Single (and Two) Piece Driveshaft = Vibes....BE GONE!!!

My stock bolts only had one or maybe two threads showing with the original set up. I got the drive shaft mounted last night and the bolts are about one thread shy of going through the nuts. I did use blue lock tight and torqued everything so I feel pretty confident that they will stay put but will be looking for an alternative for sure. However, my takeoff vibes are gone! This drive shaft absolutely fixed the problems I was having.

 

Auto or manual? Lifted? 4inch shaft or 3.5?

 

Glad to hear it was the silver bullet for you!

 

@ItalynStylion I'm considering doing this since I'm about to install a 3" lift via Deaver springs. Would you mind giving my your order# with Tom Woods that way I can say just copy this order. I have the same truck as you e.g. DCSB TRD. I'll be sure to double check against my truck but I don't want to take my shafts off to do it.

 

Read everything. 4inch shaft is most recommended

 

I've already got a 4inch shaft on really warm days

 

Order a 3inch diameter shaft then big hoss

 

You measure with the og driveshaft on the truck on level ground for the length. Your can measure the bolts with shaft on truck as well.

 

(Gonna need a mod to help me update the first post)

After a really long business trip (and some other finagling) I can finally update this post as I've finally made it to the vibration free promised land. Yes, 100% vibration free. Here's what's transpired after my first post in this thread.

Originally, I'd bought the single piece 3.5" diameter drive shaft from Tom Woods. When I was on stock gearing, it was heaven. However, when you re-gear to a more aggressive gear ratio (4.56 for me) your drive shaft will be expected to spin VERY fast. Faster than what's called the "critical speed" of the shaft which is defined as the max safe operating speed of the shaft. For me, I wasn't able to go any faster than 55mph without horrible vibrations. Just to be clear, this shaft and operating angles worked prior to gears. Another member on here who also has 4.56 gears used a 4" diameter single piece shaft and said he doesn't have any vibrations even at high speed. I can't comment on his experiences since I don't know his setup.

However, for me, the best solution for a large number of reasons was a custom version of the OEM shaft. Since the shaft utilizes an OEM carrier bearing, it has a MUCH higher critical speed RPM than a long single piece shaft. It also offers better ground clearance. The shaft I had made is very similar to the one @1MK tried once upon a time. The custom shaft uses the OEM shaft at its core but deletes the u-joint sitting directly behind the OEM carrier bearing in-lieu of a double cardan input joint. A double cardan joint is often referred to as a CV joint although it's not a true CV joint. Regardless, it serves a very important purpose in this case. A double cardan joint will tolerate an angle that's double what a single u-joint will allow. So for lifted vehicles with angles you'll pretty much never fix; it's a HUGE help. This is also what makes the single piece shaft solution from Tom Woods work so well.

I want to be very clear on WHY this fixes start off vibrations. It fixes it because the pinion angle changes SEVERELY under hard acceleration. Thus, the u-joints get out of their operating range and you get some bad shit happening where the drive shaft tries to escape the carrier bearing. This is likely what's causing so many of you to go through carrier bearings like crazy. I suspect that leaf pack selection and lift height have the most to do with this.

So to summarize, the double cardan joint placed after the carrier bearing is needed because it tolerates the change in pinion angle due to axle wrap. The two piece drive shaft, using a carrier bearing, allows you to have aggressive gearing and not have vibrations at highway speeds.

As of now, my setup is as follows...

• Icon Stage 4 lift set at 3"
• Dakar Leaf pack
• 3 degree axle shims
• 4.56 gearing
• Two piece drive shaft with double cardan joint.
• OEM carrier bearing with NO spacers.
• BFG KO2 34x10.5x17

 

I'm still leaning towards a single-piece. I'd love to have another excuse to not regear.

Has anybody here done the single-piece without shims? Right now I have roughly 4" of lift in the rear and the take-off vibe is nasty. I've also developed a very low-level oscillation vibe at almost all speeds. The kind you can only really feel in your feet. At first I thought maybe my ECGS bushing was staring to fail, but when I pop it into 4WD the oscillation remains.

 

The shims really aren't that hard to install with basic hand tools. Cheap too!

The oscillation you're feeling could possibly be a u-joint going out. Does the feeling intensify when you increase throttle position? If not, maybe a wheel bearing?

 

Does anyone have pictures of the cuts you made on the carrier bearing cross member to create clearance for the drive shaft when the rear suspension is stuffed? Also, did you take any measurements before to figure out how much to cut?

 

This is another reason why my final solution was a two piece drive shaft. No cutting required!

 

Not really. It's a very low oscillation that happens between 30-70 it seems. Sometimes I feel like I'm just imagining it - but it's there.

 

Okay, so who did this for you? Was it expensive? I have a couple local driveline shops, maybe I could take them these pics and say "do me".

 

Did you find that the one piece would contact the cross member if the rear suspension was stuffed? I'm not opposed to cutting as long as it isn't going to hurt anything structurally.

 

Same price as the Tom Woods shaft. Had it done locally. By the way, Tom Woods gave me a full refund on the shaft. Excellent people to work with. Lost my ass on shipping it back to them and I'm sure they did too unfortunately.

I ended up doing the math/geometry on my garage floor to check whether it would contact the cross member. Even with the smaller diameter 3.5" shaft it was going to hit and would need to be removed.

 

Know of anyone on here that did end up cutting the cross member? Wanting to find some pics and find out if they feel like things are ok structurally as well.

 

It's there to hold up some fuel lines. Just cut the center part out.

 

Did you cut yours out? If so, do you wheel yours pretty hard? Any issues? Thanks for your input! This site is awesome!