UPDATED: Replacing Rear Shocks: Reducing the rear end bounce.

[HuntingPudel]

<SNIP>
I wonder if some of the "long wiggle" afterwards is related to resilient bushing loading elsewhere in the suspension? If you have time during the next swap, I'd be curious to see if the graph changes if you disconnect the sway bar and repeat the body slam test?

Good call Lee. If Anton's got stock bars, we know they have their body bushings fused to them with a crazy preload (more preload in the front ones than in the rear). If he's got aftermarket bars, this shouldn't make a difference unless one side is being loaded more than the other, in which case the bar disconnected should show more amplitude rather than less. ??

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[Anton]

Good call Lee. If Anton's got stock bars, we know they have their body bushings fused to them with a crazy preload (more preload in the front ones than in the rear). If he's got aftermarket bars, this shouldn't make a difference unless one side is being loaded more than the other, in which case the bar disconnected should show more amplitude rather than less. ??

I have steeda sway bars, front and back.

 

[mkhuffman]

Here you go. Same test done with the Konis. Put the phone on the trunk, and tried to push down as hard as I could and let go. As expected, It's much more difficult to compress these Konis than the OEM shocks. (Source - tab: "body-slam-koni").

Cool, good job. That's an improvement, but interesting you can still see 2+ cycles afterwards even with them set on max. The magnitude of the second cycle has been reduced significantly, but it looks like it could use even more damping.

I wonder if some of the "long wiggle" afterwards is related to resilient bushing loading elsewhere in the suspension? If you have time during the next swap, I'd be curious to see if the graph changes if you disconnect the sway bar and repeat the body slam test?

This is what my GT looks like. 100 Hz sample rate, Z sensor, phone sitting on back edge of hatch above the bumper.

I am body slamming by pushing down on the top of the bumper on the flat part with the hatch open. Am I doing the test the same way?

In any case, it rebounds higher than the initial push down which is exactly what it feels like when I hit a bump, and it is especially noticable in the front.

I thought maybe the GT has better damping but it looks like it doesn't. I am going to buy a set following Mark's instructions when the final results are in!

 

[Anton]

Cool, good job. That's an improvement, but interesting you can still see 2+ cycles afterwards even with them set on max. The magnitude of the second cycle has been reduced significantly, but it looks like it could use even more damping.

I wonder if some of the "long wiggle" afterwards is related to resilient bushing loading elsewhere in the suspension? If you have time during the next swap, I'd be curious to see if the graph changes if you disconnect the sway bar and repeat the body slam test?

Even though that's what the graph shows, it doesn't feel like it or appear so that the car moves up and down more than once. Here's the same test where I collected gyroscope "wx" readings.

Maybe the g-force meter is extra sensitive or just inaccurate?

Here's what it shows just sitting on my table.

 

[Mach-Lee]

This is what my GT looks like. 100 Hz sample rate, Z sensor, phone sitting on back edge of hatch above the bumper.

I am body slamming by pushing down on the top of the bumper on the flat part with the hatch open. Am I doing the test the same way?

In any case, it rebounds higher than the initial push down which is exactly what it feels like when I hit a bump, and it is especially noticable in the front.

I thought maybe the GT has better damping but it looks like it doesn't. I am going to buy a set from Mark when the final results are in!

Yes, place phone near liftgate opening, start 100 Hz accelerometer, I turn around and sit down forcefully the gate to compress, feet lift off the ground an inch, then immediately stand up faster than the rebound. Pushing down forcefully works too, I was just going for max force by essentially falling on the car so I could get 0.2g of input.

@eidbanger The gyroscope measures the rotation rate or pitching of the phone (radians/sec). Since the car only pitches a very small angle, it's probably not going to be as sensitive of a measurement compared to g force with the phone placed near the rear axle.

 

[mkhuffman]

Yes, place phone near liftgate opening, start 100 Hz accelerometer, I turn around and sit down forcefully the gate to compress, feet lift off the ground an inch, then immediately stand up faster than the rebound. Pushing down forcefully works too, I was just going for max force by essentially falling on the car so I could get 0.2g of input.

@eidbanger The gyroscope measures the rotation rate or pitching of the phone (radians/sec). Since the car only pitches a very small angle, it's probably not going to be as sensitive of a measurement compared to g force with the phone placed near the rear axle.

Sounds like we did it the same way.

 

[HuntingPudel]

So I guress once all this testing is done, Lee is going to retire his trench coat? ??

 

[CAL465]

Any impact on mileage?

To early to tell. I plan taking a road trip next week.

 

[CAL465]

I have steeda sway bars, front and back.

How do you like the steed a sway bars?

 

[Anton]

Let's put the stats and data aside and be subjective for a moment.

These shocks substantially improved the ride quality on the section of road I frequently have to travel. You can see videos of the road causing the resonating bounce / gallop / pitching motion on my youtube channel. We just got back home from the same road and the wife said "no bounce", "just jolts". Which I agree with. This is exactly what I was hoping to achieve. After a year of searching for a solution, this works for my wife and I. I'm finally happy with the ride quality.

This test was done on OEM Premium tires. A while back I bought some bigger Pirellis tires (255/45/20 A/S+) and those helped some but not nearly as much as these shocks. By comparison, these shocks on OEM tires are better than the OEM shocks with the Pirellis. I bet the ride will be even better when I put on the Pirellis ?. Those should help smooth out these little jolts caused by the expansion joints.

On the OEM shocks I would look in the rear view mirror and see my wife pogo-ing (she sits with the baby in the back). Wife said that the bounce is now gone. There's still some up and down motion, but it's a jolt and settle, not a sinusoidal motion like it was before. I agree. She said that after all the things I've done with the car this is the first one where she can really feel a difference. I can see where she's coming from, b/c I don't drive like I normally do with her and the kid in the car ?, otherwise she would feel how awesome these Steeda sway bars are (@CAL465).

I also have some humps near my house. With the OEM shocks I could feel them taking an extra cycle or 2 to settle (similar to the graphs that @Mach-Lee posted). Now the car settles immediately.

Big thanks to @markboris for coming down to my place and putting these Konis on. I'm all smiles man! Still! ?

On Saturday we'll try to get some g-force data with the OEMs if we have time, so that we have a base to compare to. Looking forward to trying the Bilsteins, but I'm definitely never going back to the OEM shocks.

Happy to answer any questions or take more measurements!

 

[CAL465]

Let's put the stats and data aside and be subjective for a moment.

These shocks substantially improved the ride quality on the section of road I frequently have to travel. You can see videos of the road causing the resonating bounce / gallop / pitching motion on my youtube channel. We just got back home from the same road and the wife said "no bounce", "just jolts". Which I agree with. This is exactly what I was hoping to achieve. After a year of searching for a solution, this works for my wife and I. I'm finally happy with the ride quality.

This test was done on OEM Premium tires. A while back I bought some bigger Pirellis tires (255/45/20 A/S+) and those helped some but not nearly as much as these shocks. By comparison, these shocks on OEM tires are better than the OEM shocks with the Pirellis. I bet the ride will be even better when I put on the Pirellis ?. Those should help smooth out these little jolts caused by the expansion joints.

On the OEM shocks I would look in the rear view mirror and see my wife pogo-ing (she sits with the baby in the back). Wife said that the bounce is now gone. There's still some up and down motion, but it's a jolt and settle, not a sinusoidal motion like it was before. I agree. She said that after all the things I've done with the car this is the first one where she can really feel a difference. I can see where she's coming from, b/c I don't drive like I normally do with her and the kid in the car ?, otherwise she would feel how awesome these Steeda sway bars are (@CAL465).

I also have some humps near my house. With the OEM shocks I could feel them taking an extra cycle or 2 to settle (similar to the graphs that @Mach-Lee posted). Now the car settles immediately.

Big thanks to @markboris for coming down to my place and putting these Konis on. I'm all smiles man! Still! ?

On Saturday we'll try to get some g-force data with the OEMs if we have time, so that we have a base to compare to. Looking forward to trying the Bilsteins, but I'm definitely never going back to the OEM shocks.

Happy to answer any questions or take more measurements!

That's great! if I buy the Konis and all the other parts. Will a shop know what to do with them or should I print out your write up?

 

[markboris]

That's great! if I buy the Konis and all the other parts. Will a shop know what to do with them or should I print out your write up?

I think you should wait until Anton and I are finished testing various shocks before anything is purchased. Also, Erik is doing the same thing testing different shocks and after Anton and I come up with the best shocks we like, I am sending them to Erik for testing out. Also will be sending to one or two other members. So I think we have a little while to go because we want to make sure that one, we find the best shock and two, it has been tested by several owners on different roads.

Once we come up with something, I will list the shock model and parts needed to fit them to the car which will be very minor. Most likely a couple of spacers and washers.

 

[Mach1E]

Let's put the stats and data aside and be subjective for a moment.

These shocks substantially improved the ride quality on the section of road I frequently have to travel. You can see videos of the road causing the resonating bounce / gallop / pitching motion on my youtube channel. We just got back home from the same road and the wife said "no bounce", "just jolts". Which I agree with. This is exactly what I was hoping to achieve. After a year of searching for a solution, this works for my wife and I. I'm finally happy with the ride quality.

This test was done on OEM Premium tires. A while back I bought some bigger Pirellis tires (255/45/20 A/S+) and those helped some but not nearly as much as these shocks. By comparison, these shocks on OEM tires are better than the OEM shocks with the Pirellis. I bet the ride will be even better when I put on the Pirellis ?. Those should help smooth out these little jolts caused by the expansion joints.

On the OEM shocks I would look in the rear view mirror and see my wife pogo-ing (she sits with the baby in the back). Wife said that the bounce is now gone. There's still some up and down motion, but it's a jolt and settle, not a sinusoidal motion like it was before. I agree. She said that after all the things I've done with the car this is the first one where she can really feel a difference. I can see where she's coming from, b/c I don't drive like I normally do with her and the kid in the car ?, otherwise she would feel how awesome these Steeda sway bars are (@CAL465).

I also have some humps near my house. With the OEM shocks I could feel them taking an extra cycle or 2 to settle (similar to the graphs that @Mach-Lee posted). Now the car settles immediately.

Big thanks to @markboris for coming down to my place and putting these Konis on. I'm all smiles man! Still! ?

On Saturday we'll try to get some g-force data with the OEMs if we have time, so that we have a base to compare to. Looking forward to trying the Bilsteins, but I'm definitely never going back to the OEM shocks.

Happy to answer any questions or take more measurements!

Great that it seems to be doing the job.

I’m glad someone finally got around to trying this. I’ve been yelling “it’s the shocks” on every bounce thread since the beginning.

This was confirmed even more when I got a mag ride “failure” one time. Car rode like a 1970s school bus. Interested to hear the final results!

mag ride fail video:

 

[azerik]

I have steeda sway bars, front and back.

Ditto.

By comparison, these shocks on OEM tires are better than the OEM shocks with the Pirellis. I bet the ride will be even better when I put on the Pirellis ?. Those should help smooth out these little jolts caused by the expansion joints.

We're going to get to a point where the minor road imperfections are going to need soft compression with a harder rebound. I know it's coming but I was looking at $650 for double adjust shocks, just to try this out. I figure I'll run down the road with these singles for a bit but that the insane amount of expansion joints and over all crap road repair will drive me nuts and I'll get duals. Probably selling these singles.
I Fully expect the single adjust to mellow out the harmonic bounce, but if it's choked off with too much compression the expansion joints become a thing, possibly worse as it just jolts. Lower tire pressure will help a bit with this. And we may find the combo that makes it work. Around here my streets are criss crossed with crap road repair, take a look at my rattle wagon video from the busted front axles chattering along. Then we have asphalt to concreate expansion joints that are 2 inches ore more tall. If the shocks reacted to minor changes (the 1/2 inch of constant up down travel) we could air the tires back up and let the shocks do the job. It takes quite a bit of shock to be able to mellow the joints for a 5k car. I don't think this shock exists. Not fully sure we can build it. But we can make VAST improvements as you've already seen.

However something I just did the math on that will change things is wheel widths. Looking at my Prem I'm annoyed at the wheels being set so far in. I thought, hey if I could move those out an inch or so it'd look better. I don't really trust wheel spacers is that's kind of out of the possibilities. But I do plan on 8 inch wide wheels pretty flush with the fenders. This will actually change the leverage on the suspension. Might also slightly explain the reason the GT is also just |-| this much better, because of just |-| this more leverage. (springs and shocks withstanding) But this is a factor in softening the compression and it's ever slightly harder to push back the rebound.

I'm going to try to run the test track today on the way to iron wash Casper. Probably wont be under the car until tomorrow or Thursday.

 

[CAL465]

I think you should wait until Anton and I are finished testing various shocks before anything is purchased. Also, Erik is doing the same thing testing different shocks and after Anton and I come up with the best shocks we like, I am sending them to Erik for testing out. Also will be sending to one or two other members. So I think we have a little while to go because we want to make sure that one, we find the best shock and two, it has been tested by several owners on different roads.

Once we come up with something, I will list the shock model and parts needed to fit them to the car which will be very minor. Most likely a couple of spacers and washers.

sounds like a good plan. thanks

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