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

[tuminatr]

Been on the Konis with firmest setting for 11 days now.
Resonating bounce - still gone.
Ride quality - still improved.

Swapped out the OEM rims+tires with Pirelli Scorpion A/S+ 255/45/20 pumped up to 39 psi. I don't know how, but at first it seemed that the OEMs produced a better ride. Pirellis at 39 felt overinflated and it was a harsher ride than I remembered. I dropped down to 36psi and that solved it.

The ride quality is magnitudes better than with OEM shocks/wheels/tires. The jolts over the expansion joints are noticeably much duller than with OEM tires. Wife agrees. They're now barely noticeable.

If this is how the ride was for the MachE to begin with then there would be none of these conversations (re: bounce). It's a sporty ride. Your butt can feel the the cracks in the road and the expansion joints. But it's controlled and quickly settles back. Not galloping/bouncing in resonance.

This is a beautiful ride now and my wife and I both love it. We're still going to test the Vikings to compare. But honestly, I'm not sure that anything can make the ride better than it is now.

FYI on load and inflation of tires the 255/45/20 has a higher 105 load range and to support the same weight as the 245/45/20 103 it should be inflated to 35/36PSI. So Yes 39psi on a 255/45/20 is actually overinflated for the MME

Here is a chart highlighting pressure that will be optimal for a flat contact patch. The chart shows how much weight in LBS a tire will support at a certain PSI this is how car manufacturers set the tire pressure.

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[markboris]

It’s worth noting that Anton’s tires are wider than stock. Given the same rim dimensions as stock, that would require a lower pressure to maintain proper tread contact with the road. ??

Correct Steve. I suggested to Anton to lower the tire pressure from 39 psi to 36 psi since he has 255's instead of 245's. At 36 psi the 255's have about the same load carrying capacity as the 245's at 39 psi and better contact on the road with a less harsh ride. I am currently running 255/45's front and 285/40's rear so my tire pressures are 36 psi front, 32 psi rear.

Edit: I just saw Brian was replying the same time I was with the same info. ?

 

[txaggies07]

I have listed the exact Koni shocks and washers/spacers needed that I built up for Anton to try. However Erik is testing out some Viking shocks I built up for him and we are going to be swapping shocks between Koni's and Viking's to see which ones might be better than the other (the 4 types of Bilstein's I tested did not work out). Not only that but if the Viking's end up being better, I might be able to get them to build a shock so we don't need any extra parts to make them fit. All of this is a work in progress and each shock we try requires slightly different spacers/parts (very minor). I would not recommend to waste your money and buy something when we are not done testing yet. I can tell you, since you are the OP of one of the largest running threads we have here, that as soon as we come up with what we like, I will personally send you a set to try out. Everyone has to remember that every road is a bit different and everyone has different expectations of how a car should ride. We are trying our best to minimize bounce but can only work on the rear at this time.

Anton is running Pirelli Scorpion Zero All Season Plus 255/45/20 tires that I recommended. As far as tires go, pretty much anything is better than the OEM tires where ride quality is concerned. I have now tried over 9 different sets of tires on the Mach-E and I have also posted somewhere on this forum all the different ones and my opinions of them. I don't remember what thread it was in but it might be outdated as I have within the last 2 months changed out two more sets of tires and continually evaluating. I am not going to turn this into another tire thread but when we figure out the shock setup we like, I will then give my opinion of tires.

Thanks for everything Mark. Hopefully once there is a solid answer we can get a group buy going for the parts. Im guessing there are quite a few of us who would jump at it right away.

Either way, thank you for the continued testing to benefit all of us. You could have easily thrown some shocks on your own ride and called it a day.

 

[Mach1E]

Correct Steve. I suggested to Anton to lower the tire pressure from 39 psi to 36 psi since he has 255's instead of 245's. At 36 psi the 255's have about the same load carrying capacity as the 245's at 39 psi and better contact on the road with a less harsh ride. I am currently running 255/45's front and 285/40's rear so my tire pressures are 36 psi front, 32 psi rear.

Edit: I just saw Brian was replying the same time I was with the same info. ?

Keep in mind that lower pressure will also affect how the tires wear.

I keep mine at 36 and at only 6000 miles the edges of my tires are almost bald:

 

[HuntingPudel]

Keep in mind that lower pressure will also affect how the tires wear.

I keep mine at 36 and at only 6000 miles the edges of my tires are almost bald:

That’s why I inflate based on zone loading. The easiest way is via temperature measurement: Beat on car through some twisties, measure middle and near-shoulder temps, record, go to the next tire, and inflate or deflate as necessary, rinse and repeat. Great way to set camber on a car with little data on too. ??

I should note that since I commuted for several years in a car with no rubber in the suspension or between the subframe and the body, I am not too sensitive to ride harshness. ??

 

[azerik]

The GTPE tires are rated as 220 treadwear. There's no saving them. THat's why I skipped the P-Zero's from the GTPE. At least the stock GT Conti's I'll be running shortly are a 480m treadwear. The GTPE tires have to wear fast to produce the grip they do.

If you look at the middle of the tire you'll see those are down to 4 or mayne 3/32's Which are super close to 'replace me now'. At 3/32's most tire shops won't even touch them.

 

[brancky3]

Keep in mind that lower pressure will also affect how the tires wear.

I keep mine at 36 and at only 6000 miles the edges of my tires are almost bald:

6k miles isn't good, but not that ridiculous for a summer tire if you've been driving 'spiritedly'. I'd expect about 10k-12k out of any high performance summer tire.

 

[azerik]

The freeway data you shared almost looks like you had the car in resonance. Especially if it only gets bad at a specific speed. You don’t want to tune shocks in resonance because it will make the ride bad everywhere else. Tune them to feel good on a random/occasional bump.

Yes some of those spots are resonance. Which I thought we were trying to help solve for. I'm no stranger to suspension tuning but I was using those as 1 or more of my trouble spots. Trying to find the best combo for the mix of issues I drive on a daily basis. Some of the areas I've driven well over 22,000 times in the last 11 years. I have bumps memorized.

I did just notice yesterday the physics app was set to 1 second polling. That's not fast enough for some of this stuff. And i still don't have a way to display it worth anything.

However in running around I found a speed bump to hit. I turned off 1PD as lifting will cause the nose to dive and mess with the numbers.

The Thin Blue line is the vertical movement seen from the console at the charger.
The thin red line is side to side movement.

The Thick Red line is just the rear tires hitting the speed bump at about 5 mph
The Thick Green line is the car reacting from the speed bump. Read left to right as normal.

This is 4c/11r More to come but meetings today might kill it.

 

[tuminatr]

Keep in mind that lower pressure will also affect how the tires wear.

I keep mine at 36 and at only 6000 miles the edges of my tires are almost bald:

Yes those stock GTPE tires are not designed for longevity and you have given good accelerated example of under inflation. If you want to stay at 36psi when you replace do the 255/45/20. That size will wear normally at 36psi.

 

[markboris]

Keep in mind that lower pressure will also affect how the tires wear.

I keep mine at 36 and at only 6000 miles the edges of my tires are almost bald:

Agree but it also depends on the type of roads being driven on. Anton drives more on the highway than mountainous roads so he wouldn't have as much wear on the sides running his wider tires at 36 psi. Not to mention, his Pirelli all season tires have a wear rating of 500 which is much higher than the Pirelli summer tires on your car. There are so many factors when it comes to tires and tread wear.

 

[21st Century Pony]

That’s why I inflate based on zone loading. The easiest way is via temperature measurement: Beat on car through some twisties, measure middle and near-shoulder temps, record, go to the next tire, and inflate or deflate as necessary, rinse and repeat. Great way to set camber on a car with little data on too. ??

I should note that since I commuted for several years in a car with no rubber in the suspension or between the subframe and the body, I am not too sensitive to ride harshness. ??

This is good info - thanks!

 

[Mach1E]

6k miles isn't good, but not that ridiculous for a summer tire if you've been driving 'spiritedly'. I'd expect about 10k-12k out of any high performance summer tire.

It’s terrible.

I got 15k out of my summer tires on my 450 hp Chevy SS sedan.

Hell, I got 8k miles out of my Nitto drag radials on my 450 hp 2002 Trans Am.

I do still have life in these tires, but not much. 95% city driving, but still pretty bad.

 

[Mach1E]

Agree but it also depends on the type of roads being driven on. Anton drives more on the highway than mountainous roads so he wouldn't have as much wear on the sides running his wider tires at 36 psi. Not to mention, his Pirelli all season tires have a wear rating of 500 which is much higher than the Pirelli summer tires on your car. There are so many factors when it comes to tires and tread wear.

That’s fair.

But it still will “affect how the tires wear.”

It won’t affect it as much of more highway. But the wear rating won’t change the kind of wear, it’ll just change how quickly it wears.

Either way, lower psi will make the sides wear more quickly than the middle.

Less noticeable on street tires, but I learned this lesson very quickly when using drag radials on my daily driver.

I had to run super low psi (20) to get them to wear evenly. But it almost doubled the life. People running 25+ psi only got 4k miles or so out of the Nitto DRs.

 

[HuntingPudel]

It’s terrible.

I got 15k out of my summer tires on my 450 hp Chevy SS sedan.

Hell, I got 8k miles out of my Nitto drag radials on my 450 hp 2002 Trans Am.

I do still have life in these tires, but not much. 95% city driving, but still pretty bad.

Heh @scoopman only got about 4K miles on Mach N Cheese’s original tires. They looked to be close to (if not right on) properly inflated based on the wear pattern. ??

 

[Electric Goat]

Thanks for everything Mark. Hopefully once there is a solid answer we can get a group buy going for the parts. Im guessing there are quite a few of us who would jump at it right away.

Either way, thank you for the continued testing to benefit all of us. You could have easily thrown some shocks on your own ride and called it a day.

There will definitely be huge interest in a group buy opportunity. Myself included.

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