K/Sportster Case Oil Drain Plug

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Re: K/Sportster Case Oil Drain Plug

Postby Ferrous_Head » Thu Dec 07, 2017 5:30 pm

I would have to wonder if the shorter one was intended for KR's ?
There are good reasons why we run less oil in a race only engine. If for some reason the shorter part never got designated with an "R" part number the spare parts people might never have known they were meant for different application. This would be a purely technical error on HD's part I know. But those things do happen from time to time.
The only other explanation that comes to my mind is that originally the gearbox oil level was set higher. They did have problems with early gearboxes and maybe too much oil was found to be a factor. But if that is the case I would suspect the shorter one would have coincided with the 1-1/2 pint the FSM calls out for capacity.
"I know only too well the evil that I propose, but my inclinations get the better of me."
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Re: K/Sportster Case Oil Drain Plug

Postby mikeslemmon » Thu Dec 07, 2017 6:53 pm

what is the oil capacity difference? could it be that the oil .level was lowered to keep the dry clutch dry?
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Re: K/Sportster Case Oil Drain Plug

Postby wallaman » Thu Dec 07, 2017 7:27 pm

Based on what's been presented, there are three distinct "level" plugs. The only one I know about for sure is the the one I just pulled out of the bag that came from an old dealer buy out I did years back, and it is approximately 2" long. I also haven't been able to find any reference to any revisions to the original part number, race or otherwise. While that happens occasionally with Harley parts from that era, it isn't common, especially for there to be three distinct revisions. I don't have a fully assembled K engine (without trap door?) to test the different lengths on w/ regards to capacity. The later -54 primary is a bit deeper and that might account for the difference (even though the level plug isn't listed for 54 and later), but I'd suspect that the bigger issue is oil level and not capacity as far as keeping the trans and primary lubricated. So what is the "right" oil level?

Stan, the reason I had the NOS level plug out was to have it re-cad plated (the old cad was quite "aged"). Precise measurements will need to wait until it comes back from the platers. That said, while the pic I posted isn't perfect, you can get a pretty good idea of dimensions from the scale provided.

Thanks all for your responses. Appreciated.
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Re: K/Sportster Case Oil Drain Plug

Postby starcain » Sat Dec 09, 2017 9:23 am

Here are a couple of pictures of one of the long (1-3/4" ) 34745-52 transmission drain and oil level plugs I have. I thought maybe someone would find it interesting to see what it looks like in the case. I am no transmission guy but what it looks like to me is that the only thing that could be causing the damage to the tubes as shown in the picture is the C/S 2nd or 3rd gears. Is there anything else going on in that area? If you look at the far left one in the picture you can see a spiral groove cut into it with what looks like the same thread count as the plug itself. That had to be rubbing on something as it was going in. Although you can't really see it in the picture the far right one has the same marks but lighter. The middle one does not have those spiral marks but all have damage running lengthwise down about 3/8" from the end. I have a short one in the KK now and I am fine with that. It's worked OK for me so far. I am just trying to get a better picture of what was going on inside to bugger these tubes up. I would love to get some opinions from any of you folks that are well versed in the K transmissions.
Stan
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Re: K/Sportster Case Oil Drain Plug

Postby Vintage_hds » Sat Dec 09, 2017 10:10 am

That is an interesting set of pictures. I am not that familiar with these transmission assemblies to offer any real analysis but it would be interesting to see what it looks like when a counter shaft is set into the case. This would just be to see the relationship of the tube to the gears. I would say that all of the tubes shown have such a small amount of damage that it could be it is caused when the transmission is under torque where the shafts and gears tend to move off axis (if that is the correct terminology). Also it could be that the bearings might be a bit worn before causing the parts to come into contact with the tube.

One other observation. There now appears to be three different drain plug /tube assemblies; one short, one tall machined from a single piece of material, and one plug with a tube brazed into it.
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Re: K/Sportster Case Oil Drain Plug

Postby starcain » Sat Dec 09, 2017 11:20 am

Yes I wish I had a counter shaft to put in it but I don't. That's why I was hoping to get someone with intimate knowledge on these trannys to offer up some opinions. The one tube that you think is brazed really isn't. What you see is gasket sealer or something like that. I should have taken that off before I took the picture. It's off now and it is also one piece. The curious point to me is how they got the spiral grooves. Something was in the way as it was going in. Maybe a difference of being in neutral or in gear? 2nd or 3rd gear? Worn bearings is good a possibility which would indicate that things are really close in there.
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Re: K/Sportster Case Oil Drain Plug

Postby gearhead1944 » Tue Dec 12, 2017 7:22 am

too much endplay on the counter shaft could cause the gear to rub the tube.
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