Troca de rolamentos Movimento Central Shimano

After the PCC 2007 ride my 4 year old Bottom Bracket felt very hard and rough. To be precise it felt like it was rubbing around/with dirt. So decided to replace the whole thing (what a great excuse) but when I hear the price I reconsidered. Googled it up on the net on how to change the bearings and decided I could do it myself. Although I was fully aware that non of the bike shops in KL manage to do it. One shop manage to remove it but could not put it back together, just like Humpty-Dumpty.

The the object is this, a 2004 Shimano XTR Bottom Bracket:

The outside of the bracket is a plastic cover. Thus removing it would be the 1st step.


Now take a small screwdriver and poke the plastic cover from the insides. Make sure to poke it gently and in different places. If yours is as old as mine the plastic cover starts to become brittle, thus it breaks easily if too much force is applied. In the picture I use an exacto-knife, just to illustrate.

This is what the plastic cover looks like.

Notice that there are dirt stuck to the plastic. Needs to be removed before putting it back in.


This is how it looks without the cover. Make sure there is a small thin rubber around the bearing. Or it could be stuck to the plastic cover. Mine got stuck on the plastic cover (top image) on one side and another was still around the bearing.


Take a screwdriver and place the tip on the outer steel rim of the rim. It would help if the screwdriver was the one piece steel type; both end are steel = 1 rod and the handle was a hard plastic molded to the end. Knock the screwdriver with a hammer to force the bearing out.

I had 2 empty steel UPS cases (from the office) which was place below the bearing and elevated the bearing. The cases were separated to a slightly bigger diameter of the bearing and only touch the bearing cover (mouth of the cover, not the bearing itself). This was done so that the bearing will pop out and land in between the 2 steel cases. One guy held the bearing cover and another hammer it out.

Once out, this is how it looks like:

The stock bearing that comes together is a HIC 6805 bearing made in Japan. 6805 refers to the part number. Interestingly this number also refers to a standard bearing size 37x25x7. So basically you can walk into your local bearing shop and ask for 6805. The people there will know what it is. Although each manufacturer can have different part number. SKF's part number is 61805. Alternatively you can ask any auto spare part shop for it and they'll order it for you.

I got mine frm SKF bearing in Klang, since I work in Shah Alam. Check the Yellow pages for other bearing stores or check out this place. If the shop is asking more than RM30 per bearing then thats too expensive, walk out and find another store.


I also bought Loctite 242 - Medium Strength (blue). Its a threadlocker to secure screws from rattling and is said to prevent water and rust. Its actually in liquid form but once its dry it hardens and bound the screw to the thread. You can wiki it to know more. Oh the Santa Cruz Syndicate team uses this stuff on their racing bikes.


To put the new bearing back in. Place the bearing holder on top of a piece of wood and place the old bearing on top of the new ones. Knock the old bearing gently and around the edges of the bearing, so that the new bearing goes inside evenly. In the picture the yellow screwdriver was used just as an indicator of where to knock.


Put the plastic cover back in and reattached the bearing cover back to the middle tube. I used Loctite to hold the bearing cover and the middle tube. I also put one layer of white piping tape on the thread.


I'm actually doing an experiment. I'm using white piping tape on one end and Loctite on the other. I just want to see which on is better at preventing dirt and water.

There you have. Doing it myself without spending a bomb on the parts... ahh priceless. The bearings only cost me RM 56 (RM 28 each) and one days work. So next time you have a bearing problem, don't buy a new just change it. If you still want to buy a new one then sell yours to me

Have fun doing it yourself.

Caso vc entre no site da SKF poderá ler  e observar que eles descrevem que cada ROLAMENTO PADRÃO pertence a uma determinada série, ou seja eles já estão afirmando nesta colocação que existem rolamento fora de padrão.