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Rubber vs Poly in Leaf Springs |
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jetnoise
AMC Apprentice Joined: May/09/2008 Location: NC Status: Offline Points: 106 |
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Posted: Aug/15/2016 at 8:43pm |
I used poly bushings in another project but found it to harsh for street driving.
Has any one used a poly/rubber combination in their leaf springs before especially on the shackle side. I'm definitely going to be using rubber in the front leaf spring bushing. Just trying to decide if maybe using poly on the frame end of shake or the leaf end of the shake would be of benefit without being to harsh. Thanks |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19686 |
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There isn't much difference on the shackle end. Most of the shock/load is on the front. You might get some vibration/road noise from poly on the shackle, but shouldn't get any shock. Running rubber on one end and poly on the other will reduce noise. I think I'd run rubber on the spring and poly on the body side since the body side seems to get the most wear. Just an opinion, haven't done it.
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Frank Swygert
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jetnoise
AMC Apprentice Joined: May/09/2008 Location: NC Status: Offline Points: 106 |
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Farna I was thinking the same thing, thanks for your opinion
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uncljohn
AMC Addicted Joined: Jan/03/2013 Location: Peoria AZ Status: Offline Points: 5394 |
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A bushing that is installed where there is rotational movement between the outer shell and the inner support, the rubber flexes between the two parts as one would expect from the design. Polyurethane does not flex, but allows rotation so the moving surfaces must be very smooth to allow movement with out excessive wear.
A flaw in many Polyurethane suspension pieces. I suspect the amount of noise transmitted to the body is non-critical with rear leaf springs but have made it a habit to only use polyurethane only when rubber parts are no longer available or have a specific need for polyurethane. |
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70 390 5spd Donohue
74 Hornet In restoration 76 Hornet, 5.7L Mercury Marine Power 80 Fuel Injected I6 Spirit 74 232 I-6, 4bbl, 270HL Isky Cam |
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Red Devil
AMC Addicted Joined: Jul/10/2007 Location: Canada Status: Offline Points: 1743 |
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Urethane can be compounded in many durometers from bowling-ball hard to soft as a sponge. Aftermarket urethane bushings are often made in a higher durometer than rubber bushings to reduce deflection and allow the springs and dampers to do their job, rather than deflecting the bushings excessively first (rubber or urethane bushings act as both a spring and damper ... higher durometer = stiffer spring & less damping, lower durometer = softer spring).
I have urethane shackle bushing and it made a noticeable improvement over stock rubber ... but expect rubber replacements would have also made an improvement. Not too harsh to me, but everyone has their own preference. Biggest thing is to make sure you tighten the bolts when the suspension is in its normal loaded condition so you don't induce unwanted pre-load in the bushings ... with rubber or urethane. If you want something tunable for comfortable ride or better handling, fit adjustable dampers (adjustable shock absorbers). Hope this helps,RD. |
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jetnoise
AMC Apprentice Joined: May/09/2008 Location: NC Status: Offline Points: 106 |
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Red .... Agreed! was going to go with Bilstein shocks this time, the kyb's I've used in the past aren't my preference.
I have used KYB's up front and their GR-2 in the back before and that wasn't to bad. |
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