Low Low

[brendank]

That one there depends. If you're strictly off-road and low speed, it's ok. If you're going to go down the highway at 60 it'll vibrate some and it'll definately wear out in a hurry. Too much working angle.

That's why I said, "from what I can see". The picture is taken from a poor angle, but I'm pretty sure that it's around 20* or so, which is fine. Some u-joints can operate properly up to 37*. This is WELL below that.

Although the angle in this instance is higher than normal, the geometry of the driveshaft is proper, so I say again that it probably wouldn't vibrate.

If that were me though, I would change to a double cardan just because of wear issues.

 

[CopyKat]

 

[thegoat4]

That's why I said, "from what I can see". The picture is taken from a poor angle, but I'm pretty sure that it's around 20* or so, which is fine. Some u-joints can operate properly up to 37*. This is WELL below that.

Although the angle in this instance is higher than normal, the geometry of the driveshaft is proper, so I say again that it probably wouldn't vibrate.

If that were me though, I would change to a double cardan just because of wear issues.

I'm going to have to disagree with you on that one. I know some u-joints have enough clearance to operate at high angles, but a u-joint is a u-joint and u-joints get torsionals as the working angle increases. And 20 degrees is quite a lot. Besides that, the photo is taken from below-level, making the angle appear flatter than it really is. That angle is probably closer to 30 degrees than 20.

At highway speeds I wouldn't exceed 15 degrees even for a light driveline like that. But to each his own.

 

[CopyKat]

I'm going to have to disagree with you on that one. I know some u-joints have enough clearance to operate at high angles, but a u-joint is a u-joint and u-joints get torsionals as the working angle increases. And 20 degrees is quite a lot. Besides that, the photo is taken from below-level, making the angle appear flatter than it really is. That angle is probably closer to 30 degrees than 20.

At highway speeds I wouldn't exceed 15 degrees even for a light driveline like that. But to each his own.

I'm dropping my truck 2-3" in the back anyway. And I have a double cardian I plan to use for the back.

 

[brendank]

I'm going to have to disagree with you on that one. I know some u-joints have enough clearance to operate at high angles, but a u-joint is a u-joint and u-joints get torsionals as the working angle increases. And 20 degrees is quite a lot. Besides that, the photo is taken from below-level, making the angle appear flatter than it really is. That angle is probably closer to 30 degrees than 20.

At highway speeds I wouldn't exceed 15 degrees even for a light driveline like that. But to each his own.

I wouldn't run it either because of the premature wear on the u-joints. That is the only reason.

You're also very wrong that a u-joint is a u-joint. Some are VERY different from others.

Have you read the ~15 page 401 article on pirate regarding driveshaft and u-joint tech? I have. It's a good read for anyone who hasn't. I'm not pulling this information out of my ass. It's from a reliable source.


Anyways, it looks good Joel. I could tell from the pinion angle in the pic that you had a double-cardan somewhere in the plan. Have you figured out how much it needs to be shortened?


Nice exhaust clamps btw

 

[CopyKat]

Anyways, it looks good Joel. I could tell from the pinion angle in the pic that you had a double-cardan somewhere in the plan. Have you figured out how much it needs to be shortened?


Nice exhaust clamps btw

I've had a double cardian in the back since I built the truck. Plan to use another.

Old shaft length was around 30" and I need to pull about 8" out of it. It'll be short at 22" but not too bad.


What exhaust clamps???

 

[Totalled]

The problem is that people who don't understand drive shaft geometry tend to think "funny" things. For the people who "get it", it's not a problem.

From what I can see, I bet that setup doesn't vibrate. The only thing that I would be slightly concerned about in that picture is premature wear from the extra angle. That can EASILY be fixed by running a cv/u-joint type shaft. It's cheap as borscht to buy and swap in, too.

Actually, he couldn't even drive it, it shook so bad. He had a double cardan shaft made, and it still had some vibes at highway speeds.

Why must I continue to have to use this feature????

Like a little kid sticking their fingers in there ears and screaming "lalalalalala! I can't hear you!"



Enjoy your paranoia That anything I post is an attack on you.

Your drive shaft is still way short and at a severe operation angle. As I posted on page 1, I wish you good luck with that.

 

[CopyKat]

I don't give a fawk about your comments Pat. Your and idiot and that's all there is to it.

 

[rickcdewitt]

did you decide to upgrade to a flowmaster exhaust while there was room to work under there?looks like it from the pics,but i guess it could be a buddies example.

 

[MAKG]

OK. Enough.

This feud is old. All of us old-timers remember several different iterations, all the same. Were it not there, this site could be considerably better than it is. We all know you guys don't like each other, and BOTH of you are going out of your way to bait the other one.

Go off to your corners. Don't post in each other's threads. It takes away from the site. You both have useful and important things to add to the site. Just not at the same time, and certainly not to each other.

Pat, if you're right there either won't be a post-build followup or there will be a negative one. If you're wrong, there will (hopefully) be some evidence. Let it speak for itself. I also have doubts about the driveline angles, but it's Joel's truck and he does know what the risks are. As you know, he's very good with his geometry -- possibly better than anyone else on the board (and certainly up there) -- so I'd like to see how this evolves without all the fighting.

Joel, this is your truck and you can do what you want to it, to the extent that it doesn't endanger other drivers (not an issue in this case). Try to educate those of us around you about what you're doing, and what works. You don't try things randomly or straight out of a magazine, and you're very good with your calculations. So, though I do have some reservations about the driveline angles, I'll defer and suspend judgement until it's complete and tested. I'd urge others to do the same in this case.

 

[thegoat4]

I wouldn't run it either because of the premature wear on the u-joints. That is the only reason.

You're also very wrong that a u-joint is a u-joint. Some are VERY different from others.

Have you read the ~15 page 401 article on pirate regarding driveshaft and u-joint tech? I have. It's a good read for anyone who hasn't. I'm not pulling this information out of my ass. It's from a reliable source.

You mean this: http://www.pirate4x4.com/tech/billavista/PR-shaft/index.html ?

I can't find anything in there that states some u-joints somehow don't get more severe harmonics at high operating angles. FWIW, I'm the guy in my shop who deals with pretty much all NVH complaints so the training I've been to is probably slightly more detailed than that article. And even in all of my training and all of my experience repairing driveline vibrations there was never a special u-joint that defied physics.

There are two things that'll let you get away with excessive angles before vibration sets in: a lighter driveshaft, or a slower driveline speed. And the slower driveline speed matters a hell of a lot more.

Like I said up front: that shaft will fly just fine off-road since it'll be going slow. But since he has a doubler more than likely he'd like to be able to drive on the street. Not gonna happen with those angles.

In copykat's case, he's going to use a CV. He should be OK with that since the bend will be spread over more joints and each will see a much smaller working angle. But it'll still come down to what the final angles are and how fast the shaft will spin.

 

[CopyKat]

My 21" Long rear driveshaft is in and whadaya know it works!

No point continuing this thread. cuz my driveshaft is so short.