Topic: Why Poly Bushings?

[Plainview]

I'm trying to wrap my head around why you'd use poly bushings instead of stock rubber type.

Poly doesn't compress nearly as well as rubber, which would be bad for articulation, right? When the axle rises more on one side than the other then the spring is trying to twist in the shackle and poly will resist that far more than rubber would.  What am I missing here?

[SqWADoosh]

It is tough. Doesn't fall apart.

[Plainview [OP]]

So I guess it's an issue when you're crawling regularly...?  The stock bushings with 210K+ miles in my truck were in fine shape.

[Snowtoy]

I'm trying to wrap my head around why you'd use poly bushings instead of stock rubber type.

Poly doesn't compress nearly as well as rubber, which would be bad for articulation, right?

The amount of difference in articulation would only be measurable on an RTI ramp, if that, on a trail it would make no difference.  The cost of oem rubber bushings(if you can even find them) is why most go to poly when they need to replace rotted ones.

[H8PVMNT]

I use rubber bushings on my 1980 pickup and they definitely allow things to squirm around more.  The drawback is that if your suspension allows a bunch of flex they tend to have a fairly limited life expectancy.  This particular truck has a low slung rears up front setup and nice long shocks, so it gets tons of flex and it requires new bushings in the front maybe every 3 or 4 years.  They are shot right now in fact, I need to replace them.  I get replacements from Napa for like $2 a piece.

My 4runner has a more typical tall, flexy suspension and I use poly on it because the springs flex extremely well for themselves and the taller, heavier vehicle really benefits from the stiffer poly bushings for handling. I have had the same poly bushings on it for about 12 years and they are still good.

So yes, rubber helps a bit, but it really depends on the intended use of the truck.  If it's stock-ish then rubber is a good choice for smoother ride and a bit more flex from an otherwise inferior setup.  If you are getting a bit more, then poly.

[emsvitil]

Rubber bushings are bonded to the outer shell and inner sleeve.

So with lots of flex they'll eventually get torn apart.

Poly bushings are not bonded.   They'll rotate in the shell or on the sleeve (most likely the sleeve)

[H8PVMNT]

Mine are two piece rubber not bonded to anything. It depends on the year I think though.  I have seen the bonded ones on later model rear leafs.

[Plainview [OP]]

Thanks for the info!

The rubber bushings were only bonded at the front eye of the leaf springs - they were not bonded at the shackle end on my standard cab truck and they all came out easily.  I wish I'd saved them now, but I bet the bushings in the X-cab are fine.

I'm going to swap the new OME springs into the new X-cab truck and put the stock springs back on the standard cab before I sell it.  I put 5" shackles on the standard cab when I installed the new springs but honestly that truck sits up a little higher than I want it so I think I will just stick with the stock shackles in the X-cab and leave the long shackles in the standard cab.  Was wondering whether I really needed to go poly bushings for any particular reason but think I will stick with the stock rubber.  I know this forum is really for modified rigs and crawling so my tastes are a bit different from most people on here but I really want to keep as comfortable a ride as possible on the Xtra Cab and only lift it the 2.5" or so the OME springs and slightly taller tires provide.

I gotta hand it to Toyota - they really knew how to make good rubber back in the '80s.  All the vacuum and fuel hoses on both trucks were all still in great shape, too.

[emsvitil]

Rubber has some weird properties........

This was with IFS, but should apply.

I drove for miles and miles on a utility road (worse than washboard) and when I finally got back on pavement my steering wheel was no longer centered when going straight.     After a couple of days the steering wheel drifted back to being centered.

Didn't have the steering wheel centering problem after replacing all the suspension bushings with poly

[Plainview [OP]]

Whoa, that's weird.  Shouldn't be an issue with a solid axle though.

[H8PVMNT]

Rubber has some weird properties........

This was with IFS, but should apply.

I drove for miles and miles on a utility road (worse than washboard) and when I finally got back on pavement my steering wheel was no longer centered when going straight.     After a couple of days the steering wheel drifted back to being centered.

Didn't have the steering wheel centering problem after replacing all the suspension bushings with poly

I used to get that same stuff with IFS.