• Can't post after logging to the forum for the first time... Try Again - If you can't post in the forum, sign out of both the membership site and the forum and log in again. Make sure your COG membership is active and your browser allow cookies. If you still can't post, contact the COG IT guy at IT@Concours.org.
  • IF YOU GET 404 ERROR: This may be due to using a link in a post from prior to the web migration. Content was brought over from the old forum as is, but the links may be in error. If the link contains "cog-online.org" it is an old link and will not work.

Final Drive 1999 C10

mbsevans2722

Member
Member
I know I know it’s been posted before but here’s a short video of my issue, any input would be welcome as this thing is supposed to be safetied for roadworthiness on Monday.

 
It sure is clean! Put some seal sweller in it for Monday, then do what Bud said. If you want to keep your original, buy a used one anyway and use it till you can fix the original.
 
Ok thanks. Yes she is clean as I just finished restoring her. Was a gift from a friend of mine. Brake fluid work ok for swelling seals? How much? Teaspoon?
 
I never use volume as the amount of oil I add. I add oil until it reaches the lowest edge of the fill port.
Do not rotate the wheel while doing so, nor overfill. Overfill is bad.
Prior to doing this I would see leaks. Less oil solved it for me.

Ride safe, Ted
 
I never use volume as the amount of oil I add. I add oil until it reaches the lowest edge of the fill port.
Do not rotate the wheel while doing so, nor overfill. Overfill is bad.
Prior to doing this I would see leaks. Less oil solved it for me.

Ride safe, Ted
I wasn’t talking about rear end fluid, I was askig about seal sweller, like Dot 3 brake fluid. The rear was filled with precisely 220cc.
 
Your guess is as good as mine on the amount. I'd go with more than less. Maybe an ounce? Also like Ted said, less oil is better. So put in the dot 3 and ride it for 30 minutes, then drain it to half full. That's only for the Monday test!!!! I'm strictly guessing on all this. Good luck.

If someone disagrees with this feel free to speak up
 
Yours looks like it could be a leaking seal. (I don't recall seeing one drip like that before).
Mine would have oil on the rim/tire after a ride. I think it came out near the front of the housing.
There is a vent hole on the top somewhere. Too much oil (somehow) causes oil to come out there.
I discovered this on my (then new) C-10 after I changed the rear oil.
I drained, and refilled, but kept the level below the inner edge of the fill window.
NOTE: If you're turning the wheel with oil in it, the oil is carried by the gears and the differential will be overfull after it settles.

For now, just suck out some of the oil (Below the fill window) and see if it helps.

Ride safe, Ted
 
Last edited:
Yours looks like a leaking seal. I don't recall seeing one drip like that before.
Mine would have oil on the rim/tire after a ride. I think it came out near the front of the housing.
There is a vent hole on the top somewhere. Too much oil (somehow) causes oil to come out there.
I discovered this on my (then new) C-10 after I changed the rear oil.
I drained, and refilled, but kept the level below the inner edge of the fill window.
NOTE: Turning the wheel with oil in it, the oil is carried by the gears and will be overfull after it settles.

For now, just suck out some of the oil (Below the fill window) and see if it helps.

Ride safe, Ted
Thanks.
 
I'm going with too much oil - it's getting carried up high with the gears, and working its way out of the vent hole. I had this happen to my own '86 before I did the "just fill to to lower edge of the threaded hole" trick. I Follow this same procedure today for my 200K+ mile '95 with no issues.

The only way to know for sure is to pull the rear wheel and try to locate the oil source. If it first appears up high, it's probably the vent hole; lower is probably the main seal.

Here's the vent hole:
1656278418943.png

If you’re the type that pulls the final drive to R&R the rear wheel, I’ll throw this in here. If you go this route and have oil weeping out of the flange joint between the swing arm and the final drive once things are back together, you’ve nicked/cut the small o-ring that is located on the final drive pinion gear (Item 3 in the illustration below). Over time, these tend to harden up from age and heat, which makes them very susceptible to getting damaged when you’re trying to get the drive shaft and pinion gear splines mated back up. I highly recommend you replace that small o-ring when you have the final drive removed. New o-rings are more supple and take a little more abuse when you’re wrestling that heavy punkin’ around trying to get things lined up.

1656285500017.png
 
Last edited:
I'm going with too much oil - it's getting carried up high with the gears, and working its way out of the vent hole. I had this happen to my own '86 before I did the "just fill to to lower edge of the threaded hole" trick. I Follow this same procedure today for my 200K+ mile '95 with no issues.

The only way to know for sure is to pull the rear wheel and try to locate the oil source. If it first appears up high, it's probably the vent hole; lower is probably the main seal.

Here's the vent hole:
View attachment 33012

If you’re the type that pulls the final drive to R&R the rear wheel, I’ll throw this in here. If you go this route and have oil weeping out of the flange joint between the swing arm and the final drive once things are back together, you’ve nicked/cut the small o-ring that is located on the final drive pinion gear (Item 3 in the illustration below). Over time, these tend to harden up from age and heat, which makes them very susceptible to getting damaged when you’re trying to get the drive shaft and pinion gear splines mated back up. I highly recommend you replace that small o-ring when you have the final drive removed. New o-rings are more supple and take a little more abuse when you’re wrestling that heavy punkin’ around trying to get things lined up.

View attachment 33015
After only a 2 mile ride last evening I stopped to inspect and there was significant leakage. I pulled the rear wheel this morning took a photo cleaned it all up and now I’m letting it sit to see where the seepage is coming from I can definitely see fluid on both the bottom outside conference of the main seal and also at the bottom of the drive where the backing plate-ish and that would be the big O ring. My only question now is who has taken apart the final drive I think there’s 10 or nine bolts to replace that large O-ring ?
 
MB,
did you get a reply? My main seal is leaking too. I have a used final drive on the way but would like to replace that big seal that's around the output splines shaft. That is were my leak was coming from. Service manual talks about dunking the whole final drive in hot oil to pull that old seal out and put in a new one. There's gotta be a better way I would think. I don't have a turkey deep fryer.
-tdbru
 
I had issues with a leaking final drive when I first bought my bike back in 2014. This thread had lots of info in it:


Of course I can't remember exactly what I did to fix the issue (because it doesn't leak now) but I did not take the rear drive apart to get to that large o-ring. As a matter of fact I still have the large o-ring and ring gear seal I ordered at the time, sitting out in my garage. I do remember using something (maybe film negative?) to run around the lip of the ring gear seal to make sure there was nothing there to disturb the seal (similar to using it on fork seals to clear debris) as was suggested in this thread. Maybe this will help shed some light on your situation.
 
Thanks bpdutton.
I suspect the reason that the wheel bearing moved for Cafefill might be, and I emphasize might, that the pipe between the wheel bearings was left out or not included with the meanie wheel. the various pipes are designed to take the axle bolt tension against the wheel bearings inner race so that there is no axle bolt tension (side loading) against the wheel bearings themselves. with the pipe in my meanie wheel between the wheel bearings, there is no way my wheel bearings can shift at all as the axle bolt is tightened.

one thing I did notice is that Cafefill used Amsoil. and so did I before the final drive started leaking.

I will chase the ring gear oil seal with a piece of film negative, as suggested, and try and get all traces of gear oil out of the inside of the final drive. rinse with mineral spirits?

I will check to see if any mineral spirits leak out of the ring gear oil seal. If so I will replace that seal. if not, I may just reinstall the final drive but fill it up with non Amsoil gear oil and see if it continues to leak.

Or perhaps I'll just wait until the ring gear oil seal comes in and replace it at that time before I reinstall the final drive.

I would be very surprised if there is a component in Amsoil gear oil that would cause the seals to deteriorate. or leak. Wouldn't make any sense. but that is one thing that both Cafefill and I did before the final drives started to leak, was to use Amsoil synthetic gear oil.

thanks again,
-tdbru
 
thank you mgoodrich. That is good info. As I mentioned, I couldn't imagine that any gear oil, like Amsoil, would be incompatible with the seal materials. The only thing though I noticed in Cafefill's narrative that was common to my situation, was the use of Amsoil, which is what I put in too. Sunday I had set the removed final drive up to drain all the gear oil out. Tonight I added 230ml of mineral spirits and closed up the fill plug and spun the drive splines a bit to stir up the residual gear oil and really clean out the insides. When I tipped the pinion shaft input down over the coffee can, some of the mineral spirits started coming out the two weep hole like expected. Right now the drive is sitting upright in a normal functional position over the coffee can and I am not observing any mineral spirits leaking past the ring gear output gear oil seal. I will check in the AM. With mineral spirits being much thinner than gear oil, my assumption is that if the gear oil is leaking out the gear oil seal, I would likely see mineral spirits weeping out. so far, no leaking or weeping at all. I also held the final drive with the output splines up to see if the other gear oil seal at the other end of the ring gear shaft might be the culprit. no mineral spirits leaking out there either. when I drain out the mineral spirits tomorrow night after work I will tip the final drive such that the mineral spirits should come out the vent hole if it's open. I suspect the vent hole is open but that will be a good test of that. If the vent hole is open, I am, at the moment, at a loss for explaining the cause or origin of the final drive leak I am dealing with currently. But it's good to know that the type of gear oil, or at least the Amsoil, is likely not the cause of the leak.
thanks for the info
-tdbru
 
There is an o-ring on the drive shaft under the coupling that connects to the aft drive assy, It holds in the oil that comes out of the weep holes and into the spline area of the coupling. You need to use a long set of snap ring pliers to remove the coupling sleeve to get to that ring, I have replaced mine about every 30,000 miles. The oil leaks out into the shaft area and then out at the bottom of the drive assy. Look like the main seal to the wheel coupling is leaking.10-14.jpg
 
Last edited:
Ah ha. thanks Jpd11958,
I will see if i can find a long nose snap ring pliers and get to that front o-ring. The o-ring on the pinion shaft is fine. I haven't been able to inspect the one on the other end of the coupler, that you're mentioning to check. And yes, it looks like a main seal leak when I opened it up, but as i mentioned, the main seal seems fine. Thank you for mentioning to look at this forward o-ring also. I have the 2 o-rings for both ends of the coupler on order. I'll check this other o-ring as soon as I can get the appropriately fitting snap ring pliers so i can get to that o-ring.
thanks again.
-tdbru
 
"rear was filled with precisely 220cc." The 220 cc is when the drive is completely dry.

"I never use volume as the amount of oil I add. I add oil until it reaches the lowest edge of the fill port."

I agree with the others....over filled.
 
  • Like
Reactions: Bud
Thanks Tim,
I got the coupler off of the drive shaft tonight. Front o-ring intact, pliable, no tears. pinion shaft o-ring intact, pliable, no tears. Ring gear oil seal. seemingly fine. mineral spirits would not seep through overnight and all day. vent hole open and clear. So I am stumped as to why the final drive was leaking oil. But it was.

without a cause that I can tell or find, I'm hesitant to go to the effort to put everything back together, but I don't see any alternative at this point.

if anyone else can think of something I missed I'd be appreciative to hear about it.

with a clear vent, as the unit gets hot it would not be pressurizing so my final theory is out the window. I thought if the vent was plugged as the unit heated up the interior would pressurize and force gear oil past the ring gear oil seal. but the vent was clear.

i will be careful NOT to overfill the unit this time.

-tdbru
 
I lost drive on my '95 C-10, #3, a couple of months ago. I just heard a pop and then no power to the rear wheel. Being mechanically challenged, I've no idea what the problem is or how to fix it. So I went and bought C-10 #4, a 2006 rather than paying a mechanic to troubleshoot and fix it.
 
Still waiting on those two o-rings. Once I get them and get them installed, with the appropriate MoS2 lube on the splines, I'll get everything back together, fill the final drive, while being very careful not to over fill it. we'll see what happens after that. stay tuned while I wait on the o-rings to come in.
-tdbru
 
Are you saying that you didn't remove the rear wheel or differential to see where the problem was?
Arghhhh!!!

Ride safe, Ted
Once I decided it was a bad idea to invest a lot of money trying to fix a 27 year old motor I started stripping the bike. I swapped wheels with John Larmon and the splines in the hub looked good. So we suspected that the problem might be in the motor's output. As I said, I'm mechanically challenged and have no friends to help me out with figuring exactly what the problem is.
 
Once I decided it was a bad idea to invest a lot of money trying to fix a 27 year old motor I started stripping the bike. I swapped wheels with John Larmon and the splines in the hub looked good. So we suspected that the problem might be in the motor's output. As I said, I'm mechanically challenged and have no friends to help me out with figuring exactly what the problem is.
Did you check the splines on the drive gear in the rear wheel?

The splines sticking out from the final drive 'pumpkin' are hardened whereas the drive gear splines in the rear wheel are not.

They are a planned wear part, that can get stripped bald if not proper greased and can be replaced.
 
Did you check the splines on the drive gear in the rear wheel?

The splines sticking out from the final drive 'pumpkin' are hardened whereas the drive gear splines in the rear wheel are not.

They are a planned wear part, that can get stripped bald if not proper greased and can be replaced.
John Larmon has the wheel that was on #3 when it lost drive. I don't know if he checked the splines closely in the rear wheel. I suppose I could start up #3 on the centerstand with the replacement wheels that are on it and see if the rear wheel turns when I put it in gear. If it does turnout that the problem was in the rear wheel I'm going to be really pissed that I bought #4 and have stripped so much stuff off of #3.
 
As Stan posted about the gear splines in the rear wheel, make sure to clean out all the old grease & do a thorough check of the teeth. Took a quick look at one of mine during annual maint. a long time ago & "almost" tossed it back together, until a closer look revealed that the outer part of the teeth looked fine...but....the inner section was about down to the nubbins, which required a replacement...
 
If the replacement rear wheel is on, and the differential still on the bike, see if you can turn the wheel with the engine in gear.
Apply force for a proper check.

Let us know what you find out.

If the rear wheel is off, and the differential still on the bike.
Put the bike in gear and see if you can turn the differential.
A big pair of channel locks or a pipe wrench could be used to add a little torque.

If it turns, and the motor doesn't the problem is somewhere between the differential and the motor.
 
Last edited:
John Larmon has the wheel that was on #3 when it lost drive. I don't know if he checked the splines closely in the rear wheel. I suppose I could start up #3 on the centerstand with the replacement wheels that are on it and see if the rear wheel turns when I put it in gear. If it does turnout that the problem was in the rear wheel I'm going to be really pissed that I bought #4 and have stripped so much stuff off of #3.
PS: If it turns out to be just a rear wheel, you don't have to be mad at yourself.
,,,, I'll be glad to chastise you personally. 💩🤠🥸 <evil grin>
 
Last edited:
PS: If it turns out to be just a rear wheel, you don't have to be mad at yourself.
,,,, I'll be glad to chastise you personally. 💩🤠🥸 <evil grin>
Ted your the best!!!🤩 But if you are going to chastise me personally, I expect you to do it in person. It is a 1650 mile ride for you to get here which will give you a chance to do a Bun Burner Gold. When should I expect you to arrive?
1659721468420.png1659721293955.png
 
Last edited:
Sorry. I'm not an Iron Butt Rider/supporter.
I think that forcing yourself to stay awake and endure pain (to ride XX miles in XX hours) is dumb/unsafe.

So, I'll reword.

PS: If it turns out to be just a rear wheel, you don't have to be mad at yourself.
,,,, I'll be glad to chastise you personally Publicly. 💩🤠🥸 <evil grin>

Glad I could clarify my previous statement.
Ride "Safe", Ted

(Let the Flames Begin)
 
Sorry. I'm not an Iron Butt Rider/supporter.
I think that forcing yourself to stay awake and endure pain (to ride XX miles in XX hours) is dumb/unsafe.

So, I'll reword.

PS: If it turns out to be just a rear wheel, you don't have to be mad at yourself.
,,,, I'll be glad to chastise you personally Publicly. 💩🤠🥸 <evil grin>

Glad I could clarify my previous statement.
Ride "Safe", Ted

(Let the Flames Begin)
Just because you have no interest in riding an Iron Butt certification ride is no excuse for not coming here to chastise me personally. You can always take a week to get here if that is a more comfortable pace for you.
 
I think COG-528 is avoiding the question by picking on me.
& He's using one of my favorite ways of avoiding such a question.
I refer to this method as "Grin" and 'Dodge".

So, "was the problem "only" the wheel"?

Ride safe, Ted
 
Last edited:
Top