DIY Driveshaft Run Out

bbtank45 · Apr 28, 2016

I've built a few sets of driveshafts for buddies and myself, usually using Spicer parts machined (Carolina Driveline or Northern) to accept 2.5" x .25" wall DOM. In the past, i built the shafts on the truck rotating the driveshaft and tapping till within a certain spec....usually .01". Mocked up a dial indicator to gauge run out.

I haven't had any issues with run out's as much as .012". I am curious though; what is an allowable run out when building shafts for rock crawlers, and trail riders.....Harlan, Windrock, Rush, Badlands type terrain? What is your allowable run out?

Some of the builds have had midships front and rear.

bbtank45 · Apr 28, 2016

This is the piece I am building driveshafts for now....

gottagofast · Apr 28, 2016

The front driveshaft on my yj has had over 1" of runout (banana shape) for over two years....

I never notice it on the trail up to @40 mph but it vibrates pretty good at 55 mph in the snow on the road....

Soooo as long as you have .0X ur prolly fine.

ranger11 · Apr 28, 2016

gottagofast said:
The front driveshaft on my yj has had over 1" of runout (banana shape) for over two years....

I never notice it on the trail up to @40 mph but it vibrates pretty good at 55 mph in the snow on the road....

Soooo as long as you have .0X ur prolly fine.

What he said, we use to just weld them without checking run out and at low speed it doesnt matter if they are way out of round, if its gonna be spinning the tires at mach one .02 or less is good.

tonybolton · Apr 29, 2016

I bent a rear driveshaft at windrock on Schoolbus trail and didn't know it. And when I mean bent, I mean like 5-6" out of line. We started heading down a gravel road and I was doing my usual 30+mph and was only flagged down by my buddy behind me that I might wanna look at my rear driveshaft. I was oblivious to it and I'm usually on the freaking point when I hear strange rattle/clang/pop/thud.

As I was cruising back to the trailer on the paved road, I said "Lets see if this thing will actually make a vibration........I never noticed a damn thing and was in 3rd gear at a no windshield eye watering speed.

gottagofast · Apr 29, 2016

Come to think of it, I shortened my rear shaft... Cut the weld with an angle grinder... Wrapped a sheet of paper around to mark it.. Cut it with the same angle grinder... Tapped it back together n welded it without measuring anything... Only set phase by setting it on a concrete floor n making sure it wouldn't rock...

I've put prolly 30,000 miles on it at speeds of up to 90+ mph with no issues...

bbtank45 · Apr 29, 2016

This is good news. Sounds like I've been well within spec...

How about single ended carrier bearing midship shafts? Solid mounted drivetrain with no bushings. Similar to the below...i always felt like run out is much more critical here.