Finding a oil leak

The chain has been getting oil on it and spattering the rear tire

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Finding a oil leak


Post by kell » Wed Jul 14, 2004 1:28 am

The chain has been getting oil on it and spattering the rear tire. I think the oil comes from somewhere on the transmission because the transmission is covered with muck pretty much everywhere below the shifter top. Also it looks like the oil level has dropped some in the trans. And what little oil there is on the engine has obviously been splattered on it from the direction of the tranny sprocket. I don't think the oil's coming from the tranny top gasket. I changed it last year and it's in good shape. I thought the leak came from the homemade shifter shaft I have on there, so I opened up the tranny top and put a rubber o-ring on the shaft, inside. Still getting chain splatter. Then I got the idea of taking to the whole trans apart to replace all the seals. I took the transmission out of the bike and got the clutch hub and sprocket off, expecting to disassemble the transmission. But it's such a big job, I wonder if there is an easier way.

(A) is there some kind of bench test to find a leak in a transmission,
(B) should I just put the darn thing back in the bike and go on cleaning the mess off the sidewall, or
(C) go ahead and tear it apart and replace all the soft parts?

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Re: Finding a oil leak


Post by Billy » Wed Jul 14, 2004 4:31 am

Kell, hear me out, Is your tranny vent plugged up on your trans ?? Make sure it is free & clear. Otherwise pressure builds & it has to come out somewhere. This has caused some strange leaks that magically went away after cleaning out a blocked vent.
This IS often an overlooked- taken for granted area. ;D

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Re: Finding a oil leak


Post by kell » Wed Jul 14, 2004 7:48 am

I checked the vent first. My main problem is loads of end play in the main gear. I think the oil gets out through the needle bearing because of it. So I tore the tranny down tonight. The needle retaining ring I had in there measures .057 and I have a new one .071. I just put the new one in and there's still some slop. Not sure if it's within spec (.003-.013 end play according to Clymer) because I don't have a dial gauge. Just guessing, but by feel it still seems just a tiny bit looser than it oughta be. I think I will call a shop or try an internet search and see if I can find a washer just a little bit thicker. Going to have to guess, maybe buy a couple in the range .075 to .080. Anybody know offhand what sizes available, and where to get them?

I just remembered something. There's supposed to be a little key on the end of the mainshaft or the sprocket somewhere, but my bike doesn't have it. If that key is supposed to hold a spacer, it might explain why my main gear has so much play. Anybody have information about that? Thanks in advance.

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Re: Finding a oil leak


Post by Cotten » Wed Jul 14, 2004 1:09 pm

I think the key you refer to is the drivekey to the spacer that goes through the main seal. It does not determine main drive gear endplay.
A 'benchtest' to find leaks is simple: drain the oil and refill with mineral spirits or kerosene. It will run out of any leaks.

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Re: Finding a oil leak


Post by kell » Wed Jul 14, 2004 3:45 pm

Okay here's what I think happened: over the months of riding without that key (I guess I lost it when I changed the sprocket last year), the mainshaft spinning in the (now stationary) spacer gradually wore the surfaces down and allowed leaking. Now what I don't know is whether replacing the key and getting the spacer to spin with the main gear like it's supposed to will make everything better, or if there has been enough wear on the surfaces that I now have to replace the spacer or even the main gear. Hope not! Maybe there's somebody here that the same thing has happened to and can speak from experience.
I suppose the end play doesn't help either. I have a new washer that's slightly thicker and improves the situation. But even going from the old .057 washer to this new .071 washer, it still has a little looseness. If could maybe ride it that way ok but I suspect it's more than the .013 (max) Clymer cites. Can't give you an exact number, I don't have a dial gauge. What the heck is the proper name for that washer anyway. I can't tell which part it is on the Clymer diagram or the one in J&P. Is it a bearing retainer ring or a thrust washer or what.

Okay two questions.

(1) Is it enough to get a new key and put it in, or should I get a new spacer too. I guess would have to rip out the oil seal to do that.

(2) What is the proper name, and part number, for that washer.

By the way the previous owner had the transmission rebuilt with Andrews gears and I had to take it apart after I bought it to correct the gear spacing. The problem was with third and fourth, they were much too far apart. Anyway I got that fixed but I had to do it by spacing the whole mainshaft away from the ball bearing end, I couldn't make up the slack on the drive gear end just by putting in a thicker washer there. Not even close, must have been something near an eighth of an inch I had to move it. I bought arbor spacer shims and put them between the ball bearing and first gear. I must have done the right thing because it also greatly improved the alignment between the gears of the countershaft and the gears of the mainshaft, which had been off before. By the way I also had to jigger the gear on the kicker end of the mainshaft back out to where it belonged by putting aluminum shims between it and the tapered shaft.
Since the mainshaft seems to be the wrong length, and the main gear assembly doesn't seem to correspond exactly to the exploded parts diagram in Clymer or J&P as I gaze at it with foggy eyes, this may be a bastard application. That's why I'm uncertain about the washer terminology. But it has an outside diameter of 2 1/16".
I'm thinking I really need to get the end play right or the key will fall out or get loose enough in the slot to break. Not good. The key that was in there when I bought the bike was broken. I replaced it when I fixed the gears but forgot all about later when I changed the sprocket, now I'm paying the price.

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Re: Finding a oil leak


Post by 57pan » Wed Jul 14, 2004 4:44 pm

If it were me I would certainly replace the mainshaft seal as long as the tranny is out of the bike where you can work on it
The OEM part number for the spacer is 35171-37. The MidWest part number is 96-410 - I got one from Jireh for $9.95. The OEM number for the little key thingy is 35175-38.
The parts diagram shows a cork washer behind the mainshaft seal. I left that out when I replace the seal because the seal would not seat deep enough and the lip of the seal would have been running right over the notch in the spacer where that key goes.
I'm not sure about the number for that spacer/washer thing.

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Re: Finding a oil leak


Post by kell » Thu Jul 15, 2004 12:16 am

I'll put in a new main gear spacer, oil seal and a new .080" thrust washer.
I'm also thinking about filing another slot or two in the new spacer so I can use two or three keys. That way I won't have to worry about a broken or lost key.

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Re: Finding a oil leak


Post by mbskeam » Thu Jul 15, 2004 5:12 am

hello, many things here. main shaft is 11 3/4 LG . later model ones got longer on outside of tran, in the clutch area. The inside lg is the same on 4 speeds. replace the mainshaft gear spacer 35171-37(the hat) and key # 35175-38, if it is worn on inside from spining these are cheap to buy, use only 1 key it will hold just set end play, take 4th gear put on your spacer 35130-36 that you have ,(they come in .060,.065,.070,.080)(A shop that does older bikes like ours should have these).put in 44 roller bearings in tran main , put 4th in tran, put on hat, put on sprocket and tighten up, check end play with feeler gage shoot for .006- .009. (I think its from .003 to .012) check this on the inside between race and spacer. when installing andrews gear set, third gear end play on main shaft is .004-.017.,you do have shim in there? V-twin shows from -.005 to+.030 in .005 steps. Next is the seal, it should be .050 below edge of tran lip this will let the notch in the hat and key clear the seal edge. I rebult my trany 3 years ago and had to scronge up all this stuff that I have in a file. for just in case. counter shaft end play is from .007-.012 I shot for .010 on mine. the spining hat is what is causing the leak it tears up the seal.
ps: thanks KELL for elect info on ign.

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Re: Finding a oil leak


Post by ArizonaMike » Thu Jul 15, 2004 11:23 am

Reading the tip of finding a leak reminds me of another, possibly easier way, discovered in a car mag. Clean the tranny, then coat it by brush with talcum powder. The leak can then easily be identified.

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