat the balance of the steel. Aluminum will turn into a wave and surpass critical speed and then come apart.
http://www.wallaceracing.com/driveshaftspeed.htm
***thunder got it***
http://www.wallaceracing.com/driveshaftspeed.htm
***thunder got it***
07-31-2007, 09:35 PM
#6
TECH Addict
Thread Starter
iTrader: (10)
Join Date: Nov 2005
Location: Way out there
Posts: 2,199
Likes: 0
Received 0 Likes
on
0 Posts
Great links, thank you.
Bill, I'm going to Advanced dyno with a friend, I may have a chance to throw my truck on his dynojet when I am there. If not then, I have another friend with a shop/dynojet about 1/2 mile from my house. What is your guess for power?
Bill, I'm going to Advanced dyno with a friend, I may have a chance to throw my truck on his dynojet when I am there. If not then, I have another friend with a shop/dynojet about 1/2 mile from my house. What is your guess for power?
Trending Topics
07-31-2007, 10:07 PM
#8
TECH Addict
Thread Starter
iTrader: (10)
Join Date: Nov 2005
Location: Way out there
Posts: 2,199
Likes: 0
Received 0 Likes
on
0 Posts
I am curious too, I need to measure my driveshaft tomorrow. I put in 4" @ 72" .110" wall (I guess) mild steel and it showed 5100 rpm. That's not what I was hoping for. I did paint it black so it should hold together
07-31-2007, 10:52 PM
#10
Mine was painted black too 
Aluminum has a higher critical speed than steel IIRC. My new shaft specs out to 8575rpm (Aluminum 3.5"X.120"X54.5")
Just for reference the shaft that I had been running on was a stock shaft that had been shortened 2" and then PROPERLY balanced by a driveline shop. I was told that that length was too short so I bought another stock shaft, replaced the U-joints and cleaned it up and painted it. It never got an aftermarket balance. About the 5th pull on the dyno it let go.
I think if you take your stock steel shaft and get a proper balance on it you will be fine.
Aluminum has a higher critical speed than steel IIRC. My new shaft specs out to 8575rpm
(Aluminum 3.5"X.120"X54.5")Just for reference the shaft that I had been running on was a stock shaft that had been shortened 2" and then PROPERLY balanced by a driveline shop. I was told that that length was too short so I bought another stock shaft, replaced the U-joints and cleaned it up and painted it. It never got an aftermarket balance. About the 5th pull on the dyno it let go.
I think if you take your stock steel shaft and get a proper balance on it you will be fine.