CV driveshafts

anyone have much experience with drive shafts using CVs instead of universal joints?
the new Bronco, Im doing some design work for, has CVs on both ends of driveshaft.
Pros/Cons of this?

 

Im not an engineer but if i were to take a stab at it, I would say a cv joint is smoother in operation because with a ujoint the shaft speed slows every 90* then speeds up again producing essentially a sine wave of it's speed and also why you have to phase your driveshaft to prevent vibrations. And If I were to guess I would say a ujoint is cheaper and possibly stronger by size just because heavy duty vehicle still use ujoints over a cv axle as far as i'm aware

 

The constant velocity is definitely a plus, and I'm sure cost is why U-joints are still even used. Same reason most Tacomas still have rear drum brakes. lol

 

Im going off topic but I don't honestly have an issue with drum brakes because they last a very long time and actually have more braking power because especially with a dual servo style drum setup like on a ranger for say the shoes wedge into the drum as they're applied creating more stopping power. Downsides to drums in my opinion is heat dissipation sucks because all the action is literally contained in a cast iron drum, complexity for servicing along with having to adjust them every so often manually and if you off road they can get packed in with debris more so than disks.

The way I see it is if you can jam the brakes and all the wheels lock then unless your towing/racing/needing the extra heat dissipation the average driver will not benefit from bigger brakes or otherwise

 

Lots of people here dealing with vibrations from the two-piece driveshaft w/carrier bearing, especially after a lift is put on (myself included). A CV joint somewhere on it would be a huge help for sure. Given my own experience, a double-cardan CV joint seems more reliable than a birfield or "repezza" (whatever it's called/spelled) type CV, though I suspect this may have more to do with seal failure than a weakness within the joint itself.

 

I concur, it's not too often a rzeppa style cv joint actually fails unless either the lube is contaminated, leaks out or it's a remanufactured axle that isn't properly hardened on the working surfaces. I think it would be costly but for a driveshaft to have a cv axle would be mint. Especially since it would't have such extreme axle angle or operation like steering a fwd car for say with the wheel at full cut.

 

This Bronco DS has me wondering how much it would cost to fit a tacoma DS with CVs. But most likely not worth the cost

 

Rzeppa (I never can seem to remember that lol)


Comparing a Tacoma rear driveshaft with the same for a Jeep Gladiator on RockAuto, I do see how cost could become an issue...
I'm sure it would still be worth it to some folks though.

With more & more vehicles using CV DSs now, has me thinking of scrounging some junkyards for parts to either experiment with on the Tacoma DS, or to replace the Tacoma DS altogether (I've modified a few DSs over the years, haven't yet had one that couldn't be rebalanced afterward).

 

My assumption was always that our driveshafts are operating at 4X, + or - depending on diff ratio, the RPM that a CV joint in an axle shaft application will have to deal with. No issues there when joint angles are low, but get into some of the steeper angles that a 4x4 truck shaft will see, and that creates a lot of heat and possible low component life as a result. Anyone else have thoughts on that?

A couple of years back, curiosity led me to purchase the front CV Joint drive shaft from an AWD Lexus LS 460. It uses NTN Japan HLJ95 Series CV Joints. Interestingly, the shaft is very close in length to the Taco front, and thoughts of adapting it to my truck have occurred…. But just the front at this point. I’m game to look at the rear and start spit balling. I can snap some pics of the shafts tomorrow if there’s interest.

 

Pics please

 

If you really want to go down the rabbit hole, NTN supplies some great info in the tech papers. Their industrial division has engineering data in the catalogs. It’s fairly easy to suss out why the manufacturers use what they do… and apply it to our trucks.
Now we just need a good aftermarket source. I’ll take some of these ultra efficient 10 ball NTN units.

 

so all we need are a couple 4 bolt adaptors and change the shaft length right?

 

Potentially. I almost feel it'd be easier to make a new pinion flange with splines to accept the driveshaft than adapt the driveshaft to fit the pinion but, I'm not an engineer or machinist

 

To use the LS460 shaft? Yes, most likely. Definitely want to make sure the joints have enough movement on the slip plane.

Adapters will cost less.