Suspension Upgrade Time: KW or Ohlins or FCM?
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Joined: May 2014
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I have spoken with GWR and Ohlins. GWR essentially said the behavior is to be expected when you push any suspension to its limits, and I should have purchased their Race version to extend those limits. Ohlins said something to the effect of, "You know, GWR sells a race version that is probably a better choice for your application." 
Short of spending a bunch more money, it seems there isn't much left to do. Here are the options as I see them:
1. Buy the GWR adapter and other hardware needed to bump the rear springs to 280 lbs. That buys me more rear bump travel and a F/R ratio of 1.6 A side benefit is the ability to use any spring rates going forward, assuming I am willing to pay for re-valving. I have not actually priced this, but let's call it the $500 option. Tein (Blech!) makes a tapered spring in 280, but it is 250mm high, which is too tall for the shock body, which leads us to...
2. Buy a set of Tein (blech!) 336 lbs tapered (70-100x200) springs for the rear, and bump the fronts up 1K to 504 lbs. F/R ratio would be 1.5. If I use all Tein (blech!) springs, the cost would be $275 for the springs. Swift fronts would bump the price about $60. Ohlins told me I can increase spring rates 35% before a re-valve is required. The rears would exceed that. Re-valving costs $250 each plus shipping both ways. This option looks like at least $800.
3. Do nothing, drive the car for joy instead of speed, and put the money into the kitty for the Miata's turbo.
.
Short of spending a bunch more money, it seems there isn't much left to do. Here are the options as I see them:
1. Buy the GWR adapter and other hardware needed to bump the rear springs to 280 lbs. That buys me more rear bump travel and a F/R ratio of 1.6 A side benefit is the ability to use any spring rates going forward, assuming I am willing to pay for re-valving. I have not actually priced this, but let's call it the $500 option. Tein (Blech!) makes a tapered spring in 280, but it is 250mm high, which is too tall for the shock body, which leads us to...
2. Buy a set of Tein (blech!) 336 lbs tapered (70-100x200) springs for the rear, and bump the fronts up 1K to 504 lbs. F/R ratio would be 1.5. If I use all Tein (blech!) springs, the cost would be $275 for the springs. Swift fronts would bump the price about $60. Ohlins told me I can increase spring rates 35% before a re-valve is required. The rears would exceed that. Re-valving costs $250 each plus shipping both ways. This option looks like at least $800.
3. Do nothing, drive the car for joy instead of speed, and put the money into the kitty for the Miata's turbo.
.
info@sakebombgarage.com
If there's interest from the masses, we'll consider an FPSpec Long-Stroke version just like we did for the S2k.
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
The issue is oversteer everywhere on the track.
I have solved that to some degree by using little to no rear bar, but that induces corner entry understeer, and there is still a problem with snap oversteer in certain (not fully discovered) conditions. I *think* that snap happens due to inadequate rear bump travel, but it surprises me, so I'm never quite paying attention to all the variables, when it shoots around. That's why I'm toying with the idea of more rear spring.
I have solved that to some degree by using little to no rear bar, but that induces corner entry understeer, and there is still a problem with snap oversteer in certain (not fully discovered) conditions. I *think* that snap happens due to inadequate rear bump travel, but it surprises me, so I'm never quite paying attention to all the variables, when it shoots around. That's why I'm toying with the idea of more rear spring.
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
Important piece of information for this thread:
Ohlins' published spring rates for their RX-8 coilovers are incorrect. The actual spring rates are 80N / 8K / 457lb front, 50N / 5K / 286lb rear.
That front to rear ratio of 1.60 is pretty close to the natural frequency that has yielded a neutral car for me in the past. So, it has never been an issue of needing more rear spring. It is something else in the setup. For now, I will focus on rear bump travel and adjust ride height and (especially) preload to work on dialing in the car.
.
Ohlins' published spring rates for their RX-8 coilovers are incorrect. The actual spring rates are 80N / 8K / 457lb front, 50N / 5K / 286lb rear.
That front to rear ratio of 1.60 is pretty close to the natural frequency that has yielded a neutral car for me in the past. So, it has never been an issue of needing more rear spring. It is something else in the setup. For now, I will focus on rear bump travel and adjust ride height and (especially) preload to work on dialing in the car.
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Last edited by Steve Dallas; Jun 22, 2017 at 07:18 AM. Reason: Because BOLD
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Well that helps explain why it doesn't just understeer like a fwd sedan from the factory.
My best guess to explain your oversteer is that you are ending up on the rear bumps before the fronts. Or the bump stops are not equal under load at least.
I don't think you can avoid using the bump stops at all without going too stiff. But you can shorten them, or use packers to alter the engagement point front to rear.
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
Yeah. I was using the wrong inputs into the equation all this time. That perfectly explains why nothing was lining up with suspension theory. Now, I fully suspect lack of rear travel is what is getting me, so I will be focusing on preload and ride height to see if I can move the needle back there. I don't really want to go to stiffer springs on this car, since it will only be seeing the track a few times per year from here on out.
Well it seemed to me that you enjoy posting about it more than fixing it 
whether or not it's on the bumpstops is basic suspension tuning 101 with a piece of wire or zip tie on the shaft. Otherwise it seems to me like more front bar is needed assuming it's neither transitional nor on bumpstops and you don't want more front spring rate. If it's not that then it must be transitional; a shock tuning/valving issue. Or lastly, it's a driver input or execution issue. More importantly, it doesn't take fussing over theoretical calculations to figure any of that out. None of that is intended to be uppity, just that it really is that simple
whether or not it's on the bumpstops is basic suspension tuning 101 with a piece of wire or zip tie on the shaft. Otherwise it seems to me like more front bar is needed assuming it's neither transitional nor on bumpstops and you don't want more front spring rate. If it's not that then it must be transitional; a shock tuning/valving issue. Or lastly, it's a driver input or execution issue. More importantly, it doesn't take fussing over theoretical calculations to figure any of that out. None of that is intended to be uppity, just that it really is that simple
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
Well it seemed to me that you enjoy posting about it more than fixing it whether or not it's on the bumpstops is basic suspension tuning 101 with a piece of wire or zip tie on the shaft. Otherwise it seems to me like more front bar is needed assuming it's neither transitional nor on bumpstops and you don't want more front spring rate. If it's not that then it must be transitional; a shock tuning/valving issue. Or lastly, it's a driver input or execution issue. More importantly, it doesn't take fussing over theoretical calculations to figure any of that out. None of that is intended to be uppity, just that it really is that simple
whether or not it's on the bumpstops is basic suspension tuning 101 with a piece of wire or zip tie on the shaft. Otherwise it seems to me like more front bar is needed assuming it's neither transitional nor on bumpstops and you don't want more front spring rate. If it's not that then it must be transitional; a shock tuning/valving issue. Or lastly, it's a driver input or execution issue. More importantly, it doesn't take fussing over theoretical calculations to figure any of that out. None of that is intended to be uppity, just that it really is that simpleHonestly, I haven't taken the 8 to the track, since last September, because I have a very well-sorted Miata, that is the Easy Button of track cars. The 8 has been a touring car / daily driver since then. I have started to miss it on the track, however...
I know how simple it is. The problem is time. I am almost always instructing, when I am at the track, and that means jumping from car to car to car, with no time take a leak, much less to mess with such things on my car. Having the wrong spring rates in mind made the process frustrating, because nothing was responding as expected.
The good news is, I am building a house 15 minutes from the track. That means I will be able to run home after a session to make a change in my own garage, then run back and test it.
I'll get it there. Eventually.
What am I doing here?
Joined: Mar 2006
Posts: 3,606
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From: 2017 Miata RF Launch Edition
With the KW Variant 3, the compression is on the bottom but the rebound is on the top. I can feel the top of the rear dampers when I put my fingers in a hole near the top of the shock towers at in the truck so you don't really need cables. If you enlarge the hole slightly you can get to the top of the damper and use a 2mm hex key (or get a couple extra adjuster ***** and just leave them installed).
Last edited by NotAPreppie; Jul 12, 2017 at 10:31 AM.
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
Huge reading comprehension fail. I skimmed his post and assumed he was asking about Ohlins, since this thread morphed into an Ohlins thread over time.
Ohlins are adjustable on the car, with include remote adjusters. I have no idea about KW.
Ohlins are adjustable on the car, with include remote adjusters. I have no idea about KW.
What am I doing here?
Joined: Mar 2006
Posts: 3,606
Likes: 652
From: 2017 Miata RF Launch Edition
Speaking of which, is the adjuster on the tops of the rears of the Ohlins a hex key? If so, what size?
Thread Starter
Water Foul
Joined: May 2013
Posts: 2,521
Likes: 266
From: Republic of Texas
It is a small half-moon rod. You either attach a **** with a set screw or the remote adjuster with a set screw. You can adjust by feel with the **** (with stripped interior) or use the remote (with interior intact), which is much easier.
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Joined: Oct 2002
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From: Fremantle, Western Australia
Uhhh, I was under the impression that they don't and KW don't list any such part on their website.
With the KW Variant 3, the compression is on the bottom but the rebound is on the top. I can feel the top of the rear dampers when I put my fingers in a hole near the top of the shock towers at in the truck so you don't really need cables. If you enlarge the hole slightly you can get to the top of the damper and use a 2mm hex key (or get a couple extra adjuster ***** and just leave them installed).
With the KW Variant 3, the compression is on the bottom but the rebound is on the top. I can feel the top of the rear dampers when I put my fingers in a hole near the top of the shock towers at in the truck so you don't really need cables. If you enlarge the hole slightly you can get to the top of the damper and use a 2mm hex key (or get a couple extra adjuster ***** and just leave them installed).
What am I doing here?
Joined: Mar 2006
Posts: 3,606
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From: 2017 Miata RF Launch Edition
No need. I can touch the top of the shock with my finger tips. Have to do it through two holes behind the fabric inside the trunk. Just plunk an adjuster **** on there permanently and you should be good.
A tiny dot of Loctite blue should keep them from bouncing/vibrating up and bouncing around the top of the shock towers.
I'll know on Tuesday when my ***** come in.
A rotary tool with a sanding or grinding bit to enlarge the holes slightly would probably help. Cutting holes in the fabric is also a good plan.
A tiny dot of Loctite blue should keep them from bouncing/vibrating up and bouncing around the top of the shock towers.
I'll know on Tuesday when my ***** come in.
A rotary tool with a sanding or grinding bit to enlarge the holes slightly would probably help. Cutting holes in the fabric is also a good plan.
Last edited by NotAPreppie; Jul 16, 2017 at 09:39 PM.
Registered
Joined: Oct 2002
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From: Fremantle, Western Australia
No need. I can touch the top of the shock with my finger tips. Have to do it through two holes behind the fabric inside the trunk. Just plunk an adjuster **** on there permanently and you should be good.
A tiny dot of Loctite blue should keep them from bouncing/vibrating up and bouncing around the top of the shock towers.
I'll know on Tuesday when my ***** come in.
A rotary tool with a sanding or grinding bit to enlarge the holes slightly would probably help. Cutting holes in the fabric is also a good plan.
A tiny dot of Loctite blue should keep them from bouncing/vibrating up and bouncing around the top of the shock towers.
I'll know on Tuesday when my ***** come in.
A rotary tool with a sanding or grinding bit to enlarge the holes slightly would probably help. Cutting holes in the fabric is also a good plan.
What am I doing here?
Joined: Mar 2006
Posts: 3,606
Likes: 652
From: 2017 Miata RF Launch Edition
It only comes with 1. You're supposed to walk to all 4 corners with the one **** and adjust. I'd rather not deal with the risk of dropping my one **** and having it trapped out of reach at the top of the shock tower until I can drop the unit to retrieve it.
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Joined: Oct 2002
Posts: 477
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From: Fremantle, Western Australia
Do the fronts foul on the strutbrace with the ***** on?
Registered
Joined: Oct 2002
Posts: 477
Likes: 71
From: Fremantle, Western Australia
What am I doing here?
Joined: Mar 2006
Posts: 3,606
Likes: 652
From: 2017 Miata RF Launch Edition
They list "10mm wrench" but that doesn't match anything on the shock.
€40.00 each and I don't know that they will fit.
Or $10 each for just the ***** and they work great. You have to use a little luck but it's possible to guide the ***** onto the top of the shock bodies with one finger in each hole at the top of the shock towers in the trunk. It may help to unfasten the mount from the car and let it droop about 1" but any more than that and you run into a piece of sheet metal inside the tower.
€40.00 each and I don't know that they will fit.
Or $10 each for just the ***** and they work great. You have to use a little luck but it's possible to guide the ***** onto the top of the shock bodies with one finger in each hole at the top of the shock towers in the trunk. It may help to unfasten the mount from the car and let it droop about 1" but any more than that and you run into a piece of sheet metal inside the tower.