Shimano Roller Brakes - What grease and how much?

[Mysticyclist]

Hi Bicycletutor People,

My machine has Shimano roller brakes front and rear. I think they are due for some grease as the bike is now a year old and the rear is making occasional scraping sounds. There is a grease port, but before going ahead I wanted to check what would be the best kind of grease to use and how much to put in.

Thanks for helping.

[Bill]

Out of curiosity is this what you have? http://www.sheldonbrown.com/nexus-mech.html .

---

Sorry, let me post this, may not be EXACTLY it but something like it.....

[Mysticyclist]

(06-12-2010, 08:26 AM)Bill Wrote:  Out of curiosity is this what you have? http://www.sheldonbrown.com/nexus-mech.html .

---

Sorry, let me post this, may not be EXACTLY it but something like it.....

Hi Bill,
Thanks for responding. The picture you have included looks like a hub (or coaster) brake to me. My brake is like the one in Sheldon's picture except it is on the side of a Nexus 7-speed hub.

[xerxes]

Shimano sell a specific grease for roller brakes: http://www.jensonusa.com/store/product/CM407B02-Shimano+Roller+Brake+Grease.aspx?sc=FRGLUK&cc=USD

[Mysticyclist]

Thanks Xerxes.

I will see if the local bike shop can order some in, otherwise will get it from Jenson in the US as per your link.

Do you know how much grease to put in?

[xerxes]

Quote:Do you know how much grease to put in?

Sorry, no, I don't know much about roller brakes, but try here:http://www.sheldonbrown.com/nexus-mech.html

And check out Shimano's tech docs: http://techdocs.shimano.com/techdocs/index.jsp

You might want to shop around too, Jenson was just the first place that popped up when I googled.

[Mysticyclist]

Hi Xerxes,

Thanks again for replying.

I went through a lot of the Shimano tech-docs for different models of roller brake and it seems they have nothing to say except for the part number of the grease.

As Shimano are listing a 10mL tube as well as the 100mL bottle you located, I am wondering if this might be intended as the single "dose" amount.

Sheldon had this to say:
"The brake is lubricated without any disassembly--there's a small rubber access plug on the side of the brake unit, just pop off the plug, put the nozzle of the grease tube up against it, and squeeze." - which I think is the clue, the 10mL tube would probably be for squeezing rather than the bottle.

I'll give this a go at any rate and let you know what happens. It seems these brakes are a bit of a mystery, and no wonder as Shimano do not supply an exploded view diagram and in the tech-docs strongly recommend never attempting to disassemble one.

[Bill]

You will notice the plastic piece shown in this picture. Your hub should have the same kind somewhere within the middle or the side of the hub. Really easy to flip open. I just put lube in one 2days ago. I only used 5 drops.

[Steveroot]

I have one on a folding commuter bike. I give the hub a good healthy squirt a couple times a year. The brake, if properly installed, is quite well-sealed so the grease shouldn't go anywhere very fast.
Steve

[Mysticyclist]

Hi All,

Since my original post I have found some good information about lubricating the Shimano roller brakes.

1. Definitely use the roller brake grease available from Shimano (although it is fairly expensive), this is a demanding application due to the heat and forces generated within the brake and the lubricant is very high quality - it is a molybdenum disulphide based grease, and to me looked denser than what one usually finds say in automotive moly greases. Also it is lower viscosity so the brake will not drag and the grease can get into the braking surfaces more readily.

2. Very important to follow the instructions that come with the grease - main point is to insert the grease tube nozzle at least 12mm into the hole otherwise the grease will not reach the actual braking surface. If you look carefully you can see the cooling disc move a little when the nozzle is in far enough as it will push against it; come back just slightly from this position so the grease flows easily.

3. Shimano said you cannot really over do the grease as the excess will simply squeeze out and collect under the side cover. I was fortunate enough to be able to get an old brake and dismantle it - it looked to me like a rounded teaspoon or so of grease (say 10+mL) would be fine and my brake went well with this. Remember to rotate the wheel a bit while putting in the grease so it distributes evenly around inside the brake. Note that Shimano forbid dismantling of these brakes, and having done so with the old one I would say there is very little reason to anyway, and parts cannot be bought individually for repairs - still it was very interesting to see how it actually worked. The rollers (6) are not actually the brake, but push out three metal crescents that bind against the braking "drum" that is bonded to the centre of the cooling disc.

4. I put the grease into a plastic syringe so it was easier to see how much was going in - the grease comes in a black plastic 125mL squeeze tube. The syringe will probably need to be extended with a bit of thin plastic tubing on the end.

5. If the brake still scrapes a bit after greasing don't worry - the grease may take a little use to get fully into the right places. Heat from using the brake will encourage the grease to flow to where it is needed.

6. Some of you (like me) might be "lucky" enough to find the grease port on the rear wheel is behind the dropout. If you want to avoid taking the wheel out to gain access, try a short length of thin plastic tubing on the end of a syringe. This is fiddly and you still need to work the end of the tube in 12+ mm (be careful the end of the tube goes in straight - check it by seeing if the cooling disc moves a little; the tube can easily skew off at an angle once through the outer cover and no grease will reach the brake proper) but it can save a lot of work if the wheel is a pain to remove (mine has full chain case and hub gears).

Hope this is helpful. I will try to get together some photos of the dismantled brake to post, as it is not the kind of thing seen very often and I found even good bike shop mechanics did not know anything much about roller brakes.