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Speed governor?

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M J Enthusiast

M J

Posted
Posted

GM Trucks have been governed at this speed for almost a decade, if not longer

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SouthernSilveradoGuy85 Senior Enthusiast

SouthernSilveradoGuy85

Posted
Posted

GM Trucks have been governed at this speed for almost a decade, if not longer

 

My 98 was governed at 98 just like my '14 is. My 86 wasn't but I wouldn't have known if it was because it had a weak 305 and had the manual "granny" transmission where it had the extra low gear and only 3 normal forward gears (L-1-2-3) so it was far from being a highway truck lol. At 75 it sounded like it was going to blow up.

mrbrown88 Enthusiast

mrbrown88

Posted
Posted

My 6.2 shuts down at 111 MPH. I don't think its becuase of tire ratings because I have the same tires as a truck with a 5.3....

SouthernSilveradoGuy85 Senior Enthusiast

SouthernSilveradoGuy85

Posted
Posted

I've read on this forum where some others have a different speed. So right now the engine doesn't matter. I also don't think the axle gear ratio matters either. Maybe where you're located? Doesn't matter since I don't intend to go that fast again. I just tried it out on a country back road.

MikeNH Senior Enthusiast

MikeNH

Posted
Posted

I've read on this forum where some others have a different speed. So right now the engine doesn't matter. I also don't think the axle gear ratio matters either. Maybe where you're located? Doesn't matter since I don't intend to go that fast again. I just tried it out on a country back road.

 

If not tires than it is likely a limitation of another component like the driveshaft.

SouthernSilveradoGuy85 Senior Enthusiast

SouthernSilveradoGuy85

Posted
Posted

Ya I don't think it has anything to do with the tires' speed rating because why put a limiter of the speed just for the tire that comes on it stock since nobody ever always gets the same tire the whole life of the vehicle.

 

It could be driveshaft, the longer the drveshaft the lower the speed. I think that's the only difference with driveshafts and I don't think that matters really. That would mean the crew cab standard (6.5') would be lower than my double cab standard bed and I haven't seen a lower limiter than 98 which is mine and was my old 98.

 

Seems to not be an actual pattern with the speed, same as the vibration problems that some have. Again I don't see the reason to take a heavy truck over 100 or even over 90. The speed limit on most interstates around where I live is 70 and I've never gone above 85 while passing.

Spurshot Senior Enthusiast

Spurshot

Posted
Posted

I recall some posts about driveshafts failing at high speeds when the programming was altered. There was even some links to some aftermarket driveshaft maker. If I were going to mod the programming for high speed, I'd definitely look into the driveshaft angle. That driveshaft is a long ass shaft and will likely go through some natural harmonics as speed goes high enough. I'd also consider a shaft hoop to keep it from coming thru the floor and beating you to death.

TX14Z71 Enthusiast

TX14Z71

Posted
Posted

I recall some posts about driveshafts failing at high speeds when the programming was altered. There was even some links to some aftermarket driveshaft maker. If I were going to mod the programming for high speed, I'd definitely look into the driveshaft angle. That driveshaft is a long ass shaft and will likely go through some natural harmonics as speed goes high enough. I'd also consider a shaft hoop to keep it from coming thru the floor and beating you to death.

You're scaring me [emoji15]
redwngr Senior Enthusiast

redwngr

Posted
Posted

GM goes to a lot of effort in the owner's manual to recommend that any replacement tires have the same rating as the originals. Presumably it's enough to keeps their lawyers happy. Maybe the rating has something to do with the governor. Emphasis on the maybe.

 

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

If that was the case they would have different shutdowns depending on you gear. The driveshaft spinning faster with a 373 gear at 100 mph.

 

 

Sent from my iPhone using Tapatalk

Spurshot Senior Enthusiast

Spurshot

Posted
Posted

You're scaring me [emoji15]

That's a healthy thing sometimes.

 

 

The oem aluminum shafts are the ones you want to stay away from.

They're all aluminum in the trucks, from what little I know.

 

 

If that was the case they would have different shutdowns depending on you gear. The driveshaft spinning faster with a 373 gear at 100 mph.

 

 

Sent from my iPhone using Tapatalk

You're assuming GM would put a limit speed at the critical speed for the driveshaft. Not likely. Engineers always use a conservative "fudge factor" or "margin". Engineering folks always use the "worse case" and start there.

 

Look, nobody has a legitimate reason to drive over 100mph in one of these trucks on the street. Track racing is a different story and real organized racers learn quickly about the safety issues of a particular vehicle. I think that was what that driveshaft maker was conveying in his website.

KARNUT Senior Enthusiast

KARNUT

Posted
Posted

It really has to do more with lawyers than real product failure. The safety margin these days is over the top.

 

 

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