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Non-binding RCA Bushings?


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The 40 year old rubber in my 510 rear control arm bushings are pretty beat. I still have my Energy Suspension poly bushings from forever ago that I can replace them with, but I have plans to install Byron's adjustment kit. I keep hearing about the poly bushings binding due to the hardness of the material and that only rubber or rod ends should be used. I'm still not clear on how they bind though.


Yesterday, MotoIQ posted some poly bushings by SuperPro they are putting in their WRX project and are stated to be "engineered" to reduce binding. Should this be done to standard poly bushings or is this just a bad idea for the 510? I know about the drilling of the tension rod bushings to allow some flex, but I think the drilling would just get torn up in the rear bushings. Any thoughts on this? Is it even worth it to replace the rubber with any other material in a street car?



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I've installed poly on a number of cars and had no complaints in general. There is the obvious increase in NVH levels inside the car, but if you accept that, then it's no different than accepting the stiffer ride of a lowered car. Certain bushings, like the tension rod, shouldn't be used without modification, and on a street car that doesn't push its suspension, I've personally never felt there was an issue with binding and stress on most bushings.

That being said, I don't think there would be a single problem caused by drilling rca bushings like the tension rod. If you're worried about the edges of the holes catching, counter bore them a little. And tighten them in to place with the suspension sitting at ride height.


Those flattened sections could work, it gives the material somewhere to deflect to. At least I assume that's the purpose.

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From what I understand, the binding in the control arms comes from the adjustment bracket (Byron, Maddat, Datsport etc.) and the missalignment of the arms to the stock bracket. They are no longer rotating on the same axis and needs some deflection. I'm certainly no expert and I'm trying to understand this. But if we could put some deflection into the polyuerthane bushings, then they would be more useful and help our cars to survive our need to modify the suspension.


My thought with the drilling of the RCA bushes, is that the twisting action might cause them to rip. I believe this is what happens anyways when they bind. I might just take a chance and do the poly bushes and order more when they eventually tear apart. But all of this is a ways off. I'm just preparing for the future.



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