NA All round suspension from rough backroads to the track

[twr7cx]

Have an 89 JDM NA6 which I have pulled the front and rear suspension out of. The bushes were tired and it all looked like worn original which is now 29 years old. I've replaced the bushes with Superpro units and while there have also done the steering rack and diff void fillers.

I'm now stuck on what do to for the suspension including shocks, springs and swaybars.

A bit of background:

The vehicle is a 'toy car' for both my wife and I. It's not dríven daily and generally just dríven occasionally for the fun of it. Once the suspension is sorted I'd like to take it to a few of the local track days (maybe two or three times a year?). We live semi-rural on acreage with the end of our road and driveway being a couple hundred meters of dirt road. Our daily drivers are both 4WDs so were used to a long travel suspension on the bumps and the softer ride that the large tyres provide. At present the vehicle has OEM 14" wheels on it, I intended to change to some NB 15" in the future only due to the larger performance orientated tyre offerings.

I'm therefore looking for suspension that is suitable to handle everything from the rougher country backroads around where I live to the odd track day that I'd like to attend.

I've looked at the various coilover options, but generally just don't trust them. The $250.00 set on eBay and the $1,500.00 sets looks like they've popped out of the same factory with different anodising colours and stickers on them. So many brands that I've never heard of.

Would the traditional shocks and spring combination be a better for my purposes? I thought perhaps stick to the original OEM springs with a better quality shock (perhaps KYB AGX or Koni STR.T (orange) or Koni Sport (yellow) - would these work with the OEM springs or are they too much shock for them?) to have the softness for the rough roads? Perhaps adding Flyin'Miata Rear Shock Mounts < https://www.flyinmiata.com/1990-97-flyi ... ounts.html > and Improve Bump Stops < https://www.flyinmiata.com/improved-bump-stops.html > for additional travel?

Regarding the swaybars would it be worth then increasing these to thicker aftermarket units to flatten out the cornering or retaining the standard units?

Thoughts? Comments? Feedback? Experiences? Suggestions? please.

[bruce]

I'd try to keep it somewhere near stock specs (try to replicate that with aftermarket gear). If you firm up the ride your missus will comnplain.

[hks_kansei]

#1: if you're wanting dirt road comfort, avoid coilovers in general (unless you're wanting to spend cash on ones valved and setup for rally etc)
Most coilovers are a good bit stiffer than stock, especially at the cheaper end of the spectrum.

as far as a good compromise, You're onto a good idea with regard to better shocks on standard springs (or standard height springs with a little stiffer rate)

Adjustable shocks would likely be worthwhile, since you can soften them up for normal use, and bump the valving up more for the track.
I'd go the Koni Yellows of the ones listed.
The AGX are cheaper, but I dont believe they are manufactured anymore. Also, for dirt use, the adjusters for them are located on the shock body, behind the wheel. Annoying to reach, dirty, and frankly, will likely just end up jammed up with dirt or have the knobs break off from rocks etc.
The Koni adjusters are located on the top of the rods, under the bonnet, and inside the boot. Clean and easy to reach.

I'd do that and see how it feels, if you feel that you want more roll resistance on the track you can add swaybars at a later date quite easily.



I used to live up in country vic, and used to take my NB out onto the dirt roads every do often.
I had stock suspension, and then later, stock shocks and lowered progressive springs.
The springs were fine on the dirt, apart from the reduced ground clearance. So if you have some clearance so spare, that may be another consideration.

[greenMachine]

First up, I think you bought the wrong toy. You want rough dirt roads, you need ground clearance, long travel suspension, tyres to grip on loose surfaces. You knew that, you have not one but two 4WDs. But you bought an NA as a toy ... Sure, you can put lipstick on the pig, but you know how much difference that makes. Either accept the MX5 for what it is, and work with that, or accept you made the wrong purchase. That means minimising the dirt roads for the NA (use the 4WD, that is what they are for, no? ), and grinning and bearing a slow, torturous couple of hundred metres (!).

I have an SE (NB8B), and I have TWO KILOMETERS of dirt road to get to my place. Four klicks of dirt every time I take it for a drive. Two klicks of privately maintained dirt road (you can imagine how often it sees a grader, let alone anything else), and there is no way I am compromising my car for those two klicks. Because its a SPORTS CAR, that is why I bought it. If I want/need to hit the back roads, I'll use the Falcon wagon - horses for courses. My dirt road means lots of dodging, cringing and crawling, but so be it, that is a price I willing pay for the pleasure my SE gives me.

You want it to ride like a 4WD, but do track days? Can do, but it will do neither well. I do State level Supersprint competition, and the only compromise I make is to run an extra 5-10mm ride height. I run coilovers too, I disagree with hks, the adjustable settings allow soft ride on the road and stiff on the track and the ride height can be quickly and precisely adjusted. Having said that, crappy coilovers, just like crappy shocks, are a literal and figurative pain in the *rse.

It doesn't seem like you have done much searching on here. I don't recall any of those shocks rating highly in the many 'what are the best shocks' threads on here. But if you seriously want 'the best of both worlds', these coilovers are what you want, $4kUSD, plus shipping, plus GST, probably come in under $5kAUD by the time all the charges are added. I read that they handle the rough stuff like a hovercraft though.

Just my 2c, feel free to ignore me.

[NitroDann]

nah..



















Nah.....

[greenMachine]

This is the best I could find of Russell Battisson's (russellb) SE rally car https://vimeo.com/11594474. This car sadly bit the dust (in someone else's hands) and is no more.

More sadly, it is a reminder of the loss to this community (not to mention his friends and family) from his untimely death - RIP Russell we miss you still.

[bruce]

I happily drove my original NA on stock suspension (near new in those days) around town and then did track days on the weekend. No complaints and a great lot of fun.
Why overthink it.

[Purecaboos]

Hey All,

I have a 91 NA6 with Tien Flex-Z coil overs that is my non-work DD, track car and toy. It sees everything from the flat race tracks, highways, country roads and the shitful dirt roads in the state forests locally.

It is a little stiff on the roughest roads, but still handles well and I just go slow on the rougher dirt.

The only thing that worries me at the moment is the lack of front mud flaps as I have taken the paint off the front of the sill seam on both sides blasting it with small stones/course sand/dirt on the dirt roads.

Cheers

Greg

[93_Clubman]

Have an 89 JDM NA6 - It's not dríven daily - like to take it to a few of the local track days (maybe two or three times a year).

Assume by 'rougher country backroads around where I live' you mean sealed roads - as for your 'couple hundred metres of dirt road' just go slow as you probably already do.
Koni Sport (yellow) & King springs were extremely popular in the past, but worth first trying the Koni Sports with OEM springs if you decide to upgrade the dampers.
FM bump stops were also very popular depending on which setup you decide upon.
Your WTB for an NA8 Clubman 20mm front swaybar is worth experimenting with, but the NA6 12mm rear swaybar (as opposed to the NA8 Clubman 11mm ) should suffice for your purposes.
Something to consider:
Don't know how many kms your NA6 has done, but Guran very successfully tracked an NA6 for 5 years in NSW standard class/Type 1 starting almost a decade ago:
viewtopic.php?f=68&t=74332&p=906923&hilit=shock%2A#p906923
viewtopic.php?f=68&t=74497&p=910962&hilit=guran+na6#p910962
You can read about Little Reddy here: www.mx5cartalk.com/forum/posting.php?mo ... 0&p=934949

[twr7cx]

First up, I think you bought the wrong toy. You want rough dirt roads, you need ground clearance, long travel suspension, tyres to grip on loose surfaces. You knew that, you have not one but two 4WDs. But you bought an NA as a toy ... Sure, you can put lipstick on the pig, but you know how much difference that makes. Either accept the MX5 for what it is, and work with that, or accept you made the wrong purchase. That means minimising the dirt roads for the NA (use the 4WD, that is what they are for, no? ), and grinning and bearing a slow, torturous couple of hundred metres (!).

I have an SE (NB8B), and I have TWO KILOMETERS of dirt road to get to my place. Four klicks of dirt every time I take it for a drive. Two klicks of privately maintained dirt road (you can imagine how often it sees a grader, let alone anything else), and there is no way I am compromising my car for those two klicks. Because its a SPORTS CAR, that is why I bought it. If I want/need to hit the back roads, I'll use the Falcon wagon - horses for courses. My dirt road means lots of dodging, cringing and crawling, but so be it, that is a price I willing pay for the pleasure my SE gives me.

Thanks for the comment and thoughts but I feel that you’ve interpreted my requirements in regards to the dirt roads to the extreme or perhaps I failed to explain properly. I’m not looking to go racing around on dirt off road tracks! My driveway from my shed onto a communal shared driveway and then tarmac back country roads is about 600m at slow speeds from 20 to 40km/h. A 4WD is defiantly not required to drive 600m of a dirt road in reasonable condition. While our other cars are 4WDs, it’s mainly for when we go further into the property such as in the paddocks for the horses, towing, weekend camping trips etc. I have no intention of using the MX5 for any of that.

While it is a comoromise, it’s likely that it will still be a superior setups to stock or what’s currently in there - both in terms of ride quality and handling performance.

This is what I did.
New replacement OEM spec. Koni STR.T shocks and standard springs on my NB8A with Fat cat bump stops.
Very, very happy with that comfortable and quiet combo for daily driver duties and the odd squirt through the twisty bits.
Standard springs last forever.
The shocks I replaced were 180,000km factory fitment and totally stuffed.
I don't drive on dirt but the roads north of Toowoomba aren't high quality.

Hope this helps.
John

Thanks John.

[KevGoat]

Most comfortable all round setup I've had on the three MX-5's I've owned, was on my '90 NA6 (well - for me and my wife anyway , suspension likes/dislikes is so very individual) It was also a cheap setup too. I fitted Monroe shocks with standard height King springs and FatCat bump stops. Handled the local Adelaide Hills twisties well and for our longer holiday trips supplied good comfort. No idea how it would go for track days though as I don't really push handling limits much.

Sent from my SM-G930F using Tapatalk

[twr7cx]

Assume by 'rougher country backroads around where I live' you mean sealed roads - as for your 'couple hundred metres of dirt road' just go slow as you probably already do.

Yep, that's exactly what I mean. Regarding the unsealed parts its 40km/h at most on the better parts.

Your WTB for an NA8 Clubman 20mm front swaybar is worth experimenting with, but the NA6 12mm rear swaybar (as opposed to the NA8 Clubman 11mm ) should suffice for your purposes.

The only aftermarket option easily available in Australia seems to be the Whiteline swaybars at 24/16mm < https://www.whiteline.com.au/product_de ... 2&sq=19422 > but I'm concerned that they're too thick for my purposes and would have too much of a negative impact on the one-wheel spring of the vehicles suspension for potholes and rough parts of the roads. Am having a difficulty sourcing a Clubman front swaybar which is surprising given that many seem to have upgraded to the aftermarket options...

Don't know how many kms your NA6 has done, but Guran very successfully tracked an NA6 for 5 years in NSW standard class/Type 1 starting almost a decade ago:
viewtopic.php?f=68&t=74332&p=906923&hilit=shock%2A#p906923
viewtopic.php?f=68&t=74497&p=910962&hilit=guran+na6#p910962
You can read about Little Reddy here: www.mx5cartalk.com/forum/posting.php?mo ... 0&p=934949

Thanks, will check it out.

[CrazyRacer]

You should probably ring up MCA Suspension and have a chat to Josh.

They do both pre-configured packages to suit various requirements as well as fully customised setups if you know exactly what you want.

They start from around $1600 for the basic Blues and go up into the stratosphere for Golds. Yeah they look similar to eBay ones, but its the bits you can't see inside that make the difference and MCA have built up a pretty good reputation.

Otherwise you'll probably pick up some Koni Sport (Yellow) pretty cheap second hand which would be a decent place to start, either with standard or some King springs. They Koni Sports for the NA at least have a 3 position adjustable spring perch so you get some ride height adjustment to play with.

[RS2000]

The only aftermarket option easily available in Australia seems to be the Whiteline swaybars at 24/16mm

Signature Swaybars in Nowra make great bars to any size you want - more expensive than Whiteline though.

Most people find that 24/16 is not a good combination. My NB8A came with 22/12:
From 22 to 24 on the front is a 9% increase in diameter, & a 19% increase in cross-section.
From 12 to 16 on the rear is a 33% increase in diameter, & a 78% increase in cross-section!!!

[manga_blue]

Welcome to the MX5 club!

I suspect that your suspension requirements are very similar to mine. My NA is now a daily driver and tourer around the coastal SE corner of NSW and in the alpine country behind. I drive it on pretty average single and two lane blacktop with lumps, bumps and corrugations all over, plus the odd stretch of dirt when I get forced off by roadworks and emergency closures or I feel the need to go top down to some of our more remote spots. Up until a 2 or 3 years ago it was also being tracked around 20 times a year in NSW and Vic and covered over 4,000 laps in competition. I spent a lot of time tuning suspension so it would be competitive on the track but easily converted back to daily duties.

There are a few different factors which should guide your thoughts when you need your MX5 to be safe, quick and comfortable on bad roads. The secret lies in always allowing each wheel to move as freely and individually as possible over the bumps.

First up is bushes. They must in a good condition. You can use poly (like SuperPros) or upgraded OEM-like rubber (like IL Motorsports). Both have their pluses and minuses. They must just be in good nic.

Next is springs. Standard NA springs are rated at 2.9 Kg/mm front and 1.7 Kg/mm rear. At various times I've run firmer springs rated at 5/3, 5/4, 7/5 and 10/7 on local roads. All combos gave good grip, provided the dampers were set right, but anything over 5/4 was pretty hard on the teeth. My preference is 5/4 or a bit softer but really anything from the standard 2.9/1.7 up to 5/4 is comfortable and performs well. Passenger comfort is very important - the passenger doesn't having driving to distract him/her from being shaken about. Soft is not always what the passenger wants either. My father-in-law had a thing about yank tanks, so my wife's earliest memories about long distance car travel is being carsick in the back of Dodges and DeSotos as they wallowed up the old New England Highway. The 5/4 springs that I use pretty much are almost the softest that she'll let me use.

Next is wheels. Unsprung weight is critical. You get grip by keeping each wheel in close contact with the road. You cannot have heavy wheels on dirt or poor blacktop. They just bounce across the tops of the bumps. Buy the lightest wheels and tyres you can afford. I'm pretty anal about both, my wheels are forged from aluminium armour plating from the gun turrets of Soviet T38 tanks and I go to the dealer and weigh his tyres on my own scales before I buy.

Next is the diff. You really should have a torsen (Mazda limited slip) for rough roads to give you even drive out of the corners. With an NA6 you need to buy a full assembly and half shafts from an NA8 or NB.

Next is sways. Heavy sways are the enemies of grip on rough stuff. They tie the two wheels on an axle together so that when, for instance, the inside front wheel hits a bump and deflects up then the outside wheel is shoved up at the same time by the sway bar and you lose grip on the outside wheel. Sway bars work best on billiard smooth roads but if you go to big bars on a country car then you're effectively converting your beautifully designed supple fully independent MX5 suspension into live axles. I tried 24/16 mm bars on my car once, big mistake: it was really skittish on short bumps and corrugations and felt like a cat on acid on dirt. My preference is to minimise sway bar size, or avoid them altogether if you can can get the over/understeer balance and roll stiffness right with springs alone. My 5/4 spring setup uses an OEM front bar and no rear bar. MY next experiment will be to swap the springs to 5/2.9 and run without any bars at all. My fastest race setup ever was 10/7 with no ways.

Next comes dampers. My dampers have a range of adjustment from 1 to 16 clicks, where 1 is rock hard and 15 is OEM. I run it at 15 (OEM) day to day but sometimes dial them up one click to 14 (about 10% stiffer than OEM) for long drives on smooth roads. Anything much beyond standard on dirt or nasty choppy blacktop costs you both grip and ride comfort.

If I summed all of this up for your case I would say just make sure the bushes are good, use standard springs with standard sways, OEM spec Monroe shocks and run NB8A 15x6 wheels.

Oh yes, and do read Guran's Little Reddy thread.