Help Blew Up Driveshaft........
Mar 27, 2006 | 07:23 PM
#1
Help Blew Up Driveshaft........
Well went to dyno my truck and im still shaken. Numbers were not good on third run driveshaft went boom. It ripped in two front went one way i had to jump and busted my *** when back piece came towards me.That **** sucked thought that was it.Yeah 3rd gear pull dont know what happend. how do i know if tranny is good makes nasty noise when in park but i put it in neutral and its quiet.How do i measure for a new driveshaft and why do they want to run trucks in 2nd gear?
Mar 27, 2006 | 10:39 PM
#2
TECH Fanatic
Joined: Oct 2005
Posts: 1,379
Likes: 0
From: Woodstock Ontario Canada
Yet another victim of what happens when a truck with a REMOVED 99 mph speed limiter is taken to redline in 3rd gear.
I am a firm beleiver in 2nd gear dyno runs, much much safer.
They want to dyno trucks in 2nd gear simply because the driveshaft doesnt get spinning anywhere near the rpm it does in 3rd gear. These truck driveshafts were designed to turn no faster than 99 mph with 4.10 gears and 2wd tires(28")or a driveshaft rpm of 4400. All the other combos(3.73 or 3.42 and 4wd tires) will make the driveshaft spin at less rpm. The problem is only compounded when lower gears and tires are used.
There are lots of guys removing the speed limiters and revving to 6200 rpm in 3rd gear or 125 mph(with 4.10 gears, 28" tires) on the dyno.
And some on the street who run their trucks to say 5300 ENGINE rpm in OD which is 6900 driveshaft rpm, that gives you 153 mph.
GM TRUCK driveshafts were never designed to turn that fast. The Camaro, Vette driveshafts are another story.
Thats why I have a custom steel shaft in use.
I am glad you are OK.
peace
Hog
I am a firm beleiver in 2nd gear dyno runs, much much safer.
They want to dyno trucks in 2nd gear simply because the driveshaft doesnt get spinning anywhere near the rpm it does in 3rd gear. These truck driveshafts were designed to turn no faster than 99 mph with 4.10 gears and 2wd tires(28")or a driveshaft rpm of 4400. All the other combos(3.73 or 3.42 and 4wd tires) will make the driveshaft spin at less rpm. The problem is only compounded when lower gears and tires are used.
There are lots of guys removing the speed limiters and revving to 6200 rpm in 3rd gear or 125 mph(with 4.10 gears, 28" tires) on the dyno.
And some on the street who run their trucks to say 5300 ENGINE rpm in OD which is 6900 driveshaft rpm, that gives you 153 mph.
GM TRUCK driveshafts were never designed to turn that fast. The Camaro, Vette driveshafts are another story.
Thats why I have a custom steel shaft in use.
I am glad you are OK.
peace
Hog
Mar 27, 2006 | 10:48 PM
#3
I also have a custom fabricated steel driveshaft. It's 3.5" diameter, weighs 24 pounds (heavy ****) and has fixed yokes at both ends. The shaft itself is splined.
Why the seemingly overkill for this truck? Well, I have 4.56:1 gears and have my speed governor set at 130mph . I've hit the limiter plenty of times during some WOT blasts. That's over 6600 RPM for that driveshaft. I wanted to know the driveshaft was up to the challenge.
This is it on the bottom:
Why the seemingly overkill for this truck? Well, I have 4.56:1 gears and have my speed governor set at 130mph . I've hit the limiter plenty of times during some WOT blasts. That's over 6600 RPM for that driveshaft. I wanted to know the driveshaft was up to the challenge.
This is it on the bottom:
Mar 28, 2006 | 01:42 AM
#4
Launching!
Joined: Dec 2005
Posts: 230
Likes: 0
From: San Diego,CA
Scary to say the least. Often when the shaft goes it will break the diff housing end or tranny end/xfer case. Look for cracks and leaks. Also a good lesson on why to have a driveshaft loop. Only cost $20 at Summit and a good investment.
Mar 28, 2006 | 01:47 PM
#6
Originally Posted by phasemaster1
Well went to dyno my truck and im still shaken. Numbers were not good on third run driveshaft went boom. It ripped in two front went one way i had to jump and busted my *** when back piece came towards me.That **** sucked thought that was it.Yeah 3rd gear pull dont know what happend. how do i know if tranny is good makes nasty noise when in park but i put it in neutral and its quiet.How do i measure for a new driveshaft and why do they want to run trucks in 2nd gear?
