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This tech is for a YJ front driveshaft, but parts may apply to other Jeeps as well.
While doing some routine greasing, I noticed the u-joint caps on my front
driveshaft were spinning in the yokes. Now that's not a good sign. It means
the caps are not being held very tight, and looseness means something is
worn, bent, getting ready to break when least expexted. I hate breaking
on the trail and sometimes go to great lengths to make sure my junk is
ready.
My first step was to pull the driveshaft and inspect the u-joints. They
were in excellent condition. That's pretty much what I expected, they have
very few miles on them and I'm a compulsive greaser - every zerk gets hit
before every trip. Then I replaced the straps/bolts with new Spicer parts.
A few weeks later I greased everything again and noticed the caps were
still spinning. I took the straps off and dinged them in the middle to
tighten them up. Of course this made it further between the holes so I
had to dremel the holes a little so the bolts would go through. Now
removing any material from the straps made me very uncomfortable --
they are weak little things anyway and weakening them more just seems
wrong. A few weeks later I was greasing it again and saw that the caps
were still spinning. That's when I decided something had to be done.
Here are some photo's of the caps and how they look when they have been
spinning. Notice the shiny ring.
Now I knew it was no big deal to change the front diff yoke to a u-bolt style,
but what was the point of that if the t-case end was still straps. After all,
it sort of looked like the t-case end was spinnging the worst. I could even
see and feel the looseness on that end. I decided to take some angle measurements
on each end just to see what they were. It's a lot, at least at full droop where
I checked it at. My measurements should be worst case since the axle cannot drop
any further. The pinion joint angle is 17 degrees, and the t-case joint angle was 22
degrees. That's really too much since 10 degrees is a good max to try for. Not a lot
I can do about it though - unless I take out some lift and the shackle reversal.....
since nothing has really broke yet I don't think I need to do that. Here's an angle
picture to show you what this looks like.
I did some research and found some rumors that the same yoke that fits the D30
diff would also work for the NP 231 t-case - but nothing definate. I decided to
order some parts and find out.
Parts list:
2 - Spicer 2-94-28X, or 29428X, u-bolt kits
2 - Spicer 248091X Yoke - fits D30, D44, AMC 20, D35, and Dana 300 t-case front and rear.
If you have a salvage yard handy the parts should be pretty easy to find.
Once the parts came in I started by pulling the front diff cover to drain the fluid. That's
when I found the ARB had broke again.... so the driveshaft mod turned into a lot more.
Here's some pics of the mangled mess and the new parts:
I've already posted info on that in other threads, so I'll move on to the driveshaft job.
Next was removing the old yokes and measureing them to be sure they were close
in size. To remove pinion nuts and output shaft nuts, you should have a handy little
tool that bolts to the yoke - I don't have one. So I moved to this high - tech alternative:
The yokes come off pretty easy after the nut is removed, I did have to use a small
puller on the pinion yoke - you can tap them off if you are careful. After the yokes
were off I took measurements of the old and new yokes - here's how:
The pinion yoke was a good match, but the t-case was some different.
Old OD: 1.553"
New OD: 1.551"
Old ID: 1.140"
New ID: 1.143"
Old spline length: 1.500"
New spline length: 1.544"
Spline count on both: 27
Those measurements are pretty much the same, but the yokes are made different.
The distance from the end of the yoke to the center of the u-joint cap is a lot different.
That means the output shaft will stick out into the joint area more. A side view shows the
Difference:
The only way to know if this matters is to put it together. Once assembled and the
driveshaft installed, I turned it by hand and the output shaft was hitting the cross on the u-joint.
To cure this I took the driveshaft back out and removed some material from the output
shaft where it was hitting. I used a flap wheel in a die grinder - it leaves a very smooth
finish and no burrs so the nut should still go on and off fine.
That cured the contact problem and I completed assembling the project.
Since doing this install I've put about 600 miles of off road use on the driveshaft.
I've also done 400 or more on road but they do not count since my front shaft does
not turn in 2WD. No leaks, no funny noises or vibrations, and most importantly,
my u-joint caps don't spin.
I used all new parts for this and spent about $100. If you use salvage yard parts,
it should be around $20. Because of the difference in yoke design, the driveshaft
will need to be about 1" longer. I have a very long slip joint so this was no problem
on my Jeep - you might check yours though to make sure this will not result in the
driveshaft falling in two. I also found that the shorter yoke on the t-case brings the
driveshaft much closer to the skid plate front edge. It's not hitting, but it's definately
closer.
While doing some routine greasing, I noticed the u-joint caps on my front
driveshaft were spinning in the yokes. Now that's not a good sign. It means
the caps are not being held very tight, and looseness means something is
worn, bent, getting ready to break when least expexted. I hate breaking
on the trail and sometimes go to great lengths to make sure my junk is
ready.
My first step was to pull the driveshaft and inspect the u-joints. They
were in excellent condition. That's pretty much what I expected, they have
very few miles on them and I'm a compulsive greaser - every zerk gets hit
before every trip. Then I replaced the straps/bolts with new Spicer parts.
A few weeks later I greased everything again and noticed the caps were
still spinning. I took the straps off and dinged them in the middle to
tighten them up. Of course this made it further between the holes so I
had to dremel the holes a little so the bolts would go through. Now
removing any material from the straps made me very uncomfortable --
they are weak little things anyway and weakening them more just seems
wrong. A few weeks later I was greasing it again and saw that the caps
were still spinning. That's when I decided something had to be done.
Here are some photo's of the caps and how they look when they have been
spinning. Notice the shiny ring.
Now I knew it was no big deal to change the front diff yoke to a u-bolt style,
but what was the point of that if the t-case end was still straps. After all,
it sort of looked like the t-case end was spinnging the worst. I could even
see and feel the looseness on that end. I decided to take some angle measurements
on each end just to see what they were. It's a lot, at least at full droop where
I checked it at. My measurements should be worst case since the axle cannot drop
any further. The pinion joint angle is 17 degrees, and the t-case joint angle was 22
degrees. That's really too much since 10 degrees is a good max to try for. Not a lot
I can do about it though - unless I take out some lift and the shackle reversal.....
since nothing has really broke yet I don't think I need to do that. Here's an angle
picture to show you what this looks like.
I did some research and found some rumors that the same yoke that fits the D30
diff would also work for the NP 231 t-case - but nothing definate. I decided to
order some parts and find out.
Parts list:
2 - Spicer 2-94-28X, or 29428X, u-bolt kits
2 - Spicer 248091X Yoke - fits D30, D44, AMC 20, D35, and Dana 300 t-case front and rear.
If you have a salvage yard handy the parts should be pretty easy to find.
Once the parts came in I started by pulling the front diff cover to drain the fluid. That's
when I found the ARB had broke again.... so the driveshaft mod turned into a lot more.
Here's some pics of the mangled mess and the new parts:
I've already posted info on that in other threads, so I'll move on to the driveshaft job.
Next was removing the old yokes and measureing them to be sure they were close
in size. To remove pinion nuts and output shaft nuts, you should have a handy little
tool that bolts to the yoke - I don't have one. So I moved to this high - tech alternative:
The yokes come off pretty easy after the nut is removed, I did have to use a small
puller on the pinion yoke - you can tap them off if you are careful. After the yokes
were off I took measurements of the old and new yokes - here's how:
The pinion yoke was a good match, but the t-case was some different.
Old OD: 1.553"
New OD: 1.551"
Old ID: 1.140"
New ID: 1.143"
Old spline length: 1.500"
New spline length: 1.544"
Spline count on both: 27
Those measurements are pretty much the same, but the yokes are made different.
The distance from the end of the yoke to the center of the u-joint cap is a lot different.
That means the output shaft will stick out into the joint area more. A side view shows the
Difference:
The only way to know if this matters is to put it together. Once assembled and the
driveshaft installed, I turned it by hand and the output shaft was hitting the cross on the u-joint.
To cure this I took the driveshaft back out and removed some material from the output
shaft where it was hitting. I used a flap wheel in a die grinder - it leaves a very smooth
finish and no burrs so the nut should still go on and off fine.
That cured the contact problem and I completed assembling the project.
Since doing this install I've put about 600 miles of off road use on the driveshaft.
I've also done 400 or more on road but they do not count since my front shaft does
not turn in 2WD. No leaks, no funny noises or vibrations, and most importantly,
my u-joint caps don't spin.
I used all new parts for this and spent about $100. If you use salvage yard parts,
it should be around $20. Because of the difference in yoke design, the driveshaft
will need to be about 1" longer. I have a very long slip joint so this was no problem
on my Jeep - you might check yours though to make sure this will not result in the
driveshaft falling in two. I also found that the shorter yoke on the t-case brings the
driveshaft much closer to the skid plate front edge. It's not hitting, but it's definately
closer.
. We need a how-to or a quick-reference repair guide for the website with your write ups and others like it - really.
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