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"To Double or Not To Double??"

Tue Mar 12, 2013 6:07 am

Ok guys and gals, here's my next question, what does everyone think (or know from experience) about doubling any of the seals in the tranny, pto, or final drives :?: As always thanks in advance for the input.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 6:14 am

If you're putting double lip seals in place of single lip seals, there will probably be some benefit, as double lip designs usually are better at sealing.

If you are talking about putting 2 separate seal assemblies into the locations mentioned - the one that runs dry will burn up and you'll still just have a single seal.

Lip seals are designed to leak when they are working correctly, but the leak is supposed to be so small that you can't see it.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 6:20 am

If you're talking gaskets, I would suggest not doing that. It acutally makes things harder to seal, and was an old "trick" that people used to do just to skip the cleaning and prep process, which is something my dad used to call "half assing it!"

If you want to make sure something does not leak, remove the old seal (ALL OF IT) clean, grind, scrape, wire brush, etc., whatever you need to do to get the mating faces PERFECTLY CLEAN! Then clean again with acetone or whatever your favorite degreaser is. Then clean it again with degreaser. Then maybe clean it again. Get the hint?! Next, depending on the application I will typically use purple Permatex, or Indian Head Permatex, or, whatever the correct gasket sealant is for the application. Follow the directions for application. Lastly, bolt up the appropriate pieces and torque to specs.

By following these steps you are actually making a better gasket installation than was done at the factory, as all factory installed gaskets were done dry, with no sealants. Cork gaskets should seal dry, but the installation of Permatex products greatly enhances this, and makes up for some of the imperfections that may have occurred over the years. Also, the sealants will "help" if for some reason the surfaces are not perfectly clean, or a drop of oil runs across a surface and you don't notice it. Regardless, if you take your time, this is the best way to seal things.
Last edited by gitractorman on Tue Mar 12, 2013 6:35 am, edited 1 time in total.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 6:50 am

sounds good to me. everything sounds very logical (like the outer seal burning up) although I don't know if I will be creating enough heat in there for that to be a problem since it won't actually work anymore. I remember my father using this method years ago but probably because he didn't want to replace the parts that were causing the leaks in the first place like grooves wore in shafts and such. The local industrial seal and bearing store actually suggested doubling the seal that surrounds the axle nut on the right side final drive due to the difference in thickness. So it looks like i'm better off to only us single seals and be sure to use some type of sealant on gaskets. Almost forgot,,,,clean,,,,clean,,,,,and clean some more to remove the 65 years worth of dirt and such. Sure am glad I ask. This is such a great site, don't know what I would do without it or the members on it :mrgreen:

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 8:31 am

We're not talking about literally catching fire here. It's a figure of speech.

The outer seal will not receive any lubrication because the inner seal is preventing oil from leaking. Dry seal against dry shaft will quickly wear away the rubber lip and probably put a groove in the shaft too, even if you are not working the tractor. It's not a heat thing but it is a friction thing.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 9:15 am

Some of the seals on the older rigs, such as the brake drum shafts on H had that type originally, but the new ones are singles. The material the newer seals are made from are much better, and do not leak as easily. My personal opinion, which is worth about what I charged for it, is that it is a waste of money. Until the inner seal fails there will be no oil getting to it to lubricate where it runs on the shaft, and it will be worn to the point of not being effective by the time the inner one fails. The exception to this is if the shaft for the inner one is bad, and it leaks, then the second one would help.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 1:52 pm

I agree with gitractorman regarding gaskets. Also, keep in mind that some gaskets are made to a specific thickness to act as a spacer or shim to set clearances. The oil pump gasket comes to mind as well as the gaskets used on some governors.

Regarding the use of double seals, as a machine builder for over well over 20 years, I've seen it used sometimes in areas that historically are difficult to seal. When ever I installed double seals in an application, I hand packed grease in between each of the seals to provide lubrication for the outer seal. Also sometimes the seals are installed opposed to one another with the inner seal "lip in" to keep oil or grease in the housing and the outer seal mounted "lip out" to keep water, dust or other debris from getting into the housing. Again, I pack grease between the seals when installing.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 9:10 pm

In the OE game, we worked really hard at getting gasket coatings that would NOT stick to the housings - at least in the short term. Years ago I was testing new gasket formulations and picked up a 1800 lb transmission by the gasket that stuck the 2 housings together. We quickly ordered a new coating formula.

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 9:30 pm

Never tried it, but I once heard that chap stick was good to keep carburetor gaskets from sticking

Re: "To Double or Not To Double??"

Tue Mar 12, 2013 9:52 pm

gitractorman wrote:If you want to make sure something does not leak, remove the old seal (ALL OF IT) clean, grind, scrape, wire brush, etc., whatever you need to do to get the mating faces PERFECTLY CLEAN! Then clean again with acetone or whatever your favorite degreaser is. Then clean it again with degreaser. Then maybe clean it again.


:Dito:
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