Tacoma drive shaft vibrations.....at my wits end

[tx_shooter]

Which part are you thinking might be a tooth or two off?

 

[taco4x4rar]

Easiest way to check alignment is to put some angle finders across the yokes and make sure they are exactly 90* off from each other.

Axle warp is the leaf springs twisting into an s shape when placed under torque from the drivetrain. At take off the torque from the driveshaft will try to push the pinion up or down depending on which direction you are going throwing the pinion angle off as you accelerate, the same holds true once up to speed although to a much lesser extent. Basically any time the drivetrain is under load the pinion angle will be different than while under no load, and this needs to be accounted for when setting pinion angle.

 

[taco4x4rar]

Which part are you thinking might be a tooth or two off?

Slip yoke on the rear half of the driveshaft

 

[italynstylion]

Here's a video of the axle in motion on a few quick start offs. Surprisingly, the vibrations were not bad this morning. I think they are worse once the truck warms up a bit. No idea why that would be. Fluid in the diff being more viscous? Not sure...

Anyway, yes, the pinion angle points up just a bit when on the throttle hard. It doesn't appear to be TOO much but yes, there's a little axle wrap. Not sure how bad is bad though. I'm curious if it's different when it heats up.

My thought at this point is still to weld a double cardan joint to the rear drive shaft where it enters the carrier bearing. If the pinion angle is what's causing the vibration, a double cardan SHOULD tolerate the angle changes much more gracefully. At least that's my hypothesis. Still looking for advice. @taco4x4rar

 

[tex]

I'm not sure what's a lot of movement but when you hit the gas but I would say the pinion angle moves a lot.

 

[Oswego]

I'm not sure what's a lot of movement but when you hit the gas but I would say the pinion angle moves a lot.

Exactly what I was thinking, but I have no frame of reference as to whats too much. Makes me wonder what it looks like when my rear end is bouncing on a high speed soft sand hill climb. Must be pretty violent down there.

If memory serves me right Jandrews from TW had a nice tract bar Kevin from the old ATO modified for him when he installed it. To date I thought it was the best functioning one I had seen that wasn't on a race truck. That was 4-5 years ago.

 

[tex]

@SMKYTXN might have a tract bar on his truck but I could be thinking of someone elses.

 

[italynstylion]

Like I said, if the pinion angle is the issue, then a double cardan joint on the rear portion should really help things. I posted the question over on TW too and got a response from a guy who did exactly that. He said it was great till he broke it. Apparently he had to compromise on the size of the spline shaft going into the joint. But if done right, I'm betting this is the sliver bullet.

 

[tx_shooter]

I wonder what he did to break it.

 

[italynstylion]

I wonder what he did to break it.

No idea. I will be taking the car to Drive Shaft King in Dallas tomorrow morning to get the stock shaft modified with a double cardan input joint behind the carrier bearing. They said they could do the work and Tom Woods said they would take the single piece shaft back and issue a full refund. We shall see what happens.

 

[taco4x4rar]

I wonder what he did to break it.

Likely had to use a small joint, like a 1310 or something like that. If I were to build a two piece cv driveshaft I would either run a 1350 cv or an OEM toyota cv. Mitigating axle wrap is the bane of leaf sprung vehicles

 

[italynstylion]

Likely had to use a small joint, like a 1310 or something like that. If I were to build a two piece cv driveshaft I would either run a 1350 cv or an OEM toyota cv. Mitigating axle wrap is the bane of leaf sprung vehicles

He said, "Failure occurred at the midship stub. To convert it over, they have to use a smaller diameter and therefore it's substantially weaker. Here's the snapped off midship stub inside the stock factory yoke for size comparison. Broke on the side of a moderate difficulty trail. Nothing that should warrant a failure."

Here are the pictures he posted. First one shows the stub sheered off (very odd failure IMO) and second shows the diameter difference. But realistically, it didn't break at the joint, broke at the input stub.

 

[Silverback]

That is a pretty significant size difference in that shaft.

 

[taco4x4rar]

Damn never seen that before, I would expect to grenade the cv or the tube before breaking the stub like that

 

[tx_shooter]

I grenaded the u joint on my '87 4Runner front axle a few years ago when it was in a bind. No hard was done to the drive shaft.

The u joint took me 20 mins to replace once I was pulled out of the spot. I am not sure how I would feel about building in a smaller stub like that. U joints are cheap and easy to pack spares.

 

[italynstylion]

Damn never seen that before, I would expect to grenade the cv or the tube before breaking the stub like that

Right?!?! My thoughts exactly. I think it may have been a freak thing but I'm not 100% convinced either way. So weird.

 

[tex]

My 4runner is looking better and better every day. Boxed frame, coil sprigs out back, 1 piece drive shaft and no shutters.

 

[tx_shooter]

My biggest concern is the custom drive shaft solution on a rig that goes to Colorado pretty regular. How hard will it be to repair in the back country? A traction bar would resolve the axle wrap and provide some protection for the drive shaft. Custom parts on a trail rig are fine; custom parts on an expedition rig get dicey.

 

[italynstylion]

Valid concern Zech. But realistically, if I kept the t-case and pinion flanges OEM and the carrier bearing mount was the same; I could use any OEM drive shaft and carrier bearing. So it would be like running a stock drive shaft in terms of finding something to replace it just to get me home.

 

[Taco Loco]

Bearing on third good?