Bushings: top vs bottom. What does each do?

[Bold]

I saw some discussion about running different hardness top vs bottom bushings and that made me realize I don't know what each bushing does. In my mind they both do the same job but if running different hardness top vs bottom makes a difference, that's obviously not right but why? What is each bushing doing as you lean to one side and as you return to the middle?

[Loki700]

I could be wrong, I haven’t sat down to draw a FBD, but the bottom bushing is the one that supports your weight, and that’s really the main difference.  It makes sense to me that they would work together for turning, but if the bottom one is stiffer, then it would make the top one deform more while it deforms less.

I’ll think on this more and actually draw a FBD and get back to you on whether I change my mind.

[rob]

Also which side of the cylinder/barrel bushing contacts the hangar and which side contacts the baseplate/washer?

There’s a round edge with a smooth side and there’s a machined side with circle grooves on the surface with sharp edges and I always wonder which side is the proper setup

[Bongwater Mojito]

Also which side of the cylinder/barrel bushing contacts the hangar and which side contacts the baseplate/washer?

There’s a round edge with a smooth side and there’s a machined side with circle grooves on the surface with sharp edges and I always wonder which side is the proper setup

Recently set up some aftermarket bushings, and noticed that Independent stock bushings were installed so that machined side was facing the board in both top and bottom. Installed bottom first the other way, got some squeaking, so flipped it. Squeaking gone. Cannot be sure if it was just bushings breaking in or if the adjustment actually had effect. Theoretically the circle grooves against hanger could make some noise in bottom bushing, as it has all the weight on it, right?

Anyway, now when they're good, not going to touch them... Avoiding truck madness as long as possible.

[GBLange]

i think bottom is for turning and top is for aligning it back level/straight..i think..

[Xen]

https://shopmonkey.wordpress.com/2018/03/20/hi-kids-im-a-bushing/

[Xen]

Also which side of the cylinder/barrel bushing contacts the hangar and which side contacts the baseplate/washer?

There’s a round edge with a smooth side and there’s a machined side with circle grooves on the surface with sharp edges and I always wonder which side is the proper setup

I honestly don't think it makes fuck all of a difference, the rounded lip sure looks better on the washer side, but neither the straight or rounded edges actually touch the 'rim' of the yoke or the edge of the washer. I think this is one of the 'reading too much into it' holes we fall into and is just a byproduct of manufacturing (like treads on wheels that are only there because of the molds). Also, plenty of barrel bushings don't have a rounded edge at all.

[Bold]

I thought the treads on the wheels were there from having the final outer diameter machined on a lathe type machine.

[Xen]

I thought the treads on the wheels were there from having the final outer diameter machined on a lathe type machine.

I guess? Either way, they are part of manufacturing and not something to be 'concerned' about in terms of do they affect the wheel any (I mean, they do at first but once the treads are gone they just like any other wheel).

[Bongwater Mojito]

I honestly don't think it makes fuck all of a difference, the rounded lip sure looks better on the washer side, but neither the straight or rounded edges actually touch the 'rim' of the yoke or the edge of the washer. I think this is one of the 'reading too much into it' holes we fall into and is just a byproduct of manufacturing (like treads on wheels that are only there because of the molds). Also, plenty of barrel bushings don't have a rounded edge at all.

I guess very few if none would pass a (double) blind test with bushings in different positions. It's interesting question would anyone distinguish between, say 88A and 90A, for that matter. As you said, it's easy to fall too deep into those speculations.

[rob]

Expand Quote

Also which side of the cylinder/barrel bushing contacts the hangar and which side contacts the baseplate/washer?

There’s a round edge with a smooth side and there’s a machined side with circle grooves on the surface with sharp edges and I always wonder which side is the proper setup

[close]

I honestly don't think it makes fuck all of a difference, the rounded lip sure looks better on the washer side, but neither the straight or rounded edges actually touch the 'rim' of the yoke or the edge of the washer. I think this is one of the 'reading too much into it' holes we fall into and is just a byproduct of manufacturing (like treads on wheels that are only there because of the molds). Also, plenty of barrel bushings don't have a rounded edge at all.

What I have found is the round edge contact against the hanger helps get a more smooth and quick mush response but the sharp edge is tighter and more stable but I remembered which way the bushings face

You are right some bushings don’t even have a round edge and they’re machined both sides

And cone bushings only go 1 way

So that means sharp edge roadside and round smooth edge facing the washer

[Xen]

Expand Quote

I honestly don't think it makes fuck all of a difference, the rounded lip sure looks better on the washer side, but neither the straight or rounded edges actually touch the 'rim' of the yoke or the edge of the washer. I think this is one of the 'reading too much into it' holes we fall into and is just a byproduct of manufacturing (like treads on wheels that are only there because of the molds). Also, plenty of barrel bushings don't have a rounded edge at all.

[close]

I guess very few if none would pass a (double) blind test with bushings in different positions. It's interesting question would anyone distinguish between, say 88A and 90A, for that matter. As you said, it's easy to fall too deep into those speculations.

In the same truck, New/stock I bet I could tell with Indy 88a/90a (only because that’s what I ride) duros; broken in, doubt it. Flipped? No way.

No way I’d be able to distinguish same duro dlx bait and tackle (both sides machined) from Indy either, but I bet I could with ACEs dual duro bushings.

Comparatively, dlx stock bushings are the weakest these days. Sure they work, but after you experience better rebound in Thunders it’s hard to go back to mush.

[rob]

Expand Quote

Expand Quote

I honestly don't think it makes fuck all of a difference, the rounded lip sure looks better on the washer side, but neither the straight or rounded edges actually touch the 'rim' of the yoke or the edge of the washer. I think this is one of the 'reading too much into it' holes we fall into and is just a byproduct of manufacturing (like treads on wheels that are only there because of the molds). Also, plenty of barrel bushings don't have a rounded edge at all.

[close]

I guess very few if none would pass a (double) blind test with bushings in different positions. It's interesting question would anyone distinguish between, say 88A and 90A, for that matter. As you said, it's easy to fall too deep into those speculations.

[close]

In the same truck, New/stock I bet I could tell with Indy 88a/90a (only because that’s what I ride) duros; broken in, doubt it. Flipped? No way.

No way I’d be able to distinguish same duro dlx bait and tackle (both sides machined) from Indy either, but I bet I could with ACEs dual duro bushings.

Comparatively, dlx stock bushings are the weakest these days. Sure they work, but after you experience better rebound in Thunders it’s hard to go back to mush.

What bushings do you recommend in thunders?

[Xen]

88a concials, shaved top to get the nut flush.

Indy or riptide or venoms

[rob]

88a concials, shaved top to get the nut flush.

Indy or riptide or venoms

Gnarred

Thanks I have a set of Indy 88a cones too on stand by when I was using in my Indy mids but over the mids cause eh

Thunders hit my skate preferences better

[Obijuan91]

So did any one ever figure out what too bushing vs bottom bushing does? Bought some Indy 94s but they were too tall for some reason so I kept the 94 top and the stock bottom, wondering what’s the science here since ace runs it

[Chavo]

Bottom bushings hold most of the load. Tops keep the hanger level.

Rodney Mullen once said that the top bushing mainly keeps the truck from falling off and not much else. He advocated using a harder top bushings as was the general preference for most of the '80s (bottoms and tops were sold separately).

[Uncle Flea]

Bottom bushings hold most of the load. Tops keep the hanger level.

Rodney Mullen once said that the top bushing mainly keeps the truck from falling off and not much else. He advocated using a harder top bushings as was the general preference for most of the '80s (bottoms and tops were sold separately).

I can see that. Back in the late gk kingpin era. When we resorted to aftermarket extended king pins.  I did the opposite to be all dumpy dumpster trucked. Hard bottom whatever you got for the top that jingles and sounds like trash when you Chinese Ollie and scrape nose off every curb in a line with the posse.

I still do it but I slide my front truck on the curb an piv to continue switch to my front door. I got a route.

[Bongwater Mojito]

Isn't it so that harder top bushing is supposed to cause a snappier return to center, as most of the weight is still on softer bottom bushing? I tried this recently on Ventures, did not feel a noticeable difference between stock both (90a) vs. Indy 78 bottom + stock top.

[rikki]

Regarding the difference between the top and bottom bushings: bear in mind that the height of the bottom bushing affects the overall truck wheelbase, whereas the top bushing has no effect on wheelbase. This is all regardless of durometer/hardness. Durometer of course has no effect on wheelbase, duh.

Case in example: replace your bottom bushing with a taller one, and you'll end up with a (tiny bit, but still) longer effective wheelbase. Replace it with a shorter one, and voilà, the wheelbase diminishes.

The top bushing height mainly affects the turn and how flush the kingpin nut is (ie. the perceived looseness of the truck), but it does not affect the wheelbase.

In a nutshell: bushing height and durometer are completely different beasts. Hope this helps.

[Obijuan91]

Soooo bottom determines how stiff the turn is and too determined how fast it rebounds to center?