Cummins pilot bearing failure

BIGWOODY

BIGWOODY

Well-Known Member
Joined
Mar 21, 2005
Location
Thomasville
I've got an '11 Cummins 6spd that likes to eat pilot bearings every 40-50k miles. I replaced the clutch years ago shortly after acquiring the truck. I put a single mass flywheel and Valero clutch. 40k miles or so and after a long highway drive, I got off the an exit and noticed I couldn't get the truck to go back into gear. After fooling with it a bit I got it I'm gear and going. I noticed weird noises and eventually a rattle that sounded like it was coming from the input shaft. I pulled the trans and noticed the pilot bearing was toast. I replaced it, noise gone problem corrected. 40-50k miles and again the same issue, pulled trans again, figured maybe I didn't get it installed just right so was extra careful on the next Install. Here we are 40-50k later and again I've got the same issue. What am I missing? I probably should be asking this to a Cummins forum, but I don't frequent any. My truck is mildly tuned, the clutch is in perfect condition , stays on the highway 95% of the time and I drive like an old man. When it failed the 2nd time I swapped in another 6spd I had that was a much lower milage trans (just because I had it laying around), apparently it made no difference. Any thoughts?
 
I'd recommend droping a line down on the TDR forums. A lot of knowledgeable people there to help you work through diagnosis on this.

What's the part number on the clutch kit/pilot bearing?

How many miles on the truck?

What's mildly tuned?
 
IDK anything about a Cummings but my first thoughts where something is making the input shaft tweak. Weather it's a worn input shaft bearing or a combination motor mount trans mount issue. Sounds like the input shaft is putting pressure on the pilot bearing causing it to wear or fail prematurely.
 
Does it use a needle bearing or a larger, sealed roller bearing?

Edit: Nevermind. I looked it up on RockAuto. They all use needle bearings and that's very likely the cause of all your problems. Buckle up, I went nerd mode šŸ˜…

Needle bearings (as a pilot) flat out suck ass. They don't seal worth a damn, sling the grease out which gets them dry quick, then spin super fast because they're tiny, and then fail. The bearing needles inside of it are probably something like .090" diameter? If that. They're hauling immense amounts of ass (surface speed wise) when in motion and trying to stay lined up. There's a lot going on in there.

Needle bearing: 1" OD, .75" ID, .6875" L

Roller bearing: 1.75" OD, .75" ID, .500" L

Since you already did the solid flywheel, you can have the center bore opened up and put in a normal, sealed roller bearing (PN 1635-2RS) and probably never have to worry about it again. You can also buy a flywheel with one already in it from Valair, if you'd rather go that route. 3rd and 4th from the bottom of the page.


SKF also makes a replacement pilot bearing that uses roller balls instead of needles. It'd probably last longer, but I'd just go straight for the bigger bearing, personally, and be done with it.

Screenshot_20221216_053707_Samsung Internet.jpg



I had issues with needle pilot bearings in my 99 Silverado. It ate 3 of them, then I used a bronze/oil lite bushing until I swapped in a short crank motor and that allowed me to use a big ol' roller bearing. Hasn't been a worry since. You can see here where the short crank motor allows use of the larger bearing. Before, with a .400" longer crank snout, I had to use a tiny needle bearing that was even further down in the bore of the crankshaft.

2013-04-21_17-19-50_658.jpg



Good news is, in your case, the pilot bearing is in the flywheel. Unfortunately, you do have to pull it apart again. It's a simple fix though.

You're not the only person that's had this problem, rest assured!

I also never, and I mean ever, sit anywhere with the pedal down if the truck isn't moving. Any time the clutch is disengaged and you're not moving, the pilot bearing is spinning around the input shaft. Stop and go traffic also sucks in that regard...and in every other one :D
 
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Croatan_Kid said:
Does it use a needle bearing or a larger, sealed roller bearing?

Edit: Nevermind. I looked it up on RockAuto. They all use needle bearings and that's very likely the cause of all your problems. Buckle up, I went nerd mode šŸ˜…

Needle bearings (as a pilot) flat out suck ass. They don't seal worth a damn, sling the grease out which gets them dry quick, then spin super fast because they're tiny, and then fail. The bearing needles inside of it are probably something like .090" diameter? If that. They're hauling immense amounts of ass (surface speed wise) when in motion and trying to stay lined up. There's a lot going on in there.

Needle bearing: 1" OD, .75" ID, .6875" L

Roller bearing: 1.75" OD, .75" ID, .500" L

Since you already did the solid flywheel, you can have the center bore opened up and put in a normal, sealed roller bearing (PN 1635-2RS) and probably never have to worry about it again. You can also buy a flywheel with one already in it from Valair, if you'd rather go that route. 3rd and 4th from the bottom of the page.


SKF also makes a replacement pilot bearing that uses roller balls instead of needles. It'd probably last longer, but I'd just go straight for the bigger bearing, personally, and be done with it.

View attachment 387381


I had issues with needle pilot bearings in my 99 Silverado. It ate 3 of them, then I used a bronze/oil lite bushing until I swapped in a short crank motor and that allowed me to use a big ol' roller bearing. Hasn't been a worry since. You can see here where the short crank motor allows use of the larger bearing. Before, with a .400" longer crank snout, I had to use a tiny needle bearing that was even further down in the bore of the crankshaft.

View attachment 387380


Good news is, in your case, the pilot bearing is in the flywheel. Unfortunately, you do have to pull it apart again. It's a simple fix though.

You're not the only person that's had this problem, rest assured!

I also never, and I mean ever, sit anywhere with the pedal down if the truck isn't moving. Any time the clutch is disengaged and you're not moving, the pilot bearing is spinning around the input shaft. Stop and go traffic also sucks in that regard...and in every other one :D
Click to expand...
I actually already ordered a larger diameter roller bearing and am going to machine the flywheel to accept. I too never sit with the clutch depressed, hell I never even downshift brake pads are cheaper and easier to replace than clutches. Thanks for confirming what I already felt was the issue. I can have the trans out in about an hour so not really a big deal to fix, just a head scratcher.
 
Chris_Keziah said:
Sounds like a case of the trans centerline and crank centerline are off set. Not sure how you check that on those but that'd be where I start.
Click to expand...
This is what I was thinking. The center bore hole of the flywheel might be just very slightly off.

Somewhere are the 200-220k mile mark (6-8 yrs ago), the pilot bearing in my 01 Ram came apart and it suddenly became almost impossible to shift. I limped it home from work and pulled it apart to find all the rollers in the pilot bearing MIA and the clutch disc in multiple pieces. Since I only drive my truck maybe 1,000-2,000 miles a year and it is stock, I just went back with a stock pilot bearing (packed with grease) and stock clutch.

I also NEVER sit with my foot on the clutch pedal depressed for the reason previously mentioned of the transmission input shaft spinning super fast inside that little bearing.

I would definitely go with the big bearing mod.
 
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