[Editor’s Note: This article originally appeared in the June 2023 issue of Grassroots Motorsports. While RedShift coil-overs featured in this story are no longer available, the results from this story are still worth sharing. Additionally, alternatives can be found from companies like Shaftworks and Inertia Lab.]
Again within the day, lowered sports activities automobile life was a lot simpler: Set up Koni Sport dampers with reducing springs and grow to be one of many cool youngsters. A decrease middle of gravity decreased weight switch, and the stiffer springs helped decreased physique roll whereas warding off the bump stops.
Want a bit of extra spring? A set of Floor Management coil-over sleeves with Eibach racing springs was the reply. Have to damp these stiffer springs correctly? A Koni revalve was obtainable for that objective.
Quick-forward to as we speak, and coil-over choices are large open. Trickle-down from skilled motorsports has pushed the excessive finish skyward, with a plethora of selections as to functionality and costs to match. Penske, Moton, Öhlins, JRZ, MCS and Multimatic can all be discovered on the world’s quickest race vehicles.
Over the previous few years, nonetheless, a mid-point class has emerged. It takes its cues from the professionals however makes use of high-volume, modular parts. Price financial savings in scale are handed on to shoppers like us.
The off-the-shelf variations of those overseas-produced merchandise are usually designed for road use moderately than motorsports, however there’s another choice: Don’t purchase coil-overs. Rent a shock builder as a substitute.
Thankfully, there are shock builders who’re adept at reconfiguring these cheap, generic models to offer valving and vary of journey extra appropriate for fast lap instances. Their variations typically have bigger shafts for extra fluid motion, completely different seals for much less stiction, and non-standard physique lengths to raised match a lowered software.
One such builder is RedShift Competition. Initially a Honda-oriented provider of {custom} motorsports suspension merchandise, the enterprise expanded its choices to incorporate hottest autos.
Critically vital is the lengthy historical past of direct participation and championship success in our particular disciplines–autocross and monitor. That’s the place the know-how comes from for valving and dimensions that work proper the primary time. And in the event you nonetheless need one thing completely different after first use, revalves are additionally on supply.
We first labored with RedShift proprietor Chris Shenefield on our One Lap CRX, changing a set of {custom} high-end, triple-adjustable, remote-reservoir dampers together with his single-adjust product. That change yielded higher curb-hopping compliance whereas dropping nothing elsewhere in general tempo. It additionally resulted in a pair of SCCA Time Trials Nationals victories.
Extra just lately, we determined to maneuver our Triple Risk Miata mission to a contemporary coil-over. Whereas this strikes us up a class in SCCA Time Trial from Sport to Tuner, our actual motivation was extra consistency in our tire testing program since this automobile serves as considered one of our main take a look at mules.
Our dwelling tire take a look at monitor, Harris Hill Raceway, has been growing some bumps that make it more difficult to drive on the restrict. This uncovered a key limitation of the earlier Koni-plus-lowering spring combo: compression journey.
Because the Koni is a full-length damper designed to be run at inventory experience heights–and to work for a variety of consumers–it finally ends up on the bump stops lots when used with reducing springs. Flyin’ Miata cured a few of that with the equipped shortened rear stops that got here with the springs, however it’s actually only a Band-Help.
Maintaining in thoughts the Triple Risk nature of the mission, we wished to retain streetability on the expense of outright max tempo. So a plan was hatched to initially set up RedShift dampers with valving much like the Konis however with way more vary of journey at our lowered experience peak.
At lower than $1100, our RedShift Commonplace road single-adjust coil-overs value lower than most different choices whereas delivering spectacular lap instances.
For springs, we first approximated the charges of the Flyin’ Miata reducing springs. We then progressively stepped up the charges till the road experience turned annoying, all whereas sustaining the identical experience peak supplied by the Koni/Flyin’ Miata setup. We recorded our lap instances to trace goal efficiency enhancements, and we took subjective notes as to steadiness, clearance and experience high quality with every mixture.
To guage fitment, we used two well-liked tire units from our latest testing program: the 235/40R17 Falken Azenis RT660 and 245/40R17 Nankang Sportnex CR-S, all mounted on 17×9-inch Kogeki wheels from Flyin’ Miata.
Our take a look at regime included a 45-minute freeway drive to the monitor, two or three classes to seek out the efficiency limits, and a return journey over nation again roads.
How a lot for these single-adjustable coil-overs custom-valved for our particular software? How about $1095 full? That’s cheaper than the opposite setup and a couple of quarter of what you’d spend for high-end motorsports dampers. Can we go quicker whereas spending much less? Let’s discover out.
Spherical 1: Setting a Baseline
- spring charges: 6K/4K
- finest lap: 1:26.66
The RedShift setup options adjustable damping, however we began with them on the beneficial baseline setting–once more, keep in mind that remark about working with a shock builder.
The primary time on monitor with the brand new setup was eye-opening. For positive, we’d achieved the first objective of getting the automobile off the bump stops. On the restrict, bump/dip-induced breakaway was way more progressive, making the automobile extra constant–though we did should relearn tips on how to drive the automobile on the restrict.
Beforehand, on the Koni/Flyin’ Miata setup, we’d mildly toss the automobile into turns to fight the bump-stop-induced understeer. As soon as settled, we’d go to throttle early and onerous to assist rotate the automobile off the flip. Our quickest lap with this setup–and that’s after dialing within the quickest damper settings–was 1:26.68.
On the RedShift dampers, each compression and rebound are adjusted along with a single knob, whereas our Konis function solely adjustable rebound. Backing off compression might help soften the road experience. Images Credit score: Andy Hollis
Driving the RedShifts that method had us dropping the tail both on entry or exit. With the steadiness shifted now to gentle oversteer, we discovered ourselves braking a bit of simpler and earlier, carving into the flip, carrying extra pace mid-corner, and extra easily making use of throttle only a contact in a while exit. It was simply as quick, however it took some experimenting to get there.
With the shock settings softened, the experience high quality driving to and from the monitor was glorious regardless of the standard harshness of the 200tw Falkens.
Some spreadsheet evaluation defined the steadiness: The 6K/4k setup delivers experience frequencies which can be 16% stiffer within the rear relative to the entrance. That is typical for a road setup to ship a cushty “flat experience” over bumps, however it’s not ideally suited for motorsports. As a short lived repair, we disconnected our 14mm Fiat 124 rear anti-roll bar and located extra impartial dealing with whereas reducing our greatest lap with the RedShifts from 1:26.73 to 1:26.66.
Spherical 2: Going Stiffer
- spring charges: 8K/4K
- finest lap: 1:26.35
Searching for a extra everlasting steadiness answer, we upped the entrance spring price to 8K, night out the experience frequencies entrance to rear. Trip peak and shock settings remained the identical as earlier than.
The outcomes weren’t precisely what we had been anticipating, because the automobile continued to be a bit of free. The entrance finish, nonetheless, additionally felt extra responsive–our stiffer price had gained us some entrance grip. Extra roll resistance was protecting the entrance tires a bit flatter within the turns. The automobile was equally fast with and with out the rear bar, however simpler to drive with out. Most significantly, our lap instances had improved by a few tenths.
The damper physique has graduations on the threads to maintain monitor of perch and physique size changes extra simply. We needed to alter the latter to maintain static experience heights the identical when becoming stiffer springs. Images Credit score: Andy Hollis
On the road, experience high quality was noticeably stiffer however nonetheless fairly comfy. In reality, adjusting the damper stiffness had a better affect than the spring price.
Spherical 3: Even Sooner?
- spring charges: 10K/4K
- finest lap: 1:26.11
This mix delivered magic on monitor. One other couple of tenths had been shaved off our lap instances, and the steadiness felt excellent. At this level, we had solely stiffened the entrance springs, and on monitor we nonetheless ran the preliminary, beneficial shock settings. We did attempt it with the rear bar disconnected, however understeer then reared its ugly head.
The unhealthy information got here on the experience dwelling: The experience high quality had begun to veer down the race automobile path. It was particularly noticeable within the pit of our abdomen within the compression of a dip. Thump!
The light-weight alloy our bodies of our coil-overs ship an unsprung weight financial savings of two.5 kilos per nook. Images Credit: Andy Hollis
Though much more spring price may have presumably made the automobile faster on monitor, we nonetheless wished to maintain it streetable. This outcome was not stunning–examine the sidebar on experience frequencies for extra particulars right here.
Fortunately, we’ve got a set of 300tw Continental Excessive Contact Sport tires on OE BBS wheels that present extra sidewall flex to melt issues for longer-term road utilization.
Ultimate Comparability: Customized vs. Off-the-Shelf
We had one final query: How a lot additional had we actually come throughout this improvement work? Since one of these take a look at program takes a whole lot of calendar time, many variables can creep into the outcomes, particularly climate and monitor evolution.
For our ultimate comparability–the {custom} dampers versus the off-the-shelf ones–we would have liked to run back-to-back assessments on each setups throughout a really slim window.
A transfer to a distinct tire for this a part of the take a look at additionally necessitated the revised baseline, as we match the brand new Nankangs that carried out so effectively in final concern’s tire take a look at. Our CR-S tires now sported about 3/32 inch of tread and had been faster than ever.
On the RedShift setup with the 10K/4K springs and the Nankang tires, we shortly discovered ourselves within the 1:24 vary–new territory for this automobile–with a quick lap of 1:24.61. The road drive additionally felt a bit extra comfy than earlier than, because the Nankangs aren’t fairly as harsh over highway irregularities.
As soon as on the Koni setup, we had been solely in a position to come inside a half-second of the RedShifts with a finest lap of 1:25.13. That outcome matched the sooner long-term enhancements when operating on the Falkens.
To correctly clock the rubber suspension bushings throughout coil-over set up, it’s crucial to tighten all connections with weight on the wheels. We simulate this by jacking up every decrease management arm with the anti-roll bar disconnected earlier than torquing all of it down. Images Credit score: Andy Hollis
Trying on the knowledge confirmed that the time delta largely got here throughout high-speed nook entry in addition to a fast left-left-right sequence that delivers durations of lengthy lateral loading with undulations difficult roadholding. The automobile made extra peak grip on the RedShifts and saved it extra persistently.
In contrast, the Koni setup was a bit higher at placing down energy onto the again straight exiting the very tight Flip 7. A brand new dip had just lately emerged proper at that flip’s throttle-up level, with the extra tossable Koni setup permitting an earlier exit at power-up as a result of it counters throttle-induced oversteer with bump-stop-induced understeer.
Searching for the very best of each worlds, we reinstalled the RedShifts and returned to the monitor with a brand new plan: We’d lastly make a damper adjustment aimed toward a dynamic dealing with repair.
There’s slop within the front-upper management arm mounting bolts that can have an effect on the camber settings. Utilizing a pry bar on the entrance bolt whereas tightening will add an additional ¼ diploma of destructive camber. Images Credit score: Andy Hollis
That strategy smoothed out the bump sufficient that we persistently nailed a sequence of our quickest laps ever, with a better of 1:24.22. Information evaluation confirmed that we’d picked up the misplaced time accelerating down the again straight.
Closing out this part of suspension improvement, we had been now setting instances a full second faster than the unique setup whereas delivering extra constant laps–all whereas nonetheless sparking pleasure on the road. We’ll name {that a} win.
Plus, we’ve but to benefit from the corner-weighting functionality of our coil-overs, so there’s nonetheless extra unlocked potential.
Feedback
Though admittedly I’ve at all times performed entrance wheel drive vehicles, I normally go along with a bit larger experience frequency within the rear than the entrance. That is to ‘catch up’ the rear to the entrance when going over a bump and stage out the fore/aft roll of the automobile (prevents a ‘porpoising’ movement). It would not take a lot, possibly like 10-20% extra within the rear.
It is at all times improved the steadiness of the automobile for me.
The damper physique has graduations on the threads to maintain monitor of perch and physique size changes extra simply. We needed to alter the latter to maintain static experience heights the identical when becoming stiffer springs.
By adjusting the physique size, you had been additionally adjusting your obtainable suspension journey. This a extremely widespread oversight. Higher to regulate the perch peak and maintain the vary of journey the identical.
One good thing about stiffer springs: lowering the vary of journey used. We took notes to see how every setup affected rub over bumps on monitor. The narrower and shorter 235mm-wide Falkens solely rubbed a bit with the preliminary 6K entrance spring setup; the contact disappeared with the 8K and 10K charges. The taller, super-fat 245mm Nankangs had been one other story, with huge contact at 6K, gentle rub at 8K and eventually clearing absolutely at 10K.
This seems to be like the standard confusion that happens. You adjusted the journey vary when putting in the stiffer springs. The stiffer springs did not scale back the vary of journey, the change in shock geometry did. Stiffer springs (with no different modifications to geometry, simply the perch peak location) is not going to change the doable vary of journey. They will simply lower the frequency at which the suspension will get into the far ends of journey. However there’s at all times a bump large enough to hit the top of your journey. If you wish to forestall rubbing, the factor to do is to regulate the doable vary of suspension journey and to grasp that is what you are doing. You do not even need the springs on the automobile while you’re setting that, the best way to do it’s to completely compress the suspension and alter so you might have clearance. Then you definitely set up the springs and set your experience peak.
Should you’re getting an excessive amount of bumpstop activation, you want a better spring price or a better experience peak, however no change within the shock physique size as soon as it’s set.
Despatched an inquiry on my software because the choices are fairly skinny.
Humorous Andy talked about the konis and floor controls. The final time I had a mirage, the spokes crew helped me construct out a {custom} set based mostly off of rabbit struts within the entrance. It was like oh yeah been there performed that.
Keith Tanner stated:
This seems to be like the standard confusion that happens. You adjusted the journey vary when putting in the stiffer springs. The stiffer springs did not scale back the vary of journey, the change in shock geometry did. Stiffer springs (with no different modifications to geometry, simply the perch peak location) is not going to change the doable vary of journey. They will simply lower the frequency at which the suspension will get into the far ends of journey. However there’s at all times a bump large enough to hit the top of your journey. If you wish to forestall rubbing, the factor to do is to regulate the doable vary of suspension journey and to grasp that is what you are doing. You do not even need the springs on the automobile while you’re setting that, the best way to do it’s to completely compress the suspension and alter so you might have clearance. Then you definitely set up the springs and set your experience peak. Should you’re getting an excessive amount of bumpstop activation, you want a better spring price or a better experience peak, however no change within the shock physique size as soon as it’s set.
Excellent segue into the subsequent installment. 🙂
I’ve right here some spacers (actual thick packers) to regulate point-of-contact of the bump cease and in addition a set of helper springs to do the identical going the alternative strategy (perch motion). The spacer strategy is on the automobile now, dialed in in order that even the most important bump will clear absolutely with the fattest tire/wheel combo I run.
The problem with simply shifting the perch by itself is that the spring turns into unloaded and rattles round in sure circumstances. The rear of my CRX is particularly susceptible to this. For that one, we did inner droop limiters. However the extra widespread answer is helpers, as it’s exterior and simple to put in.
As soon as I get via the subsequent spherical of tire testing, I will be enjoying round with the 2 approaches to check/distinction.
With these adjustable size our bodies, you do not want the bump cease spacers. You possibly can simply alter the shock physique size. And yeah, both longer essential springs or helpers in the event that they’re free at full droop. As soon as the principle spring is unloaded, you are mainly out of journey anyhow.
With the quantity of journey obtainable within the ND suspension, I believe we use a 12″ lengthy rear spring on our Fox setup.
Keith Tanner stated:
With these adjustable size our bodies, you do not want the bump cease spacers. You possibly can simply alter the shock physique size.
Really, I do. Even absolutely prolonged, there is not sufficient physique size to get the bump cease the place it must be.
The unhappy a part of all of that is that I did not have to do any of this till this one explicit despair within the monitor immediately acquired actually extreme….
Are you able to get an extended insert out of your builder? It will offer you extra shaft journey as a bonus. I would have an interest to listen to how this setup copes with crests at pace.
Tough tracks are extra fascinating than easy ones 🙂
Keith Tanner stated:
Are you able to get an extended insert out of your builder?
Probably. However the helper spring setup is probably going the ultimate reply. At this level, my use case is solved with the spacer, and I’ve acquired three tire assessments within the queue … so I am not in an enormous hurry to get again to the coilover detailing. “Perfection is the enemy of excellent” and all that…
I reached out with an inquiry concerning the S30 Z automobile chassis. They’d a really quick response time and supply buyer valved BC coilovers for my automobile, which is an intriguing possibility.
Comparable pricing as a number of the larger finish choices obtainable off the shelf, however probably superior high quality.
Thanks for sharing!
Do they provide upgraded springs? Like Eibach/Hyperco/Swift? I’ve learn loads of stuff about generic springs not at all times matching the marketed price.
Primarily simply curious as my automobile already has a set of constructed coilvers and if I alter them will probably be to maneuver as much as MCS or JRZ or related.
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