Too good to be true? Custom-built coil-overs at off-the-shelf prices

Andy
By Andy Hollis
May 23, 2023 | Koni, Shocks, Coil-overs, RedShift Competition | Posted in Suspension & Handling , Features | From the June 2023 issue | Never miss an article

Photography Credit: Politipixs

Back in the day, lowered sports car life was so much easier: Install Koni Sport dampers with lowering springs and become one of the cool kids. A lower center of gravity reduced weight transfer, and the stiffer springs helped reduced body roll while keeping off the bump stops. 

Need a little more spring? A set of Ground Control coil-over sleeves with …

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BA5
BA5 GRM+ Memberand HalfDork
5/23/23 10:23 a.m.

Although admittedly I've always done front wheel drive cars, I usually go with a bit higher ride frequency in the rear than the front.  This is to 'catch up' the rear to the front when going over a bump and level out the fore/aft roll of the car (prevents a 'porpoising' motion). It doesn't take much, maybe like 10-20% more in the rear.

It's always improved the stability of the car for me.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/23/23 10:42 a.m.

The damper body has graduations on the threads to keep track of perch and body length adjustments more easily. We had to adjust the latter to keep static ride heights the same when fitting stiffer springs.

By adjusting the body length, you were also adjusting your available suspension travel. This a really common oversight. Better to adjust the perch height and keep the range of travel the same. 

One benefit of stiffer springs: reducing the range of travel used. We took notes to see how each setup affected rub over bumps on track. The narrower and shorter 235mm-wide Falkens only rubbed a bit with the initial 6K front spring setup; the contact disappeared with the 8K and 10K rates. The taller, super-fat 245mm Nankangs were another story, with massive contact at 6K, mild rub at 8K and finally clearing fully at 10K.

This looks like the typical confusion that occurs. You adjusted the travel range when installing the stiffer springs. The stiffer springs didn't reduce the range of travel, the change in shock geometry did. Stiffer springs (with no other changes to geometry, just the perch height location) will not change the possible range of travel. They'll just decrease the frequency at which the suspension gets into the far ends of travel. But there's always a bump big enough to hit the end of your travel. If you want to prevent rubbing, the thing to do is to adjust the possible range of suspension travel and to understand that's what you're doing. You don't even want the springs on the car when you're setting that, the way to do it is to fully compress the suspension and adjust so you have clearance. Then you install the springs and set your ride height.

If you're getting too much bumpstop activation, you need a higher spring rate or a higher ride height, but no change in the shock body length once it is set.

bmw88rider
bmw88rider GRM+ Memberand UberDork
5/23/23 12:02 p.m.

Sent an inquiry on my application as the options are pretty thin.

Funny Andy mentioned the konis and ground controls. The last time I had a mirage, the spokes crew helped me build out a custom set based off of rabbit struts in the front.  It was like oh yeah been there done that. 

Andy Hollis
Andy Hollis
5/23/23 1:29 p.m.
Keith Tanner said:

This looks like the typical confusion that occurs. You adjusted the travel range when installing the stiffer springs. The stiffer springs didn't reduce the range of travel, the change in shock geometry did. Stiffer springs (with no other changes to geometry, just the perch height location) will not change the possible range of travel. They'll just decrease the frequency at which the suspension gets into the far ends of travel. But there's always a bump big enough to hit the end of your travel. If you want to prevent rubbing, the thing to do is to adjust the possible range of suspension travel and to understand that's what you're doing. You don't even want the springs on the car when you're setting that, the way to do it is to fully compress the suspension and adjust so you have clearance. Then you install the springs and set your ride height. If you're getting too much bumpstop activation, you need a higher spring rate or a higher ride height, but no change in the shock body length once it is set.

Perfect segue into the next installment.  :)

I have here some spacers (real thick packers) to adjust point-of-contact of the bump stop and also a set of helper springs to do the same going the opposite approach (perch movement).  The spacer approach is on the car now, dialed in so that even the biggest bump will clear fully with the fattest tire/wheel combo I run.

The challenge with just moving the perch by itself is that the spring becomes unloaded and rattles around in certain circumstances.  The rear of my CRX is especially prone to this.  For that one, we did internal droop limiters.  But the more common solution is helpers, as it is external and straightforward to install.

Once I get through the next round of tire testing, I'll be playing around with the two approaches to compare/contrast.

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/23/23 2:27 p.m.

With those adjustable length bodies, you don't need the bump stop spacers. You can just adjust the shock body length. And yeah, either longer main springs or helpers if they're loose at full droop. Once the main spring is unloaded, you're basically out of travel anyhow. 

With the amount of travel available in the ND suspension, I think we use a 12" long rear spring on our Fox setup. 

Andy Hollis
Andy Hollis
5/23/23 2:45 p.m.
Keith Tanner said:

With those adjustable length bodies, you don't need the bump stop spacers. You can just adjust the shock body length.

Actually, I do.  Even fully extended, there isn't enough body length to get the bump stop where it needs to be.

The sad part of all of this is that I didn't need to do any of this until this one particular depression in the track suddenly got really severe....

Keith Tanner
Keith Tanner GRM+ Memberand MegaDork
5/23/23 3:31 p.m.

Can you get a longer insert from your builder? It would give you more shaft travel as a bonus. I'd be interested to hear how this setup copes with crests at speed. 
 

Rough tracks are more interesting than smooth ones :)

Andy Hollis
Andy Hollis
5/23/23 3:47 p.m.
Keith Tanner said:

Can you get a longer insert from your builder?

 
 

Possibly.  But the helper spring setup is likely the final answer.  At this point, my use case is solved with the spacer, and I've got three tire tests in the queue ... so I'm not in a huge hurry to get back to the coilover detailing.  "Perfection is the enemy of good" and all that...

birdmayne
birdmayne GRM+ Memberand HalfDork
5/23/23 4:31 p.m.

I reached out with an inquiry about the S30 Z car chassis. They had a very fast response time and offer customer valved BC coilovers for my car, which is an intriguing option.

Similar pricing as some of the higher end options available off the shelf, but potentially superior quality.

 

Thanks for sharing!

 

z31maniac
z31maniac MegaDork
5/23/23 5:31 p.m.

Do they offer upgraded springs? Like Eibach/Hyperco/Swift? I've read plenty of stuff about generic springs not always matching the advertised rate. 

Mainly just curious as my car already has a set of built coilvers and if I change them it will be to move up to MCS or JRZ or similar. 

birdmayne
birdmayne GRM+ Memberand HalfDork
5/23/23 6:25 p.m.

They offer Swift springs as an upgrade. 

They claim to be on par with MCS, JRZ,  etc

84FSP
84FSP UberDork
5/23/23 6:53 p.m.

Hmm this would be the ticket for my Mk1 Rabbit.  It currently sits on custom damped standard body bilsteins with Ground Control Coilover Hats and 550/450 rates f/r.  Would like a nice balanced setup that is adjustable as it has never felt as balanced as I'd like.

malibuguy
malibuguy GRM+ Memberand HalfDork
5/23/23 10:33 p.m.

I have a set of the Standard Street series on my Yaris and adore them so much I became a dealer for RedShift.

I love how I can wind them down and they ride better then any old drop spring and damper combo I had on it.  Yet I can crank them up for race use and it works so damn well.

They have an 'X' factor during cornering I have never experienced before...granted my previous coilover experience is largely limited to low end dampers such as FortuneAutos, BCs, D2s and Ksports (back in the day).  The Standards just rock and I love them.  I cannot wait to be able to get a system for my autoX car.

/end fanboi post ❤️

z31maniac
z31maniac MegaDork
5/23/23 11:44 p.m.
malibuguy said:

I have a set of the Standard Street series on my Yaris and adore them so much I became a dealer for RedShift.

I love how I can wind them down and they ride better then any old drop spring and damper combo I had on it.  Yet I can crank them up for race use and it works so damn well.

They have an 'X' factor during cornering I have never experienced before...granted my previous coilover experience is largely limited to low end dampers such as FortuneAutos, BCs, D2s and Ksports (back in the day).  The Standards just rock and I love them.  I cannot wait to be able to get a system for my autoX car.

/end fanboi post ❤️

I have a set of 8th gen Fortune Auto 500s on the '23 BRZ with custom valving and rates with the Swift springs. I had a set of Ground Control with Koni's on the '15 BRZ. 

The FA's are not only slightly stiffer in rates, but also ride DRAMATICALLY better on the street than the GC setup could ever dream of. 

CrashDummy
CrashDummy Reader
5/24/23 7:18 a.m.

I'd be curious to see how the pace of the custom coilovers (which you've shown are faster than the Koni setup) compares to something like the XIDAs. If you're chasing tenths, is it worth it to spend more on the XIDAs? 

Andy Hollis
Andy Hollis
5/26/23 11:37 a.m.
CrashDummy said:

I'd be curious to see how the pace of the custom coilovers (which you've shown are faster than the Koni setup) compares to something like the XIDAs. If you're chasing tenths, is it worth it to spend more on the XIDAs? 

Maybe?

In my case, the extra pace came from a specific issue I was trying to solve: consistency of grip over a bumpy surface.  XIDAs would have likely given the same positive pace result for that issue.  Any other potential benefits, I can't say.

Pete. (l33t FS)
Pete. (l33t FS) GRM+ Memberand MegaDork
5/26/23 1:21 p.m.
BA5 said:

Although admittedly I've always done front wheel drive cars, I usually go with a bit higher ride frequency in the rear than the front.  This is to 'catch up' the rear to the front when going over a bump and level out the fore/aft roll of the car (prevents a 'porpoising' motion). It doesn't take much, maybe like 10-20% more in the rear.

It's always improved the stability of the car for me.

This is generally how the OEs tune the suspension, which is why cars tend to have much larger stabilizer bars in the front than the rear, even with neutral handling.

Andy Hollis
Andy Hollis
5/27/23 10:17 p.m.
Pete. (l33t FS) said:
BA5 said:

Although admittedly I've always done front wheel drive cars, I usually go with a bit higher ride frequency in the rear than the front.  This is to 'catch up' the rear to the front when going over a bump and level out the fore/aft roll of the car (prevents a 'porpoising' motion). It doesn't take much, maybe like 10-20% more in the rear.

It's always improved the stability of the car for me.

This is generally how the OEs tune the suspension, which is why cars tend to have much larger stabilizer bars in the front than the rear, even with neutral handling.

Yep.  Called "flat ride".  And it's mentioned in the story in the discussion on ride frequency.

CrashDummy
CrashDummy Reader
6/1/23 12:31 p.m.
Andy Hollis said:
CrashDummy said:

I'd be curious to see how the pace of the custom coilovers (which you've shown are faster than the Koni setup) compares to something like the XIDAs. If you're chasing tenths, is it worth it to spend more on the XIDAs? 

Maybe?

In my case, the extra pace came from a specific issue I was trying to solve: consistency of grip over a bumpy surface.  XIDAs would have likely given the same positive pace result for that issue.  Any other potential benefits, I can't say.

GRM should commision a test of this. For science! 

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