Final drive repair

Some here may know of Franks final drive leak I commented on in another thread here. Well, pulled him apart and repaired today. Wish all fixes were this easy.



The final ready for disassembly. Leak was thought to be at the seal around the ring gear, which is what the wheel hooks to via a splined connection anyone who's changed their own tires is familiar with. When I removed the wheel, the seal was dry and clean. What was leaking was the large o-ring that seals the ring housing to the final drive unit. Once all the nuts and the two bolts (frontal area) are removed, gently, evenly pry the assembly free. DON'T LET IT POP OUT AND FALL!!! Easy does it there Hercules. The lower of the two bolts came out very hard-I feared WC's Sumo guy had moved down the assembly line to final drive area, and fully expected to find the bolt threads liberally coated with aluminum. Thankfully, wasn't the case. Went back in just as hard, but accepted correct torque without complaint.



The ring gear assembly. The offending o-ring fits around the outside edge in a machined groove. Note the nice wear pattern on the ring gear teeth.



The final housing exposed. Note the washer sitting near center-this is a thrust washer that fits over the ring gear snout. Forget to re-install it and in it's original orientation, and you will become familiar with University Motors low low pricing and friendly customer service. Rather than cleaning out the quite spotless housing, I left it as is, everything was nice and clean already, and well lubed-better to leave it this way. Already removed was the gray plastic dust shield, be sure to re-install if you've taken it out-it just pops in and out, though only one way-be sure to orient it correctly. Just for giggles, I located and back-flushed with 3M 08880 brake clean, the only Rad-Approved® brake cleaner, the vent hole, which vents into the smaller area just above the small bearing housing (you can see the casting bulge leading up to it) All nice and clear.



The new o-ring and our friend Mr Mobil 1.



Coat the o-ring and the housing with a liberal dose of M1 grease for ease of assembly as well as o-ring protection upon installation. Don't forget to grease up the small seal on the other side of the drive, which is next to the roller bearing still in the housing.



When inserting the ring gear assembly back in, apply pressure evenly and gently until the housing settles in-you may likely need to turn the ring gear via the splines to allow mating with the pinion, necessary due to the helical design. No need to mark positions or anything-all the teeth are pals. Don't forget the thrust washer! Cross torque the nuts and the two bolts, nuts at 14 lbs, bolts to 29 lbs.



All back together. Note the job was done with the final drive in the bike-a real plus as the bike made for a nice steady platform, no need to remove unless pinion seal service is also required. The wheel is actually doing 35 mph in this pic, gotta love fast cameras. Since the ring gear is pressed into the bearing in the housing, and the shim pack is part of this, there is nothing to fear concerning re-setting the gear lash, so it's pretty easy to do. If the seal I originally suspected of leaking does indeed weep come hot weather and fast riding, I wouldn't hesitate to pull it all apart again and pop it out and replace. The o-ring and seal are about $12 outta U motors, hardly worth having a dealer do it, with all the crap and downtime associated with that tactic, warranty or no. I do have the YES, but it's for major crap only, tic-toc, should I ever need it. At 28 thou, Frank has been reliable as a stone, and but for the recall TPS, has yet to have some furriners fingers massaging his innards. He likes this, and has communicated to me my methods are fine by him......

Let's hear it for the Raaaad-man! :clapping:

A fine job, sir. Thanks for documenting it so thoroughly.

This write-up is definitely fit to print (albeit to file)

Stef

Most excellent rad!

Great pics, first I have seen of the final drive taken apart.

Cooool!

DAFFY SKOOTER G????? If so, tis accurate, be sure...... Oh, and thanks!

Nice write up, thx,

- Mark

Excellent Write Up!!!!!

This will come in handy for others.

Red,

Thanks for the very nice post...very enlightening. Great Job and glad to hear Frank is better now...have a super spring season.

This is great stuff. It helps us all. Thanks.

warsw said:

This is great stuff. It helps us all. Thanks.

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I had a flat rear tire at the 1000 mile mark on my '06. So, While apart, I pulled the shaft to discover very little grease on the splines. If nothing else I feel better that I looked. Thanks to those on the site who mentioned this in past posts. Thanks to the great pictures, also.

Nice documentation Rad.

Comsider the small possiblity that those two bolts might have had a loctite or sealant on them to prevent oil leaks which would make them come out hard. Not that the holes are tapped into a "wet" area but often a cast aluminum part like the final drive housing will have some porosity in the parent metal. Often the bits of porosity connect internally thru the casting. Often the drilled and tapped hole will intersect this porosity causing oil to seep into the bolt hole, around the bolt threads and out beside the shank of the bolt where it weeps under the head of the bolt to atmosphere. It's about a 1 % chance/probability of an oil leak but build enough final drive housings (like Yamaha does) and sooner or later a seeper will show up due to porosity. So.....it is pretty common in the industry to put a sealant or loctite/anearobic material on the bolts at assembly to guard against an oil leak. That would make them come out hard even though there is little or no evidence nor other apparent need for the sealant. The studs are probably sealed the same way but since they didn't need to come out no one notices.

If you do notice any seepage around one of the bolt heads just pull it and reinstall with a wicking grade of loctite. Chances are you'll never notice a problem due to the random and rare nature of this type of problem and, even if yours had a propensity to leak like this, the previous application of sealant probably sealed up the porosity when the bolt was installed at the factory.

No loctite. Top bolt came out easily, lower one seemed like it did have loctite, but nothing on it, nor in the hole. I really didn't see any reason for it to come out as hard as it did, and was just as tight going in, requiring a wrench after the first couple threads, and took a wrench getting it out, right down to the last couple threads. No evidence of cross threading, no evidence of bad threads. Could be that the ring gear housing (or the hole) was machined just a hair off, interfering with the smooth turning of the bolt, though I can't say I saw any evidence of galling on the ring gear hsg. :unknw:

Excellent write up and pics. Saved this to the FJR file already.

I can't help but wonder why that oring would leak. Being a static installation it should be good forever. Did you happen to notice an deformity or a cut on the original oring?

Great write up Rad....thanks for the information.... :good: ....

S76 said:

Excellent write up and pics. Saved this to the FJR file already.
I can't help but wonder why that oring would leak. Being a static installation it should be good forever. Did you happen to notice an deformity or a cut on the original oring?

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Its the stoppies. When this heavy a piece of machinery has the rear wheel return to earth, the hammering on the O-ring is bound to cause seepage.

:yahoo: Good write up, Radman. Thanks for being the one playing "FJR Discovery Channel".

WTF? It's still blue! :dntknw:

Nice write-up, though.

S76 said:

Excellent write up and pics. Saved this to the FJR file already.
I can't help but wonder why that oring would leak. Being a static installation it should be good forever. Did you happen to notice an deformity or a cut on the original oring?

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+1 Is there some way for wear to occur on the O-Ring? Was it brittle (maybe from heat)? Any clues at all as to the cause?

Excellent write-up, Radman !!

Printed out and in my book.

Good Stuff.

KD

Mucho Thanks.

After a careful inspection of the o-ring, the only fault I could find was erosion on the edge that contacted the final drive housing. Where the o-ring for the most part was smooth and shiny, the suspect area appeared like it had been sanded with 80 grit. This appeared in several areas on the ring, and was the result, I think, of a dry install at the factory. There were no flat spots, no tears, no peels, or twists that I could find. After a quick 25 mile run into work this AM, admittedly in cold weather (40 degrees), but at my usual get to work speeds (up to 95 mph), the wheel is dry. Time will tell, as will some speed when hot, when the rear got good and hot, and the leak was at it's worst. But so far, :thumbsup:

For those of you sitting on the edge of your seat, waiting to find out....did the repair work? Is Rads wheel clean? Did Mobil1 destroy the quality seal Mammy Yammi installed? Is Rad really Johnny Wa.....ahem. No leaks. In fact, the seal was probably bad all along, just never as obvious as it had become. Franks back wheel had always had a predilection for accumulating crud-as my first shaftie, I was not concerned as my chainers had always been much worse. Well, the back wheel is still spotless, much cleaner after several hundred miles than it ever has been, including when brand spanking new. I can only surmise the seal had been dribbling ever so lightly all along, the erosion I found may have been a defective o-ring, or a dry install had chewed it up enough to cause micro-tears, not unheard of in o-ring installs-hence warnings to always lube seals liberally when installing. I had thought there was another possibility-and so checked to see that yes, indeed, there was lube in there to leak out if it was gonna. No Beemer Burns for this clown. End of report.