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Keith Tanner
Keith Tanner MegaDork
1/23/20 11:58 a.m.

Disclosure: MaXpeedingRods sent me a set of coilovers in exchange for a review. As part of that arrangement, I have a referral code and link that will get you 8% off orders over $200. The link is https://bit.ly/2RdsHvb and the referral code is Keith.

About me (in case you're finding this via search engine): I have worked at Flyin' Miata for over 18 years, and one of my primary roles has been suspension development. I have done clean sheet coilover design for every generation of Miata. I've written three books on the Miata, one of which was heavy on handling theory. I am not reviewing these coilovers as a representative of Flyin' Miata, but that is my background.

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These coilovers retail at $246 shipped at Maxpeedingrods.com, which is scarcely believable. I know that my colleagues in the suspension industry are trying to figure out how to deal with the flood of suspension pieces at this price point. Are they any good? Well, I'm going to review these without taking cost into consideration, looking just at the merits of the components. You can decide for yourself if the attributes and the cost line up.

First, an unboxing picture. They didn't travel all that well on the way from California. A couple of dings in the aluminum bits but no real damage that is apparent.

Here's a front (top) and rear coilover. Two-piece bodies, aluminum upper mounts with spherical bearings (which a section of the industry calls a "pillowball"), springs, etc. They are available in a range of colors, I chose gold for luck. And yes, these are studio shots because our photo booth is right beside my desk and it's easier than putting them on the floor :)

They certainly look good when you pull them out of the box.

Contractually required logo shot. And also a very entertaining slogan.

Other than the upper mounts, these are made of steel and you can feel it in heft. The fronts weigh 11.25 lbs fully assembled. A Fox Racing setup is 8.25 lbs.

Color matched wrenches are a nice touch. The allen key apparently fits the adjustment knob, which moves easily so it doesn't seem completely necessary. Note: if you've been to Harbor Freight, you know exactly what these coilovers smell like.

Not pictured: instructions. That's because there weren't any. The sales page for these coilovers gives a suggested damping setting, and otherwise you're on your own. The lock nuts for the lower section were loose on delivery which means you can rock it back and forth on the shock insert, which feels really bad and would lead to all sorts of rapid wear and noise if you didn't know to tighten down those nuts.

Those big washers are there to act kinda like Torrington bearings, allowing the spring to twist as it compresses and extends. It's a nice touch. Oddly, the rear shocks had a plastic piece as well as the steel bit. That's a better choice, but why not on the front?

I did not tear a shock apart to investigate the internal build quality because I cannot see a way to recharge the gas. I think they're a monotube, which would imply that there should be some pressure in there. They don't seem to mind getting turned upside down which also means monotube. Odd.

The spherical bearing in the upper mount is loaded axially, which is not something that spherical bearings like very much. They can hammer loose. One solution is to specify a bearing with a very tight fit - we do this on one of our products. These bearing are amazingly tight. Too tight to move. They're there to allow the shock shaft to change angle as the suspension cycles, but if they don't allow it we have potential for all sorts of stiction problems as the shock gets side loads.

The upper nut is 18mm across the flats, which is a weird size for a Miata :)

So there's your unpacking and initial inspection.

infinitenexus
infinitenexus Reader
1/23/20 12:03 p.m.

Awesome, looking forward to more.

Keith Tanner
Keith Tanner MegaDork
1/23/20 12:28 p.m.

One problem right out of the gate, and it's related to that two-piece shock design. The big advantage of this type of shock is that it lets you use a generic shock cartridge in multiple applications, simply changing out the upper mount and the lower section. That's good for cost containment.

There's a bunch of marketing that says it also allows you to adjust preload, which is a great example of trying to build a feature out of misinformation. Preload is not a factor in car setup unless you get to the point where the preload exceeds the load on that spring, and the suspension does not compress when the car is placed on its wheels. I have seen suspensions (with adjustable preload, ironically) set up this way but it's the sign of something else being wrong. Outside that edge case, the suspension has no idea how much preload is on the spring until you hit the limits of droop travel. Adjustable preload just means there are many ways to assemble your shock wrong.

The problem is that it limits your available shock travel. The actual shock cartridge has to be shorter than the complete shock body length. A single piece shock has more room inside the tube to package a long shaft (heh heh) and thus provide more travel. In some applications, this may not matter. In the rear suspension of a Miata - any Miata - this is critical. I learned while developing rally suspension that travel is god, even on the track. Suspension with room to move lets you hit berms harder, keeps the car more settled over crests and generally keeps the car from having unpredictable behavior as you reach the limits of travel. I've read autobiographies by Mark Donahue and John Horseman (aka GT40, 917) chasing handling problems that were discovered to be a lack of travel.

As you adjust the shock body length, you are trading off compression travel for droop travel. You only have so much to play with, so you have to choose how it's allocated. On a rock crawler, you want lots of droop and you don't need compression. On a street car, I think a ratio of 2:1 compression to droop is a decent ballpark. On a track (or a low street) car, compression is important. In reality, in a lot of cars you want all the compression travel you can get. This is particularly true of lowered cars, and critical on NA, NB and ND Miatas.

So, the right way to set your "preload" on a Miata is to make the shock bodies as short as you can until you hit suspension limits, then set the ride height with the spring perch. That's exactly how a well-designed single-piece shock is done.

On the MaXpeedingRod coilovers, the crucial rear doesn't get short enough. With the shock body as short as it can go, it's still 3/8" longer than a Fox or Bilstein or V-Maxx. This means you're leaving more than half an inch of compression travel on the table, and that's significant in this application. Some of that is due to the design of the upper mount, which is designed to take bumpstop loads on a washer that sits below the spherical bearing. If the bearing were moved up and the body of the mount used for the bumpstop support, you'd get a lot of this lost travel back again.

With the shock in that minimum length state, the fully extended length is 1" shorter than other suspensions. So you've lost about 1.5" of droop travel. This means you're losing roughly 2" of overall wheel travel in a car that is highly travel-constrained in the first place. This is a problem. It's particularly a problem when you consider that a lot of customers in this price bracket are looking for maximum drop, and they're going to get to know their bumpstops very well.

The front shock body has more room available inside, so the lack of shaft travel is less of a problem. You cannot use the shock at minimum body length or you'll have your tire hard into the wheel well structure. It looks like overall shaft travel is about what you'd expect to see, so the correct setup would be to match the body length of a stock shock and then set your ride height with the spring perch. The spring is fairly short so coil bind may become a problem - the Fox and V-Maxx suspension use a spring that's a full 2" longer.

I will be installing them on a 1990 Miata in a few days for on the road testing and confirmation of range of motion. I have some concerns about interference between the upper control arm and the very large diameter shock body, but we'll see how that fits. Then we find out how the damping works - it feels fairly soft when cycling the shocks by hand, but as long as it's right for the springs that's okay. Spring rates are 391 front and 335 rear, which is going to lead to a lot of oversteer unless the rest of the car is adjusted to suit. General rule of thumb for this chassis is approximately a 3:2 front:rear ratio.

morello159
morello159 Reader
1/23/20 12:31 p.m.

Looking forward to performance reviews. I'm strongly in the camp of "better to spend money on a higher quality spring/damper package than cheap coilovers" (looking at you, BC Racing coilovers)  so this should be an interesting read. 

Keith Tanner
Keith Tanner MegaDork
1/23/20 12:38 p.m.

I have another 1990 Miata in my garage that has stock springs and Koni Sports on it. I'll be using it as a basis for comparison as well as some of the higher end coilover setups I have available to me, as "my stock suspension is totally trashed so I need anything!" is a legitimate market for both the MaXpeedingRods and the Konis.

My personal take on coilovers: they allow the use of standardized spring sizes for suspension tuning, and they allow adjustment of ride height and corner weighting. Both useful attributes for a certain part of the market. Otherwise, they're just a spring and shock. Being a coilover does not imply anything about the damping or construction quality, good or bad. Not in the Miata world, I know it's different in other applications where the spring is not mounted on the shock. My MGB, for example, used to be leaf sprung in the back and now runs a coil-over-shock setup.

The springs on the MaXpeedingRods are a 70.5mm ID, which is basically 2.75". That's an odd spring size, 2.5" is far more common. Unfortunately, the perches won't take a 2.5" spring so you're may have difficulty sourcing alternate springs if you want to use different rates.

AnthonyGS
AnthonyGS Dork
1/23/20 12:49 p.m.

The Mazda chassis and suspension engineers that worked on the Miata and 3rd gen RX-7 were a good group.  I bet an NA with stock springs and lowly Koni SRTs would handle more predictably and might even be faster on a track or autoX course.  

rodknock
rodknock Reader
1/23/20 12:57 p.m.

Count me in as being interested how it stacks up performance wise as well. Also the thread tags are hilarious. 

Keith Tanner
Keith Tanner MegaDork
1/23/20 1:12 p.m.
AnthonyGS said:

The Mazda chassis and suspension engineers that worked on the Miata and 3rd gen RX-7 were a good group.  I bet an NA with stock springs and lowly Koni SRTs would handle more predictably and might even be faster on a track or autoX course.  

One of their primary chassis guys right now shares my beliefs about the importance of travel. The chassis guy for Singer is the same. Guess what? They both have rally backgrounds.

The STr.T (I think that's right) is basically valved the same as a Koni Sport on full soft. At least, in the Miata application.

Forgot to mention - the MaXpeedingRods have a two-year warranty against manufacturing defects. And in handling them, they feel like they're well made. Nice clean threads everywhere, no weird resistance in the adjusters, etc. There's no faulting the machining quality on the bits you can see, which is not always the case.

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
1/23/20 1:34 p.m.

Why can't I see any pictures ?

Dusterbd13-michael
Dusterbd13-michael MegaDork
1/23/20 1:45 p.m.

This is enlightening so far!

Can you gut one after road testing ro see what the innards are like?

Keith Tanner
Keith Tanner MegaDork
1/23/20 2:03 p.m.
DeadSkunk (Warren) said:

Why can't I see any pictures ?

Can't explain that, they're hosted on my own server the same as all my other build threads. 

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
1/23/20 2:21 p.m.

In reply to Keith Tanner :

Pictures are visible now. I must have dozed off with my hand on the mouse and did something in my sleep. blush

Lof8 - Andy
Lof8 - Andy Dork
1/23/20 2:21 p.m.

Its almost unbelievable that they can produce a set of 4 coilovers that look that good for that price and be profitable.  On one hand, I've cobbled together some low buck suspensions that performed fairly well.  On the other hand, i will be surprised if you're impressed by the performance of these.  I hope I'm wrong.

DeadSkunk  (Warren)
DeadSkunk (Warren) PowerDork
1/23/20 2:44 p.m.

Are the shock cartridges identical front and rear? Same damping force?

_
_ Dork
1/23/20 2:55 p.m.

As somebody that had these on a 97 roadster, I can firsthand tell you that the fronts will go entirely too low. To the point that you can't even turn the wheels. The rears won't go low enough to match the fronts. And the dampening feels like you have butter for shocks. I bottomed out a lot over high speed bumps and dips, and I can tell you it was not because of the ride height. When I swapped back to stock suspension, which was the factory Miata springs and KYB gr2, I finally had a more stable handling Miata.

dps214
dps214 Reader
1/23/20 3:14 p.m.

Does FM have a shock dyno? I'd love to see the curves from these things and how consistent they are.

spacecadet
spacecadet SuperDork
1/23/20 3:14 p.m.

livestream comparing the shocks currently happening

link since my embedded video doesn't seem to work on my mobile device.

 

https://www.facebook.com/flyinmiata/videos/606337499913733/

Keith Tanner
Keith Tanner MegaDork
1/23/20 3:35 p.m.

Thanks for linking that. We'll post that video to YouTube later and I'll embed it for those who aren't Facebookies. It's mostly a video explanation of my second post talking about two piece shocks and travel, and I don't mention the shock brand in it because they were simply a convenient example to use. The statements made about the two-piece shocks apply equally to Ohlins!

 

Front and rear cartridges do appear to be slightly different in overall length. We don't have a shock dyno (I wish!) so I can't check the damping curves or consistency. The softest setting is really soft which makes them great for doing demos, but of course that's not really meaningful compared to where they'll be used.

_
_ Dork
1/23/20 3:38 p.m.

And have we verified the spring rates yet? I know Keith said what they were, but I didn't see anything about the springs being verified. Most "cheap Chinese" springs are off by A LOT. 

Keith Tanner
Keith Tanner MegaDork
1/23/20 3:56 p.m.

I don't really have a way to do that other than trying to jury-rig something absurdly dangerous.

I'll be able to tell consistency of spring rate by the perch heights when it's installed and leveled. Then we see if they start to sag.

AngryCorvair
AngryCorvair MegaDork
1/23/20 4:01 p.m.
Keith Tanner said:

I don't really have a way to do that other than trying to jury-rig something absurdly dangerous.

 

in for video!

ProDarwin
ProDarwin UltimaDork
1/23/20 6:46 p.m.
Keith Tanner said:

I don't really have a way to do that other than trying to jury-rig something absurdly dangerous.

I'll be able to tell consistency of spring rate by the perch heights when it's installed and leveled. Then we see if they start to sag.

 

Edit:  Diameter seems right, can't you just use an olympic weight set to test the rate?

 

ProDarwin
ProDarwin UltimaDork
1/23/20 6:49 p.m.
AnthonyGS said:

 might even be faster on a track or autoX course.  

This I think is interesting.  I could very well see a garbage coilover setup still "outperforming" stock stuff on an autox course, simply because of stiffness.  Even moreso on a strut car where camber loss is one of the biggest issues you are fighting with the stock suspension.

It may work like crap in all other conditions though.

It would be a fun test.

AnthonyGS
AnthonyGS Dork
1/23/20 9:34 p.m.
ProDarwin said:
AnthonyGS said:

 might even be faster on a track or autoX course.  

This I think is interesting.  I could very well see a garbage coilover setup still "outperforming" stock stuff on an autox course, simply because of stiffness.  Even moreso on a strut car where camber loss is one of the biggest issues you are fighting with the stock suspension.

It may work like crap in all other conditions though.

It would be a fun test.

I'm hoping Keith does something like this too.  I hinted at it, and he has an NA with stock springs and Koni yellows.....  Yes sometimes by not allowing a suspension to travel via high spring rates you get good times in certain conditions.

 

MrJoshua
MrJoshua UltimaDork
1/23/20 9:38 p.m.
ProDarwin said:
AnthonyGS said:

 might even be faster on a track or autoX course.  

This I think is interesting.  I could very well see a garbage coilover setup still "outperforming" stock stuff on an autox course, simply because of stiffness.  Even moreso on a strut car where camber loss is one of the biggest issues you are fighting with the stock suspension.

It may work like crap in all other conditions though.

It would be a fun test.

The challenge MR2 that got second in the Autocross was sporting Cheapo Ebay Coilovers IIRC.

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