Bad Vibration after Front Driveshaft Install

[Boostnu]

I would say if you want to run in 4hi you will have to give up some more caster so you can get the shaft more inline. The fad lets you run the higher caster in 2wd but in 4hi the axle is locked in so you will feel the vibration. I’ve heard that the 1350 joints are more prone to do it then the 1310s. I’m running an ultimate 44 in the front of mine so no fad and I’m on the lower end of caster so my pinion angle is more in line.

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[ShadowsPapa]

I would say if you want to run in 4hi you will have to give up some more caster so you can get the shaft more inline. The fad lets you run the higher caster in 2wd but in 4hi the axle is locked in so you will feel the vibration. I’ve heard that the 1350 joints are more prone to do it then the 1310s. I’m running an ultimate 44 in the front of mine so no fad and I’m on the lower end of caster so my pinion angle is more in line.

No cross or cardan type joint can run that sort of angle without vibration. it's not the size or part number, it's the angle of the joint (and the outer diameter of the circle that it makes when turning)
You could put any cross in there of that size (outer diameter) and it would be subject to the same sine wave type speeding up and slowing down two times per revolution.
There's a reason for CV joints (and they are just as strong, just not as well liked on the trail due to boot issues and not as easy to service them on the trail should you actually bust one0
Physically, a real CV will handle the power fine, and work higher angles, and not be prone to any vibration because - well, CV is constant velocity. And gee, I've been talking about shaft velocity this whole time and how that vibration is the constant changing of the rotational speed of the pinion.
It's like your 14 year old driving a stick for the first time. You've seen the TV shows of someone learning a stick. That's what that poor pinion is being put through.

 

[Boostnu]

No cross or cardan type joint can run that sort of angle without vibration. it's not the size or part number, it's the angle of the joint (and the outer diameter of the circle that it makes when turning)
You could put any cross in there of that size (outer diameter) and it would be subject to the same sine wave type speeding up and slowing down two times per revolution.
There's a reason for CV joints (and they are just as strong, just not as well liked on the trail due to boot issues and not as easy to service them on the trail should you actually bust one0
Physically, a real CV will handle the power fine, and work higher angles, and not be prone to any vibration because - well, CV is constant velocity. And gee, I've been talking about shaft velocity this whole time and how that vibration is the constant changing of the rotational speed of the pinion.
It's like your 14 year old driving a stick for the first time. You've seen the TV shows of someone learning a stick. That's what that poor pinion is being put through.

You think something like the high angle shaft teraflex makes for the jk would work good if they would ever release one for jl/jt?

https://teraflex.com/2012-18-jk-4dr-high-angle-rzeppa-cv-driveshaft-rear-3-6-lift.html

 

[Lunentucker]

Drive Shaft Angles Explained - YouTube

 

[ospreyfe55]

I would say if you want to run in 4hi you will have to give up some more caster so you can get the shaft more inline. The fad lets you run the higher caster in 2wd but in 4hi the axle is locked in so you will feel the vibration. I’ve heard that the 1350 joints are more prone to do it then the 1310s. I’m running an ultimate 44 in the front of mine so no fad and I’m on the lower end of caster so my pinion angle is more in line.

Yeah I figured I’m going to have to play with some compromise. I talked to Will at MetalCloak and I think I’m going to shoot for about 5degrees of caster. He told me they have a 392 at the shop and they had to run somewhere around 4 degrees just to make it feel right. I’m going to set my upper control arms to 20” which puts them right at the factory specs. I still have the longer lowers so it should be ok. I ran about 5 degrees last year and it seemed to be ok.

 

[Boostnu]

Yeah I figured I’m going to have to play with some compromise. I talked to Will at MetalCloak and I think I’m going to shoot for about 5degrees of caster. He told me they have a 392 at the shop and they had to run somewhere around 4 degrees just to make it feel right. I’m going to set my upper control arms to 20” which puts them right at the factory specs. I still have the longer lowers so it should be ok. I ran about 5 degrees last year and it seemed to be ok.

Yeah I figure you will end up in the 4.5-5 range. The 392s dont have fad like my axle. I think I’m around 4 with mine.

 

[ShadowsPapa]

Drive Shaft Angles Explained - YouTube

Pretty much what i've been saying - this guy gives numbers.
He says 10 degrees max, that's assuming you match at each end.

But check him out at about 5:27 or so where he says if there's a double cardan, you pretty much need to match the pinion to the shaft.
Then again he hits it at 7:00.
He must have been listening to me where I said you need to rotate the pinion up to match the shaft, but doing that takes out your caster.

So isn't that what i've been saying here and in a couple of other long threads on this?

I guess, thanks, you just totally reinforced what I've been saying. ?

 

[ShadowsPapa]

Yeah I figured I’m going to have to play with some compromise. I talked to Will at MetalCloak and I think I’m going to shoot for about 5degrees of caster. He told me they have a 392 at the shop and they had to run somewhere around 4 degrees just to make it feel right. I’m going to set my upper control arms to 20” which puts them right at the factory specs. I still have the longer lowers so it should be ok. I ran about 5 degrees last year and it seemed to be ok.

So in other words, their shafts force you to do things that may not work for steering and suspension just because they are making a killing on so-called "performance shafts".

4 degrees is not even in the factory specs for caster.
Hacks.

 

[Lunentucker]

Pretty much what i've been saying - this guy gives numbers.
He says 10 degrees max, that's assuming you match at each end.

But check him out at about 5:27 or so where he says if there's a double cardan, you pretty much need to match the pinion to the shaft.
Then again he hits it at 7:00.
He must have been listening to me where I said you need to rotate the pinion up to match the shaft, but doing that takes out your caster.

Som isn't that what i've been saying here and in a couple of other long threads on this?

I guess, thanks, you just totally reinforced what I've been saying. ?

I always do better with audio-visual presentations.
But to answer your question, we had chicken tenders and homemade mac-n-cheese.

 

[ShadowsPapa]

Very interesting topic to me as well. I have recently also installed Adam's drive shafts front and rear and have a rear vibration at 70 mph and above. They are both as you stated, double Carden on the T/C sides and single 1350 u-joints at the axles. Now I don't run at speed in 4hi so the front hasn't shown an issue but it could be vibrating as well. The rear on the other hand definitely has some high speed vibration. Interesting thing is it's WAY worse on deceleration like going down a hill or cancelling the CC. As soon as I hit 68 mph it stops. I believe I can adjust my pinion angle as mentioned above and resolve my issue but beyond that I'll take it to a local shop and have it balanced. Kind of disappointing considering what these things cost but it IS an aftermarket part that is installed on a modified vehicle. I do not believe the drive shaft to be defective but anything is possible.

These so-called performance shafts, which IMO, is highway robbery for the prices, force people to compromise to be able to get by with their designs.
I say "get by" because it's a severe compromise to have to give up caster, and you still have a cross type joint running a fair angle that isn't any stronger, and in many cases with high angles, far weaker, than a true CV joint.
I guess a person needs to choose parts, and compromises, based on their true intended use.
Sadly, many of these go into Jeeps and trucks that don't see the sort of trail abuse that would justify not going with a true CV.

The one and only advantage of these shafts is that you can carry a spare joint in the toolbox and replace it on the trail (unless you mess up the actual shaft or the yoke!)
So if you only bust the joint (because they aren't strong running at severe angles) and need to replace the joint - advantage point to shaft like this. Otherwise, I see none.

 

[kevman65]

Pretty much what i've been saying - this guy gives numbers.
He says 10 degrees max, that's assuming you match at each end.

But check him out at about 5:27 or so where he says if there's a double cardan, you pretty much need to match the pinion to the shaft.
Then again he hits it at 7:00.
He must have been listening to me where I said you need to rotate the pinion up to match the shaft, but doing that takes out your caster.

Som isn't that what i've been saying here and in a couple of other long threads on this?

I guess, thanks, you just totally reinforced what I've been saying. ?

Watch it again Bill, he's talking about the rear not the front.

He references the front shortly, but never discusses it other than you have to give up caster to maintain drive shaft alignment.

 

[ShadowsPapa]

I always do better with audio-visual presentations.
But to answer your question, we had chicken tenders and homemade mac-n-cheese.

Man, that's among my wife's favorites. But I have to watch the grease for a bit.........


Maybe you missed this.......... you can not only see the effect on the sprockets with tape, but can hear it.
https://www.jeepgladiatorforum.com/...-front-driveshaft-install.80795/#post-1314929

 

[ShadowsPapa]

Watch it again Bill, he's talking about the rear not the front.

He references the front shortly, but never discusses it other than you have to give up caster to maintain drive shaft alignment.

I know exactly what he's talking about - but the same applies. You have to rotate the pinion up to match the shaft.
It's exactly the same whether it's rear or front, other than the front will see steeper angles due to the shorter driveshaft length.
Doesn't matter which shaft - same rules exactly. You need to keep that shaft and pinion in a line with each other.

Why would front vs. rear matter?

I guess I could dig out my AMC/Jeep vibration troubleshooting class guide................

 

[kevman65]

I know exactly what he's talking about - but the same applies. You have to rotate the pinion up to match the shaft.
It's exactly the same whether it's rear or front, other than the front will see steeper angles due to the shorter driveshaft length.
Doesn't matter which shaft - same rules exactly. You need to keep that shaft and pinion in a line with each other.

Why would front vs. rear matter?

I guess I could dig out my AMC/Jeep vibration troubleshooting class guide................

You assume the TC sits level, he alluded to the fact it is canted towards the rear, so the front is already coming out above centerline, so there is a difference.

 

[ShadowsPapa]

You assume the TC sits level, he alluded to the fact it is canted towards the rear, so the front is already coming out above centerline, so there is a difference.

Don't even begin to tell me what I assume. You think this is my first foray into 4x4s or transfer cases or drivetrains?
Holy cow - where did you get that i "assume" the transfer case sits level?

And that's really only a variable because the lift and distance from t-case front yoke to front pinion yoke will impact the angle of the shaft coming forward out of the transfer case.

Still doesn't matter - same rules apply.

Only the exact numbers will vary based on the vehicle and the lift and the length of the shaft.
I never assumed anything at all. I know the whole drivetrain typically sits lower in the rear - no engine or transmission or transfer case sits level with the chassis. All tilt downward toward the rear.
I've worked on enough drivetrains to realize all of that LOL.
Why in the hell would a guy who started with cars and trucks, including 4x4s decades ago, assume the transfer case sits level when I have yet to see one that does.

Damn, I must have a busted mount or something, the rear of my transfer case is sagging!
Shit, the front is tipped up, all the fluid is going to run to the back!

Come on, man, give me some credit!
Everything I said applies, and that video actually reinforces what I was saying, it doesn't contradict it in any way at all.

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