Speed limiter???
Cargo Master
Joined: Apr 2003
Posts: 2,057
Likes: 424
From: Too close to Houston
There are many driveshaft critical speed calculators out there if you search.
Here’s one from Spicer. https://spicerparts.com/en-emea/calc...rpm-calculator
For a two piece driveshaft I don’t know if you’d run a separate calculation for each or if it has to be looked at as a combined unit. Of course any slop in the carrier bearing could change things considerably…
Here’s one from Spicer. https://spicerparts.com/en-emea/calc...rpm-calculator
For a two piece driveshaft I don’t know if you’d run a separate calculation for each or if it has to be looked at as a combined unit. Of course any slop in the carrier bearing could change things considerably…
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
There are many driveshaft critical speed calculators out there if you search.
Here’s one from Spicer. https://spicerparts.com/en-emea/calc...rpm-calculator
For a two piece driveshaft I don’t know if you’d run a separate calculation for each or if it has to be looked at as a combined unit. Of course any slop in the carrier bearing could change things considerably…
Here’s one from Spicer. https://spicerparts.com/en-emea/calc...rpm-calculator
For a two piece driveshaft I don’t know if you’d run a separate calculation for each or if it has to be looked at as a combined unit. Of course any slop in the carrier bearing could change things considerably…
Hotshot
Joined: Mar 2017
Posts: 10,150
Likes: 1,369
From: Chaz
Someone wanted to “swang” in a V6 Camaro recently and ALMOST clipped me. So I ran him off the road a short distance later. He realized I give 2 cares about my rear fender/bumper (no contact made).
I noticed at around 120, maybe 125-130, quick math via RPM the driveline does make a weird noise. I backed off there. I routinely run around 100 in the left lane when traffic is moving that fast as well without issue but any much faster for long distances and you can tell there is some harmonics no bueno.
CCSB 6.7 6 speed 3.55 with 35.1” tires. Do the math. But I wouldn’t suggest sustaining over 100 long distances. You can do the conversion on your driveshaft speed using my math. My speedometer isn’t recalibrated.
Its more the driveline than the tires as mentioned and in my opinion as well. Oh yeah forgot to mention I don’t have a speed limiter.
I noticed at around 120, maybe 125-130, quick math via RPM the driveline does make a weird noise. I backed off there. I routinely run around 100 in the left lane when traffic is moving that fast as well without issue but any much faster for long distances and you can tell there is some harmonics no bueno.
CCSB 6.7 6 speed 3.55 with 35.1” tires. Do the math. But I wouldn’t suggest sustaining over 100 long distances. You can do the conversion on your driveshaft speed using my math. My speedometer isn’t recalibrated.
Its more the driveline than the tires as mentioned and in my opinion as well. Oh yeah forgot to mention I don’t have a speed limiter.
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
As I already mentioned it's not really about the situation I was in. That was just for context for how I found out about the speed limiter. But no **** banking off and letting an idiot start doing that in front of me with the next couple vehicles a 100 yards up for an unknown amount of time. I don't need a ******* in front of me that may cause an accident I end up involved in. I'd much rather be in control of what variables I can be in control of.
Cargo Master
Joined: Apr 2003
Posts: 2,057
Likes: 424
From: Too close to Houston
As I already mentioned it's not really about the situation I was in. That was just for context for how I found out about the speed limiter. But no **** banking off and letting an idiot start doing that in front of me with the next couple vehicles a 100 yards up for an unknown amount of time. I don't need a ******* in front of me that may cause an accident I end up involved in. I'd much rather be in control of what variables I can be in control of.
Now you can remove your speed limiter if you wish, I really don’t care. But think about it, you are taking a chance playing with unknown variables and possibly risking others on the road. This whole mess started because you were concerned about someone else you judged a possible danger to others.
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
But he didn’t cause an accident on his way up to you and apparently didn’t cause an accident after you goosed it to get away from your perceived danger. As others have said if you had backed off a mph or two he would have continued on his merry way. He was probably using adaptive cruise and just locked onto your tailgate for a bit.
Now you can remove your speed limiter if you wish, I really don’t care. But think about it, you are taking a chance playing with unknown variables and possibly risking others on the road. This whole mess started because you were concerned about someone else you judged a possible danger to others.
Now you can remove your speed limiter if you wish, I really don’t care. But think about it, you are taking a chance playing with unknown variables and possibly risking others on the road. This whole mess started because you were concerned about someone else you judged a possible danger to others.
I think you're missing my point here. I'm saying he could've caused an accident. Regardless of the fact that he didn't I didn't want that possible hazard in front of me. And as he was driving in my blind spot in the lane to the left of me with no vehicles in front of him I highly doubt it was adaptive cruise control. There was no vehicle to adapt to and adaptive cruise control wouldn't let him follow that close if it was messing up and adapting to me.
How exactly would I be putting others at risk by getting away from someone on a mostly empty desert highway? I know I didn't mention that it was a desert highway but now you know that.
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Frmr Ford Trans Engr
Joined: Aug 1999
Posts: 24,704
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From: SE Florida
The way that could happen is if a tire blows or the driveshaft disintegrates due to the excess speed, causing you to lose control and hit someone else.
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
Ok fair response. Though I highly doubt that would happen if it was for a short period of time. Sure if i was pushing the limits everyday that would be an issue, but to get away from the occasional idiot, i doubt it.
Cargo Master
Joined: Apr 2003
Posts: 2,057
Likes: 424
From: Too close to Houston
The thing is, you’re basing your decisions on what you “think” might happen or not. As an engineer I learned early in my career that if you don’t “know” it’s right you have to consider it’s wrong. That’s why you have to calculate things like critical driveshaft speeds. The engineers at Ford set the limiter as they did for a reason. Unless you know the reason or the safety factors used in calculating the limit you’re just guessing. Again, I don’t care what you do to your truck. The odds of it having any affect on me or mine is infinitesimally small.
I can say though that critical speeds of rotating machinery are called that for a reason. You have to push through or back out of critical speeds very quickly. Seconds at these speeds can be disastrous.
I can say though that critical speeds of rotating machinery are called that for a reason. You have to push through or back out of critical speeds very quickly. Seconds at these speeds can be disastrous.
More Turbo
Joined: Jul 2023
Posts: 742
Likes: 332
When I had my 17 F150 5.0 and tuned with Oz, S&B intake and Borla exhaust, a buddy in a Chevy Silverado decided to pass me at about 120 and he had literal smoke coming off his tires.....Once we slowed down I let him know and his tires were only rated for 110 and since that day, I have decided to be a lot smarter with excessive speed in a truck....
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
The thing is, you’re basing your decisions on what you “think” might happen or not. As an engineer I learned early in my career that if you don’t “know” it’s right you have to consider it’s wrong. That’s why you have to calculate things like critical driveshaft speeds. The engineers at Ford set the limiter as they did for a reason. Unless you know the reason or the safety factors used in calculating the limit you’re just guessing. Again, I don’t care what you do to your truck. The odds of it having any affect on me or mine is infinitesimally small.
I can say though that critical speeds of rotating machinery are called that for a reason. You have to push through or back out of critical speeds very quickly. Seconds at these speeds can be disastrous.
I can say though that critical speeds of rotating machinery are called that for a reason. You have to push through or back out of critical speeds very quickly. Seconds at these speeds can be disastrous.
I mean yeah you're not wrong there. However, unless I'm mistaken here, don't engineers usually set the limits lower than necessary for the general public due to stupidity of the general public? I mean I'm not trying to do 120+ or even 100+, but hell I can't go into the 90's safely for 20-30 seconds to be able to pass or put distance from someone else more efficiently?
Mountain Pass
Joined: Sep 2005
Posts: 235
Likes: 84
From: West TN
Not really sure how it's done on these but if you really want that bit extra anyway you might can oversize your tires and not adjust the cluster, or keep them but adjust the cluster to smaller tires? I just went from 31" to 35" on my '96 F350 and it's crazy to think that it now can go faster than a brand new one lmao.
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Mountain Pass
Joined: Aug 2024
Posts: 187
Likes: 31
Exactly! The powers that be (engineers&lawyers not the illuminati&one world order) decided unless you wanna void that warranty by a tune and delete on the truck you shouldn't be driving above X speed for any reason in these trucks. Besides, if you had went 120 the idiot who was tracking you would have just sped up too...
Not really sure how it's done on these but if you really want that bit extra anyway you might can oversize your tires and not adjust the cluster, or keep them but adjust the cluster to smaller tires? I just went from 31" to 35" on my '96 F350 and it's crazy to think that it now can go faster than a brand new one lmao.
Not really sure how it's done on these but if you really want that bit extra anyway you might can oversize your tires and not adjust the cluster, or keep them but adjust the cluster to smaller tires? I just went from 31" to 35" on my '96 F350 and it's crazy to think that it now can go faster than a brand new one lmao.
Yeah you're probably right that the guy pacing me would've just caught up to me at which point he would've gotten the finger.
Cant change tire size due to the fact that I'll be using this truck for hotshot trucking. Pretty sure I need to keep it mostly stock