onespeedbiker

I inherited some Specialized loose ball mtb hubs a while back and decided to deal with them today; I was told the axles were not spinning freely. Indeed, although smooth, it felt like the axles were dragging on something. I took apart the hubs and it looked like the hubs had recently been rebuilt with Shimano day-glo green grease. The problem was it had turned into what appeared to be a non-hardening glue. The viscosity was well beyond what is optimal and it adhered to everything; it also looked like the chrome was pealing of the ball bearings on one side, so I replaced the bearings (the front was also missing a bearing). After I repacked the bearings with Phil Wood grease the axles spun like they were new. So I'm wondering what happened here?

wroomwroomoops

What makes grease turn into glue? Peroxidation, i. e. oxidative rancidification via the free radical pathway.
Silicone oil/grease is impervious to oxidative rancidification, organic (carbon-based) lubricants, however, aren't.

EDIT: I shall add that peroxidation is promoted by increased temperature and the presence of a catalyst.

I had a spray bottle of some fine chain lubricant (similar to what SRAM uses on their chains) that had become useless due to peroxidation during storage at the importer's warehouse - it has become very sticky and wouldn't lubricate. Simply put, the conditions in that spray bottle were favorable to peroxidation. The lubricant by itself (applied to the chain) is supposedly extremely stable.

robo

I hate that stuff. It does separate into day-glo green oil and goo, and stains paint to boot.

The ends of the head-tube, top of the seat-tube, and area around the BB on my frame are all stained this weird yellow-green color becuase I used Shimano grease when installing the parts.

This has made me very suspicious of brightly colored greases and lubes.

HillRider

The simple answer is separation and/or evaporation-oxidation of the oil part of the grease (grease is oil thickened with a soap-like compound). I've seen the same phenomenon with an old (1986) Bridgestone that sat unused for over 10 years. When I disassembled the hub, bottom bracket and headset, the OEM "grease" had turned into something resembling dried rubber cement.

I've never used Shimano's house brand grease except I presume that's what they use in their new hubs and they have been fine as received except for refining the bearing clearances. I wonder if the hubs you have problems with weren't actually rebuilt by the previous owner but he just added additional grease to what ever brand was already there. There are greases that work fine by themselves but are incompatible when mixed with others.

cbuddy2005

neglect

Flying Merkel

Time.

Grease needs to be cleaned out & replaced every few years, more if it's white grease. I have no experience with green glop. I have used Moly-D hi temp automotive grease for years. It lasts a long time.

onespeedbiker

This is what I thought. I should have added that the story was the hubs were recently rebuilt before they stated to gum up.

wroomwroomoops

Well, that changes everything. You'll have to repack the hubs yourself - and clean them properly before you add the new grease.

speedy25

Interesting thread. I had not thought of peroxidation but offer my explanation that solvents within the product eventually evaporate and leave a solid.

So far any of the greases I have used have solidified on anything I have worked on. It sounds like the Shimano oils are not very long term stable. Has anyone found any others that are similar? The only bicycle specific lube I have is a tube of Park grease and so far its OK, but I dont have any aged results yet.

-SP

onespeedbiker

That goes without saying; cleaned out the glo green and replaced with Phil Woods green