1992 Rocky Mountain Experience - UPDATE.. AVID Arch SUPREME

[shutter]

Hi, thanks! My bearings are notchy... that may be part of the problem... I'm going to start by flicking the cover off the bearing... you can use the tip of a knife blade to remove the cover on a sealed bearing (it's just plastic) to get inside... I suspect there is some gunk packed in there.. after a good blast with brake cleaner and a re-pack with bearing grease I should be able to snap the cover back on and then they should be more smooth... I did it with the bearings in one of my race face headsets and it worked perfectly... I'll start by blasting it with 3M penetrating oil as a temporary check to see if that helps... then I'll grease the bearings...

But I suspect that it has something to do with the spring itself....

That big horseshoe spring is what spreads the arms apart... IF that spring is bent the wrong way the arms will not spring out, that's the issue I'm having on the front... I think the horseshoe spring thing needs to be bent back into shape (just like is done with the spring itself on V-Brakes... I'm sure we have all done that to bring some life back into old V-Brakes... two quick bends and they are nice and springy again...

your thoughts?

thanks!

 

[syncrosfan]

I'm afraid the "notchyness" might come from brinelled races rather than dirt and gunk (especially since those bearings don't do a full revolution movement but rather a max 45 degrees back and forth under load). I just spent 50 bucks on 8 replacement bearings (688 2RS) but I got the fancy SKF ones with the extra hardened races, you can get those bearings pretty cheap too if you're willing to go Chinese (myself I use only SKF, pay more but they will last forever).
As far as the spring goes, why don't you take both springs out, from the rear brake and the front one, and just compare them to each other. If the front one is more compressed then it is definitely a spring issue. You could also replace the plastic spring stops with some custom made ones that have a bigger diameter at the notch (that would also slightly increase spring tension).

 

[shutter]

I'm afraid the "notchyness" might come from brinelled races rather than dirt and gunk (especially since those bearings don't do a full revolution movement but rather a max 45 degrees back and forth under load). I just spent 50 bucks on 8 replacement bearings (688 2RS) but I got the fancy SKF ones with the extra hardened races, you can get those bearings pretty cheap too if you're willing to go Chinese (myself I use only SKF, pay more but they will last forever).
As far as the spring goes, why don't you take both springs out, from the rear brake and the front one, and just compare them to each other. If the front one is more compressed then it is definitely a spring issue. You could also replace the plastic spring stops with some custom made ones that have a bigger diameter at the notch (that would also slightly increase spring tension).

Good call! I'll start by comparing front and rear springs... that will tell me right off the bat...

then I can try to cold set the front one to match the rear if they are different

If they do match then I'll play the bearing game =)

thanks!

 

[syncrosfan]

I swapped out the main pivot bearings yesterday. It's a little bit of work but now the bearings feel butter smooth (zero friction). The old bearings displayed quite a bit of rust on the inside of them (looked normal on the front side, but once I pressed them out there was some rust and muck on the inside). Oddly enough once I pressed them out, the old bearings seemed to turn fine which leads me to believe the "notchyness is due to them being over-torqued onto the canti-studs by some ham-fisted-twat (my arch nemesis on soo many VRC parts I bought over the years, get a torque wrench people!) in any case an easy remedy could be for you to carefully press out the old bearings, clean them and re-press them in carefully without putting too much pressure on the aluminum spacer that sits in between them (would make a world of difference). If you chose to do so let me know and I'll talk you through the steps (you defo need to unscrew the bearing holding cylinder from the arms though).

 

[shutter]

cool thx!! good to know =)

 

[Wild Hare]

"Ham fisted twat"..... I love it, too funny. I've added that to my vocabulary of insults. Thanks for that!

I've been an arch supreme fan since you cold buy them new. I had a set years ago and it was the first item I acquired now that I'm getting back into the hobby. I've crafted a makeshift bearing tool for now but should be getting one soon. When I do I'm going to try to have replicas machined. I'm also planning on having some springs made as well. While tearing down the brakes for rebuild a gave all of the aluminum a mirror polish... WOW what a difference! Highly recommend it. As for the bearings, I'm going to try some ceramics. Thanks for sharing a great build thread.