TL;DR Is building my own suspension setup (out of circle track parts) worth the time and effort or should I just buy what others have already done at a higher cost?


Sorry if this has been brought up before. I have searched pretty hard on here and found very little on this subject.

I am building a car to compete in my local autocross region and some HPDE events. The car is being built for a class where the only restriction is 140tw tires or higher (Street Tire Modified, ETRSCCA). This allows for some creativity and perhaps some "outside of the box" ideas.

Being from Tennessee there is no lack of circle tracks, asphalt and dirt, but a huge lack of anything requiring right hand turns. This leaves the local used aftermarket slim for quality Miata parts.

The car has been very budget minded and it will continue that way. My car is a 1990 NA1.6, around 1800lbs, RX7 clutch type diff, MS2, RB tubular front bar, all poly bushings with zerk fittings, 195/15 R1Rs, stripped and cut up. It is decently competitive locally and my driving is still improving, but I am finding my current suspension to be less than adequate. With the season half-way over I think I want to take on suspension during the down time (December to early March).

Here is my brainstorm:
- 1/8 inch steel plate with provisions for mounting in the stock strut tower
locations.
- Weld a capture eyelet on the bottom of the plate for shock bearing.
- Buy local threaded body shocks (Penske, Afco, Bilstein, ect.).
- 700/400 in/lb 2.25" springs (revalve will likely be needed)
- I am not sure of the shock lengths needed for the front and rear, keeping
pitch weld height around 3"/3.25" and spring length short but no coil bind.
- Budget of around $1500.

This is not something new as some have already done something similar.
hingstonwm FP Miata for instance.


Just to give you an idea, these came up for $650 shipped on ebay.



I would love some input from people that have tried this before. I know there is a huge following for Xida's, FCM and other proven shocks, but this car is more a test of my ability and understanding than a pure competition machine. I want to go faster, but I want to learn why I am going faster and understand what my changes are doing. The build process is just as, if not more, important as the end result to me.

 

I think the only way I'd attempt is if you have an easy/cheap way to alter the valving and lengths of the body and shaft. Otherwise, at $1500, you're too close to proven setups to bother with something that is going to be sub-par.

 

^ I'd agree...spend the $1500 on something proven.


If you must build them yourself- save some money and do the ebay/bilstein thing.

 

<p>Aren't feals pretty close to that range? ThePass has had some good things to say about those. Definitely on my radar.</p>

 

Road Race Feal 441 are $1599 and that includes your choice of spring and approriate valving for the springs. ThePass and I both run them on our cars, they are fantastic for the money. I just ran an autocross in a super bumpy lot and high speeds (70+mph), and even with 14kg/8kg spring rates it was very composed.

 

<p>Yes those. They are very high on my want list. I have a feeling that a good shock setup is going to be above my diy range. No matter how hard I try. Maybe some day.</p>

 

You know, I asked ThePass on his YouTube page if he liked the Feals and if he would recommend them for autocross, but didn't get a reply. I have a friend with a Celica All-trac that runs Feals and he said they felt great compared to his Tein SS setup.

I don't think shock rod length would be an issue if someone had done this and knew already. It is just the revalving part that is an unknown cost, and I would need someone with a shock dyno willing to take the time to do it as well.

I am not opposed to the Feal idea, but I would love to see a shock dyno for them. I hear that Odi will custom valve them, but there is some sort of issue with him giving you a dyno sheet of your shocks. Intellectual property or something.

 

They are fantastic for both autocross and track but at the end of the day it boils down to what you are preparing the car for. Setting up the car for autocross is different than the big track. I autocross in between track events for fun because the local autocross events are long (>1.5 miles) and fast (70-90MPH sections).

Shock dynos do, in theory, allow others to copy your set up...so I don't blame him for not handing them out all the time. However, during the process of helping Odi re-design the shocks we had him run my set on the dyno and send the files over so we could show others.

Front Shocks:

Rear Shocks:

 

I just realized they were also posted on the Good-Win site. I am really happy to see the adjustment **** show nice progression.

The car and myself really only have access to autocross, so it is going to be set up primarily for that. I would probably put a rear bar back in it for an HPDE event. I would love to see more people post their review on the FEALS.

 

Not very many are running them. But they are on my list. I don't really see any other competitors in the ~1500 range. Aren't Xidas 5-800 more?

 

OP, I haven't tried what you want to do but I don't know that you would be able to accomplish it in your budget number. I am going to guess that a revalve for a set of shocks like this is going to be $200 per shock and that's on the low end. That plus $650 is already at your budget but you would somehow have to stumble upon proper shock lengths for front and rear and with pistons and other hardware in the shock to make it worth to do just a revalve and not a piston change or something else.

And FWIW, it looks like the the pic for Hingstown is a custom ordered set of shocks not some circle track shocks that just happened to fall in his lap. You can get Penske 8300 with miata upper attachment points. Something tells me he just chose not to.

 

There is a somewhat local business that revalves a variety of shocks for ~$75 each (shims are cheap), with no machining work. Also $5 a shock to dyno them. $200 a shock might be common in places like California but Tennessee is ripe with circle track cars, and these guys put big money into them. It shows in the availability of parts and services here.

Although Hingstonwm's car may not have a shock set from a circle track car the execution is still the same. Although he is using tubular lower control arms, which probably give more clearance.

A friend messaged me this a few hours ago. Although it is a mod car, you can still see the stock upper control arm and these are DA AFCO shocks that started life going left.

 

Yes, my shocks were penske at the time the pic the OP posted was taken, they came on the car when I purchaswed it. The issue I had with my suspension was the shock body was to short and the spring perch sat below the upper control arm, this caused clearance issues. This set up would work if the shock bodies were longer, I got rid of the current set up and went to a set of Jesse Prather Mototrsports Afco shocks and don't regret is for a minute!

 

Do you remember your measurements?

 

Ok really its not that hard to do what you are suggesting and take a shock that has top and bottom eye mounting and get it on a Miata.

Two-Six Motorsports Shock Packages

However, to make it financially feasible you are going to have to get a set of shocks that are about the same size as the Miata uses and has internals that can be revalved to do what you want with just shims (cheap right?).

From a quick search, a front shock is about 20" long with a 13" body and a rear is about 16" long with a 9" body. For a lowered Miata you will want a smaller shock body to avoid the shock bottoming out all the time. First issue I see from looking at examples of the shocks is that most circle track cars use fairly long shocks with lots of travel.

So lets say you find a set that has the measurements you need. Considering that these were only meant to turn left, on a car that is nothing like a Miata, what are the chances that this has the hardware inside the shock to make it work well on a Miata. There is more to getting the damping curve you want than merely changing shims. Plus a revalve for $75 might be for someone who is making a change on his circle track car, not for someone who is going from circle track valving to auto-x valving on a completely different chassis. And a shim from a factory Miata Bilstein is not the same shim on a Penske/AFCO/JRZ. There is a reason why the big money shocks cost so much and the valving so equal batch to batch.

Might I be talking out of my ***.... damn probably am. I have no experience with circle track cars and know little about shocks in general. But something tells me that a car that has asymmetrical suspension geometry, a solid rear axle, possibly 1200 lb springs front and 200 lb springs rear, weighs 3000 lbs, needs to put power down very well and only turns left *might* have such different shock requirements than a Miata that the shock while physically able to bolt on will have to be re-engineered otherwise. And that re-engineering is going to put you over budget.

Having said that, even paying $2500 for a set of Penskes/AFCO/etc is a good deal. A premium shock is a still a premium shock. And once you get it dialed in, local rebuilds for $75 a shock in a short time (lets say two weeks?) is a steal and a time warp compared to other shocks.

 

Is this Qualcomm?

If so, what the hell are you driving that you're hitting 90 MPH?

 

Yep, Qualcomm. 90mph autox in Miatas bro
The corvettes have seen over 100. Depends on the course design, but we all participate/instruct with the BMWCCA who design fun courses with a blend of technical sections and open high-speed sections.

Sorry about that. 7 or 8 different emails, PMs on various forums, lots of ways to contact me but I get very few comments on youtube so I forget to check there. I think I responded once but then didn't notice your follow-up question. Yep, I love them. Basically what Sean said. My rates are even stiffer than his and it's still composed in bumpy autox settings. The rest of the car is set up for big track, and I just drive it down to the autox and run it for fun without bothering with changing settings, so it's admirable how well it does with that in mind.

-Ryan

 

Are your $1500 circle track shocks at least aluminum bodied bilsteins or even better penskes? If not I'd probably just spend the extra $500, save the fab work and run xidas. If you are going to go through with it, copy the FP car you showed the picture of, but do it in the non moronic way of having the supper shock perch like even with the top of the shock tower like a stock spring so you can get all the bump travel you need still. And dont forget the high rate helper springs.

 

Huh.

Been 5 or 6 years since I ran there, but I don't recall ever running out of 3rd gear.

Maybe they're laying out the courses differently, or maybe I'm just slow.

I do think it's cool that you can see the old course layouts in the form of spent rubber in the Google Maps aerial view.

 

Yes, there are some nice DAs' that come up from time to time as well. Although the lengths are proving to be somewhat a problem.
I noticed that ThePass had them on the Feals in his video. I didn't realize they were proving so important. I probably couldn't get them in my set budget range.