U-joints, what to expect?

[WizeOne]

I came from the automotive service and parts biz. Decades ago the auto industry left the u-joints in the dust bin (at least for front wheel drive axles that required gross articulation) and went to constant velocity joints. They did this for the obvious reason that you could make sharp turns much smoother, without pushing a U-joint assy to it's outer limit. I also believe that they may be stronger and take more torque than u-joints.

Here is my question. At the outer edges of the allowed turn radius of a Merc outdrive, is it common to begin to feel the effects of the u-joints reaching their articulation limit? In other words, a subtle binding/chattering/vibration?

 

[Don S]

Re: U-joints, what to expect?

Here is my question. At the outer edges of the allowed turn radius of a Merc outdrive, is it common to begin to feel the effects of the u-joints reaching their articulation limit?

Absolutely, they make noise and vibrate at max turn. Worse with some trim angles.

 

[WizeOne]

Re: U-joints, what to expect?

Absolutely, they make noise and vibrate at max turn. Worse with some trim angles.

Thanx!

 

[JustJason]

Re: U-joints, what to expect?

I've always wondered why they never adopted some kind of CV joint to drives. Seems like it wouldn't be a major deal to do. But I guess the cost of tooling up isn't the cheapest thing either.

 

[jtybt]

Re: U-joints, what to expect?

The CV joint crossed my mind, too. Maybe the problem would be clearance. The CV might require a boot within the bellows.

 

[dr_bowtie]

Re: U-joints, what to expect?

yea but most CV joints cannot handle the load like the u-joint could....

 

[Mischief Managed]

Re: U-joints, what to expect?

yea but most CV joints cannot handle the load like the u-joint could....

CV joints have been used for years on surface drives. CV joints can handle huge amounts of torque. They are used in the last stage of all the torque multiplication of the transmission and the final drive in a car.

As an example, a 2007 Acura TL engine makes 233 ft-lbs of torque. First gear is 2.7:1 and final drive is 4.31:1. If first gear, the car put 233*2.7*4.31 or 2711 ft-lbs of torque through the front wheel CV joints.

 

[dr_bowtie]

Re: U-joints, what to expect?

eh...dont care bout no wimpy ricer....

talking purely as the OP stated...front axles of 4x4 trucks...

they used to have straight axles with u-joints in the end and in the late 80s early 90s switched to CV shafts in differential housings...

to date these newer types cannot hold the toque output/input the older straight axle types can....I have seen WAY many CV shafts ripped apart from over powering...

the CV shafts were designed into the systems just as the OP stated...for steering effectiveness...the CV shaft will still continue travel where the U-joint starts to bind...this is why the adoption of double U-joint coupler...

I have also built a few ricers where I have totally ripped the CV joint out..they simply dont hold up under power unless you spend the money for the high dollar units...