Final Drive Seal - Viton or Regular?

[Groover]

My final drive seal failed after about 1000 miles. I used the better supposedly "Viton" brownish one. Oil started spewing all over the rear wheel after about 100 mile highway run two-up going about 70mph average. Parking using the side stand just collects oil on the rim too (after a ride). I checked the level, and it's not overfilled (maybe it was before the blow-out). The oil coming out looks normal w/moly.

Should I use the regular seal or try the Viton one again? I'll check the large bearing again, though last I checked it seemed ok. Why did this blow so soon? What should I look for?

Thanks in advance for any assistance.

[Antietam Classic Cycle]

I always use the brown Viton seal. Did you polish the surface on the hub the seal runs on? Might help to "burp" the rear drive any time you remove the fill or level plugs. Get it up to operating temperature, remove the fill plug and reinstall.

[Groover]

Great tips. I didn't do any of those. I'll go with the Viton seal again then, and do those things you mention (polish and burp).

Thanks again.

[TOMB]

It could be the inner seal that let go.
If you replaced the outer seal because of mileage the inner seal.had the same mileage to
TOMB

[Groover]

Is that on the inside of the bearing? I replaced the outer (large) seal because I had the wheel off and thought I should do that just to have a new one at that point. Ironically, I checked the final drive level oil right before this particular trip (since I don't normally go that far). I wonder if that's what messed with the pressure inside (based on the burping Charlie mentioned). All was fine before I checked the level, so now I'm suspicious... will I be able to polish the hub without opening the final drive (with just the wheel and seal off?)

[pete roper]

Check where the oil is coming from. If it's wet and oily inside the hub it's the inner seal.

This seems to be a fine example for the old maxim, "If it ain't broke? Don't fix it!"

[pehayes]

Could be the smaller inner seal.  Check out this thread:

http://wildguzzi.com/forum/index.php?topic=84899.0

Down the page has some nice pics of oil coming from the center of the hub which indicates inner seal leakage.

Could also be the transmission output shaft.  Oil leaking there will migrate down the shaft tube to overfill the rear drive.

Patrick Hayes
Fremont CA

[Groover]

Ok, thanks again for the replies. I know what to look for now to differentiate between inner and outer. I'll post results here once I get around to dealing with this. I did put a new seal on the transmission output shaft recently as well, and the fluid in the final drive housing wasn't overfilled when I checked (before and after) so I think that seal may be OK. I did use Valvoline grease with Moly on the shaft joints, knuckle and wheel splines, as well as Moly in the final drive. Could all that Moly contribute to eating up the seal(s)?

[pehayes]

Ok, thanks again for the replies. I know what to look for now to differentiate between inner and outer. I'll post results here once I get around to dealing with this. I did put a new seal on the transmission output shaft recently as well, and the fluid in the final drive housing wasn't overfilled when I checked (before and after) so I think that seal may be OK. I did use Valvoline grease with Moly on the shaft joints, knuckle and wheel splines, as well as Moly in the final drive. Could all that Moly contribute to eating up the seal(s)?

The 'not overfilled' condition on the rear drive may be misleading.  If the transmission leaks back to the rear drive, the excess leaks out.  So, you start out with a full rear drive and end up with a full rear drive.  You have described a leak, so it has to come from somewhere and that somewhere must now be lower on oil level.  You might wish to drain, measure, and reinstall the transmission fluid just to confirm that its volume has not changed.

Patrick Hayes
Fremont CA

[Groover]

Point taken - Everything is due for an oil change at this point, so this will be a good time to check all that with new measurements.

Thanks again.

[Groover]

Turns out my memory failed me (yet again..). I used the blue seal last time. Just getting into this today motivated by following some builds in the new builds section if this forum, plus it's finally nice out!




photo upload
 Safe to say this is the outer seal failure? I hope so, and I guess we'll find out soon!

[Antietam Classic Cycle]

Turns out my memory failed me (yet again..). I used the blue seal last time. Just getting into this today motivated by following some builds in the new builds section if this forum, plus it's finally nice out!




photo upload
 Safe to say this is the outer seal failure? I hope so, and I guess we'll find out soon!

Looks mostly like grease fling to me, not gear oil leaking. Clean off the excess grease and see if there's gear oil really leaking.

I've been using Wurth SIG 3000 Spline Grease specifically because it doesn't fling off like just about everything else I've tried.

[Groover]

just drained the oil, and gonna swap out this seal with the brown one. It was leaking pretty bad last I rode it, to where it was just unsafe (oil all over the tire). I don't have that greese you mention, going to dale around to see if the place near me has it. I may have been a little too generous with the greese last time, I'm sure that's not helping. I used valvoline dura blend.

[Antietam Classic Cycle]

just drained the oil, and gonna swap out this seal with the brown one. It was leaking pretty bad last I rode it, to where it was just unsafe (oil all over the tire). I don't have that greese you mention, going to dale around to see if the place near me has it. I may have been a little too generous with the greese last time, I'm sure that's not helping. I used valvoline dura blend.

I doubt you'll find SIG 3000 locally, I get mine from MG Cycle. Prior to that I used Permatex 5th wheel grease and that worked pretty well.
https://www.permatex.com/products/lubricants/specialty-lubricants/permatex-fifth-wheel-lubricant/

[pehayes]

Did you ever drain the transmission to check the volume in there?  I had repeated leaks from a 98EV rear drive.  Problem went away when I replaced the output shaft seal at the transmission.  Measuring the fluid volumes was the empirical evidence of oil transfer out of the transmission and down the tube to overfill the rear drive.

Patrick Hayes
Fremont CA

[Groover]

Thanks again. I called autozone by my house, and they don't have that either. I think I'm just gonna go with the valvoline stuff, just a little less this time. Got the new seal in, pushed it in a little more than the last time. I think the outer lip of the seal was barely on the gear last time. Pushed in about 1mm in deeper. Fingers crossed, all will be good cause I really don't want to replace the inner seal!

[Groover]

I might be replacing all few fluids tomorrow and get them right. I don't think it was overfilled though, but maybe. This is what came our from the final drive (I don't know how large the container is, maybe 8 oz.

[pehayes]

The rear drive will NOT appear overfilled.  The static level of oil at 250cc is just below the lip of the seal.  If extra oil gets in, it easily passes the seal lip and the result goes all over your tire while the tide level in the drive box remains at the lip level.  The empirical evidence comes from discovering the transmission oil BELOW normal level of 750cc.  DO NOT rely on any of the 'level' plugs on the side of the transmission or the rear of the rear drive box.  The only way to verify that is to drain and measure the transmission fluid volume.  Stop working in ounces.  Get a measuring pitcher with metric dimensions.  You can re-use what  you drain.  You can't measure now because you don't really know how much was put into the transmission.  You need to drain, measure, reinstall, and then add whatever is necessary to make the standard level in the transmission.  Then, ride it for some miles and re-drain and re-measure.  If you document 750cc put in then you should be able to measure 750cc when you drain and measure.  If that level or volume goes down it can only go two places.  Either it leaks to a puddle on the ground, or, via the output shaft seal it leaks through the driveshaft tunnel to the reardrive and thereafter leaks past the big seal to spray onto you wheel.  Now is the time to do it right before we get into the best of the riding season.

Patrick Hayes
Fremont CA

[Groover]

Thanks again for the replies and suggestions. I changed all the fluids using exact metric measuring, burped the final drive box, and there is still a leak. It hasn't dropped enough oil to be a detectable if I were to drain the gearbox oil at this point to check the level difference, so I'm keeping an eye on things externally for now. I did still have some wet grease in the drive that meshes with the wheel (I probably should have wiped it more), so 'maybe' and I'm hoping it's just left over that needs to spew out (doubt it), but that's my wishful thinking. Starting to think that it's the other (outer) seal in the final drive. I only had time to ride this around the block a few times this weekend, but this is what I see after a short ride. This happens after only a few miles basically.







Just wanted to give an update here and a thanks again for the help and suggestions provided. I'll keep this thread updated with the final solution and after I put a few more miles on the bike.

[pehayes]

I suggest that if your hub is still showing that much loss on a simple short ride, then you still have a leakage problem.  Usually, the spline grease does not become a fluid fling problem until it gets good and hot on a long ride so as to liquify the grease.  It is either a damaged seal surface, or a bad seal.  Since you have just changed the big seal, your symptoms are now pointing at the smaller inside seal or the output shaft seal at the transmission.

Patrick Hayes
Fremont CA

[Groover]

Were the "factory" large seals black in color from this era? Were those not good? (and are they even available, or were ever?)

I just picked up a used rear assembly that I'll be swapping this one out with. I'll keep and rebuild this one for a future project in the works. The "new one" has and "R" stamped on top by the input shaft (I don't have a photo showing that) - Anybody know what that may indicate?

Thanks again.

[rodekyll]

I had to look into this when I was choosing a front crank seal for the Breva project.  As I'm understanding it, there are two basic types of seal material, "viton" (which is a brand name) and its family, and the "buna" family.  There are a crapload of trade names and variants, so when you see a material referenced, try to find which family it belongs to.

The viton stuff does better at extreme hot temps and buna variants do better at extreme cold.  So unless you plan to run in the <+5f temp ranges, viton should be the choice.  Here's an excerpt from an article by a Mr. Anonymous Source, quoted only on the condition that his name not be used:

" . . . Viton and Buna seals have several very crucial differences that make them especially well suited to certain applications. While both Viton and Buna seals both serve as great sealing options at moderate temperatures, Viton is far superior to Buna for high temperature applications. Viton seals provide an indefinite seal for temperatures up to 400°F, and for temperatures up to 600°F they offer an excellent seal for more than 48 hours. Buna on the other hand is only effective up to 250°F. However, Buna seals provide a low temperature sealing option with effective sealing down to temperatures of –22°F, while temperatures below 5°F render Viton seals ineffective as they become quite hard and inflexible.

Along with temperature, other environmental conditions differentiate these two seals. An exceptionally broad range of chemical resistances make Viton seals a perfect option for most applications involving oils, fuels, and mineral acids, and these seals also boast excellent resistances to oxidation, ozone, UV exposure, weather, fungus, and mold. While also boasting some chemical resistances, Buna is much less universally resistant than its Viton counterpart suffering degradation from weather and ozone exposure. For most circumstances, however, this is not an issue, and Buna seals also offer the benefit of superior abrasion and tear resistance making them more suitable for more heavy duty industrial applications. . . . "

Ok -- I can't stand Anonymous Source.  He's often making stuff up.  The citation is:

http://www.humphrey-products.com/content/viton-vs-buna-which-seal-for-your-applications

There are a lot of articles out there saying the same thing.  This one is an easier read than most.

[Groover]

Great info! Thanks for posting that. I opted to go with the Viton ones again, and I also got the Viton for the outer (small) when I get into that rear drive box to rebuild it. Looks like it has a nice reinforcement pattern in the molding. The large brown also had some reinforcement webbing (tried to capture that in the photo comparing the two types), but not as drastic as the smaller one shown on MG cycle. https://goo.gl/0qR7mI

I'm pretty sure heat is what messed up the small seal on mine. It was a very hot day, two-up for about 200 mile round trip on the highway, and likely still the original seal from 1981.

[DAMMAG]

As a matter of interest what method did you use to replace the rear seal?

Did you tap it in or use some sort of method to pull it in?

Or did you remove the carrier that the seal is in, replace the seal and replace the carrier?

I had a heap of trouble replacing mine in situ and ended up using the last method.

[Groover]

As a matter of interest what method did you use to replace the rear seal?

Did you tap it in or use some sort of method to pull it in?

Or did you remove the carrier that the seal is in, replace the seal and replace the carrier?

I had a heap of trouble replacing mine in situ and ended up using the last method.

I used a sharpened small flat screwdriver to stab (with a hammer) the large blue seal about half way between the inner and outer part (where the metal plate ends inside the seal). Once that was stabbed in, then I pried the blue seal off using another small screwdriver laying on its side as the fulcrum, that was iffy, so I just ended up prying off the edge of the geared hub and be done with it. It popped off very easily (probably because it had only been in there for 2-years). As far as putting the new one in (the brown one) I tapped lightly round and round the edges back and forth trying to get it in a few mm deep at most and level, once secured enough where I didn't have to hold it, I used the old blue seal stacked on top of the brown as buffer while hitting that harder, still randomizing the pattern to keep it level while going in (think star-shaped pattern when tightening car wheel lugs). Not a lot of space between the swingarm legs, so a smaller hammer would be best (I used one laying on its side for most clearance)

That's how I typically remove seals that can be accesses externally. Sometimes they're not easy as that one to get good leverage, so I'll use hook-type tools to pull them off somewhat, but in this case, there is plenty of room for leverage.

That's my high-tech precision hacking method

[PeteS]

The rear drive will NOT appear overfilled.  The static level of oil at 250cc is just below the lip of the seal.  If extra oil gets in, it easily passes the seal lip and the result goes all over your tire while the tide level in the drive box remains at the lip level.  The empirical evidence comes from discovering the transmission oil BELOW normal level of 750cc.  DO NOT rely on any of the 'level' plugs on the side of the transmission or the rear of the rear drive box.  The only way to verify that is to drain and measure the transmission fluid volume.  Stop working in ounces.  Get a measuring pitcher with metric dimensions.  You can re-use what  you drain.  You can't measure now because you don't really know how much was put into the transmission.  You need to drain, measure, reinstall, and then add whatever is necessary to make the standard level in the transmission.  Then, ride it for some miles and re-drain and re-measure.  If you document 750cc put in then you should be able to measure 750cc when you drain and measure.  If that level or volume goes down it can only go two places.  Either it leaks to a puddle on the ground, or, via the output shaft seal it leaks through the driveshaft tunnel to the reardrive and thereafter leaks past the big seal to spray onto you wheel.  Now is the time to do it right before we get into the best of the riding season.

Patrick Hayes
Fremont CA

About 25 years ago Manfred Hecht rebuilt my LeMans Transmission. At the time he told me and another Guzzi friend to not use more than 650ccs of tranny oil to keep pressures down and oil in. Been doing that ever since with no problems as have all the Guzzi riders I know in this area. We don't just putt around either. Done about a dozen track days on the LeMans.
As for viton vs Buna-N (aka nitrile) they should work equally well in their temperature range for the gearbox and rear drive. Given the Lemans has endured many below  0 F days Nitrile would be my first choice. Any contact with gasoline Viton in the only way to go.

Pete