Speed limiter delete

[Transient]

On 6/16/2021 at 7:07 PM, GTPprix said:

Well to be completely honest its considerably more involved than just the tire rating; many of these trucks have tires rated well beyond the top speed they are limited at. The Trucks actually have several limiters and whatever one is the lowest is the one the system utilizes. Generally this is the transfer case limit or everyones favorite the driveshaft limit  [b]If you hang around long enough with the high speed guys about 50% of the time they have a driveshaft pretzel horror story lol[/b]

Yup.  Spent my fair share of time racing on the Bonneville Salt Flats.  Well, not really racing, but having fun driving stupid fast.  I've seen many driveshafts grenade at one end or the other.  What's been said by previous posters about u joints failing, etc, I've seen happen at over 200 mph (fortunately from very far away).

 

With that said, if I had the money to buy a truck just to see how fast I could push it, I would.  I want to know what the mechanical top speed is for every car.  I hate electronic limiters.  Who's in?  Let's all chip in.  I'll drive for free because I think it's fun.  At 130 we only need a fire extinguisher.  If we achieve 130 the next goal is 150.  We'll need to start talking roll cages at that point.  I've done 172, and I'll happily do it again.  Let's see if we can push a brick through whip cream thick air.

 

All those in support, send money to my venmo.  First goal is $75k.  I'm thinking a 2wd RST with the 6.2 and 10-speed is the way to go.  What do you guys think?

[slaveforthewave]

On 5/2/2020 at 2:58 PM, Silverado4x4 said:

Tires and driveshaft. Once a driveshaft comes out of balance at those speeds it will destruct with in seconds.

Congratulations! this might be one of the dumbest armchair internet engineering comments I've read in a long time.

 

You think the rotational speed of the drive shaft is even close to as relevant as how much torque is being put through it? Wow. I am impressed that you felt confident enough to post this like it was meaningful or correct information.

 

Unfortunately it's completely absurd and meaningless. The forces of spinning fast are significantly less than the input forces under high RPM and high torque. Your driveshaft is a lot more likely to explode off the line when you gun it then by doing faster speeds. I don't know why people that have no idea what they're talking about love to throw their two cents in like it's valid or meaningful.

 

But great job having a tenuous understanding of basic physics principles

Edited March 29, 2025 by slaveforthewave
spelling

[swathdiver]

16 hours ago, slaveforthewave said:

Congratulations! this might be one of the dumbest armchair internet engineering comments I've read in a long time.

 

You think the rotational speed of the drive shaft is even close to as relevant as how much torque is being put through it?

 

You can drag race all day long and not break a driveshaft with a stock or relatively stock truck.  Take it up to 112 mph or so and you can add your photos of twisted driveshafts to the others (K2s) on this site.

 

It seems to me that GM makes them to run up to about 5,000 rpms or so.  

[PunchT37]

2 hours ago, swathdiver said:

 

You can drag race all day long and not break a driveshaft with a stock or relatively stock truck.  Take it up to 112 mph or so and you can add your photos of twisted driveshafts to the others (K2s) on this site.

 

It seems to me that GM makes them to run up to about 5,000 rpms or so.  

BS. I have a 630 hp `68 to `72 A body GM product. If you can get out of the hole, you`re good to go.

[swathdiver]

9 hours ago, PunchT37 said:

BS. I have a 630 hp `68 to `72 A body GM product. If you can get out of the hole, you`re good to go.

So why did all those guys leave their driveshafts twisted into pieces on the highway on this forum who hit 112 mph?

 

Don't forget, unlike a Turbo 400, most of these guys had two or more overdrive gears.  

 

Enquiring minds want to know.

[KARNUT]

It must be a GM thing about the drive shaft. Usually it’s about the speed rating of the tires. I know by tuning all my trucks I’ve exceeded the governed speed. In my travels over the years I’ve been on roads that were flat for miles. I may have exceeded the limit. If it is a drive shaft issue. Shame on GM for building such a weak component. I think of all the times my father had his Buick singing a high speed song back in the day. Never a thought those bias ply tires would blow. Of course it’s not politicly correct to live on the edge anymore. We are restrained by devices to protect the weak minded and physically uncoordinated from themselves. Everyone ends up being afraid of everything. Speaking for myself I’ve had more fun testing the limits in safe spaces, most of the time. Then living in constant fear. Spare me the lecture of having fun can kill. I could be just plain talented or lucky. It doesn’t matter I had a blast. Oh I almost forgot my last new unrestricted truck easily did 130. I didn’t even quiver. Neither did the truck.

Edited March 30, 2025 by KARNUT

[PunchT37]

4 hours ago, swathdiver said:

So why did all those guys leave their driveshafts twisted into pieces on the highway on this forum who hit 112 mph?

 

Don't forget, unlike a Turbo 400, most of these guys had two or more overdrive gears.  

 

Enquiring minds want to know.

112? I wasn’t there. 
 

Most driveshaft failures I’ve seen are at launch on a prepped track. Ring and pinion, broken axles too. 
 

Speed can be a factor too. Especially if out of balance. 
 

Overdrive? All the driveshaft cares about is gear ratio and tire height. These new trucks have tall tires compared to the T400 days. I’ve been close to 150 with a stock 1970 driveshaft with 3.08 gears and a 275/60/14 tire. 
 

I have lost my balls these days to do that again. 
 

I have been 125 in my 2000 1500 split shaft truck. 16 inch wheels. Lucky, I guess. 
 

 

[KARNUT]

44 minutes ago, PunchT37 said:

112? I wasn’t there. 
 

Most driveshaft failures I’ve seen are at launch on a prepped track. Ring and pinion, broken axles too. 
 

Speed can be a factor too. Especially if out of balance. 
 

Overdrive? All the driveshaft cares about is gear ratio and tire height. These new trucks have tall tires compared to the T400 days. I’ve been close to 150 with a stock 1970 driveshaft with 3.08 gears and a 275/60/14 tire. 
 

I have lost my balls these days to do that again. 
 

I have been 125 in my 2000 1500 split shaft truck. 16 inch wheels. Lucky, I guess. 
 

 

In my amateur drag racing days. Usually test and tune. I would run street tires. No more sticky than Mickey Tomson Is. To limit hard launches. My toys were street cars most had AC. Especially when I got older. Hot here in Texas. I had a favorite road I traveled for top speed that’s to busy now. My 94 Impala ss has my personal top speed record on it. It was very stable had speed rated tires and would shift to over drive under full throttle. Second one almost a decade later with my Trailblazer ss on the same road. Everything else in between. My last was my wife’s 2011 Genesis shortly after we got it. I remember buying my wife’s Acura Intagra R in 2001. We left the dealer hit I-10 towards lake Charles. We easily almost doubled the speed limit. We broke two no nos. Going over the speed limit and break in. Both of those we still have. Neither have Z rated tires anymore. I’m a good boy now. The roads I travel are too crowded anymore.

[swathdiver]

On 3/30/2025 at 8:01 AM, PunchT37 said:

112? I wasn’t there. 

Me too, I drag race but only a few times a year now for fun.

 

These shafts are breaking because they are not made for turning more than 5,000 rpms at speed, that appears to be their "critical speed". 

 

These new trucks have 2 or 3 overdrive gears and are computer limited to the speed rating of their tires, generally speaking. 

 

So the shafts are made as light as possible to be as efficient as possible and are designed to be near those limits.

 

I once hit 148 mph in my Buick GN, just did the math, that driveshaft was turning just over 6,700 rpms! 

 

Yours at the same speed would have been turning just over 5,850 rpms.

 

When aluminum driveshafts first came out for our cars, we twisted them into pretzels while power-braking them for launch.  Went back to steel and no more problems.

 

I have a question for you, is there less stress on the drivetrain power-braking the car for launch or flashing the converter off idle for launch?  

 

I've been flashing the converters off idle for launch in our trucks but not sure if there's a few tenths to be gained by power-braking them.  On the other hand, it's 117 miles to home and don't want to leave parts all over the 60 foot!

[PunchT37]

30 minutes ago, swathdiver said:

Me too, I drag race but only a few times a year now for fun.

 

These shafts are breaking because they are not made for turning more than 5,000 rpms at speed, that appears to be their "critical speed". 

 

These new trucks have 2 or 3 overdrive gears and are computer limited to the speed rating of their tires, generally speaking. 

 

So the shafts are made as light as possible to be as efficient as possible and are designed to be near those limits.

 

I once hit 148 mph in my Buick GN, just did the math, that driveshaft was turning just over 6,700 rpms! 

 

Yours at the same speed would have been turning just over 5,850 rpms.

 

When aluminum driveshafts first came out for our cars, we twisted them into pretzels while power-braking them for launch.  Went back to steel and no more problems.

 

I have a question for you, is there less stress on the drivetrain power-braking the car for launch or flashing the converter off idle for launch?  

 

I've been flashing the converters off idle for launch in our trucks but not sure if there's a few tenths to be gained by power-braking them.  On the other hand, it's 117 miles to home and don't want to leave parts all over the 60 foot!

Depends on your converter and cam. Most can find rt by loading the suspension 1`st. So, a 1500 to 2000 foot brake then converter stab.

 

My car is better flashing from idle as the torque is very high and will blow the tires off if power braking.

 

Back to driveshafts, I used to work on police cars. Noticed, on a regular Crown Vic, the shaft was steel vs the aluminum on the police package. Used to have the big "Police" pink stamping on them.

[Transient]

I prepped track is going to have more grip for the tires due to the track glue (assuming 1/4 or 1/8 mile track).  That's more force loaded onto the drive shaft on green.  The traction coefficient on a normal road, on salt, dry lake bed, etc is lower.  I can see why both arguments are true.  Something needs to give when pushed past the limit.  I've seen axles and transmission bell housings break on launch at the drag strip, too.  Imo, a broken drive shaft or u-joint is a good day when compared to the alternatives.  I've also seen drive shafts grenade at 200+ mph.  I've seen drive shafts twist like a pretzel in the first 60 feet.  Both arguments are correct absence of detailed explanation. 

Edited April 1, 2025 by Transient

[PunchT37]

If one is nervous about his driveshaft blowing apart after a speed increase, he could still have his cake…
 

https://www.dennysdriveshaft.com/

[typhoon186]

On 5/5/2020 at 6:19 PM, JohnTz said:

Do you really want to take these high, loose un aerodynamic vehicles with truck tires with a significant forward weight bias at speeds higher than 100? 

Yes

[typhoon186]

On 7/16/2020 at 3:05 PM, GTPprix said:

Contact us from the website if you'd like to discuss all of these are custom at this point but I know one of you said you reached out but we did not get anything just an FYI. 

I just contacted you about this

[GETGONE]

On 3/30/2025 at 3:34 AM, swathdiver said:

So why did all those guys leave their driveshafts twisted into pieces on the highway on this forum who hit 112 mph?

 

I've run mine to 112 countless times with zero issues. 31K miles and still going strong. Took it to a test and tune and ran about a dozen passes trying various launches, no issues. Best of 14.2 in the 1/4.