Marlin Crawler 25mm steering pin upgrade.

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Jun 25, 2021
Marana, AZ
Recommended when going to 37's?

I've never had a trunnion bearing fail...........yet since running 35's. I do have upgraded knuckle studs and I run KOYO or Nachi bearings. I also run hydro assist but I put a spacer in the ram to limit stroke just as the steering stops are reached.

I did see one trunnion bearing fail on an axle I setup on 35's. It was a Chinese bearing on my son's truck, he drives like a maniac and it still took a couple years to fail.

So far so good on my truck but I'm going to a heavier beadlock wheel and larger heavier tire.

I know the 8" diff and axles have their limits as well. I've upgraded everything else. I'm asking if the trunnion bearings and pin upgrade would be a worthwhile investment. If so I'm going to take advantage of the holiday sale.

Anybody eliminate their trunnion bearing failures by doing this upgrade?
i honestly don't see much benefit. imo failure of trunions is lack of maintenance or abuse.
technically it seems youre "upgrading" to a smaller bearing?
I also thought the bearing would be smaller. They end up with more rollers and Marlin says that they are stronger. The angle of the rollers are also different.

I'm no engineer so I am definitely no expert in the matter. Thanks for the reply gnob.
I was hoping for more replies. I guess I'll stick to my usual strategy and run what I have and upgrade if and when it fails.
A buddy of mine fell off a ledge and landed the stock bottom trunion on a rock. Smashed in the bearing pretty good. Otherwise I havent heard of a failure. Its possible due to the type of hit that Marlins bearing would have failed there also.

From a pure upgrade standpoint, I could get behind how the bearing would handle more load if the angle is changed as well as smaller and more pins to spread the load. Although I'm not sure it is a necessary upgrade.

If the preload is right and the caps are tight, I dont really see the stock trunion as a weak or failing point in normal circumstances of supporting the knuckle.

I recall reading something about only using Koyo or Nachi trunions due to them having a more laid back angle than a random off the shelf numbered bearing that fits. Might have even been on Marlins website I read that.
My buddy has these for sale. I think it seems like the most bullet proof upgrade as there is nothing to fail. Shameless plug below

Thats a pretty hardcore option. Dunno if I'd daily those. Robust, but not sure about how they'd wear, if you'd be chasing preload, if the steering wheel return to center would be stiff. You'd have to be one with the grease gun for sure.
One of my local wheeling buddies has them on his 85 Xtra Cab. He has had zero issues in many years. They need to be set up properly just like the bearings do. Get it too loose or too tight and you'll have issues.

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