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cv vs u-joint
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Author:  BuggyGuy81 [ Sun Jun 07, 2009 9:42 pm ]
Post subject:  cv vs u-joint
I recently ran into a guy that was running small drive_shafts with u-joints on the end. Wich is better in the woods standard cv or the u-joint style?
Author:  khaney01 [ Sun Jun 07, 2009 9:51 pm ]
Post subject:  Re: cv vs u-joint
I've got U-joint shafts in mine out of a Datsun 280zx. If you are running stock length trailing arms you won't find anything any stronger. If you are using extended trailing arms they won't last a weekend. With the longer trailing arms the ujoint has to accelerate and then stop 4 times per revolution over twice the distance for which they were designed to operate. A CV joint has more pivot points and is better able to stand the stress.

If you ever plan on going with extended arms go ahead and spring for the 930's. 8)

Image
Author:  buggiejunky [ Sun Jun 07, 2009 11:45 pm ]
Post subject:  Re: cv vs u-joint
i run u joints and they have lasted more then a weekend with a 2276 and 2x3 arms ??? so whats up with that ????
Author:  khaney01 [ Mon Jun 08, 2009 3:32 pm ]
Post subject:  Re: cv vs u-joint
buggiejunky wrote:
i run u joints and they have lasted more then a weekend with a 2276 and 2x3 arms ??? so whats up with that ????


There's an exception to every rule. :D

What kind of axles are you running?
Author:  Odyknuck [ Mon Jun 08, 2009 4:49 pm ]
Post subject:  Re: cv vs u-joint
You can buy "U" joint axels with telescpoing splines that will handle the extremes of travel however be prepared to spend at least 1200 Bucks.
Author:  Stevo [ Mon Jun 08, 2009 4:56 pm ]
Post subject:  Re: cv vs u-joint
These are what im puting in and they claim 35deg!
http://www.driveshaftsuperstore.com/New%20Products!.htm
Author:  ImmortalSoul219 [ Mon Jun 08, 2009 5:07 pm ]
Post subject:  Re: cv vs u-joint
Those look crazey heavy! I would rather snap a cv on the trail than break a trans. Thats why I stick with type 2 cv's. Its easy to just bring extra cv's. A trans is a hole nother story.
Author:  khaney01 [ Mon Jun 08, 2009 5:34 pm ]
Post subject:  Re: cv vs u-joint
The axles that I run are splined and travel is not the problem. The problem is the u joint not being designed to move such a long distance, stopping, and reversing direction so fast. If the joint has to move much further than a the bend in a "normal" driveshaft it is not happy. I have tried various different ujoints and some are better than others. I've had the best luck with spicer.
Author:  Baddvw [ Mon Jun 08, 2009 7:34 pm ]
Post subject:  Re: cv vs u-joint
ImmortalSoul219 wrote:
Those look crazey heavy! I would rather snap a cv on the trail than break a trans. Thats why I stick with type 2 cv's. Its easy to just bring extra cv's. A trans is a hole nother story.


I totally agree with you, I do too think that I rather break a CV than an expensive transmission.
Author:  BuggyGuy81 [ Tue Jun 09, 2009 2:15 am ]
Post subject:  Re: cv vs u-joint
thanks for all the info! If I were to go the route with the u-joints what mods are needed if any to bolt on.
Author:  Maddog [ Tue Jun 09, 2009 8:14 am ]
Post subject:  Re: cv vs u-joint
If you break a u-joint,you stand a good chance of destroying the ears.
It is very unlikely that you will just be able to replace the joint if the ears are all bent or broken .
Author:  buggiejunky [ Thu Jun 11, 2009 6:02 pm ]
Post subject:  Re: cv vs u-joint
i guess u guys just need to figure out what to run then u wont have to change thoses cv any more im not light on the pedal and i run a heavy 8 ply uncut tire and if i ever do tear on up i can shortin my limt strap and put a stock bus axle and cvs right in it so its all good
Author:  buggiejunky [ Thu Jun 11, 2009 6:03 pm ]
Post subject:  Re: cv vs u-joint
oh yea i got about 100 bucks in my stuff with new joints
Author:  Stevo [ Thu Jun 11, 2009 6:41 pm ]
Post subject:  Re: cv vs u-joint
buggiejunky wrote:
oh yea i got about 100 bucks in my stuff with new joints

hope you didnt buy those autozone axle wannabes! They are junk.
Author:  chris38375 [ Thu Jun 11, 2009 7:11 pm ]
Post subject:  Re: cv vs u-joint
ive seen the u-joints built out of 1 ton chevy u-joints,if they willhold up to that they will hold up to a 150 hp vw
Author:  gasman [ Thu Jun 11, 2009 7:54 pm ]
Post subject:  Re: cv vs u-joint
i have seen some cool axles and i even own a set of 280z axles set up for a buggy and they run fine.but if ujoints was better then they would be running them in everything built and not cv's.a cv is better for alot of reasons imo,but thats mo.and like everything if you make something stronger then that makes something else weaker.me personally i would rather change a cv than tear down a tranny and that is the next thing in line if your axles won't break then the tranny will.and yes you can spend lot's of money and beef it up.but if you don't have a bullit proof tranny with all the goodies then don't spend time and money on something thats going to make it your weak link.and theres my 2 cent.chad :mrgreen:
Author:  buggiejunky [ Fri Jun 12, 2009 12:12 am ]
Post subject:  Re: cv vs u-joint
i guess if u got the right combination then u got it if u dont then u dont so how long will my stock trans last ?????
Author:  buggiejunky [ Fri Jun 12, 2009 12:30 am ]
Post subject:  Re: cv vs u-joint
i think some of u guys r just hard headed automotive makers used u joints in front axles for ever still to this day so if they wont take abuse y do they use them ??? i myself have put 450 horse to the front end of a 5800 pound truck with 36s forward backward turn this and that way very rarely breaking them now i ve used them in a 1200 pound buggy with half the horse and as far as the trans goes weight plays a big factor in how long it will last i ve went from 3500 pound bus with about 100 hp to a buggy with about 160 hp but only weights 1200 pounds i dont know i guess well just see how long it lasts but i know that side shifts r still pretty cheap for 250 ill buy them all day
Author:  chris38375 [ Fri Jun 12, 2009 2:16 am ]
Post subject:  Re: cv vs u-joint
buggiejunky wrote:
i think some of u guys r just hard headed automotive makers used u joints in front axles for ever still to this day so if they wont take abuse y do they use them ??? i myself have put 450 horse to the front end of a 5800 pound truck with 36s forward backward turn this and that way very rarely breaking them now i ve used them in a 1200 pound buggy with half the horse and as far as the trans goes weight plays a big factor in how long it will last i ve went from 3500 pound bus with about 100 hp to a buggy with about 160 hp but only weights 1200 pounds i dont know i guess well just see how long it lasts but i know that side shifts r still pretty cheap for 250 ill buy them all day

i agree
Author:  khaney01 [ Fri Jun 12, 2009 9:14 am ]
Post subject:  Re: cv vs u-joint
The axles in the front end of trucks just travel up and down which is something they can easily handle. In a buggy they are swept back and travel in a arc which is not what they are designed to do. If you want to get on google and do some searching you can find the whole theory of design for a u joint. The needle bearings are only able to cope with a very short throw back and forth at relatively slow speeds. In a buggy axle the joint moves in too many directions at once which moves the needle bearings more than they can stand for long.

In my first post I was talking about the needle bearings going bad quickly. Even with them bad the design will let you run them for a while before the cross breaks.
Author:  chris38375 [ Fri Jun 12, 2009 9:46 am ]
Post subject:  Re: cv vs u-joint
has anyone ever been out west,75% of the 800 hp buggys run u-joints with slip axles and long trailing arms,extremely long travel,they work,run what u want to,theres alot of good axle and joint choices
Author:  RaceBugg1098 [ Fri Jun 12, 2009 10:26 am ]
Post subject:  Re: cv vs u-joint
If U-joints were the way to go, wouldn't all the $150,000-200,000 class one race buggies run them? Alot of them are running "series 30" cv joints. Some choose to run fixed cv joints with a plunging axle and some run the conventional plunging cv. I am yet to see one running u-joints. Aside from race buggies the normal "u-joint" set-up results in running a shorter axle and moves the axis of the joints closer causing you to loose travel. When they advertise 35* of angle, it might be true, but you would need to run 35* to equal the same as a 930 at 28*. I'm not saying that "u-joints" are bad, thats the joy of buggies, you won't find two that are the same. :mrgreen:
Author:  Baddvw [ Fri Jun 12, 2009 10:35 am ]
Post subject:  Re: cv vs u-joint
Alot of them sandrails on the West coast that I seen so far are running mostly 934's, very little that I seen one with a set of U-joints, I have a subscription of Sandsport magazine and don't hardly seen any so far. I am running 930's now, I have broke a couple so far due to jumping and then landing under throttle and clutching it when the tire bit too hard, I also ruined 2 axles, but they were JUNK empi ones, I went through polishing the CV's and now are running SAW axles, no more problems since then, about $700-$1000 will do for a good set of CV's and SAW axles will be the best bang for the buck and should never have to go back. In my opinion of the U-joint axles is that if they break, it could go slapping all over the place hitting your brake lines, a broken piece could come flying out and hit somebody. I heard one time that somebody had a set of U-joints on his buggy and went on climbing a hill then the axle broke cutting his brake line and he flew backwards off of the hill, I don't know how bad it was or him getting hurt, but I rather let the CV explode inside of the boot, then slowly back off of the hill then change it. OK, then why do VW run CV's on their cars and buses? I would rather leave it in stock form and run better CV and axles. I think I would rather spend $700-$1000 on the correct parts if my life depends on it, not on some junk U-joint setup. Sorry for being like this but I just want to lay down my opinion :mrgreen:
Author:  khaney01 [ Fri Jun 12, 2009 11:06 am ]
Post subject:  Re: cv vs u-joint
Baddvw wrote:
I heard one time that somebody had a set of U-joints on his buggy and went on climbing a hill then the axle broke cutting his brake line and he flew backwards off of the hill, I don't know how bad it was or him getting hurt, but I rather let the CV explode inside of the boot, then slowly back off of the hill then change it.


I remember that. I think it was Chuck Cook. I've got a guard against such a thing happening with mine but a broke u-joint would still cause some pretty good damage.
Author:  Kyle [ Fri Jun 12, 2009 11:59 am ]
Post subject:  Re: cv vs u-joint
Constant-velocity joints allow a rotating shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play.

The u-joint suffers from one major problem: even when the drive shaft axle rotates at a constant speed, the driven shaft axle rotates at a variable speed, thus causing vibration and wear. The variation in the speed of the driven shaft depends on the configuration of the joint, which is specified by three variables. This is on a level plane also not like the arms in a buggy.

That is why cv's are better......CONSTANT VELOCITY.

The u-joints in your truck can withstand that power because they are always flat in a solid axle. They turn when you steer, which any 4x4 will know that is when you break the ujoints. Its never going straight its appling the power while turning that breaks them. Now if you ran a OX or CTM u-joint they have brass bushing bearing and no needles. Very strong and pratically indestructable.
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