Remove main pivot bolt to release rear triangle

larkim

Chainstay has snapped and a new part is on the way.

But I'm struggling to pull the main bolt from near to the bottom bracket. Partly because the stay has snapped so it doesn't have the same strength, but mainly because I've got to pull a large bolt through some internal bearings which appear to have something of an interference fit.

Having us unscrewed the bolt so that it has moved outwards a little, it seems that now I just need to brute force the bolt of of its place. But a) I've no specialist tools (do I need one?) and b) no prior experience!

It's a hollow bolt so I'm not super confident of drifting it out with a Allen key or similar, but if that's the best solution I will give it a go.

Some photos of what I'm taking about.

mully79

If your going to hit it out, try and find a drift thats softer than the axle. Copper pipe, wooden dowel etc.
Failing that, find a washer etc thats slightly smaller than the axle to spread the load evenly if you end up hitting it with something hard like an allen key.

larkim

Brute force won in the end. Thanks for the tips, a softer drift worked well. But I did force the outer bearing apart so...

Next challenge - how to remove the pivot bearing. It's a bit like an HT bottom bracket - a bearing pressed in on either side of the frame and a spacer tube down the middle. I've got a homemade press, but can't see how I could use that to pull the bearings out. I could pull them into the frame, but obviously don't want that, I need to get something on the inside to push out and that doesn't seem feasible.

mully79

Have you got any kind of edge behind the bearing or is it perfectly sized to the spacer ?

larkim

The spacer is a bit loose, so maybe I can get the edge of a flat screwdriver in there. A job for tomorrow I think.

mully79

Ive used shield anchor bolts instead of a blind bearing puller but it can be hit and miss.
Hitting with screw driver is last resort as it needs to come out perfectly straight otherwise it may ovalise the hole.

larkim

Light tapping around the bearing with a screwdriver or similar might be the only option. Not had a go just yet, but with the internals being bearing - spacer - bearing I can't even see how a blind puller would be able to remove the knackered bearing as it won't have much to purchase on. The spacer can drop to the side a little, but as the spacer is the same diameter as the internal of the bearing, exposing one side of the bearing hides away the other, and if the spacer is centred then there's no edge to grip at all.

Maybe an expanding bolt could work, but I'm not sure how I'd get the necessary force to pull away from the frame.

The frame is pretty robust at that point so it wouldn't be too sensitive to ovalling, but I've not yet got the replacement stay or bearing so there's no immediate rush to get it sorted today.

larkim

Bearing has disintegrated, so the 14mm expanding bolt to fit the 14mm internal diameter of the bearing to allow it to he pulled, so now I've just got the outer race to press out. I'm going to need a bigger boat*....

*bolt

larkim

Final update on this - erred on the side of caution and avoided the screwdriver solution, so bought a cheap bearing puller from https://www.bearingprotools.com/collections/bearing-pullers-single/products/bearing-puller who were very helpful in determining the right size etc.

One side came out without too much hammering, the other side needed a heavier hammer and a bit more aggression, but in the end they both slid out straight so shouldn't have caused any damage.

Refitting the new bearings was simple too with a properly sized puller from the same supplier with some copperslip in the bearing seats so all back up and running. The only negative was that I forgot to put back in the hollow spacer which sat around the pivot bolt and presumably provides some resistance against compression forces. In two minds as to whether to bother extracting the new bearing on one side and reinserting as I'm not sure if that will damage the brand new bearing or how important the spacer actually is.

Might have to give that a go though as I don't like the idea of having a part spare!

mully79

Nothing better than the right tool for the job other than a big garage to store them all in !
i would fit the spacer, it will help keep bearing forces even and in the correct plane.

larkim

Yeah, think you're right. Probably easiest to remove when the copperslip is fresh too. Ordered a spare bearing in case I damage one on removal to fit the spacer.