Looking at a frame that uses a trunnion shock.
Not looked at this type of mount in any detail, but want to check how the hardware fits.
Quick googling suggests some trunnions are through axle type, but most are direct bolt in.
I gather these just mount using a threaded bolt each side. Is there a bush on each bolt for the shock to slide against and to protect the frame mounts? It's not obvious just by looking at them from afar.
TIA
Depends on the frame, they tend to have bushes top and bottom, and the manufacturer should give you the info, i.e. 22x8 bottom and the spacers for the top, i've not seen a bolt through trunnion though, always two threaded holes at the top (which is the standard), trunnion is a specific size, 54mm, but manufacturers use the spacers to make sure the mount doesn't go directly onto the bearings.
Banshee use a bearing in the linkage which the trunnion bolts go through into the shock.
Yeah, there's usually an the bolt which goes through the outer bearing cap (sometimes incorporated into the bolt head), through the bearing and then through a small spacer into the trunnion, it's an M10x1.0 bolt, so as before, never seen a through bolt as all trunnions should be threaded.
Ah, so there should be a bearing in the frame/linkage?
It's a Scott spark type setup, with the shock mounted upside down, trunnion into the frame. Would make sense if there was a bearing in it, but I didn't think they did.
What's the frame
I'm in a similar position, awaiting a frame with a trunnion. Not used one before. As far as I'm aware the upside down shock position (like a Scott spark) the trunnion end doesn't rotate much if at all. So I'm thinking there won't be bearings and it'll just be a bolt to the frame job?
So I’m thinking there won’t be bearings and it’ll just be a bolt to the frame job?
Found out that the one I'm looking at has small bearings pressed into the trunnion mount.
If you think about the job the bolts will do, small movement, but every compression, in dirt. loaded directly on the frame it wouldn't take long for the holes to wear, hence my concern to start.
Spark/genius/Ransom use an igus bushing with a metal sleeve. Bolt goes through and preload the sleeve against the trunion mounts.
As it's "upside down" compared to most others, there is very little rotation here as such bearings would be pointless.
I actually just replaced the trunion bushes for the first time on a 2017 spark plus thats on its 3rd owner and has been ridden plenty in all conditions.