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Mss track kit VS H&R vtf kit

blaqsheep

Drag Racing Champion
Location
Canada
Car(s)
IS38 GTI
@emichel6888 Looking at the Ground Control website and it has a field for Desired Spring Rate. Do you know what the choices are? What did you choose?
His spring rate up front is 475#, not sure about the rear.

You can always reach out to GC for advice on choosing the right rates for your needs.
 

DarkArrow

Go Kart Newbie
Location
Golf R

jmblur

Go Kart Champion
Location
Massachusetts
Car(s)
2017 Golf R
I contacted GC about their kit a couple weeks ago. Here's their response.

We can set the kit up for what you're looking to do. It does not have preload to it, so at full droop the spring does drop away from the perch, helpers are $74 per corner.
Typically the lowest rate we try to send with the kit is 425f/550r, we can go lower than that, but we can't guarantee that you won't have issues with coil bind or bottoming out in that situation.
There shouldn't be an issue with salt, all the aluminum parts are anodized, steel parts are either zinc plated or powdercoated.
so, they will do helper springs, but that will obviously limit drop. I was asking about somewhat softer springs (halfway between this and stock). I ran some numbers and the stock Golf R setup is somewhere around 1.4hz front, 1.7hz rear (more confident in front number than rear). This is at the high end of normal passenger cars. Sedan race cars are generally somewhere around 1.5-2. over 2 the ride can get rather harsh. (full aero cars are 3-5, because they need to support the additional aero load, unless you do something funky like the Koenigsegg 3 damper/spring setup).

the GC springs put you at 2.1 and 2.4hz. This is pushing it for DD use and bumpy tracks, and higher than I personally want for my dual use car. If I had my druthers, I'd probably aim for roughly 50% stiffer than stock, which would put spring rates around 300/375, for 1.75/2.0.

hope that helps some people out!
 

emichel6888

Passed Driver's Ed
Location
TX
Unfortunately no, when fully compressed they add about an inch of height, so if you installed these you would not get a desirable ride height. If you try to use a shorter main spring to compensate for that added height it limits the spring travel and that can (and does) cause the spring to bottom out. There is not a lot travel in this suspension, you really don't want to do anything that lessons spring travel, and helper springs will do that. The only way to effectively use helper springs is if you could lower the bottom perch to offset the height of the helper spring when fully compressed, which is what they do with struts designed to be a coil over like the B16 kit. I found it was just easier and works just fine to live with the fact that there is a gap when the car is lifted. Like I said it slides together when lowered, so it is not even an issue. and if you are concerned that it could get out of alignment you could just do what I did above.
 

emichel6888

Passed Driver's Ed
Location
TX
I contacted GC about their kit a couple weeks ago. Here's their response.



so, they will do helper springs, but that will obviously limit drop. I was asking about somewhat softer springs (halfway between this and stock). I ran some numbers and the stock Golf R setup is somewhere around 1.4hz front, 1.7hz rear (more confident in front number than rear). This is at the high end of normal passenger cars. Sedan race cars are generally somewhere around 1.5-2. over 2 the ride can get rather harsh. (full aero cars are 3-5, because they need to support the additional aero load, unless you do something funky like the Koenigsegg 3 damper/spring setup).

the GC springs put you at 2.1 and 2.4hz. This is pushing it for DD use and bumpy tracks, and higher than I personally want for my dual use car. If I had my druthers, I'd probably aim for roughly 50% stiffer than stock, which would put spring rates around 300/375, for 1.75/2.0.

hope that helps some people out!
The problem with this car is limited suspension travel. So when you try to go with a "comfortable" spring rate, the weight of this car causes it to bottom out far to easily, and if you lower the ride height further reducing suspension travel... This car does not exactly ride great stock IMO, perhaps compared to most other sports cars it does, but not compared to typical mid tier sedan/SUV, and when you start driving fast and hitting bumps it crashes, which I really hate.

I have these spring rates, it is firmer but not nearly as much as you would think, perhaps because the damper plays a big factor in frequency response and these are adaptive dampers. Of course comfort is somewhat subjective, I drive about 20,000 miles a year in this car, and that includes many long trips 300-600 miles in a day, it really is not as bad as you might think. Even with these high spring rates it rides much better than a Focus RS, and many of sports cars I have driven. I am no spring chicken and if it was really that bad there is no way I could live with it for this sort of usage, and I have been living with it for almost a year now. I don't feel beat up at all taking it on long trips, it is firm but not harsh, at least for me.

There are just to many variables that basic simple calculations just cannot account for, especially when it comes to something as subjective and ride comfort. The best thing anyone can do when trying to decide is to try find someone that already has the suspension components you are considering and see if you can get a ride.
 

jmblur

Go Kart Champion
Location
Massachusetts
Car(s)
2017 Golf R
There are just to many variables that basic simple calculations just cannot account for, especially when it comes to something as subjective and ride comfort. The best thing anyone can do when trying to decide is to try find someone that already has the suspension components you are considering and see if you can get a ride.
There are definitely a bunch of calculations that I haven't done (the damping plays a big role in ride comfort), but I also don't love the idea of doubling the spring rate with the same dampers. At the end of the day suspension is a spring mass damper system, and changing only the spring rate but not the dampers can have negative effects on actual performance. The calcs I'm using are part of how suspension engineers tune a car's suspension (along with many others), and while they only get you close, they're an important part in determining overall ride and traction characteristics.

Many think that a stiff ride is "sporty" and so sports cars (especially ones without significant aero) are often oversprung compared to actual performance benefits because of marketing. Most "race" modes only actually work on glass smooth tracks. Cornering, braking, and acceleration traction is often improved by (relatively) softer spring rates and less damping in MOST real life situations. In other words... "Because race car".

That said, the R definitely has room for improvement. Either through bump stop tuning or stiffer springs. The reason you can't go softer on the coilover conversion isn't necessarily that the suspension will bottom out, but that the springs with the conversion have relatively low total travel before they hit coilbind. That's a significant problem and way worse than hitting bump stops, since there's no variable spring rate increase, it's just an immediate step function. Big fucking problems if you hit a bump mod corner and get spring bind!

Not saying the ride isn't decent with the GC kit... But it's higher than I'd want it personally based on my preferences. The fact that the minimum spring rates are determined based on the available spring travel and not the desired performance characteristics doesn't give me warm fuzzies.
 

DarkArrow

Go Kart Newbie
Location
Golf R
I contacted GC about their kit a couple weeks ago. Here's their response.



so, they will do helper springs, but that will obviously limit drop. I was asking about somewhat softer springs (halfway between this and stock). I ran some numbers and the stock Golf R setup is somewhere around 1.4hz front, 1.7hz rear (more confident in front number than rear). This is at the high end of normal passenger cars. Sedan race cars are generally somewhere around 1.5-2. over 2 the ride can get rather harsh. (full aero cars are 3-5, because they need to support the additional aero load, unless you do something funky like the Koenigsegg 3 damper/spring setup).

the GC springs put you at 2.1 and 2.4hz. This is pushing it for DD use and bumpy tracks, and higher than I personally want for my dual use car. If I had my druthers, I'd probably aim for roughly 50% stiffer than stock, which would put spring rates around 300/375, for 1.75/2.0.

hope that helps some people out!
Let me preface this by saying I have little to no knowledge of how to calculate hertz based off all the different numbers needed.

That being said, Karl Taht, who is a member on here, wrote an article about motion ratios, hertz, and other suspension pieces here. While this is for a GTI, his calculations end up being 8kg/9kg to keep a 1.6-1.8hz ratio. I would imagine with the increased weight of the R, the spring rates would be slightly higher? I know there's some assumptions in some numbers being used, but the end results are very different than yours. Since it seems you know more about this, maybe look into his article and see how your numbers differ from his?

I've ridden in @Cliff 's Ground Control setup prior to him switching to Ohlins, and it rode really well on track and is probably the route I'll end up taking when I can save up enough (instead of spending on track days). I know he didn't mind the ride as a daily, and has taken numerous long road trips to tracks in other states. I'm sure he'll chime in more.


Unfortunately no, when fully compressed they add about an inch of height, so if you installed these you would not get a desirable ride height. If you try to use a shorter main spring to compensate for that added height it limits the spring travel and that can (and does) cause the spring to bottom out. There is not a lot travel in this suspension, you really don't want to do anything that lessons spring travel, and helper springs will do that. The only way to effectively use helper springs is if you could lower the bottom perch to offset the height of the helper spring when fully compressed, which is what they do with struts designed to be a coil over like the B16 kit. I found it was just easier and works just fine to live with the fact that there is a gap when the car is lifted. Like I said it slides together when lowered, so it is not even an issue. and if you are concerned that it could get out of alignment you could just do what I did above.
Good to know, I'll keep this post bookmarked for when I plan to get the ground controls. Thanks for posting a lot of useful information on vortex and here. (y)
 

emichel6888

Passed Driver's Ed
Location
TX
There are definitely a bunch of calculations that I haven't done (the damping plays a big role in ride comfort), but I also don't love the idea of doubling the spring rate with the same dampers. At the end of the day suspension is a spring mass damper system, and changing only the spring rate but not the dampers can have negative effects on actual performance. The calcs I'm using are part of how suspension engineers tune a car's suspension (along with many others), and while they only get you close, they're an important part in determining overall ride and traction characteristics.

Many think that a stiff ride is "sporty" and so sports cars (especially ones without significant aero) are often oversprung compared to actual performance benefits because of marketing. Most "race" modes only actually work on glass smooth tracks. Cornering, braking, and acceleration traction is often improved by (relatively) softer spring rates and less damping in MOST real life situations. In other words... "Because race car".
Normally I would agree, but I did not do this for it to feel "sporty", I did it to fix what was a serious issue for the type of driving I do. Based on where and how I drive, I was bottoming out the stock suspension almost daily, and it was an under steering pig, I truly hated the stock suspension on this car. The tracks I drive on are far from "glass smooth", that must be nice. Sway bars alone did almost nothing for this car IMO, even this coil over system alone won't fix the under steer issue, however it does allow you to run more camber and caster up front, and that combined with a few other tweeks have made this into a very balanced car that can take a bump hard mid corner without slamming into the bump stops and easily rotates in a very controlled manner.
I was also very skeptical about such high spring rates with the stock dampers, but Cliff gave it glowing reviews and the folks at GC seem to know a thing or two about suspension so... Is it ideal? No of course not, I have driven cars that are severely under dampened and this is not like that, not nearly as bad as you might think. I don't know if it is because these are not fixed dampers? They do apparently rapidly adjust damping rates based on several factors, so perhaps the spring to damper ratio is much wider than with traditional fixed rate dampers? Does your calculation take into account the dynamic dampers? All I know if that it works, and as someone that tracks this car on occasion and has been doing track days on various cars for 30 years, I can say that it definitely helped performance at 10/10. Is it ideal no, but a good compromise for a street car that occasionally sees some track time, absolutely. Even for street driving the turn in and balance is night and day from stock, and the only penalty is a somewhat firmer ride.

That said, the R definitely has room for improvement. Either through bump stop tuning or stiffer springs. The reason you can't go softer on the coilover conversion isn't necessarily that the suspension will bottom out, but that the springs with the conversion have relatively low total travel before they hit coilbind. That's a significant problem and way worse than hitting bump stops, since there's no variable spring rate increase, it's just an immediate step function. Big fucking problems if you hit a bump mod corner and get spring bind!
Trust me, I am well aware of coil bind issues with this setup, that is what caused this:
20190323_152326.jpg


I think I might be one of the first to get this kit after Cliff. I believe he had a custom 475/650 spring rate, GC felt that might be a bit to extreme for most folks so they they recommended I try 425/550. First the rear springs they sent me were way to tall, so after that the picture above was the result of the initial 425 straight spring up front. That is when they sent me a 475 barrel spring and that seems to work and is most likely the same one Cliff had.

Not saying the ride isn't decent with the GC kit... But it's higher than I'd want it personally based on my preferences. The fact that the minimum spring rates are determined based on the available spring travel and not the desired performance characteristics doesn't give me warm fuzzies.
Well, Cliff tracked this setup for years, I have used it for over a year now myself, and all I can tell you is that it works really well. Cliff and I also had a lot of differences such as rear spring rate, I run LCA's he did not, different camber plates, alignment settings... Is it ideal? No but it is substantially better than stock and the comfort penalty is not nearly as bad as you might think. I do not consider myself any sort of suspension guru, but I am hardly a novice, I am just sharing my own real world experience with this setup. I have done a lot of experimentation with spring rates, camber plates, alignment settings... As you can see it hasn't all been smooth plug and play, this is based on actual experience not theory or feelings.
 

Cliff

Go Kart Newbie
Location
San Francisco Bay Area
Car(s)
2015 Golf R
I've ridden in @Cliff 's Ground Control setup prior to him switching to Ohlins, and it rode really well on track and is probably the route I'll end up taking when I can save up enough (instead of spending on track days). I know he didn't mind the ride as a daily, and has taken numerous long road trips to tracks in other states. I'm sure he'll chime in more.
This year should make it easy to save up for mods, Jeff - there aren't as many track days as a normal year. Which is good for me as I've had to replace my water heater, refrigerator, and couch this year...

I've written enough about GC's suspension kit and I don't have anything new to add. Look forward to seeing you in a few weeks at Laguna.
 

jmblur

Go Kart Champion
Location
Massachusetts
Car(s)
2017 Golf R
Let me preface this by saying I have little to no knowledge of how to calculate hertz based off all the different numbers needed.

That being said, Karl Taht, who is a member on here, wrote an article about motion ratios, hertz, and other suspension pieces here. While this is for a GTI, his calculations end up being 8kg/9kg to keep a 1.6-1.8hz ratio. I would imagine with the increased weight of the R, the spring rates would be slightly higher? I know there's some assumptions in some numbers being used, but the end results are very different than yours. Since it seems you know more about this, maybe look into his article and see how your numbers differ from his?
My numbers are somewhat approximate for now - if I get into coilovers I'll get better measurements (actually putting a scale under suspension with springs removed, direct measurement of rear motion ratio, etc.), So I'm partly with numbers I've sourced rather than directly measured. Golf R also has stiffer springs from stock ( 196lbs/in / 3.5kgf/mm front and 252/4.5 rear).

The other numbers I'm using, fwiw, are .97 motion ratio for front, .7 rear (averaged from a few sources I found, one being Karl's), 3262lbs split 60.5/49.5 (i neglected driver weight, which slightly lowers this frequency, but I haven't confirmed wet weight either). 130lbs unsprung weight which is, admittedly, a swag.

Did find a small error in my calcs that puts frequency at closer to 1.45/1.6 stock, but the overall point stands.

GC springs at 425/540 are equivalent to 7.6/9.8 kgf/mm fwiw.

For pure track use with sticky rubber, just over 2 is actually a good place to be, so I don't doubt Cliff's excellent track performance. The struts also are fairly capable but I've been unable to find minimim/maximum achievable damping rates so hard to do any evaluation of the without a dyno (I probably could do spring rates but I don't have equipment to evaluate dynamic rates).

All that said... I'm not sure there's a better option with stock struts. Roll can be controlled with sway bars but the dive/squat can't. The only thing I could see making a difference there would be the DSC Sport controller but it's rather absurdly priced at $1200. If it was half that I'd almost certainly try that route first.

(Also note I'm an engineer so I tend to default to calcs and numbers In the absence of personal experience with any given product. There's a lot of underengineered product out there so I tend to be pretty skeptical until I have first hand experience or significant data to back up performance)
 
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jmblur

Go Kart Champion
Location
Massachusetts
Car(s)
2017 Golf R
This year should make it easy to save up for mods, Jeff - there aren't as many track days as a normal year. Which is good for me as I've had to replace my water heater, refrigerator, and couch this year...

I've written enough about GC's suspension kit and I don't have anything new to add. Look forward to seeing you in a few weeks at Laguna.
@Cliff One thing I'd be interested in - would you recommend doing the same path you did and use GC until the stock struts for then go Ohlins, or save up and go right to the Ohlins?
 
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Cliff

Go Kart Newbie
Location
San Francisco Bay Area
Car(s)
2015 Golf R
@Cliff One thing I'd be interested in - would you recommend doing the same path you did and use GC until the stock struts for then go Ohlins, or save up and go right to the Ohlins?
If I had to do it again, I'm not sure that I would. I spent a lot of money last fall on the Ohlins, I/C, and diff, money that would cover a significant fraction of the purchase price of a Cayman S or GTS. And having done all that work on my car, I still want to buy a 981 Cayman.

The adjustability of the coilovers allows me to fine tune the handling of the car in ways that are not possible with DCC (or Damptronic) shocks. The downside is that the rear cancellers have failed again. Fortunately, Ohlins is warrantying them again, but if these canceller failures continue to occur I might end up saying screw it and going back to the GC springs with Bilstein damptronic shocks.
 

emichel6888

Passed Driver's Ed
Location
TX
The only thing I could see making a difference there would be the DSC Sport controller but it's rather absurdly priced at $1200. If it was half that I'd almost certainly try that route first.
Agreed, also I read where someone bought one and could not get it to work as it created all sorts of error codes. Apparently they had gotten it to work on some other VAG car (Audi TT I believe) and just assumed it would be plug and play with the Golf R. However, if they can get it to work on this car and maybe come down on the price, I am also in. Perhaps someone can find a way to reprogram the stock controller like they have done for the engine, DCT, and the Haldex ECU's.
I would love to have a JB4/Cobb tuner for the DCC, heck I would even consider a software only. Say where you give them your spring rates, ride height, wheel/tire specs, and driving preferences...
 
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