broke driveline on Dyno
03-02-2009, 12:40 PM
#31
TECH Fanatic
iTrader: (1)
Join Date: Dec 2003
Location: Halifax, Nova Scotia
Posts: 1,708
Likes: 0
Received 0 Likes
on
0 Posts
Gm balances the drive shaft to match the tire rating and governed speed of the vehicle.
if you end up on a dyno in 3rd gear you will end up well beyond what it is balanced for.
A high speed balance before going to dyno can sometimes prevent failure, not always. the longer the shaft the worse it will shake, but it's kinda of hit and miss, some have a problem, some don't.
My 07 gmt900 2wd xcab had a 96" alum one piece shaft and it probably looked like a skipping rope the one time I tried to dyno the truck, shook so bad i shut it down.
if you end up on a dyno in 3rd gear you will end up well beyond what it is balanced for.
A high speed balance before going to dyno can sometimes prevent failure, not always. the longer the shaft the worse it will shake, but it's kinda of hit and miss, some have a problem, some don't.
My 07 gmt900 2wd xcab had a 96" alum one piece shaft and it probably looked like a skipping rope the one time I tried to dyno the truck, shook so bad i shut it down.
03-02-2009, 04:58 PM
#32
TECH Regular
Thread Starter
Join Date: Mar 2003
Location: Mission Tx
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
03-02-2009, 05:14 PM
#33
Gm balances the drive shaft to match the tire rating and governed speed of the vehicle.
if you end up on a dyno in 3rd gear you will end up well beyond what it is balanced for.
A high speed balance before going to dyno can sometimes prevent failure, not always. the longer the shaft the worse it will shake, but it's kinda of hit and miss, some have a problem, some don't.
if you end up on a dyno in 3rd gear you will end up well beyond what it is balanced for.
A high speed balance before going to dyno can sometimes prevent failure, not always. the longer the shaft the worse it will shake, but it's kinda of hit and miss, some have a problem, some don't.
03-05-2009, 06:25 PM
#35
TECH Enthusiast
Join Date: Dec 2005
Location: Lake Village,AR
Posts: 722
Likes: 0
Received 0 Likes
on
0 Posts
thrown driveshaft
My 07 nnbs rcsb truck with 5.3,3.42's,handheld tune,AEM cai,Borla catback at 120 mph out came the driveshaft. Tore up my exhaust,and the gas tank. It's a one piece steel shaft. Now I scared to run over 75 LOL!!!
03-20-2009, 08:47 AM
#37
TECH Regular
Thread Starter
Join Date: Mar 2003
Location: Mission Tx
Posts: 426
Likes: 0
Received 0 Likes
on
0 Posts
this is a 5.3 I still don't have the final number cause when the driveline broke, some how a wheel cylinder broke also and the wheel cylinder was on back order. I just got it today and I should put everything back together today and off to the dyno again.
04-04-2009, 03:01 PM
#38
TECH Fanatic
iTrader: (4)
Join Date: Jun 2003
Location: Chicago Burbs
Posts: 1,528
Likes: 0
Received 0 Likes
on
0 Posts
You guys. This isn't a torque power issue. Like some have mentioned it is pretty much a factory balance issue. GM isn't going to spend more money to guy high speed balanced shafts that go above the fuel shutoff speed. Typically, this has been happening on the standard cab/longbed and ext car/short bed trucks with the long 72" AL driveshafts. They just aren't balanced well enough for these high speeds and say adios when the speed gets high enough. The speed at which they start to resonate is mush lower than say a shorter 1 piece steel or AL shaft. In fact, the 1 piece AL shaft in the reg cab short beds is actually better for high speeds than steel due to the weight savings and larger diameter. Strength is in the steel though. I think a lot of the failures with the shorter ones would be due to the u joints, not vibration. It's good to dyno these in 2nd gear though as a lot of people have pointed out.
