Bushing Durometer (Hardness) (1 Viewer)

[ryanwk628]

I am acquiring parts to replace my springs and want to take out some of the harshness, so bushings is one component I have been researching. I considered rubber but as I already have greaseable shackles and pins felt am inclined to stick with poly. Also I would not have to borrow the special tool from the local parts store.

Poly vs Rubber:

All of this results in a highly increased lifespan, lasting as long as the car does for many owners. On the Shore hardness scale, rubber bushings read between 18A and 60A (similar to a pencil eraser), while Polyurethane usually resides in the 80A to 95A range (similar to a skateboard wheel). Since the bushings reside in areas of movement in the chassis and suspension system, different hardness materials will affect both comfort and vehicle handling. With polyurethane filling these areas, the joints and linking points in the suspension have less cushion to impact and torsion. This ultimately translates more details of the road surface into the chassis, providing a stiffer ride. Whether or not car owners prefer this change all comes down to personal preference.

Polyurethane is typically measured on the Shore A scale and can be anywhere from 0 to 100.

Depending on where you look, poly bushings can range from 62 (softer than a tire) to over 100 (harder than a shopping cart wheel.) That link is a good interview with Energy Suspension. CCOT, speaking more narrowly about spring bushings says 65 (soft) to 88 (hard) is typical, and that makes sense.

It would make sense that softer bushings are less harsh, deflecting and dampening vibrations. However harder bushings would likely have a longer service life (when they are not asked to deflect too much) and provide more "road feel." I'm looking for softer myself but want to share this information as I find it.

Bushing and Shore A Durometer

CCOT HFS Poly - 80
Energy Suspension Hyper Flex - 95 (per their tech support)
Skyjacker - 88
OME - TBD
Terrain Tamer Pro bushes - 85
Ironman - approx. 95 (described it as skate board wheel)
SOR - TBD
OE Rubber - Typically around 60 but can harden over time towards 70

Red vs Black?
Quote From Energy Suspension's Official Website:

"Both are our Energy's HYPER-FLEX™ performance polyurethane formulations. Energy has impregnated selected black polyurethane components with graphite — to add a lubrication property.

If anyone has any additional data please let me know and I will add it, thanks!

Edit: I will be updating this as I get more info

 

[WarDamnEagle]

If you were talking the suspension of a Ferrari or other supercar then I would say it would matter. In a 40? I seriously doubt you could tell the difference between 60 and 90 durometer bushings. They're leaf springs. Now you might be able to dampen some of the vibration and tell a difference with the body mounts. Just my thoughts.

 

[ryanwk628]

If you were talking the suspension of a Ferrari or other supercar then I would say it would matter. In a 40? I seriously doubt you could tell the difference between 60 and 90 durometer bushings. They're leaf springs. Now you might be able to dampen some of the vibration and tell a difference with the body mounts. Just my thoughts.

Im getting rid of my rough country lift with the goal of making the ride better. It is terrible right now, and yes, a lot of that is overarched springs and bad shackle geometry. I don't expect bushings to take out bumps, but I do want them to flex when I need them to. People replace a flexible rubber bushing with a rigid poly one, along with drilled pins for grease and people wonder why they brake off road. There's a big difference in hardness between a car tire and a grocery cart wheel. I do know rubber helps dampen vibrations from having been in cars before and after that replaced rubber with poly, and would be inclined to go with rubber except I already have the greaseable hardware, so I'm looking for the softest poly I can find.

They are relatively inexpensive so why not?

 

[WarDamnEagle]

Im getting rid of my rough country lift with the goal of making the ride better. It is terrible right now, and yes, a lot of that is overarched springs and bad shackle geometry. I don't expect bushings to take out bumps, but I do want them to flex when I need them to. People replace a flexible rubber bushing with a rigid poly one, along with drilled pins for grease and people wonder why they brake off road. There's a big difference in hardness between a car tire and a grocery cart wheel. I do know rubber helps dampen vibrations from having been in cars before and after that replaced rubber with poly, and would be inclined to go with rubber except I already have the greaseable hardware, so I'm looking for the softest poly I can find.

They are relatively inexpensive so why not?

I probably didn't explain my thoughts very well. By all means replace your springs, shocks, and bushings. I'm just saying for a given set of springs and shocks on an FJ40 don't expect to find any discernable difference by bushing durometer hardness assuming said bushings fit properly and are of good quality. Also if you think softer poly is the ticket then I see no harm in going that direction. I would put most of my research into the shocks and springs as I think that's where you will be able to move the needle on ride quality.

 

[ryanwk628]

I probably didn't explain my thoughts very well. By all means replace your springs, shocks, and bushings. I'm just saying for a given set of springs and shocks on an FJ40 don't expect to find any discernable difference by bushing durometer hardness assuming said bushings fit properly and are of good quality. Also if you think softer poly is the ticket then I see no harm in going that direction. I would put most of my research into the shocks and springs as I think that's where you will be able to move the needle on ride quality.

Thanks, I think I have a plan for shocks and springs. Skyjacker soft rides which seem to have great shackle angles out of the box with Bilstein's up front and OE style longer shocks (T100 I think) in the back since not much goes on back there. I have the shocks, hardware and am reusing my shackles and pins. Bushings were the last outstanding part and I was really leaning towards rubber for a lot of reasons. I just ordered some poly bumpers for my swing out tire carrier build from McMaster and the wide range of durometers (30 to 100) sent me down the poly bushings rabbit hole lol. Since Im not chasing "road feel" and couldn't find any info I figured I would post it here

 

[peesalot]

All I can say is that if off roading mildly or aggressive the rubber(softer) bushings will split and distort quickly, the greasable pins usually have edges where they are milled to let grease in, those edges cut the soft bushings. IMO use urethane and get it soft with springs and shock combo. Although the softer bushing lets the spring twist a bit more letting it articulate a bit more.