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Pilot Bearing Mistakes...

R

RAVC1

NAXJA Forum User
Location
Michigan
I am currently converting my 88 XJ Limited from the AW4 to an AX15. I have found a multitude of other issues during this project but, by far the largest faux pax was committed by myself earlier this evening.

So I ask myself, "What is it that can make an adult male beat a pilot bearing into its cavity on the rear of a crankshaft for 40 minutes with a 48 oz dead blow hammer and stacked sockets before he realizes that what he really needed to do was to place the pilot bearing in the freezer the night before to make the job much less effort?"

Better days lie ahead!

Rick

 
Um, yeah replace that pilot bearing. If you damage it, you'll find out later when it starts to whine and destroys the input bearing in the tranny. I neglected to replace it when I rebuilt the tranny, thinking the PO did the pilot bearing when he replaced the clutch. About 30k miles later, I had a torn up input shaft and bearing from the seized pilot.
 
Interesting point...

I do not think I damaged the pilot bearing; I was striking a 21 mm or 22 mm deep well socket backwards, such that the ratchet end of the socket was against the pilot bearing.

Late in the process, I switched to a larger socket also used backwards and the same 22 mm socket within it simply because it made it easier to strike the socket(s) and drive the pilot bearing in further without hitting my fore finger knuckle!

That said, you do make a very good point. I may pull it and replace it anyway.

Thanks,

Rick
 
Even without the freezer trick, I have never had a pilot bearing that hard to install. It would probably be in your best interest to take it out and make sure nothing else was wrong.
 
Just imagine if it was that difficult to get in how difficult it is going to be getting it back out...
 
I certainly made the call to locate one but no luck; I could not get one until Monday and that will not work.

Another oversight I may have made is I did not try to "clean" the pocket in the crank before installing it; meaning I think it would have been a good idea to polish the surface with a Dremel wire brush. I lubricated the crank pocket and the perimeter of the pilot with 10W-30.

As long as the input shaft of the AX15 still fits into it (which I think it should) I'll just plan to order one and replace it in 4 weeks or sooner. I have another NP242 I need to test so dropping the drive train is warranted.

I bet my crank shaft end play is real sweet!

Thanks for your comments; they have helped me think about this.

Rick
 
The original pilot bearing came out easily. Someone taught me the hydraulic method (i.e., fill the cavity behind the pilot with grease and find something to strike with a hammer that corresponds the the pilot ID. This method works well.) for removing pilots years ago.

The replacement pilot was also a NAPA B041. This is made with a SKF bearing; this is why I purchased it. This was in my freezer overnight before installation but it still took me close to ten minutes using my 32 oz dead blow hammer. Not a significant improvement in reduction of effort. I think I understand this.

Dino Savva's website summarizes pilot bearing choices when converting to a 5-speed, or using one, in combination with a stroked 4.0L. Find these comments here: http://www.jeep4.0performance.4mg.com/tech_specs.html

The early AX15 has the smaller pilot on the end of input shaft. The pilot bearings on the after market I am familiar with possess an OD=1.055." The larger pilot, later model year, AX15 transmissions use a pilot with an OD = 1.000." If you use a newer AX15 with a Renix vintage 4.0L you are recommended to use the later pilot bearing for the AX15 (recalling the NV3550 was used in 2000, 2001.).

I have no real knowledge about topics like "interference fits" but 0.0275" seems to be large relative to what I have heard regarding to this type of press fit. I did not measure the diameter of the pocket in my crank nor did I measure the OD of my B041.

I have used NAPA as a source for my pilot bearings/bushings for many vehicles/years. Presumably, the B041 is okay in this example too.

Thanks for your comments; they made me think.

Rick
 
I also decided to order two of the 33004041 pilot bearing/bushing from my local Chrysler dealer to better understand this issue.

I will post again sometime this weekend.

Rick
 
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