Driveshaft U-joint Phasing

[fluidfloyd]

From time to time the subject of how to build a drive shaft comes up. The term phasing the u-joints comes up and some folks get a little confused. So here is a link that demonstrates this subject. Hope this will help those that have questions.

George

http://www.macsmotorcitygarage.com/2014/07/26/video-driveshaft-angle-and-phasing/#more-39570

 

[Mike]

Here is the video contained on the linked page -

 

[Swampdog]

That is why the use Constant Velocity Joints on Front Wheel Drive car.

 

[baddawgcustoms]

Thanks for posting that. I always knew being out of phase caused vibration, but never knew it actually causes such a variation in speed. Learn something new every day!

 

[Keeper]

Very cool. Nice to see how things work!

 

[fluidfloyd]

Thanks for posting that. I always knew being out of phase caused vibration, but never knew it actually causes such a variation in speed. Learn something new every day!

My pleasure Dale!

 

[Screaming Metal]

Hahaha....yep, you can hear that when you see a raised 4x4 pass you going down the street....everyone wonders about the sound and vibration of those trucks that are raised about a foot ot two....its hard to keep a even speed on those 15+ degree driveshaft angles unless you spring for the CV Joints....

 

[fluidfloyd]

Screaming'

As you well know, a lot of the off road guys will run Double Cardan joints to help with the large angular issues. They were also used in some of the long wheel based big Lincoln Town Cars to get away from having to run two drive shafts.

"A double cardan joint consists of two universal joints mounted back to back with a center yoke; the center yoke replaces the intermediate shaft. Provided that the angle between the input shaft and center yoke is equal to the angle between the center yoke and the output shaft, the second cardan joint will cancel the velocity errors introduced by the first cardan joint and the aligned double cardan joint will act as a CV joint."

As most hot rods have fairly short shafts they seldom have a need for these types of u-joints. But then you knew that didn't you!

George

 

[baddawgcustoms]

Screaming'

As you well know, a lot of the off road guys will run Double Cardan joints to help with the large angular issues. They were also used in some of the long wheel based big Lincoln Town Cars to get away from having to run two drive shafts.

"A double cardan joint consists of two universal joints mounted back to back with a center yoke; the center yoke replaces the intermediate shaft. Provided that the angle between the input shaft and center yoke is equal to the angle between the center yoke and the output shaft, the second cardan joint will cancel the velocity errors introduced by the first cardan joint and the aligned double cardan joint will act as a CV joint."

As most hot rods have fairly short shafts they seldom have a need for these types of u-joints. But then you knew that didn't you!

George

I sort of resent that statement about hotrodders having short shafts.

 

[Screaming Metal]

Screaming'

As you well know, a lot of the off road guys will run Double Cardan joints to help with the large angular issues. They were also used in some of the long wheel based big Lincoln Town Cars to get away from having to run two drive shafts.

"A double cardan joint consists of two universal joints mounted back to back with a center yoke; the center yoke replaces the intermediate shaft. Provided that the angle between the input shaft and center yoke is equal to the angle between the center yoke and the output shaft, the second cardan joint will cancel the velocity errors introduced by the first cardan joint and the aligned double cardan joint will act as a CV joint."

As most hot rods have fairly short shafts they seldom have a need for these types of u-joints. But then you knew that didn't you!

George

Hahaha....Yea George, its funny. The weekend guys that go thru the whole raised truck thing just use the std. heavy duty spicer crosses, while the serious out there use the double cardans....I just smile and shake my head.
One of my safety issues is with driveshafts. I built a motor for a guy, and I drove the car since no-one was there to drive it down the track. About 2/3rds the length of the track, just hitting 8 grand on the tach (setup to hit 8800 thru the lights), the driveshaft came on up thru the floorboard to visit me. The only thing that saved my ass was the bottom of the rollcage.
Some igmo left off the top half of the safety loop off....and this was on a full tube frame.
Thats the last all out run I ever did in a competition car....been too damn scared since. I'll build motors all day long, but I won't ever go over 1/2 track under full power....
Short shafts??????HA!!!!!!! Sometimes short is good! Its all in how its articulated!!!!!!

 

[fluidfloyd]

I sort of resent that statement about hotrodders having short shafts.

Dale...I never infer anything about someone's personal business. I leave that up to their better half.

 

[fluidfloyd]

Hahaha....Yea George, its funny. The weekend guys that go thru the whole raised truck thing just use the std. heavy duty spicer crosses, while the serious out there use the double cardans....I just smile and shake my head.
One of my safety issues is with driveshafts. I built a motor for a guy, and I drove the car since no-one was there to drive it down the track. About 2/3rds the length of the track, just hitting 8 grand on the tach (setup to hit 8800 thru the lights), the driveshaft came on up thru the floorboard to visit me. The only thing that saved my ass was the bottom of the rollcage.
Some igmo left off the top half of the safety loop off....and this was on a full tube frame.
Thats the last all out run I ever did in a competition car....been too damn scared since. I'll build motors all day long, but I won't ever go over 1/2 track under full power....
Short shafts??????HA!!!!!!! Sometimes short is good! Its all in how its articulated!!!!!!

I've just been discussing drive shafts, diameters, lengths and critical speeds with Mark Williams. If people ever looked at the numbers it would cause them to think about drive shaft safety loops in a hold different light. I have seen folks build small diameter shafts either due to clearance issues or thinking there is less precipitating weigh to deal with. They are usually wrong on both accounts. That's a big chunk of iron slinging around in the car with you and it won't be pretty by any means. Lose one of those and you might damn well end up short for sure! Then your better half may not be your better half anymore. Stay safe!

George

 

[choppinczech]

Saw this on another site.

 

[choppedtop]

Good demo. I would like to have seen the angles the same, on different plains, but with the joints out of sync. Wonder what that would do?
Lee

 

[Mike]

Threads merged.

 

[fluidfloyd]

Threads merged.

Up playing late are you! Actually I'm glad you did merge them as I get confused and think Damn...I think I've seen this already. Double thinking for a double vision stumbling soul. It does get confusing at times. Thanks Boss!

George