Better Driveshaft? Remove Governor?

TedH · January 30, 2007

I read an article in Chevy High Performance a while back about a project Silverado that ate its driveshaft once the speed limit was raised via a reprogramming of the computer. Apparently, the rev/speed limit is set at 85mph since the driveshaft begins to self-destruct due to bad harmonics at speeds higher than that. I recall that my truck has an aluminum driveshaft and my speed limit is governed at 85mph...

Is this problem applicable to my 2003 Silverado Ext Cab, 4.8L, Z71? If so, any sources for replacement shafts if I ever want to boost the speed limit (if I also boost hp)?

redvett · January 30, 2007

The drive shafts wont destruct due to that kind of speed. If your truck has the OEM size tires on it it should be speed limited to about 90-97 mph. Changing tire size will affect the speed limiter. The reason the limiter is on the vehicles is because the tires will self destruct. If you have tires on your truck that are speed rated for say 100mph its not wise to go faster than that. Your taking your life in your own hands and dangering others.

Billdog350 · January 30, 2007

I've had by truck to 95+ with the governor turned off and no issues with the driveshaft. Redvett is 100% correct...you need to worry about tires desintegrating above a certain speed.

I had some cheap "phantom" brand tires on my 1994 K1500. When we dynoed it, the dyno guy had to program in the speed rating of the tires so he knew when to stop the dyno run...however I wanted to run it to redline so that was like 110mph in 4th gear....the tires got REAL hot and we decided to stop doing the high rpm runs pretty quickly.

ATMINF · January 30, 2007

Most driveshaft issues start to come about at the 1150-120+MPH range(in our trucks). Some trucks are good to go much higher while others start to have bad vibrations at a little over 100MPH. When you basically build a million vehicles there is going to be some "range" in the quality of the balancing of the driveshafts. For the most part our trucks are good at 90-95 all day long and for short bursts over 100, but if you want to drive over 100 for a while, get a sportscar,you gotta remember our vehicles are "trucks". Hope this helps!

TedH · January 30, 2007

The drive shafts wont destruct due to that kind of speed. If your truck has the OEM size tires on it it should be speed limited to about 90-97 mph. Changing tire size will affect the speed limiter. The reason the limiter is on the vehicles is because the tires will self destruct. If you have tires on your truck that are speed rated for say 100mph its not wise to go faster than that. Your taking your life in your own hands and dangering others.

I'm running the 20" Goodyear Eagle LS tires/wheels from a 2003 Silverado SS. Bought them from a former brother-in-law (ex-wife's brother) shortly after I purchased my Z71 in 2003.

I'm not driving it at high speeds often or for long bursts; I have my two Corvettes for that. I inquired ONLY because I'd read the driveshafts are only good for 85-90mph and didn't want to risk raising the speed limiter if it was going to be a problem.

Rolandd · January 30, 2007

Was there not a thread a while ago about 1-piece driveshafts versus 2-piece driveshafts and steel versus aluminum? If you are planning on a lot of high speed driving you might be able to find a 2-piece setup for your truck and install it to stablize the driveshaft. I know that the early 90's Crown Victoria's had a 1-piece aluminum driveshaft on the police package cars, however this may have been for faster accelleration.

redvett · January 30, 2007

The drive shafts wont destruct due to that kind of speed. If your truck has the OEM size tires on it it should be speed limited to about 90-97 mph. Changing tire size will affect the speed limiter. The reason the limiter is on the vehicles is because the tires will self destruct. If you have tires on your truck that are speed rated for say 100mph its not wise to go faster than that. Your taking your life in your own hands and dangering others.

I'm running the 20" Goodyear Eagle LS tires/wheels from a 2003 Silverado SS. Bought them from a former brother-in-law (ex-wife's brother) shortly after I purchased my Z71 in 2003.

I'm not driving it at high speeds often or for long bursts; I have my two Corvettes for that. I inquired ONLY because I'd read the driveshafts are only good for 85-90mph and didn't want to risk raising the speed limiter if it was going to be a problem.

I am hopeing you have had the PCM recalibrated for the tire size you now have on because it changes engine calibrations, trans shift points, ABS operation and SDM operations.

If you have an 1984 & up Corvette like i do than all the drive & half shafts are aluminum.

TedH · January 30, 2007

The drive shafts wont destruct due to that kind of speed. If your truck has the OEM size tires on it it should be speed limited to about 90-97 mph. Changing tire size will affect the speed limiter. The reason the limiter is on the vehicles is because the tires will self destruct. If you have tires on your truck that are speed rated for say 100mph its not wise to go faster than that. Your taking your life in your own hands and dangering others.

I'm running the 20" Goodyear Eagle LS tires/wheels from a 2003 Silverado SS. Bought them from a former brother-in-law (ex-wife's brother) shortly after I purchased my Z71 in 2003.

I'm not driving it at high speeds often or for long bursts; I have my two Corvettes for that. I inquired ONLY because I'd read the driveshafts are only good for 85-90mph and didn't want to risk raising the speed limiter if it was going to be a problem.

I am hopeing you have had the PCM recalibrated for the tire size you now have on because it changes engine calibrations, trans shift points, ABS operation and SDM operations.

If you have an 1984 & up Corvette like i do than all the drive & half shafts are aluminum.

When I first installed the Eagle LS's on the truck, I consulted with others on the site regarding any differences in tire height. Bottom line was that the two tires were equal in total height; the 16" wheeled tires were as tall as the 20's; just had a taller sidewall compared to the 20" tire's shorter sidewalls (oh, and they were not quite as wide as the 20's either). The 16" tires were the Michelin tires sold with the truck by GM. If any differences, they were minimal.

desrtrat · February 1, 2007

the speed limiter is set not for the drive shaft, but for more the speed raiting of the tires.i have only heard of 2 people who shafts came apart on them. both were on dynos, pushing 550-600 RWH/TQ

Ape0r · February 1, 2007

As a third year mechanical engineering student, I can tell you that if that son of a bitch is vibrating hard enough to fall apart, YOU'LL KNOW IT! The only thing you need to worry about when tuning your truck is the crankshaft speed - I don't recommend messing with any engine rev limits, these are put there for a reason, as I'm sure the crankshaft comes much closer to its first natural frequency than the driveshaft ever will.

As a Silverado owner with an uncapped speed limiter, I can tell you my truck did 105 mph just fine ;).

Did the driveshaft itself fail, or did excessive vibration cause the u-joints to give out? This case seems a little more realistic. You don't have anything to worry about. Natural frequencies (e.g., the speeds at which a piece of rotating equipment will break apart) are very exact numbers.