oil on the good foot

[bikerphil]

Thinking about this, with a double lip seal, do both lips actually make contact on the crankshaft? From my memory I would say no because the crankshaft in our engines is too short. There are triple lip seals available so maybe this could be an option!?

Not a triple lip, but the Timkin brand should be good quality, 70 durometer nitrile....

https://www.directpneumatics.com/290...x48x8-r2ls32-s

Wondering about the quality of some of these seals, could some be made in China and be a lesser quality? May be time to get one of the best quality.

[speedlimit85]

Napa makes 2 that are the right size:

https://www.napaonline.com/en/p/NOS12736 Looks to be viton

https://www.napaonline.com/en/p/NOS12749 Looks to be buna

[speedlimit85]

GEARBOX SEAL: FKM OR NBR ?



How self-evident is the correct sealing of a gearbox? A standard rubber seal is used in many gearboxes. But these seals often do not fulfill the requirements of a gearboxes due to the high speeds, dynamics and duty cycle of the application. And what if an application is placed in a special environment? Or when it is a special application?

In this article we discuss the characteristics and properties of High-end sealing materials and the questions that you might ask yourself before you make a choice.


GEARBOX SEALING MATERIAL


To keep the lubricant inside and contamination outside of our gearboxes, Apex Dynamics is using seals for its gearboxes. The seals on the input and output side of the gearbox of Apex Dynamics are vulcanized around a steel support, so that the seal is form-retained and can always be found with a metal detector. Depending on the application, two high-quality materials are used as standard: FKM and NBR.
VITON® / FKM SEAL

Viton® is the trade name of this type of elastomer from inventor Dupont. But in practice we also call it Fluorocarbon or FKM. In this article we will use the name FKM.
NBR SEAL


NBR is also called Nitrile or Nitrile rubber and stands for Nitrile Butadiene Rubber. If it is hydrogenated, it becomes HNBR (Hydrogenated Nitrile Butadiene Rubber).

FKM and NBR are two commonly used elastomers for high-end sealing applications, and not without reason. Both materials are suitable for a wide range of applications. They offer excellent compression resistance and both are resistant to most oils and lubricants, especially petroleum-based lubricants. In addition, applications with moderate temperatures between -15° C and 110° C are suitable for both types, making both materials a very good choice for heavy industrial use.
WHICH SEAL IS OPTIMAL FOR YOUR APPLICATION?



Due to the wide range of available materials it is sometimes difficult to determine which seal is most suitable for your project. In many cases, a fairly simple assessment of the elasticity or tear resistance that your application requires is sufficient, but sometimes it is crucial to pay more attention to the choice of materials.

Important circumstances to consider are:

• Temperature of your application/environment
• Chemical resistance

TEMPERATURE OF YOUR APPLICATION/ENVIRONMENT




Standard FKM connections can continuously seal at temperatures up to approximately 205° C. Standard NBR, on the other hand, is only effective for continuous sealing at temperatures up to 110° C. But at temperatures below -20° C, standard FKM seals are again less effective because they become relatively hard and inflexible. Special FKM joints can offer low temperature capacities of -40° C, but standard NBR works successfully at -35° C and even up to -55° C with a special composition.
CHEMICAL RESISTANCE


FKM has a wide range of chemical resistance, making it ideal for most applications with oils, fuels and mineral acids. FKM also offers excellent resistance to oxidation, ozone, exposure to UV radiation, weather and fungi. Although NBR also supports some of the same chemical resistances, it is much less universally resistant than its FKM counterpart, and is affected by weather and ozone exposure. But NBR has superior wear and tear resistance and is therefore better suited for heavier, industrial applications.
CHOICE OF SEALING MATERIAL

In short, consider the following conditions to get a good idea of which sealing material fits the best your application:

• Fabrics in process and environment
• Required tear and abrasion resistance
• Temperature
• Chemical resistance
• Lifespan

[bikerphil]

I went back and checked my purchases and yep, Eric you are right, Buna rubber for the ignition side. The one I used for the alternator side I bought from a different source and they didn't list which type it was, but it also is still holding up.

[speedlimit85]

Phil you have the buna https://www.oringsandmore.com/metric...-ref-cr563065/

I now have the viton https://www.oringsandmore.com/fkm-oi...rice-for-1-pc/

[DEEBS11]

Another thought: If Buna is good until 257°F and your oil is around 250°F on a hot summer day. Well...there it is. It will work but not forever. It would have to start breaking down in that environment. Starting with a weep and ending with a larger leak. Wear issues.

[DEEBS11]

This is the one that I installed on my XS11.

https://www.ebay.com/itm/202555196571

It worked for a few thousand miles. It was during the hot summer months pushing a sidecar. I'm guessing it got real hot and started to wear. The install must have gone well because it did not leak for a long time indicating a wear issue and not a tear or abrasion during install. It was also not a directional seal as was the factory original. I'm not sure if the double lip was a factor. I had posted here info from a seal company that a double lip seal needs lubrication in between the two to keep it from drying out and abrading. I used red rubber grease in between but I suspect that is a low temp grease and failed with high heat. Maybe Mobile 1 synthetic grease next time with a Viton seal. I will install this soon.

[bikerphil]

Honestly I'm not sure of which type seal I am using, though I am going to try to find out.

[DEEBS11]

I think you should perhaps, at times, question your mechanic's sources.

[speedlimit85]

I was talking to a mechanic friend about the difference between viton and buna rubber seals for the crankshaft. His opinion is buna is better for this and that's the one Phil has working. I got 500 mi with a dry foot with the viton seal but if needed, the buna is a better replacement.

The original split case may not work if the seal sat on a shelf for 30 yrs- one on ebay had a manufacture date of 1987.

[speedlimit85]

After it set overnight, got it back together, runs great - need to put miles and see if it is sealing. new seal 65,100 mi

I'm trying to cancel the order for the 7mm seals- I don't think it'll work.

Might get more https://www.oringsandmore.com/metric...-ref-cr563065/

Working on Phil's bike and on mine it was for a while...

[DEEBS11]

This is good too. I would try to do this without removing the head or the cylinders. Just the cam chain tensioner.

https://www.youtube.com/watch?v=6Fj83JafQ8Y

[DEEBS11]

Here is one that shows the cases split. You can clearly see the seals on the crank.

https://www.youtube.com/watch?v=d1qO7yNJL1U

[DEEBS11]

Check this XJ1100 guy. He did what we did but never follows up on what happened. No part 3.

https://www.youtube.com/watch?v=TMHnk8aHzyE

https://www.youtube.com/watch?v=MasE5xGaEC0

[DEEBS11]

However, that seal would work if you pulled the engine & split the cases. The head would have to point down onto a work bench and try to remove the lower case. The crank would then have to be lifted slightly in order to slip the stock seal on (both sides). Might require unbolting the connecting rods for clearance. I did this once to a Honda Nighthawk motor to replace the alternator chain. Pulling the XS11 motor out is really not that difficult. I have done a few. Maybe it's time to fix it correctly the hard way.