Trek rail bearing replacement

AndyS2

Member
Jul 31, 2023
11
5
sheffield
How long a lifespan are people getting out of the main pivot bearings, the 3803's?

I replaced mine with a kit from Trek, as seen in post #18 above, and after 600miles and 8 months, both bearings are full of grit, seized and rusty. They were packed with Mobil XHP222 grease and the bike gets washed after each ride.

I can see I'm going to have to strip, clean and re-grease a lot more often!
 

Weeksy

Well-known member
Subscriber
Dec 13, 2019
646
714
Newbury(ish)
It varies, we've tried all different 3803's although it's in a Session 9 race bike. It's still the same bearings. Don't be fooled into thinking the Enduro ones will last any longer as in our experience for this application they seem not to. The Session has 2 sets, one main bearing, one rocker linkage and both take a hammering. The inside of the sleeve gets proper dirty too and i often wonder if it's dirt running in through the seatpost, but i 've not proven/tested that.
You'd think being double thickness the 3803s would last longer, but for us, they really don't.

I don't know if it's exactly the same on the rail but the Session has a bolt that's 30Nm at the main pivot and i've also noticed that sometimes even with Locktite that still either comes loose, or needs undoing and re-torqueing. Onlt last week i noticed a little play there, but it wasn't that long since i'd done them. So i removed bolt, cleaned it up and torqued it and it was again sweet.
 

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