Bad Vibration after Front Driveshaft Install

[WILDHOBO]

I wouldn't want any less than 4 degrees. Not on these and not with the larger tires.

With a stock driveshaft where the output and pinion shafts are parallel, the maximum shaft angle is 15 degrees.
7 degrees is a recommended max (for highway speeds)
Consider these are single cardan joints without a second joint to take out driveshaft speed fluctuations, you really need to be keeping it down, in fact, just off of straight (about a degree) is recommended for joint life.

He can do some math, figure the shaft angle, the joint angle, where the pinion is at vs. caster, but frankly, for a street driven Jeep, no way I'd take it down to 4 degrees of less caster if it was 80% street/highway. No way.

I didn’t say to go lower than 4. Just that it doesn’t need to be 6.5. 5 is just fine. And I’m at a 4” lift on 37’s. It steers like a car.

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[ShadowsPapa]

I would hope a double cardon at the TC would be enough but I'm worried i may have to run limiting straps to jump safely. I don't have any issues stock but i'll have a fair bit more stroke with Fox elites and i do like having lots of caster. its starting to look like 6 will be the max.

That ONLY takes care of that end of the shaft, because that's a severe angle due to transfer case tilt. The problem is you have a single cardan joint at the pinion running a severe angle and no second joint to cancel out the rpm changes of the shaft so the pinion is changing RPM down and up, down and up, every single revolution. That's a lot of jerking motion on the joint, pinion, yoke, etc. OK if crawling in rocks, but still quite a stress on that front joint and that's why they use the number of joint they do.

 

[ShadowsPapa]

I didn’t say to go lower than 4. Just that it doesn’t need to be 6.5. 5 is just fine. And I’m at a 4” lift on 37’s. It steers like a car.

Yes, 5 is fine - but I threw that out there because he's not going to be happy if he has to lower it much below 5.
I'm at about 4.5 and I would not be willing to take less. It's fine, very good, in fact, but it's been lower and I wasn't as happy. (I added the longer LCAs)
It sure doesn't need to be 6, and going over that can add other issues for some. 4.5 to 5.5 or 6 seems to be a happy number.

 

[PuddleJumper]

That ONLY takes care of that end of the shaft, because that's a severe angle due to transfer case tilt. The problem is you have a single cardan joint at the pinion running a severe angle and no second joint to cancel out the rpm changes of the shaft so the pinion is changing RPM down and up, down and up, every single revolution. That's a lot of jerking motion on the joint, pinion, yoke, etc. OK if crawling in rocks, but still quite a stress on that front joint and that's why they use the number of joint they do.

Does anyone make double cardon at the TC and CV at the pinion?

 

[ShadowsPapa]

Does anyone make double cardon at the TC and CV at the pinion?

For the JK, yes, everyone and their cousin makes 'em for the JK.
I wonder why.

 

[PuddleJumper]

For the JK, yes, everyone and their cousin makes 'em for the JK.
I wonder why.

I bet I can make one fit or i can just go to driveshaft shop and have one built

 

[WILDHOBO]

Yes, 5 is fine - but I threw that out there because he's not going to be happy if he has to lower it much below 5.
I'm at about 4.5 and I would not be willing to take less. It's fine, very good, in fact, but it's been lower and I wasn't as happy. (I added the longer LCAs)
It sure doesn't need to be 6, and going over that can add other issues for some. 4.5 to 5.5 or 6 seems to be a happy number.

To achieve the best compromise for extreme wants like jumping or high speed sustained 4wd use, you really need 8 adjustable control arms to really dial everything in.

 

[WILDHOBO]

I bet I can make one fit or i can just go to driveshaft shop and have one built

I may actually have my new, not yet installed front, rebuilt by the shop that made it. It’s a double cardan at the t case and single 1350 at the pinion. I might ask them if they can swap that 1350 for a strong cv.

 

[ShadowsPapa]

I bet I can make one fit or i can just go to driveshaft shop and have one built

That's just it - you can have a pro shop make a shaft for less, with the same joints as the catalog shafts.
A racing axle shop made the rear shaft for my Eagle. The front is no worry because the front differential hangs from the engine mounts, so that's a pretty straight shot and even lifting the car that shaft is running straight. The rear is short and with leaf springs, you really have to watch angles because they change under acceleration and deceleration.

 

[PuddleJumper]

That's just it - you can have a pro shop make a shaft for less, with the same joints as the catalog shafts.
A racing axle shop made the rear shaft for my Eagle. The front is no worry because the front differential hangs from the engine mounts, so that's a pretty straight shot and even lifting the car that shaft is running straight. The rear is short and with leaf springs, you really have to watch angles because they change under acceleration and deceleration.

ahh gotcha. Thanks

 

[ShadowsPapa]

I may actually have my new, not yet installed front, rebuilt by the shop that made it. It’s a double cardan at the t case and single 1350 at the pinion. I might ask them if they can swap that 1350 for a strong cv.

A true CV can actually stand more pressure/torque at greater angles than a cardan joint. They are about the same at low angles, but the cardan falters at greater angles.

 

[Wheelin98TJ]

That's just it - you can have a pro shop make a shaft for less, with the same joints as the catalog shafts.
A racing axle shop made the rear shaft for my Eagle. The front is no worry because the front differential hangs from the engine mounts, so that's a pretty straight shot and even lifting the car that shaft is running straight. The rear is short and with leaf springs, you really have to watch angles because they change under acceleration and deceleration.

Just don't go to Fleet Pride. Expensive.

 

[JTenn]

It was a whirlwind. Got to a friends place near gattlinburg after 11pm Saturday night. Did Windrock the next day, amd headed towards home on Monday.

Man that's quite a hike!! We just got back from Moab last Monday so it's likely we crossed paths. @ospreyfe55 instead of spending dollars repairing your oem shaft, You should at least check what it would cost to change the single Carden end of the Adam's to a double Carden? That may be the cheapest solution at this point. I get it that money has already been spent on expensive shafts and no more should need to be spent but it seems you're going to spend $$ either way. Based on this conversation it sounds like this approach would resolve your issue, @ShadowsPapa , correct?

 

[WILDHOBO]

Man that's quite a hike!! We just got back from Moab last Monday so it's likely we crossed paths. @ospreyfe55 instead of spending dollars repairing your oem shaft, You should at least check what it would cost to change the single Carden end of the Adam's to a double Carden? That may be the cheapest solution at this point. I get it that money has already been spent on expensive shafts and no more should need to be spent but it seems you're going to spend $$ either way. Based on this conversation it sounds like this approach would resolve your issue, @ShadowsPapa , correct?

Seems like a good idea to me.

 

[ospreyfe55]

So is the reason the OEM shaft doesn’t vibrate is because of the CV joint at the TC? Because the OEM style is a 1300 series joint at the axle and CV at the TC. And wouldn’t the CV just get tore up at the axle side due to the angles?

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