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Bushing Replacement

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Old Feb 29, 2016 | 12:48 PM
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Default Bushing Replacement

A friend of mine works at a local machine shop and has offered to make some new bushings for me. I am looking to replace all bushing in the front end, install a new trac bar, add a steering box support, and add a steering stabilizer. When I mentioned all of this to my friend, he said that a guy at the shop was making his bushing out of cast nylon for a Wrangler. I want opinions. What are your thoughts on nylon bushings? I can get the nylon for free and only pay for the labor involved. Should I go with the nylon bushings or just buy some good urethane bushings?
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Old Mar 1, 2016 | 01:13 AM
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Nylon makes fine bushings..why not?
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Old Mar 1, 2016 | 10:02 AM
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I know its durable, just wasn't sure about the stress level versus urethane bushings. Thanks for your input.
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Old Mar 2, 2016 | 02:15 AM
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Originally Posted by Jason 99XJ
I know its durable, just wasn't sure about the stress level versus urethane bushings. Thanks for your input.
It'll probably outlast Urethane, especially if it's in an application that moves or swivels.
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Old Mar 2, 2016 | 07:45 PM
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Urethanes are more like rubbers. Nylons are more like plastics.

Looks like the tensile modulus of of urethane falls between 400 and 4,600psi. Nylon appears to be on the order of 400,000psi. On hardness scales, nylon is much harder than urethane. At break, urethane has much more elongation than nylon (200%-400% as opposed to 50%).

Nylon is stronger and stiffer. You will get a much harsher ride with more noise and vibration. The nylon may be prone to brittle failure and/or cracking. In any joint that requires two or more degrees of motion, the nylon may not properly deflect and the joint may bind (ex: control arms). Nylon would would work well in joints with pure rotation (ex: sway bar). Nylon is hydroscopic, meaning it attracts moisture. It may swell on humid days causing binding, and shrink on dry days causing loose fitment. Because it is more like plastic, nylon has a shorter expected lifetime than polyurethane.

It would seem to me that installing nylon bushings in many ways defeats the purpose of having bushings. I suggest poly bushings, they will do you well.

Last edited by NM-XJ; Mar 2, 2016 at 07:48 PM.
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Old Mar 3, 2016 | 06:17 AM
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Originally Posted by NM-XJ
Urethanes are more like rubbers. Nylons are more like plastics.

Looks like the tensile modulus of of urethane falls between 400 and 4,600psi. Nylon appears to be on the order of 400,000psi. On hardness scales, nylon is much harder than urethane. At break, urethane has much more elongation than nylon (200%-400% as opposed to 50%).

Nylon is stronger and stiffer. You will get a much harsher ride with more noise and vibration. The nylon may be prone to brittle failure and/or cracking. In any joint that requires two or more degrees of motion, the nylon may not properly deflect and the joint may bind (ex: control arms). Nylon would would work well in joints with pure rotation (ex: sway bar). Nylon is hydroscopic, meaning it attracts moisture. It may swell on humid days causing binding, and shrink on dry days causing loose fitment. Because it is more like plastic, nylon has a shorter expected lifetime than polyurethane.

It would seem to me that installing nylon bushings in many ways defeats the purpose of having bushings. I suggest poly bushings, they will do you well.


Correct.


I would not use nylon. Further, I think it would distort over time and retain it's distortion.
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Old Mar 3, 2016 | 10:16 AM
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Thanks guys! Im needed sway bar bushings, so I think I will pick up a pair at the local parts store and have my buddy copy them in nylon.
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