Sway bar end links - what's the deal? . . . .

[mikedc]

In the last century the end links were all little rubber donuts. Now on modern stuff they are commonly using little ball joints. I assume the ball joints make a noticeable improvement since the OEMs are paying the extra cost.

What about the poly versions of stock rubber end links? Do they feel any tighter than (fresh) rubber? How do they hold up over time?



Any thoughts?

[Hotwire]

In my experience the poly end link bushings have a higher durometer rating, meaning they're harder and they "tighten"up the sway bar response. But for some reason I haven't been able to make poly last long.

[mikedc]

Is there really a detectable difference between rubber vs poly end links? Or is it just an assumption? Poly sway bar stuff is usually installed during a bigger poly chassis rebuild.

How do the poly ones fail? I know poly items tend to crush down a certain amount (which is partially why the OEMs don't use them). Is that the problem on poly end links?

I'm surprised there is so little info on the net about this. There are 20 years of discussions about control arms and body mounts.

[Mr Nick]

I've never seen any legit back to back testing between rubber and poly end links. I'd bet lunch that the car has to be otherwise very well dialed in and consistent, along with a skilled driver..., to notice any different between the two. However, poly does deflect less than rubber so one can assume the sway bar will see a load sooner when cornering compared to rubber, so on paper they should be better and become a "may as well" type upgrade.

That said, I like this and would probably go this route in the future:

[mikedc]

Those are interesting.

Honestly, my instinct is to doubt there is any real-world gain to be had over stock rubber end links. But the OEMs have switched to little ball-jointed links on so many cars. Those look more expensive than rubber. The OEMs made the switch for a reason.

[83hurstguy]

Cost on the part is one thing, but you have to consider the assembly line aspect, too. New style end links have an assembled joint and two nuts. The old school assembled stack of parts was a recipe for a mess - assembler drops parts everywhere, stuff goes in out of order and causes an issue, etc.

Anytime you can allow the compliance you need while eliminating the compliance you don't need, it's a win-win. High end sway bars either use rod ends/heims or the OEM style links, so I'd say you have a design with a more responsive roll control with minimal NVH impact.

[mikedc]

That does sound plausible. The simpler assembly process.

But I still wish there was some back-to-back testing on this. Rubber, poly, and ball-jointed.

I suppose it would raise the next question - how much flex is coming from the main sway bar mounts (the center section of the bar that twists)?

[streetk14]

ridetech uses delrin bushings on the sway bar kit I got from them. No OEM is going to use poly due to its NVH characteristics. Mostly the squeaking issues and the requirement to keep them lubed. Delrin has lubricating properties and doesn’t need to be greased, while also having very little deflection. But take a look under something like a new BMW M2, and you won’t see anything like that. Bushings are rubber usually, but a lot of thought and engineering goes into the compound to balance handling and NVH.

That said, I’d run an OEM ball joint style link if given the option. Years ago I had a set like that on my ‘67 that I got from air ride (now Ridetech). I won’t use any poly on my car these days. Everything I have is either delrin or R-joints. All depends what you’re going for.