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flex joint vs. poly vs. rubber

L

lankchevy

NAXJA Forum User
Location
sw mo
when i bought my new lca's a while back, i asked for some RE lcas with a flex joint, the owner said he didnt stock them anymore and only stocked them with poly bushings, i asked why and he told me that he had numerous complaints about the flex joints not flexing as good as the polys did in peoples rigs. after we talked for a while i ended up buying a set of bds lca's with poly bushings at each end.(exact same as RE fixed lca's and $30 cheaper) when i went in wanting more expensive RE flex joint lca's. so my question is, what is everyones opinions on the flex joint vs. a poly bushing vs. rubber bushings? with YOUR experiance is there realy a differnce? im going to build new uppers in the near future and thought i would ask to see if i should invest in some flex joints for them.

kolby
 
i dont know, i was asking to see what everyones opinion was, aparently your opinion is the guy is on crack. lol. have you had flex joints and poly joints on a rig with the same springs and everything else before? was there realy a differnce, because my xj has quite a bit of flex and the polys dont seem to be having a problem with it, there are about 3 things that look like they are limiting my flex before the bushings.
 
I've never had a flex joint so I can't comment on those. But I've had poly joints for 4 years now and rubber for several years before that. I like the poly. My joints aren't what limit my flex and my front and rear suspensions are balanced really well. The poly has a good feel to it too, not too much give but not harsh either.
 
Poly sucks,Rubber is better than that!No way to compare them to flex joints!
 
i would think that as long as your polys werent what was limiting your flex, then there would be no diff between polys or flex joints. so in other words unless you have a buggy with insane twist, then flex joints are kind of a waste of money. but i could very easily be wrong. has anyone switched from poly to f/j control arms(everything else the same only control arms differnt) and have some kind of accualy data to back u the differnce?

kolby
 
I never tried both, but when i had my MJ lifted 5" with RE springs, RE trackbar and bracket, RE uppers with flex joint and ProComp lowers with POLY bushings the flex sucked! I checked the steering, trackbar, shocks, brakelines, driveshaft, LCAs hitting.... nothing was binding. The only thing I could figure it was was the Poly bushings in the LCAs.
 
When I first tried some Pro-Cr^p arms' I ate the bushings(sleeves also) up every other weekend!
 
My opinion would be a "best of both worlds" setup for a DD/TR.

use a superflex on the axle end and use the rubber or poly on the frame end. the Rubber gives you a better/smoother ride while still flexing. the superflex transmits a lot of road noise in the the vehicle. but it flexes really well.
 
Rawbrown said:
the Rubber gives you a better/smoother ride while still flexing. the superflex transmits a lot of road noise in the the vehicle. but it flexes really well.
Click to expand...


I was waiting for this to come, have you experienced this so-called road noise and vibration from having non-rubber joints? Or do you think this is what happens just because others say this?

I have the RE arms with rubber one end, joint other. Noticed nothing different from stock with one less rubber end. My brother has a poly (Johnny Joint) and heimed suspension...still notice nothing different. It's all a freaking joke in my opinion. I read the same statement everywhere I go.

Maybe in a honda or something you can notice a difference, but with any of our modified jeeps, it's all in your head.
 
gearwhine said:
Maybe in a honda or something you can notice a difference, but with any of our modified jeeps, it's all in your head.
Click to expand...

Last time I checked, my ears are in my head and that's exactly where I can tell the difference. I attribute it all to really good batteries in my Miracle Ear.

Ron
 
yes I experienced it first hand. I went from stock LCA's to custom LCA's with RE superflex joints on both ends. I hear and feel a lot more road noise now than with stock. FYI, all of RE's contorl arms utilize rubber at one end. Poly is still soft compared to a heim and as such it will still absorb shock loads/road noise.



gearwhine said:
I was waiting for this to come, have you experienced this so-called road noise and vibration from having non-rubber joints? Or do you think this is what happens just because others say this?

I have the RE arms with rubber one end, joint other. Noticed nothing different from stock with one less rubber end. My brother has a poly (Johnny Joint) and heimed suspension...still notice nothing different. It's all a freaking joke in my opinion. I read the same statement everywhere I go.

Maybe in a honda or something you can notice a difference, but with any of our modified jeeps, it's all in your head.
Click to expand...
 
gearwhine said:
I was waiting for this to come, have you experienced this so-called road noise and vibration from having non-rubber joints? Or do you think this is what happens just because others say this?

I have the RE arms with rubber one end, joint other. Noticed nothing different from stock with one less rubber end. My brother has a poly (Johnny Joint) and heimed suspension...still notice nothing different. It's all a freaking joke in my opinion. I read the same statement everywhere I go.

Maybe in a honda or something you can notice a difference, but with any of our modified jeeps, it's all in your head.
Click to expand...
Just took the Superflex joints out of the axle end of my U&L arms, couldn't take the shock and the noise. Damn front end felt like it was comming apart on dirt roads. I sure as heck felt the difference when I put the RE arms and stock rubber back in yesterday...


--ron
 
If your asking about RTI#'s,who cares!You can "force" any thing to flex,that includes the CA mounts and the entire Uni-body(start looking for stress cracks).My PC arms flexed good they just cost 25$ a week to maintain!And they were doing alot of damage to the mounts!
 
what kind of #'s do you need? the differences between flex and rubber joints need to involve some of the basic characteristics of the two.

Rubber acts as an Isolator, it doesn't transmit much road noise because it can deflect or "distort" during the "shock" and then return to its original shape. it allows for several degrees of misalignment which again is distortion while it has a memory. this is rubbers ability to return to its original shape. so its going to resist against flex but it will allow it.

now flex joints, rod ends, heims, and johnny joints are what I would consider "hard" joints. they can provide high degree's of misalignment and exelent durability. but they will not absorb any shock.

here's how you can compare the two... jump with your knees bent when you land. your knee's absorb the landing. now jump again with your knees straight when you land and don't let them flex. Hurts right?... right...

now there is something else to consider, when you flex your front axle, the geometry changes on either side. the side that drops wants to twist. this changes the distance between two of the control arms a little bit. its much easier to have rubber to deflect enough to compensate for the change. thats why guys like Goatman have removed one of there upper control arms.

theres a few things to think about...
 
Rawbrown said:
what kind of #'s do you need? the differences between flex and rubber joints need to involve some of the basic characteristics of the two.

Rubber acts as an Isolator, it doesn't transmit much road noise because it can deflect or "distort" during the "shock" and then return to its original shape. it allows for several degrees of misalignment which again is distortion while it has a memory. this is rubbers ability to return to its original shape. so its going to resist against flex but it will allow it.

now flex joints, rod ends, heims, and johnny joints are what I would consider "hard" joints. they can provide high degree's of misalignment and exelent durability. but they will not absorb any shock.

here's how you can compare the two... jump with your knees bent when you land. your knee's absorb the landing. now jump again with your knees straight when you land and don't let them flex. Hurts right?... right...

now there is something else to consider, when you flex your front axle, the geometry changes on either side. the side that drops wants to twist. this changes the distance between two of the control arms a little bit. its much easier to have rubber to deflect enough to compensate for the change. thats why guys like Goatman have removed one of there upper control arms.

theres a few things to think about...
Click to expand...


Oh what do you know about Rubber anyway. ;)
 
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