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Front U-joint to CV joint conversion Dana 30

wilcharl

wilcharl

NAXJA Forum User
Location
Wash DC
Guys:

I have thought this out... And I know that CV joints are crap and u-joints are much better.... That being said I wnat to know if a u-jointed Dana 30 would accept CV joint axel shafts?

Why do i want to do this? #1 is time, and I know it only takes a few mins with a harbor freight press to punch out the u-joints

#2 my jeep NEVER goes off road... strcitly a daily driver and intercity + highway miles the only time it has ever seen 4 wheel drive was stuck in snow...

Going with the CV joint option gives me a mx free assembly (yeah i know they have lifetime greesed u joints)

but this is the deal... if its a direct swap, i can pop the axel hubs slide out the u-joint shaft slide in the cv joint assembly pop the axel hub back on and we are cooking with gas....

I have searched and cant find a definate yes just nay sayers to the CV joint...
 
Bounty Hunter said:
Sure you can, as jeepers often swap the other way around on ZJ's.
Click to expand...
Swapping the other way's fine, you just knock the brearing out, there's no seat for the bearing though when going from u-joint to CV type.
 
It will work fine. Early XJ's had CV joint instead of u-joints. Same setup.
 
Im getting mixed respones guys... this has me worried....
 
wilcharl said:
Im getting mixed respones guys... this has me worried....
Click to expand...


Then try it. Post your results here, so the next guy that wants to downgrade his front shafts can search for a proven answer..
 
wilcharl said:
Guys:

I have thought this out... And I know that CV joints are crap and u-joints are much better.... That being said I wnat to know if a u-jointed Dana 30 would accept CV joint axel shafts?
Click to expand...

I think you got it backwards. While the CV joints can be a PITA to service. They help eliminate vibration and joint wear at steep driveshaft angles. Most people upgrade to CV joint driveshafts. A CV joint is just two u-joints mounted in a connecting yoke with a spring in between.
 
87xjco said:
I think you got it backwards. While the CV joints can be a PITA to service. They help eliminate vibration and joint wear at steep driveshaft angles. Most people upgrade to CV joint driveshafts. A CV joint is just two u-joints mounted in a connecting yoke with a spring in between.
Click to expand...

This thread is not talking driveshafts though, its talking front axle shafts. Your thinking of a double cardon joint, misnamed a "cv" joint a lot.
 
I think im going to try it ... i agree with the previous poster that the CV joint is a technological superior design to the u-joint and for highway only i think its a good "downgrade"
 
cal said:
This thread is not talking driveshafts though, its talking front axle shafts. Your thinking of a double cardon joint, misnamed a "cv" joint a lot.
Click to expand...
Ah, I missed the "axle shaft" line. So he is thinking of replacing a u-joint axle shaft with a CV joint axle shaft? It's pretty confusing what he wants and why!
 
87xjco said:
I think you got it backwards. While the CV joints can be a PITA to service. They help eliminate vibration and joint wear at steep driveshaft angles. Most people upgrade to CV joint driveshafts. A CV joint is just two u-joints mounted in a connecting yoke with a spring in between.
Click to expand...
Nope.

You are thinking of a "double cardan" joint, as is usually used in high angle drive shafts. Although a double cardan is often referred to as a CV (constant velocity) joint, it is not the same as a true CV joint such as used in the early XJ front axles.
 
87xjco said:
Ah, I missed the "axle shaft" line. So he is thinking of replacing a u-joint axle shaft with a CV joint axle shaft? It's pretty confusing what he wants and why!
Click to expand...


yeah. I see two problems.

1) a CV joint of sufficiant strength will not fit in the alotted space. MAAAYBE it will, I run alloy-usa tube seal's so i have a hair less space than some other may, but its not likely.

2) If you do get it to fit, you will probably not have room for a proper protective boot. The joint will get dirt in it and go dry and then fail rather quickly. More quickly if this were not mainly a street jeep, and very quickly if he got into the mud, but far, far quicker than u-joints in any case. On a street rig, its not such an issue, but if it were a trail rig, trail repair would be near impossible if one failed. Granted, most of the time a u-joint breaks on a dana30 it takes the shaft with it, theres always that chance of easy repair.
 
Wilcharl, yes you can swap to the cv joint shaft. Any that come from an XJ or ZJ are the correct length.

Cal, are used on older XJ's with selectrac. They fit just fine, although they would interfere with your tube end seals. As for trail use. They are no different to pull than a u-joint shaft. Shafts rarely survive when a u-joint fails so you really need to carry complete shaft assy. to effect a trail repair in most cases. Here's where the cv shaft has an advantage. Even without a spare shaft, you can gut the cv when it breaks, and reinsert the shaft into the boot, and slide it back in place. The boot will support the shaft well enough to drive it that way, and you aren't left with the diff seal open to contamination. I've done it and driven the rest of the day with 3 wheels pulling and then flat towed it home before repairing. They also don't provide the chance to see your strg. knuckle seperate from the hsg. as the ears on a u-joint shaft can do when they climb over each other after a joint breaks.

Stay tuned for pics.
 
Here is a cv joint from my friends TJ. First pic is the cv end of the axle shaft, then the diff. end, where you can see the end of the shaft deformed from banging against the crosspin. Third is the cv stub, cracked, and last the pieces that were big enough to hold. This Jeep is running 37" MTR's. The cv's were installed after breaking a couple u-joints on 35's. It broke on an undercut log step. The one that I broke didn't look near as bad, but I don't have any pics. The stub on mine was reusable except for the fact that I didn't have a soft hammer to seperate it without deforming the OD. Most of the destruction in these pics is probably due to the fact that he drove it for almost two weeks after breaking it, before tearing it down.







 
wilcharl said:
Guys:

I have thought this out... And I know that CV joints are crap and u-joints are much better.... That being said I wnat to know if a u-jointed Dana 30 would accept CV joint axel shafts?

Why do i want to do this? #1 is time, and I know it only takes a few mins with a harbor freight press to punch out the u-joints

#2 my jeep NEVER goes off road... strcitly a daily driver and intercity + highway miles the only time it has ever seen 4 wheel drive was stuck in snow...

Going with the CV joint option gives me a mx free assembly (yeah i know they have lifetime greesed u joints)

but this is the deal... if its a direct swap, i can pop the axel hubs slide out the u-joint shaft slide in the cv joint assembly pop the axel hub back on and we are cooking with gas....

I have searched and cant find a definate yes just nay sayers to the CV joint...
Click to expand...
I have read and re-read your request in still don't get your point.
CV joint's are weaker that U-Joint's
CV joints are harder to service than u-joints.
CV joints do have some advantages over U-Joints but in the front of a solid axle jeep is not one of them.
 
langer1 said:
I have read and re-read your request in still don't get your point.
CV joint's are weaker that U-Joint's
Any proof of this, as in technical data? Or just the opinion of the masses?

CV joints are harder to service than u-joints.
I've replaced hundreds of u-joints, and serviced hundreds of c/v joints in the frt. axles of Jeeps. Neither one takes more time than the other once you do a couple.

CV joints do have some advantages over U-Joints but in the front of a solid axle jeep is not one of them.
What difference does the vehicle make? The cv transfers power smoothly, the u-joint doesn't. Which sounds better to you?
Click to expand...

Wilcharl, I use my TJ extensively offroad. I swapped cv's in for the same reasons you want to. Smooth operation, and less maintenance. I have had them fail, but I also had multiple u-joint shafts fail prior to swapping them out. For your case, they certainly aren't a downgrade as some people think. There is a reason they were used in certain apps from the factory.
 
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