Another rear drive box vent thread

[Pressureangle]

When I put the bike together a few years ago for my long trip, I went around looking for a reason for, and solution to, gear lube being forced out of the rear drive seal and onto the rim. I ended up drilling a hole in the filler plug and pressing a grease zerk with ball removed into the hole, and running 3-4 feet of tubing up the swingarm and along the frame, exiting by the rear turn signal. In the main it was ok, but at high speeds and unknown distances it still emptied about half the gear oil out of the box over my 10k mile trip. Whilst overlooking my deficits for the 2021 South'n Spine Raid, the tubing disintegrated. So I went looking again. I replaced the zerk with a brake bleeder, tapped and screwed in. The single hole in the bleeder faced forward, away from the flow of lube inside. Way better than the zerk, but still came home after 50 miles with some drool on the wheel, too much to tolerate. So here's my plan. I looked online at axle vents etc, and found one from a jeep with a plastic skirt under it, and a conical spring inside to 'filter' and decant oil back to the axle. I couldn't make it fit under the drive stay rod... but it did give an idea. I stole the spring out of it, went looking for a skirt and found that a brass PEX adapter was a very nice, very tight press into the underside of the fill plug. I wound the spring into the hole and pressed the adapter in with the bench vice, hopefully protecting the bleeder hole from any direct oil splash. Now, on to the testing. 
Yes, I've considered that it may shake loose. No, I'm confident that it can't-it's tight but not so tight to worry about cracking or splitting while pressing it. 

[docc]

18 minutes ago, Pressureangle said:

 . . . .  found one from a jeep with a plastic skirt under it, and a conical spring inside to 'filter' and decant oil back to the axle. I couldn't make it fit under the drive stay rod... but it did give an idea. I stole the spring out of it, went looking for a skirt and found that a brass PEX adapter was a very nice, very tight press into the underside of the fill plug. I wound the spring into the hole and pressed the adapter in with the bench vice, hopefully protecting the bleeder hole from any direct oil splash. Now, on to the testing. 
Yes, I've considered that it may shake loose. No, I'm confident that it can't-it's tight but not so tight to worry about cracking or splitting while pressing it. 

 

This, I have done too many times to count . . .   ("Back in the day" . . .)

[docc]

Alright, alright . . . "those kinds of posts" . . . I should report myself. To myself. Again.

Looks like you have your solution, @Pressureangle. It will be interesting to hear your results.

The V11 reardrive has substantially more capacity than the earlier Sport. (370 ml vs 250 ml?) and is vented. (Was your '97 Sport-i originally unvented?)

I suppose using the V11 vent system would still let too much oil out?

Breather Plug  GU19206501

Gasket             GU01528930

Oil Plug            GU01351230

Gasket             GU01154230

[Pressureangle]

26 minutes ago, docc said:

This, I have done too many times to count . . .   ("Back in the day" . . .)

Yeah, but this time the *skirt* is brass.

[Pressureangle]

Docc, I don't know about the V11 vent system. The 'Sport rear takes 250cc, I used Lucas 80/140 'super duper high performance' gear oil, with about a tablespoon of Jet-Lube open gear and cable grease, which appears to be pure Moly with enough grease to make it stick to stuff-I use that on the spliney stuff. 

So, after ~20 miles of "3 miles in the middle was 80-100mph" The housing temp was 116*F after 5-6 miles home @ 35mph. 

But yay, there is no trace of oil at the tip of the bleeder, I didn't even put a hose over it so I could be certain. Saturday I'll go beat it up where I can hold 70-100 for 1-15 miles, and take the temp gun with me. 

I know y'all have recorded drive temps, what's the norm? 116*F isn't even worth talking about in automotive axles.

 

[docc]

That looks like an awesome result! And you feel that it is still actually "venting?"

We checked reardrive temps with an IR reader at one of the SpineRaids as a (rolling) TechSession. Let me see if I can find that . . .

[Pressureangle]

11 minutes ago, docc said:

That looks like an awesome result! And you feel that it is still actually "venting?"

 

Yes, it's a tiny hole but it only has to pass air as fast as the rear end can heat it. I'll add the hose by Saturday, to keep track of any oil that gets out, keep water out, and hopefully keep the heat cycles from drawing in any meaningful amount of our summer humidity. 

[Pressureangle]

Oh, and I have to say that the Caruso gears have made a *Yuge* difference in top end running as well as bottom. I have to ask myself if I'm imagining things. In the past, it seemed to take a very long time to get where it would go, indicated about 130. Although I've opened the airbox top since my last WOT speed adventure, 100 came and went so fast at part throttle it's like I sprouted an extra cylinder. We may check that Saturday.

[Lucky Phil]

48 minutes ago, Pressureangle said:

Docc, I don't know about the V11 vent system. The 'Sport rear takes 250cc, I used Lucas 80/140 'super duper high performance' gear oil, with about a tablespoon of Jet-Lube open gear and cable grease, which appears to be pure Moly with enough grease to make it stick to stuff-I use that on the spliney stuff. 

So, after ~20 miles of "3 miles in the middle was 80-100mph" The housing temp was 116*F after 5-6 miles home @ 35mph. 

But yay, there is no trace of oil at the tip of the bleeder, I didn't even put a hose over it so I could be certain. Saturday I'll go beat it up where I can hold 70-100 for 1-15 miles, and take the temp gun with me. 

I know y'all have recorded drive temps, what's the norm? 116*F isn't even worth talking about in automotive axles.

 

You could replace the big and bulky rear drive torque arm with an aftermarket unit with rod end fittings which would give you a lot more room to play with the vent solutions. Your oil deflector of some sort seems like a good idea.

Ciao  

[Pressureangle]

1 minute ago, Lucky Phil said:

You could replace the big and bulky rear drive torque arm with an aftermarket unit with rod end fittings which would give you a lot more room to play with the vent solutions. Your oil deflector of some sort seems like a good idea.

Ciao  

I keep thinking that myself, but given the bashing of parts by the straight cut transmission, I like the idea of the bit of cushion provided. Getting a hose that fits and stays on is a challenge, to be sure. 

[docc]

Well, I had a great time scrolling through the South'n SpineRaid archives looking for the reardrive temps TechSession. It was South'n SpineRaid five, 2008, but I can't find the data (our forum lost a bunch of posts and threads back then). I'll have to load up the IR gun and get some temps off mySport for comparison. Re-shoot yours at sustained highway speeds or after repetitive accel/decel @Pressureangle

2008/ 4th South'n SpineRaid: