One Piece Driveshaft

[Muddy Fenders]

I put a machinist rule across the dent and it really shows the depth. I am going to wait to hear from Shawn on what to do with the shaft but I won't install it like this.

I think of the pop can scenario.
you can put a lot of weight onto an empty pop can, until you impose a stress onto the side.
then it crushes easily.
plus, no matter what, that dent has taken the alignment out, even if only a few 0.000".
Good on them for agreeing to set it right for you.

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[Jason B]

Here's the math to determine drive shaft RPM. 20168/tire diameter in inches = x, (X)ring and pinion gear ratio = drive shaft rpm at 60mph. 20168 is the number we have figured out but you can check the math by finding the circumference of a tire (lets use 30 inches as an example for tire diameter) 94.25" then seeing how many times that goes into the number of inches in a mile (63,360). 63,360/94.25=672.33. Likewise 2,0168/30=672.26. A tiny bit of difference depending on how you do it but essentially the same result. So now that we know how many rotations a tire has to make to travel one mile we also know that if you are driving 60mph that is 1 minute per mile. So the rotations to drive 1 mile is going to be the tire revolutions per minute (rpm) when you are driving 1 minute per mile (60mph). Now we multiply this by the gear ratio, as a 3.73 ring and pinion gear means that the drive shaft is spinning 3.73 times faster than the tires. This is your drive shaft RPM at 60mph. In our example a 30 inch tire and 3.73 gears is going to result in about 2507 rpm at 60mph. With that 60mph RPM figured out it is as simple as multiplying that by the ratio of speed/60mph. So 75mph/60mph=1.25. 1.25x our established example 60mph rpm of 2507 equals 3,009 rpm at 75mph. That's the math I used to create our calculator. Tire diameter and gear ratio figures the RPM at 60 then speed on the slide bar divided by 60 = a ratio, that ratio times rpm at 60 equals the rpm at that speed. I think I made that more confusing that I needed to but hopefully that makes sense.

The important thing to remember with this is that it doesn't matter if your engine is redlining or if your engine is dead and you are coasting downhill at 60mph, the drive shaft rpm is the drive a product of tire diameter and gear ratio.

Regarding the 4,000 max that I've put on our shafts. That is about 97mph in a vehicle with 30.1" tires and 3.73 gears. Everyone: Please don't drive that fast, even if the truck can technically go faster than that. Going to bigger tires without re-gearing decreases the drive shaft RPM. Also, my 4,000 limit is conservative. There's the factors such as DOM tube, and the long spline we are using that will increase the critical speed to a number higher than the speed the Spicer calculator comes up with, which is about 3,800 rpm (4,000 is barely more than their calculator says). But if you read the part in my text file linked in my previous post my friend the engineer, using some of dana/spicers own numbers, comes up with something closer to 6,000 rpm, even after applying a safety factor of .75. 6,000 rpm is almost 150 in a ranger with 30" tires and 3.73 gears. So depending on which math you are following, the shaft could be safe up to 150 mph. I'm choosing to be much more conservative though and basically I'm telling people not to drive 100 mph or above. Or, you get a choice, you can choose to have a shaft two piece shaft that shudders (if you are one of the unlucky ones) or you can choose to have a shaft with a speed limit of around 100mph (depending on tire diameter etc.). It is admittedly a bit of a pick your poison scenario.

Bottom line though, we've seen from the video posted earlier on the thread what the @quangdog's stock shaft does. Instinctually I have a lot more fear about that shaft spinning at 4,000 rpm than the one that has been shown to not bang side to side as it rotates.

That's a lot of numbers to figure it out. I just figured at 75MPH the Ranger engine runs about 2,000 RPM. Divide that by the final gear ratio of 0.63 comes out to 3174.6 drive shaft RPM at 75 MPH, close enough to the 3134 you came up with.
Of course, your calculator will work for various scenarios, not just standard Ranger values.

 

[Shawn at Tom Wood's]

That's a lot of numbers to figure it out. I just figured at 75MPH the Ranger engine runs about 2,000 RPM. Divide that by the final gear ratio of 0.63 comes out to 3174.6 drive shaft RPM at 75 MPH, close enough to the 3134 you came up with.
Of course, your calculator will work for various scenarios, not just standard Ranger values.

It is indeed a lot to figure out with other ways to get to the same result. We figured out the math this way and created the calculator long ago so that we can figure out the drive shaft RPM on any vehicle. It is easy to apply it to just about anything without knowing the transmission gear ratios and without it mattering which gear you are in. All you need to know is the tire diameter, ring/pinion ratio, and vehicle speed.

Side note: One of the main ways we use drive shaft RPM is to help us to identify the proper size and strength components for an application. If your shaft is spinning slowly there is more load/effort required to move the vehicle forward. If it is spinning fast there is less load/effort required. Think of riding a bike uphill in various gears. When you have to stand on the pedals to move forward you have a greater chance of breaking something than if your legs are spinning around the pedals quickly. We use this all the time to help determine the proper strength shaft in Jeeps.

 

[AvalancheFX4]

I bought this kit, which is in a TSB, for the F-150 slip joint clunk. So far this grease has lasted, on my Ranger, the longest without clunking. I cleaned out the parts of the slip joint with surgical precision and put the new grease in and secured the boot. I gave up with the dealer and did it myself.

I cross referenced the grease in the kit from the Ford part number and it is Tribogel pa6110lcs. I had no luck trying to purchase it directly.

https://www.levittownfordparts.com/sku/9l3z4w602a.html

Nice piece of information. Any how to videos for this fix? What kind of tool is needed for the new clamp?

 

[navsnipe]

Nice piece of information. Any how to videos for this fix? What kind of tool is needed for the new clamp?

Quandog did a great video on how to do this. I used heavy duty zip ties to secure the boot after I was done. I think he showed how to close the clamp in the video.

 

[AvalancheFX4]

Quandog did a great video on how to do this. I used heavy duty zip ties to secure the boot after I was done. I think he showed how to close the clamp in the video.

Just saved it , thank you. Just turned 7k on the odometer definitely feeling it when the weather warms up.

 

[TJC]

Found the time this evening to install my Tom Woods Driveshaft.

Low speed shudder gone. High speed shake n bake gone. Went to 75mph, smooth as silk.

When I pulled the stock 2 piece driveshaft, it was obvious that the driveshaft ends are out of phase. Somewhat surprised by this,

Tony

 

[Justin says...]

Found the time this evening to install my Tom Woods Driveshaft.

Low speed shudder gone. High speed shake n bake gone. Went to 75mph, smooth as silk.

When I pulled the stock 2 piece driveshaft, it was obvious that the driveshaft ends are out of phase. Somewhat surprised by this,

Tony

I know nothing about driveshafts but, how can one tell if its out of phase? Is there something I can check for (visually) under the truck?

 

[Muddy Fenders]

I know nothing about driveshafts but, how can one tell if its out of phase? Is there something I can check for (visually) under the truck?

They are all out of phase.
Ford designed it that way for some reason.
Its not the smoking gun for the vibration some seem to think it is.

 

[NotBudule]

It would be interesting if somebody who switched to one piece could take their two piece to a local shop and let them spin it up , maybe some can be balanced or phased , or at least an answer as to why some wobble so bad , thanks to this thread , I think ? mine is doing it a little ... this place proves inception if nothing else...

 

[landiscarrier]

Found the time this evening to install my Tom Woods Driveshaft.

Low speed shudder gone. High speed shake n bake gone. Went to 75mph, smooth as silk.

When I pulled the stock 2 piece driveshaft, it was obvious that the driveshaft ends are out of phase. Somewhat surprised by this,

Tony

Good to hear! I just have the low speed shudder (4-8mph) but in a lot of stop and go traffic it's annoying! How difficult was it to change? How much time?

 

[Big Blue]

They are all out of phase.
Ford designed it that way for some reason.
Its not the smoking gun for the vibration some seem to think it is.

Actually I think Spicer designed them that way. It is common practice with their heavy duty truck two piece driveshafts. Check their site.

It would be interesting if somebody who switched to one piece could take their two piece to a local shop and let them spin it up , maybe some can be balanced or phased , or at least an answer as to why some wobble so bad , thanks to this thread , I think ? mine is doing it a little ... this place proves inception if nothing else...

I agree, mine is smooth, but why are some so bad? Is it the center bearing? Would need to replicate the driveline angles to be a valid test.

Unfortunately Ford will be help in this analysis, with the 5G ending production.

 

[navsnipe]

Actually I think Spicer designed them that way. It is common practice with their heavy duty truck two piece driveshafts. Check their site.

I agree, mine is smooth, but why are some so bad? Is it the center bearing? Would need to replicate the driveline angles to be a valid test.

Unfortunately Ford will be help in this analysis, with the 5G ending production.

I have noticed on my truck the cooler the outside temperature, the milder the shudder. The center bearing support material inside the aluminum frame is very soft. I can pull on it and deflect the driveshaft with very little effort. I don't have another vehicle with a two piece driveshaft to compare it to but I do remember my 1994 Ranger 2wd supercab center bearing was much stiffer material.

 

[Big Blue]

I have noticed on my truck the cooler the outside temperature, the milder the shudder. The center bearing support material inside the aluminum frame is very soft. I can pull on it and deflect the driveshaft with very little effort. I don't have another vehicle with a two piece driveshaft to compare it to but I do remember my 1994 Ranger 2wd supercab center bearing was much stiffer material.

Very interesting observation. Could they have gotten a bunch of center bearing with too soft of durometer material? They probably wanted to stay as soft as possible to eliminate vibration transfer. But, manufacturing variability bit them and some are a little too soft. Might be a fine line between controlling the vibration and causing it. Nice catch.

 

[navsnipe]

Very interesting observation. Could they have gotten a bunch of center bearing with too soft of durometer material? They probably wanted to stay as soft as possible to eliminate vibration transfer. But, manufacturing variability bit them and some are a little too soft. Might be a fine line between controlling the vibration and causing it. Nice catch.

Quandog's video definitely shows the center bearing deflection on take-off.

I was talking with a family member a few months ago that works for a drivetrain manufacturer, but not Dana, said support and mount materials are a huge compromise between comfort, efficiency, rigidity, and vibration. He was the one who got me thinking about the center bearing mount.

I've used urethane inserts on transaxle and transmission mounts on some previous cars, VW's and Audi's. I've found while it will reduce the deflection and slop in power transmission the vibration will become intrusive to the quality of the environment inside the vehicle. In most cases I took the inserts out and put the stock mounts back. The only exception was my 2013 GTI as the rear transaxle mount insert helped mitigate front wheel hop on spirited take-offs.

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