Front Drive Shaft Update

[Tazzieman]

No, just experience in manufacturing and polymer science

Ah, the old Bad Batch theory!

 

[ECrider]

No, just experience in manufacturing and polymer science

my heart wants to say yes but the head says no

 

[Zimm]

No, just experience in manufacturing and polymer science

That’s why I suggested changing cv’s periodically may not be the solution. You may toss a good one for a bad one.

 

[CRH]

That’s why I suggested changing cv’s periodically may not be the solution. You may toss a good one for a bad one.

From the various quotes on milage and lift v's no lift, I have a very similar view to yourself. Some have quoted high speed driving as a factor, others it's the offroad use, then it's the lift and finally a combination of everything where some have gone and others haven't.
I'm on just short of 30k miles and it's been basically all road use and mainly UK motorways. Last time I looked it was ok, but currently I can't get down there but will check as soon as I can, last time was probably July ish. If I'm looking into failures like this I would assume it's a variance in manufacture or materials.

In our industry we are being pushed to use a % of recycled polymers but they are not suitable and degrade with each use. This has caused intermittent failures for some. I would never recommend recycled content for my products but some do as it offers a monetary saving (tax). Some get misty eyed about the savings and the suppliers have them believe all will be perfect, until it isn't. Black products are much easier to hide recycled materials, which some do. I am not saying any recycled materials are involved or are even detrimental to the CV joint.

This is also before we see who actually manufactured the rubber and if they were the best or the cheapest. Even the best make errors in mouldings or the initial compounding?

Quick AI explanation

Yes, traditional rubber recycling methods, like grinding into crumbs, cause some degradation, but newer technologies like devulcanization aim to break sulfur bonds to recover usable material with minimal property loss, allowing for higher-quality recycled rubber for new products, though some degradation or property changes (like becoming less elastic) can still occur depending on the process and application.
Traditional Recycling (Mechanical)
Process: Grinding vulcanized rubber (like tires) into small particles (crumbs).
Degradation: This method doesn't break the sulfur cross-links, so the rubber acts more like a filler, reducing the overall quality and elasticity of new products. Properties like strength and flexibility can decrease.
Advanced Recycling (Devulcanization)
Process: Uses chemicals, heat (microwave, thermal), or ultrasound to selectively break the carbon-sulfur (C-S) and sulfur-sulfur (S-S) bonds, allowing the rubber to be reformed.
Reduced Degradation: This aims to return the rubber to a workable state without significantly damaging the polymer backbone, making it suitable for higher-value products.
Outcomes: Can create new compounds with less loss of mechanical and physical properties, approaching "virgin" material quality.
Key Takeaway:
While rubber's vulcanized (cross-linked) nature makes it tough to recycle without some property loss, innovative devulcanization methods are minimizing degradation, allowing for more effective, closed-loop recycling and material recovery.

 

[Texas Grenadier]

I drew this side profile of the boot and drive shaft. Is the red area where the pinching occurs?
View attachment 7919666

Yes, but your rendering is upside down for the differential angle.

 

[Zimm]

From the various quotes on milage and lift v's no lift, I have a very similar view to yourself. Some have quoted high speed driving as a factor, others it's the offroad use, then it's the lift and finally a combination of everything where some have gone and others haven't.
I'm on just short of 30k miles and it's been basically all road use and mainly UK motorways. Last time I looked it was ok, but currently I can't get down there but will check as soon as I can, last time was probably July ish. If I'm looking into failures like this I would assume it's a variance in manufacture or materials.

In our industry we are being pushed to use a % of recycled polymers but they are not suitable and degrade with each use. This has caused intermittent failures for some. I would never recommend recycled content for my products but some do as it offers a monetary saving (tax). Some get misty eyed about the savings and the suppliers have them believe all will be perfect, until it isn't. Black products are much easier to hide recycled materials, which some do. I am not saying any recycled materials are involved or are even detrimental to the CV joint.

This is also before we see who actually manufactured the rubber and if they were the best or the cheapest. Even the best make errors in mouldings or the initial compounding?

Quick AI explanation

Yes, traditional rubber recycling methods, like grinding into crumbs, cause some degradation, but newer technologies like devulcanization aim to break sulfur bonds to recover usable material with minimal property loss, allowing for higher-quality recycled rubber for new products, though some degradation or property changes (like becoming less elastic) can still occur depending on the process and application.
Traditional Recycling (Mechanical)
Process: Grinding vulcanized rubber (like tires) into small particles (crumbs).
Degradation: This method doesn't break the sulfur cross-links, so the rubber acts more like a filler, reducing the overall quality and elasticity of new products. Properties like strength and flexibility can decrease.
Advanced Recycling (Devulcanization)
Process: Uses chemicals, heat (microwave, thermal), or ultrasound to selectively break the carbon-sulfur (C-S) and sulfur-sulfur (S-S) bonds, allowing the rubber to be reformed.
Reduced Degradation: This aims to return the rubber to a workable state without significantly damaging the polymer backbone, making it suitable for higher-value products.
Outcomes: Can create new compounds with less loss of mechanical and physical properties, approaching "virgin" material quality.
Key Takeaway:
While rubber's vulcanized (cross-linked) nature makes it tough to recycle without some property loss, innovative devulcanization methods are minimizing degradation, allowing for more effective, closed-loop recycling and material recovery.

I would also like to see a fresh one sliced in half. These are shaped in mold, and the if they wanted to control where the flex was occurring, the thickness would be tapered down in that area. Basically, I don't believe the thin part of the cross section is due to "wear". I don't believe material is just fluffing off, and it's not "extruding" as suggested because there wouldn't be molecular dislocation caused by elastic deformation. There's simply not enough heat being generated. I think its simply a case of the unit spends more time at an angle than the design allotted for, and the bonds are breaking causing a crack, and if there is any variability in the material that can cause a point of more focused elasticity, it's failing there, sooner.

You seem to know much more about material science than I do, so, how does that read as a simple explanation...

 

[Texas Grenadier]

Well, you can buy one off Amazon and have it late same day or tomorrow. Cut it open and show us.

TeraFlex JL/JT Factory... https://www.amazon.com/dp/B0CKKD9BJ4?tag=globalgrena0b-20

Would you be willing? Thx!