Synthetic Gear Oil and Bearing Races

Joined
Jan 31, 2004
Messages
166
Location
Santa Margarita California
So I am doing some transmission work on my 1950 Farmall Cub. One of my coworkers, I work at a Diesel repair shop, informed me that on his 07 Harley Davidson he switched from the stock gear lube to a full synthetic gear lube. He told me that he came home from work one day and found a big leak coming out of his pinion seal. He took it apart and he found that the ball bearings races had come apart and all the balls were in the bottom of the transmission. So can a full synthetic gear oil cause bearing failure? It just does not make sense. The coworker explained that this happened because the oil was to slick and instead of the balls rolling they just slid in the bearing? So I am just curious is this fact. I am replacing all the bearings in my 50' farmall and wanting to fill it with a good synthetic. I know it is overkill being that the transmission is a three speed and a sliding gear type, but I am curious.
 
Joined
Dec 19, 2004
Messages
7,430
Location
beaver land EH?
 Originally Posted By: John With Beastly 302
So I am doing some transmission work on my 1950 Farmall Cub. One of my coworkers, I work at a Diesel repair shop, informed me that on his 07 Harley Davidson he switched from the stock gear lube to a full synthetic gear lube. He told me that he came home from work one day and found a big leak coming out of his pinion seal. He took it apart and he found that the ball bearings races had come apart and all the balls were in the bottom of the transmission. So can a full synthetic gear oil cause bearing failure? It just does not make sense. The coworker explained that this happened because the oil was to slick and instead of the balls rolling they just slid in the bearing? So I am just curious is this fact. I am replacing all the bearings in my 50' farmall and wanting to fill it with a good synthetic. I know it is overkill being that the transmission is a three speed and a sliding gear type, but I am curious.
Think logically for a second bud: ball bearings and bearing races are one of the hardest metal (intentionally hardened that way to do the job) around. It's just coincidental that he suffered from oil leaks in his hog and then the balls fall off of the race. While seal leaks may or may not be an issue when dealing with syn switch over, I would be seriously cautious when associating a bearing (balls falling off the race) with the switching to syn. Q. p.s. tell your coworker he's full of it and also pass on a bearing ball/roller/bearing race and a 16oz hamma and ask him to pound on it and see what happens.
 
Last edited:

John With Beastly 302

Thread starter
Joined
Jan 31, 2004
Messages
166
Location
Santa Margarita California
I know I thought he had to be pilling my leg, and I truly think he is. His only proof is that he says that he has heard about this problem on the internet. So who knows were he is getting his information and whether or not it is true.
 

Kestas

Staff member
Joined
Jun 4, 2002
Messages
14,047
Location
The Motor City
A bearing will NOT come apart because synthetic lube was used. Though there is such a phenomenon called "skidding damage" on bearings, it does not immediately result in bearings falling apart. Skidding damage is typically reserved for applications where there is high acceleration and low loading, such as some air tools. I would tend to think operator error is involved somewhere. Given the arrogant attitude that is pervasive among Harley owners, coupled with a glib tongue, I's say your coworker came up with a good fairy tale.
 
Joined
Dec 19, 2004
Messages
7,430
Location
beaver land EH?
 Originally Posted By: Kestas
Given the arrogant attitude that is pervasive among Harley owners, coupled with a glib tongue, I's say your coworker came up with a good fairy tale.
LOL! Hog owners tend to have a lot of fairytales. Afterall: wouldn't that be in their blood if not in their culture? IMHO Kesta is right on the money RE: skidding damage but otherwise, bearing doesn't simply fall off the race...period. ***Another hog myth busted!!!*** Q.
 
Last edited:
Joined
Sep 5, 2006
Messages
19,479
Location
Chicago Area
It's odd that he noticed no noises or decrease in function [actually this is typical harley rider mentality] but only was aware of a problem after he saw a leak.
 
Joined
May 5, 2008
Messages
446
Location
York, PA
 Originally Posted By: mechtech2
It's odd that he noticed no noises or decrease in function ....
How could you possibly notice a noise on a Harley?
 
Top