Driveshaft geometry

Trevor · January 25, 2016, 04:07 PM

Stumbled upon this video and thought some here might find it interesting. Some good tidbits on driveshaft geometry, pinion angles, etc

https://www.facebook.com/Trustmeiamamechanicalengineer/videos/652429238232016/

binch · January 25, 2016, 10:44 PM

Can't seem to view the link.... ???

Trevor · January 26, 2016, 05:43 AM

Try that new link Bill. I had copied it off of RTE's Facebook page, and since I never use Facebook I obviously screwed up somewhere on the initial attempt.

binch · January 26, 2016, 08:11 AM

Now that's a good video....explains a lot of detail in there. I wonder how a double cardinal works in all that? Thanks Trevor ;)

Red90 · January 26, 2016, 09:04 AM

Quote from: binch on January 26, 2016, 08:11 AM
Now that's a good video....explains a lot of detail in there. I wonder how a double cardinal works in all that? Thanks Trevor ;)

A DC joint is 2 u-joints inline that are 90 degrees out of phase. This phasing more of less cancels the oscillation of the joints as the intermediate "shaft" is forced to be at equal angles to the joints through the centering ball.... The end result is the output shaft rotates more or less evenly with the input shaft. In a driveshaft, where the other end has a single u-joint, you want as little angle at that other end as practical as that single joint will impart an oscillation. Mud like clear?

binch · January 26, 2016, 12:13 PM

More good info.. Thanks John :D

Thunderball · January 28, 2016, 06:25 PM

This is an AWESOME post! It really got me thinking about the rear Rotoflex shaft on my D1. I was wondering if you fellas have experienced these Rotoflex shafts failing? If so, was it a result of lifting your rigs or just normal wear and tear? Or have you guys preemptively converted your shafts to U-Joints (and was this a viable solution)?

Regards,

Justin

binch · January 28, 2016, 07:52 PM

I've had ours on our disco 11 since 2001 and it's still running fine, with no signs of cracking or failing. But I can see pressing your luck with a lift that it wasn't designed for. ;)

B-Red · January 28, 2016, 08:49 PM

We experienced a "blow out" with debris flyingeverywhere in MOAB. EVEN ON A REGULAR STOCK, you can sheer the rotoflex if you approach an incline the wrong way. It's a fail safe mechanism to prevent damage to the gears. Not a pretty site though.

Red90 · January 28, 2016, 08:58 PM

I don't think they like lifts much. Most people bring a spare. They are easy to change. No problem going to a u-joint. That is the way they were before the cushy North American crowd got them.

https://discoweb.org/rotoconversion.htm

Matt H · January 28, 2016, 09:59 PM

Quote from: B-Red on January 28, 2016, 08:49 PM
We experienced a "blow out" with debris flyingeverywhere in MOAB. EVEN ON A REGULAR STOCK, you can sheer the rotoflex if you approach an incline the wrong way. It's a fail safe mechanism to prevent damage to the gears. Not a pretty site though.

If your thinking of the orange G4 (not Trevor's) that blew it's driveshaft on the hells revenge then I don't think it was running stock suspension?

It's not a fail safe and it doesn't protect anything. It's there to absorb vibrations.

Thunderball · January 28, 2016, 10:05 PM

Thanks for the input Gents! I do feel like I may have hi-jacked this thread a little...but this has been very educational. My fathers Series IIa is bone stock and we've never had issues/messed around with prop shafts etc. Jesus Murphy B-Red, sounds like you were a bit shafted afterwards (yes, pun intended...horrible, yes)?

Quote from: Red90 on January 28, 2016, 08:58 PM
I don't think they like lifts much. Most people bring a spare. They are easy to change. No problem going to a u-joint. That is the way they were before the cushy North American crowd got them.
https://discoweb.org/rotoconversion.htm

- Thanks for the link, this definitely adds some perspective.
I just pulled the trigger on some new terrafirma's 2+ MD's for the D1 and should probably convert the shafts while I'm down there. I will be doing all the wrenching myself (the old man will probably 'supervise' with a stubby or two in hand), is there anywhere in the Calgary region that I could go to pick up parts for something like this? Or talk to the blokes from TRS?

Cheers,

Justin

Matt H · January 28, 2016, 10:18 PM

Be sure to take a close look at the front driveshaft on a D2 that you intend to lift. The cat cooks the grease out of the DC and it fails.

binch · January 29, 2016, 08:32 AM

Quote from: Matt H on January 28, 2016, 10:18 PM
Be sure to take a close look at the front driveshaft on a D2 that you intend to lift. The cat cooks the grease out of the DC and it fails.

With catastrophic effect!!!! Ask Johno...... If you are lucky you will notice the warning sign that feels like a tire slightly out of balance. If you deal with it early enough you can rebuild them for a fraction of the price of a new one.

Trevor · January 29, 2016, 06:05 PM

Quote from: B-Red on January 28, 2016, 08:49 PM
We experienced a "blow out" with debris flyingeverywhere in MOAB. EVEN ON A REGULAR STOCK, you can sheer the rotoflex if you approach an incline the wrong way. It's a fail safe mechanism to prevent damage to the gears. Not a pretty site though.

Weeelll, that wasn't a stock rig Emad, nor was it anywhere near normal circumstances. That rotoflex explosion was 100% driver error. Jim took the wrong line, and then got on the excelerator exactly when he should have come off it.

Jim has a 3" RTE lift in his D2 (which equates to about 4" lift actual), and that's too much for a rotoflex. I think stock they are a really reliable piece of equipment. I talked with Bill Davis at GBR a fair bit about them when I was looking to swap mine out of my D2. He sees a 2" lift as about the upper limit for the rotoflex.