Polyurethane vs rubber for rear leafs

[donw1986]

Restoring my 86 short bed , have new factory style leaf springs for rear, wondering which is a smoother ride , poly or rubber? I am keeping it at stock hieght and putting in a 300 hp crate motor so would like to have a good suspension but not a rough ride

[Pontiac1976]

If your just doing the leaf springs and you do not have a heavy leaf set up heavy duty shocks set up it should be firmer. I did 76 Pontiac no frame poly there. it's a little bit rougher but so much more firm.
I switching over to ploy on the Truck every thing but the body to frame conversion. They are front wheel k frame vans rubber mounts for the last 10 yr.
I run 8 leaf +1 helper 77 half ton fleet med smooth ridding shocks. So is rougher mostly because the amount of leaf's my tighter dropped k-frame rubber mounts. As far a the ride with poly on leaf's I do not know yet.
If when it become bad ride for me. And I want a smother ride I then may change to bag helper set up for the smoother ride.
You could put air shock on the rear and play with the psi to soften the ride to take out the roughness.

[Shugalou]

I put Poly's in my leafs and when I took them to get re-arched the guy asked why i went poly. I told him I thought it was supposed to be better and he said in his drag truck a poly bushing broke and sent him to the wall. I'm not dragging my truck so that is less of a concern to me but I figured I would add his story for ya to consider.

[donw1986]

Thanks for the reply, im not dragging my truck either but did you notice a difference over the rubber in the ride quality

[cadillac_al]

I have used poly trans mounts and they all crack in just normal driving. I'm not sold on the durability.

[Tom]

Poly is extremely hard and much more ruff riding then rubber, its a well known fact. You do not want it.

[Justins76]

I've removed just about all the poly bushings I've ever used and gone back to rubber, even on my Firebird. The streets here are in a constant state of disrepair, so I need the rubber to try to attempt to get somewhat of a compliant ride. I say stick with rubber, poly is too harsh for the street.

[Shugalou]

Everything was shot when I replaced it and I redid the entire suspension including shocks so I didn't have a good baseline to compare it too, but the ride is fine. Keep in mine that I only did poly for the leafs so doubt it would be very noticeable. I'm sure cab mounts might show a bit more of a difference

[SBTork]

Originally Posted by Justins76

I've removed just about all the poly bushings I've ever used and gone back to rubber, even on my Firebird. The streets here are in a constant state of disrepair, so I need the rubber to try to attempt to get somewhat of a compliant ride. I say stick with rubber, poly is too harsh for the street.

I could not agree more. Poly is much too harsh for the street. I've had poly control arm bushings in my Suburban for 5-6 years now and I'm totally over it. I got some junkyard control arms, going to restore them with new rubber bushings and install them. Poly will rattle anything and everything, even going over a pebble is noticeable.

[Kudzupatch]

Someone put poly bump stops on my Suburban and it was no different that hitting the frame when it bottomed out. For a street car I wouldn't use them except in the sway bars.

[lilpoindexter]

Poly bushings squeak...super annoying. I put them on a car I built in the 90s, and hated it. Now i only put poly bushings in the sway bars...no where else...maybe a bump stop...but definetly no where in the suspension or engine or trans mounts.

[MikeB]

I don't remember the last time I used a rubber mount or bushing for anything. The cab mounts on my son's 69 C10 have been there since the mid 1990s and look like new. Also, I drove a 55 sedan another 8-10 years after installing poly control arm and sway bar bushings. So naturally, I used them when I rebuilt the front end and installed new rear leaf springs on my square. They especially hold up well on sway bar end links that see a lot of forces in multiple directions. I seriously doubt any additional harshness will even be noticed in a pickup. What you WILL notice is less wallowing, quicker steering response, less body movement, etc.

That said, there may be some China-cheapies out there that don't hold up well, but I mostly use Energy Suspension, and I think the 69 C10 stuff was Prothane.

[Pontiac1976]

Ok my 2wd 1/2ton 77 truck was use all year around in 1990 w/77 bushing they suck sloppy wore out lots of body roll w/ 235/75/15 factory 6x7 rallys. I change the body mounts 94 to K-frame mounts witch are a little harder rubber then 77
just the top hat so I dropped about a 1-1/2 on the body the all steel flat bed frame. In 2007 I started working on the bushing and everything else, what I want or option I like. I drive a car or truck I push it ever turn they come to on snake road I come to. most of my cars or trucks are Heavy .I had drill out a few sway bar bolts broke off over the year in the truck the old and new rubber do not hold up to in the sway bay as long on my truck for my driving. I have changed about 8- 1/2set out. Tires height and your suspension have to work to getter if you want smooth ride more side wall lighter shocks slow to med pop back will give you smoother ride, start to loose handling. on the stock suspension So it really how much you want put up with one way or the other. smooth ride sloppy ------middle------ harsh better cornering. My truck was set up very harsh for 1500 lbs trailer 4200 lbs car I was pulling 8 leafs 1helper drove pretty smooth with the trailer and car but when I had the truck by it self drove harsher then a school bus I drove it like that for 6yr trucks weight 5600lbs. Your never going to get a car ride out stock 73-90 truck So wise tire size body bushing, shocks ( oil, gas, air,) good parts(newer) that what side of the middle you can live with the best. speaking of air shocks they might be the best adjustable to some one tire size for smoother ride. But most truck air shocks are set up for loads. If they had air shocks that had dual setting air in lets for up and down this would help most any one truck with just tire side wall size.

[Palf70Step]

Only issues I have had or seen with poly bushing in suspension is squeaking, unless they have zerk (grease) fittings to keep them lube. They do stiffen the suspension some, but not really noticable differences if the rest of the suspension is good.

I will NEVER use poly for body mounts. Too many friends I know end up with cracks in the body sheet metal. Now this is for trucks/cars that are street driven, a lot, on good and bad roads. Poly just doesn't absorbed enough flex to not damage sheetmetal. If it is mostly a trailor queen or seldom driven, or seldom driven hard, then probably OK. I prefer the rubber though on suspension just because I don't like the squeaks and less grease fittings to look after.

[MikeB]

Bill -- I can honestly say I've never had a squeaky poly bushing, but have always used the supplied/recommended grease liberally on installation.

As for cab mounts, I used poly on the 69 C10 because the brand new GM bushings I bought at a Chevy dealer started to crack after just a couple years. Maybe they were NOS, with an emphasis on the "O".

Since then (the 1990s), I've only checked the poly mounts themselves, not the floor sheet metal, but I'd bet dollars to donuts the floor is fine. Also, isn't the metal double thickness at those points? Or did the cracking occur at other places?

Do your friends' trucks see a lot of jarring off-road use? And what's the general condition of the cab sheet metal?

[Palf70Step]

Some were 4x4, others just bad roads, and some are doing the parking lot ralleys (forgot what they are called - autocross??). And yes most of the cracking is where the double plate meets the regular sheet metal.

[Tom]

I put poly cab bushings on my 79 c10 here in AZ, no frost heaves or potholes to deal with. They were terrible. I use poly for sway bar bushings and that is all.

[Rich84]

I have poly cab mounts for about 5 years. When I put them in I did not notice a difference compared to the old dry-rotted rubber ones. I was only looking to level the body, not really expecting a change in the ride. I added a sway bar with poly bushings and it made an amazing difference in handling.

[MikeB]

Originally Posted by Rich84

I have poly cab mounts for about 5 years. When I put them in I did not notice a difference compared to the old dry-rotted rubber ones. I was only looking to level the body, not really expecting a change in the ride. I added a sway bar with poly bushings and it made an amazing difference in handling.

When I did that on the 69 C10 I mentioned above, the only difference I noticed is the cab hasn't sagged since then (around 25 years).

Pick your poison. And remember, we're talking about trucks here not Cadillacs.
https://www.suspension.com/blog/rubb...sion-bushings/

[Wikid61]

https://p-s-t.com an impregnated or hybrid rubber & poly material. I like them on my Impala, but have yet to install them on my C-10.