Main drive gear oil seal

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nanonevol
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Main drive gear oil seal

#1

Post by nanonevol »

I took my main drive gear to a local (not Harley specific) machinist to have the bushing replaced and sized to the main shaft.

I also left him with the small oil seal only to show him that space would be needed for my installing it later.
Well, they misunderstood and thought I wanted the small seal installed too and called to explain that they could not machine
the hardened gear to make the seal fit.

This makes me believe that I may have a '38-'64 gear (#35065-38) that did not use the seal.
Or maybe the machinist doesn't understand how the seal installs which would make two of us.

How can I tell if it is a gear that doesn't use the seal and if so, should I replace it? It is in otherwise nice shape.

thanks for reading.
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Re: Main drive gear oil seal

#2

Post by RooDog »

The easiest thing to do would be to buy a new gear with new seal & bushing from either H-D or Andrews, The cost is up to you....
nanonevol
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Re: Main drive gear oil seal

#3

Post by nanonevol »

Would a new gear still need the bushing sized or is it done?
Mongrel505558
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Re: Main drive gear oil seal

#4

Post by Mongrel505558 »

nanonevol wrote: Mon Oct 18, 2021 5:13 pm Would a new gear still need the bushing sized or is it done?
It would need a new bushing sized. I doubt you can press out the one you have and reuse it without distorting it. I've sized them with an adjustable reamer with good results. Takes time, though. A lot of passes, increasing the diameter in very small increments and measuring each time. I was told by the owner of a Harley-Dealership who started as a mechanic and is a good machinist that you can use a 1" reamer because the clearance is built into the shaft, which should measure about .9995". 1" might be a big bite to take starting out, without working up to it. Haven't tried it. I did practice using the adjustable reamer on worn bushings. If your machinist did a good job sizing the bushing in the gear you have then you shouldn't have much leakage without using the seal in question.
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Re: Main drive gear oil seal

#5

Post by 59Panman »

Doesn't Saddlebagrail machine the drive gears for these seals? Maybe contact him?
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Re: Main drive gear oil seal

#6

Post by RooDog »

Th "Super Nut" negates the need for that seal , if you have the room for it....
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Re: Main drive gear oil seal

#7

Post by nifty »

MDG seal to mainshaft
Introduced 65, can retrofit back to 36? 39? (by changing, or re-machining main drive gear, i.e. at thread end, machine new counterbore for new seal)
IMO Anyone who says they can't re-machine MDG doesn't know about ceramic inserts and therefore is not a real machinist in a real machine shop.

12022 Transmission mainshaft drive gear seal, 65-85, ID 1” x OD 1.250” x 3/16” wide. Stock 4 speed seals measure 1.252 OD

Stock seal recess depth in MDG varies between 0.215” - 0.230”.
Ensure MDG bush does not extend into recess of MDG where it can foul seal.

OE single lipped seal has garter spring, sealing lip & garter project at rear/inside, do not press seal to bottom of recess, or seal will be destroyed, garter exerts pressure on seal lip, can’t stack two in stock recess,

Some guys re-machine recess deeper, IMO If recess deepened it gets dangerously close to undercut at sprocket nut thread, IMO danger of breaking off thread of main drive gear*. (especially if you are foolish enough to use crazy OE nut torque 120-150ftlbs, IMO 80 ftlbs is ample for chain rear drive applications. *this may be the only point Ray Duguay and I disagree on.

Some people claim they use Evo 5 speed MDG shaft seal in 4speed MDG, but 12035B Evo seal is .266” wide and 1.263” OD. I could live with the protrusion of deeper section seal, but I’m not going to beat it in with over 10 thou seal crush!

Supa-nut/Duo-Seal works 36-64; will not work 65-69 with stock aluminum primaries, will work 70up with stock aluminum primaries only if stock OE narrow primary bearing used; supanut can be re-machined slightly to work with stock aluminum primaries and non stock 1/2" wide bearing and stock primary seal. All of this only applies to rear chain drive, rear belt you are on your own. I use & like supanuts

Andrews 204260 Stock Replacement Main Drive Gear (4th, 26T) 1936-1976, approx 1.629” bearing area OD for loose rollers, has recess for 65up spec mainshaft seal. (replaces 35065-38 and 35065-65). Has no provision to positively seal spacer/collar. Comes with pre-sized bush, last one I bought was max loose tolerance, on new Andrews mainshaft. (.0025”)

Nifty
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Re: Main drive gear oil seal

#8

Post by nifty »

Supa Nut will not work pre 65 with early OE clutch hub (rear extension must be machined off, or late style hub used. All repop clutch hubs appear to be late style.

I don't use the Supa nut / duo seal o-ring, use master gasket instead.

ALL INSTALLATIONS: Vital that supa nut inside seal lip does not contact end of MDG, check with wax, clay or Prussian blue.
If inside steel part of supa nut contacts/bottoms at end/tip of MDG before sprocket tight, MDG distorts/cones inwards and buckles at spline roots, shaft seal distorts into buckled spline roots, shaft seal destroyed, leaks oil. Also sprocket not tight so oil leaks between spacer & splines.

Sprocket and or nut may require spacing to avoid above.

Nifty
nanonevol
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Re: Main drive gear oil seal

#9

Post by nanonevol »

Thank you X 4. Lots of info, thank you for taking the time.

I won't name them but it's a large machine shop that specilizes in car race motors.
I had heard of machining the gear for double seals so I was surprised to hear the guy say he couldn't do it for one.
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Re: Main drive gear oil seal

#10

Post by RooDog »

Name the shop!
Not only do we need to know who the good guys are, but also those who are not so good. If what you are saying is true, then why keep it a secret?
You would not be trash talking them, but rather giving the brothers here a heads up should we be looking to that same shop for service....
Or are you skeered?
Good service shops/people are getting harder and harder to find. Almost all the automotive machine shops in this Knoxville, Tennessee, area are gone, and most of those that remain don't do motorcycle work. The local chrome shop, who I traded with for years, and raved about their great work, left about four years ago. So lets keep the information about the both the good, the bad, and the ugly, available for those of us seeking service and parts...
Nobody seems shy about trashing Tedd's V-Twin, and your guy ain't sacred either, now is he?
....RooDog...
nanonevol
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Re: Main drive gear oil seal

#11

Post by nanonevol »

Ha! Yeah why the hell not. They are ABT Machine in Holliston MA
http://www.abtmachine.com/?fbclid=IwAR3 ... daun5YveTA

To be fair they got a nice close tolerance on the bushing, "a thou and a couple" is how he put it.

Question: Is this groove for an O-ring? I've heard of the Andrews gears machined for an O-ring.
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Re: Main drive gear oil seal

#12

Post by doc9339 »

I always post this when it comes to tranny leaks

I didnt read the whole post, so sorry if I repeat: But i have found that while most folks will change out all the appropriate seals, use super nuts etc, and still have leaks, they have over looked one thing. If the main shaft is worn, which is common with older trannies, you can change all the seals in the world and do a complete rebuild, but it will still leak if the main shaft is worn. The main shaft is the one thing that many when rebuilding dont take the the time to mic out or replace when its worn

Some will try to move the main shaft on an assembled tranny and think that no wiggle means the shaft is good to go. Thats not the case here. If its not within specs, it will leak right at the main seal

Also, my exp had been that when you have a 4 speed leak, it really doesn't matter what manufactured type oil, or weight you are using. It will still leak. Even when 90wt gets hot, it gets thinner and will leak if there is place to seep by.

Since you have your tranny apart (?) grab that main shaft and mic out the area where the shaft goes thru the main seal area. I forgot the spec, but memory says right at 1.00 inch. double check the correct spec yourself. Ill bet your main shaft is worn right at the suspect area

Rememeber, there was a time when these trannys didnt leak
nanonevol
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Re: Main drive gear oil seal

#13

Post by nanonevol »

Thanks Doc but you lose your bet 'cuz it's a new shaft. I miked it 1" .
ABT thought the spirals would help hold the oil back which I suppose they do some.

This trans is for a Paugho 45" project BTW. I don't know anything about Harley primarys/clutches yet so didn't understand a
lot of what "nifty" was saying above. I'm hoping to run a hand lever, dry clutch, chain primary.
So I don't know if I can use the Supa Nut
These are some of the parts I got in the package:

Image
Mongrel505558
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Re: Main drive gear oil seal

#14

Post by Mongrel505558 »

nanonevol wrote: Tue Oct 19, 2021 5:34 pm Thanks Doc but you lose your bet 'cuz it's a new shaft. I miked it 1" .
ABT thought the spirals would help hold the oil back which I suppose they do some.

This trans is for a Paugho 45" project BTW. I don't know anything about Harley primarys/clutches yet so didn't understand a
lot of what "nifty" was saying above. I'm hoping to run a hand lever, dry clutch, chain primary.
So I don't know if I can use the Supa Nut
These are some of the parts I got in the package:

Image
The shaft should be less than 1" - more like .9985" to .9995". I just measured one this morning (brand new old stock Made in USA OEM Harley part number 35039-65) at .9990". The difference between 1.0000" and .9990" - is .001". When we're talking about a published range of .002" to .003" for bushing-to-shaft clearance, that .001" becomes very important.
nanonevol
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Re: Main drive gear oil seal

#15

Post by nanonevol »

Right, I read somewhere that "the clearance is built into the shaft". Some of it anyway.
Who are we to question why?
I did actually measure mine at "hair" under an inch but my measuring accuracy doesn't go beyond half a thou.
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