Varg - Gear Oil Change

[Kurlon]

Seals dislike pressure differentials.

 

[Foss]

I just pulled off the short hose blocker and replaced it with the original hose. There was a small vacuum I could hear with air rushing into the gearbox. This kind of tells me I have a good vacuum seal, if my oil change results a milky color (water), I’ll assume the ingress point is this breather hole.

Here is stark’s response:

Service Support (Stark Future)

Apr 29, 2024, 17:17 GMT+2


Hi,

Thank you for pointing this out, we will review the manual for this operation.

Best regards,
Stark Future Team

 

[Torqu3]

Heating and cooling cycles requires airflow in and out, breathing. If you only let air out with a one way valve, air will find other ways in under vacuum, such as bearing oil seals, gaskets etc. Other substances such as dirt and water can follow the air breathing if you don't control where this happens.

 

[rayivers]

Heating and cooling cycles requires airflow in and out, breathing. If you only let air out with a one way valve, air will find other ways in under vacuum, such as bearing oil seals, gaskets etc. Other substances such as dirt and water can follow the air breathing if you don't control where this happens.

Only disagree with two things; requires (I'd sub "sometimes requires") and will ("may"), as I've seen many gaskets/seals/etc. not leak at all under 100+ bar differentials, sometimes for decades. My replies at this Stark Varg potential-gearbox-oil-contamination thread are intended only to help mitigate or eliminate that specific problem, not sidetrack into a gasket/seal/thermal properties discussion.

 

[Torqu3]

You are 100% correct. But this isn't a pressure vessel, and the seals will be designed as such. It's a gearbox with an open breather tube.

 

[rayivers]

It's a gearbox with an open breather tube.

It is! Mine surely won't be, in one direction anyway

 

[Theo]

Like many if you I guess, I'm not sure what to think; my YZ250 has similar hoses for the gearbox, the carbuator and the powervalve that as far as I know are not regulated via any kind of one way valve and yet it doesn't seem to me that there are problems with signficant amounts of water entering them.

Here is the abstract of an article about the importance of breather hoses; I surely haven't bought the access to the article, but the abstract already answers the queston about the fact that it's either needed or not.

So far I've thought about a couple of possible improvements for the situation:
1- replace the black breather hose with some transparent fuel hose so that we can see through it and become aware of any droplets,
2- seal the breather hose with one of those inflatable balloons that kids use for parties, so that differences in volumes can be compensated even though the crankcase is sealed; here is a cross section view of what I mean:

 

[Kurlon]

One big difference between the breathers on something like a YZ250 vs the Stark is the anticipated internal temps. On a gas burning engine it is expected and desired that certain areas get up above the boiling point of water. This drives out moisture from the system via the breathers as you operate the bike. Cars rely on this as well, and it's a big reason why vehicles used for short trips tend to have worse service histories, if not driven long enough to get things up to temp, moisture builds up. Hybrids like my Jeep will even force engine use when there is plenty of battery if the oil hasn't seen good operating temps in awhile to drive out moisture.

Vargs don't get that warm internally, at least not intentionally, so I'd be a fan of a more proactive means of keeping moisture out if possible, or I'd be going to a much more frequent oil change interval when there is a chance of moisture ingress from washing, water crossings, operating in rain/muggy weather/etc.

 

[Torqu3]

Exactly

 

[Foss]

One big difference between the breathers on something like a YZ250 vs the Stark is the anticipated internal temps. On a gas burning engine it is expected and desired that certain areas get up above the boiling point of water. This drives out moisture from the system via the breathers as you operate the bike. Cars rely on this as well, and it's a big reason why vehicles used for short trips tend to have worse service histories, if not driven long enough to get things up to temp, moisture builds up. Hybrids like my Jeep will even force engine use when there is plenty of battery if the oil hasn't seen good operating temps in awhile to drive out moisture.

Vargs don't get that warm internally, at least not intentionally, so I'd be a fan of a more proactive means of keeping moisture out if possible, or I'd be going to a much more frequent oil change interval when there is a chance of moisture ingress from washing, water crossings, operating in rain/muggy weather/etc.

And this is why I change my oil every Moto now. Doesn’t take a lot, and it isn’t expensive.

 

[Theo]

It is! Mine surely won't be, in one direction anyway

Hey rayivers, I see in your signature that you own an Alta: does it have any problems with moisture in the gearbox? Does it have a breather hose?

I'd like to know the answers for the same questions from someone who owns an E-XC Freeride or any other electric motorcycle with an oil lubricated gearbox...

 

[rayivers]

Hey rayivers, I see in your signature that you own an Alta: does it have any problems with moisture in the gearbox? Does it have a breather hose?

I've never seen or read about an Alta gearbox breather hose - not sure the Alta's IP67 rating would allow it. I've never seen any evidence of water in my oil, either through the sight glass or during oil changes.

 

[Theo]

I heard some starks had a very short breather that made it easy to get water in. Mine has a long hose that runs up to the top of the subframe and down again.

If the breather hose is the one highlighted in green in the attached picture of my bike, then apparently mine is routed in the same way.

 

[Torqu3]

Mine as well

 

[happyinmotion]

While we're talking about Stark gearbox oil, does it need GL-4 or GL-5 oil? GL-5 is better for high wear situations like hypoid gears but is more corrosive to yellow metals. GL-4 suits spur gears but is less common these days - my local shop had none.

I checked with Stark support. Their answer: both API GL-4 and GL-5 oils can be used in the gearbox without issue.

 

[Chaconne]

While we're talking about Stark gearbox oil, does it need GL-4 or GL-5 oil? GL-5 is better for high wear situations like hypoid gears but is more corrosive to yellow metals. GL-4 suits spur gears but is less common these days - my local shop had none.

I checked with Stark support. Their answer: both API GL-4 and GL-5 oils can be used in the gearbox without issue.

I have been using this:

It meets or exceeds GL-5. Anyone use something else?

 

[happyinmotion]

The API oil specifications are tight enough that there's no meaningful difference in performance between the brands, no matter how much the oil companies spend on advertising to convince us that that oil is special.

I used whichever 75W-90 GL-5 oil came in the smallest size, coz a litre should last ten oil changes.

 

[Chaconne]

The API oil specifications are tight enough that there's no meaningful difference in performance between the brands, no matter how much the oil companies spend on advertising to convince us that that oil is special.

I used whichever 75W-90 GL-5 oil came in the smallest size, coz a litre should last ten oil changes.

Ya agreed. They do charge double for the synthetic like Lucas vs the non-synthetic regular brand which is also GL-5.

 

[Foss]

For whoever has done a motor swap… has stark actually taken back the old motor? I am now stuck with a motor which works but has a bad bearing which I think I could fix and have a back up motor if they never take it back lol

 

[blbills]

I'm using Amsoil 75W-90.