CV Joints

Technical and Repair Discussions

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PostPosted: Wed Mar 21, 2012 8:49 am
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PostPosted: Thu Apr 24, 2014 5:04 pm
Yes to bring this back around, I am running the tri lobe inner CV joints and I put on new boots over the winter and I noticed that the inner left ( short side ) one was doing a pretty good job of leaking a small amount of grease on the transmission case after each run. I am using the stock steel clamp and feel like I have it pretty tight but does anyone have a trick on getting it to seal like the other side is? I did try a zip tie around the out edge in addition to the metal clamp with not much success. It was suggested to me to try a small plastic straw ( WD-40 or Brake clean type ) in the boot to try and let gas build up escape.
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PostPosted: Thu Apr 24, 2014 9:26 pm
Perfect...You should see a small amount of greese spun on the case after every session.
I leave the left inside (short side) boot loose so air can escape.
Also...I pull the boot off once every event and check it.
You don't need to check the outer CV.
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PostPosted: Fri Apr 25, 2014 9:17 am
WhatsThatNoise wrote:Perfect...You should see a small amount of greese spun on the case after every session.
I leave the left inside (short side) boot loose so air can escape.
Also...I pull the boot off once every event and check it.
You don't need to check the outer CV.


Really? We crush the boot a little before clamping, don't usually have a problem.

Not sure why you don't need to check the outer CV....
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PostPosted: Fri Apr 25, 2014 9:53 am
To repack with grease, you are just pulling back the boot adding grease and replacing. Not removing the axle. Correct? What do you do about the metal boot clamps. Replace them each time?
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PostPosted: Fri Apr 25, 2014 10:26 am
Well... I pull everything apart every winter, which means taking the CVs off the half shafts. I then clean out the old grease, repack thoroughly with new, and then put everything back together. I haven't yet found a way to reuse the clamps, and even if I did, I'm not sure I'd want to. As long as I'm able to pull down the clamps nice and tight, I've never needed to use the straw trick in the boot, but YMMV.
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PostPosted: Fri Apr 25, 2014 3:12 pm
WhatsThatNoise wrote:Perfect...You should see a small amount of greese spun on the case after every session.
I leave the left inside (short side) boot loose so air can escape.
Also...I pull the boot off once every event and check it.
You don't need to check the outer CV.



So you are saying that you leave the inside boot a bit loose for the gas to escape and that it is normal for them to leak on the outer part of the boot? I find it odd that the boot should be leaking at all, pulling the boot off is not really hard I just am surprised that it needs to be checked after each event to make sure there is grease in there.


Anyone else have a sealing trick they would like to share?
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PostPosted: Fri Apr 25, 2014 4:09 pm
ctkellett wrote:
WhatsThatNoise wrote:Perfect...You should see a small amount of greese spun on the case after every session.
I leave the left inside (short side) boot loose so air can escape.
Also...I pull the boot off once every event and check it.
You don't need to check the outer CV.



So you are saying that you leave the inside boot a bit loose for the gas to escape and that it is normal for them to leak on the outer part of the boot? I find it odd that the boot should be leaking at all, pulling the boot off is not really hard I just am surprised that it needs to be checked after each event to make sure there is grease in there.


Anyone else have a sealing trick they would like to share?


I'm no engineer, but have my doubts about the "excess pressure" issue. Really, how hot can it get? Starting pressure is 0 lbs at ambient temperature. Even if it heats up to 175 degrees, what sort of PSI will that create? And why can't a very flexible boot handle that increase in pressure?

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PostPosted: Fri Apr 25, 2014 5:39 pm
The Ideal gas law is derived from Bolye's law and Charles' law is PV=nRT where n is the number of moles of gas and T is in degrees Kelvin or K. 0 degrees C is 273 degrees K, so air tempature is about 300 degrees K. R has something to do with molar mass and avogrado's number and is a constant in this case anyway, My memory tells me it is around 8 but I wouldn't bet on that. (after all I was wrong once today already, I got out of bed and my feet hit the floor, to which I heard my wife mumble "damn it")

First off the number of moles of the gas in the boot is very small and as stated R is a constant. Assuming the operating tempature rises 50 degrees then there is about a 20% change in tempature. I think it is safe to say that the small mole number of the air in the boot is going to dominate the calculation. So a 20% change times very very small leads me to estimate that the pressue volume change in the boot is about the equvaliant of a mouse fart!
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PostPosted: Fri Apr 25, 2014 8:54 pm
Lee Spuhler wrote:The Ideal gas law is derived from Bolye's law and Charles' law is PV=nRT where n is the number of moles of gas and T is in degrees Kelvin or K. 0 degrees C is 273 degrees K, so air tempature is about 300 degrees K. R has something to do with molar mass and avogrado's number and is a constant in this case anyway, My memory tells me it is around 8 but I wouldn't bet on that. (after all I was wrong once today already, I got out of bed and my feet hit the floor, to which I heard my wife mumble "damn it")

First off the number of moles of the gas in the boot is very small and as stated R is a constant. Assuming the operating tempature rises 50 degrees then there is about a 20% change in tempature. I think it is safe to say that the small mole number of the air in the boot is going to dominate the calculation. So a 20% change times very very small leads me to estimate that the pressue volume change in the boot is about the equvaliant of a mouse fart!


That's what I said, but with a LOT less thinking.
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