Final drive bearings

[jmnjrpa]

I am in process of changing out my swingarm and doing the final drive mod. I wanted to powdercoat the final drive before installing. After pulling the gears out I found roller bearings for the shafts instead of ball bearings. My question is- are these bearings made of the same stuff (unobtainium) as the rear wheel bearing?? I sure don't want to mess with them if they are as there is a good chance of tearing them up getting them out. Anyone else gone there before? I really don't want to experience it myself. For those that don"t know, you have to remove bearings and seals (and anything else 400 degrees F will damage) before powder coating.

BTW- Have to change out the swing arm to continue to run the 140 tires I have. Ground out a spare (removed .04/.06) and have it powder coated and ready to install.

[crazy steve]

Why would you have to disassemble these? When I took mine apart for polishing, I simply unbolted the ring gear and pulled that out, then to get the pinion out I removed the countersunk screw in the mounting face and pulled the pinion as an assembly. The only thing left in the housing is the inner pinion support bearing and the heat won't hurt that (although I would thoroughly clean it so as not to bake any oil into it).

Now, the pinion did come out hard; I heated the housing to 200 degrees to reinstall it, and it slipped right in. If I had to do it over, I'd heat it to remove it also. The pinion seal should take that temp...

'78E original owner

[jmnjrpa]

No

400 degrees F is in the temper range for bearings (carbon steel). The seals and grease would ignite before then.
Most plastics and rubber are distroyed before reaching 400 F.
I found 2 roller bearings in the case and 1 on the rack.

[trbig]

Flash point for regular automotive oils is 420-480... usually more additives brings it even higher. Normal automotive GREASE is at least 480 degrees.

I can't tell you about the seal, but 400 degrees isn't going to hurt the grease or the bearings. Plus, the whole unit isn't going to get to that temp in the 15-20 minutes or so that it takes to cure the powder coat.


Tod

[trbig]

Well..

Reading further.. I have seen a couple of gear lubes with a flash point of 375. So.. not knowing what's in there, it's iffy and not worth a fire in your house. Though I still say the whole unit isn't going to get to that temp in that short time.. you may be erring on the side of safety, so disregard my last post.


Tod

[WMarshy]

Although I dont know exactly which seal you are talkin about or its relative location, my suggestion is talk with your powder coater and ask him what his oven is set at. I use to work on a powder coat line and our oven was sub 400 degrees... Still, 375 might be enough to break down a seal that had 30 yr oil bath. If his is set at 375 or higher I would be concerned for the seal as the temp can fluctuate some depending on his oven...

[jmnjrpa]

Yeah,

The powder I am using sets at 400/410 F.

Tod, being aluminum the whole thing will heat up fast. Grab one end of an aluminum rod and apply heat to the other end and you will be amazed at how fast the heat transfer is.

I think I may just rattle can it if I cant find the bearings cheap. Better safe than sorry. Would like to know if anyone else has crossed that bridge.

[tinman905]

I used a Dupli Color caliper paint on my final drive . It's held up nice .

[randy]

VHT caliper paint cures at 200 degrees for 20 minutes. I painted and baked my calipers with it. It's good stuff with a nice satin sheen. As close to powder coat as you can get out of a rattle can.

[jmnjrpa]

Good Idea

200 degrees can be tolerated. I have baked Rustoleum at 160 and had good results. Won't be as deep a black as I have in powder but a lot safer!

Thanks ALL!

[81xsproject]

So, if your worried about the grease burning, why not just spray the piss out of it with carb/brake cleaner to remove all the grease? If the bearing itself can handle the heat, it should be fine after that.

[jmnjrpa]

Rust

Not the kind that you use a wire brush on but enough to reduce the bearing life. Bearings are ground to a super fine finish. Within minutes of cleaning them you would develop enough rust to reduce a good bearing to 2nd rate. It won't destroy it immediately but its days are numbered.

[trbig]

VHT paint...

I used this stuff on some headers, then cooked them in an oven. The fumes were HORRIBLE. I used the aluminum colored ceramic highest temp they have (1800 degree?? Don't remember now) and it stunk to high heaven. I put them on the bike afterwards and rode 30+ miles to the inlaws with my family following in the car, and it gave them all a headache from the fumes following way behind me going down the road!

Duplicolor didn't have the same problem and offers just as high temp.

Tod

[jmnjrpa]

Wasn't looking for

a pi$$ing match so I did not refute some opinions but I have been in this industry for 40 years so if anyone would like they can absorb some of this.

Steel as in ball bearings, roller bearings, races, and hardened shafts are heat treated. This process involves heating the steel up to red hot and holding it there for a predetermined length of time (different alloys have different requirements in both heat and time). The next usual step is quenching which again is predetermined by alloy. Quenching (usually) involves a rapid cooling of the steel (in again a predetermined solution of water/oil/air). The process up till this point has been focused on getting the steel to maximum hardness (this is determined by a "C" scale Rockwell hardness tester). Problem with this is at the same time the steel is getting hard it also develops brittle tendencies so a third operation called tempering is employed. Once again we have the variable that the type of alloy determines temperature. In tempering the idea is to remove the brittleness while maintaining as much hardness as possible.

The following is a good reference.
http://www.anvilfire.com/FAQ-article...0anvilfire.com

Just for comparison let's analyze the top two lines for 1095 steel. Note from 100 degrees F to 420F we have lost 4 hardness points. Now, not everybody tempers bearings because of this issue. Some use cheaper grades of steel and maintain the quenched condition with the belief that bearings are usually not subject to impact, therefore the brittleness is not an issue.

All finish machining and grinding is performed after heat treat because of warpage and material stress issues.

Heat and/or age hardens most materials from plastic to aluminum but I will not cover that here.

Without the knowledge of material, tempering, and hardness testing the only safe HEAT is below 300F.

FYI - The best tempered carbon steel is 62/64 Rockwell "C" scale but it will be 66/67 before tempering.


As for the melting points of plastic the following chart is an excellent reference.
http://www.dynalabcorp.com/documents...Properties.pdf


Note: Of all the materials listed only 2 will not melt at 401F (205C).
So, unless you absolutely know exactly what material you are dealing with then heat can be disastrous.

Furthermore there is the posiblity of some plastics releasing toxic gases in an over heated condition.

I will not cover HEAT to oil/grease AS Tod noted previously that some grease and oils present may flame at lower temps than thought.

So please everyone, SAFETY FIRST!!

[jmnjrpa]

Tod

I have my oven in the shop with venting. You are right about the fumes as they will make your eyes cross. It is nice to know that duplicolor does not have the same issues.