Any Interest in HPA Custom Coilovers?

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As much as I want a quality set of custom coilovers, I've been turned off by the price. Don't get me wrong, I'm sure TCK's S/A system at $1750 is worth every penny but it's still expensive in my opinion. Ground-Control does offer a system that's competitively priced at $1849 (which includes their camber plates) but that really doesn't leave us many options besides those 2... not even considering AST & Motion since those are even pricier.

Thus, I've been talking with Harold @ HPA and he offered the possibility of custom setup, similar to what they offer for the 1-series crowd, Koni Single Adjustables with Swift Springs. Pricing would also be similar:

http://www.hpashop.com/product.sc?pr...categoryId=166

I'm aware there are cheaper coilover systems such as KW V1 and H&R Street Performance but none offer the benefits of linear springs such as TCK & GC. However, the HPA system would be similar to that of the TCK S/A but $200 less. So is anyone else interested in these coilovers?

Btw: review of the HPA coilovers here

[jra]

Gc offers a Coilover conversion kit for $400 or so. Add new konis and it's still less expensive

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Originally Posted by jra

Gc offers a Coilover conversion kit for $400 or so. Add new konis and it's still less expensive

Correct, and I actually did look into those a few months back...

But the point of this thread is to compare apples to apples, HPA S/A kit to the GC S/A kit. And while the conversion kit is a cost-effective solution, assuming you're pairing them up with Koni yellows, I don't like how it requires you to grind off the metal tab on the sides in order to get the sleeve to sit fully flush.

Also, the general consensus from GC users is that the ride is more harsh then oem, whereas HPA & TCK require stock comfort. So given similar prices between GC and HPA, I offer up the HPA kit to those who prefer the same performance benefits without sacrificing ride quality.

[jra]

Gotcha...wasnt trying to bring down the thread. another way to fit the sleeve is to notch the gc collar. I understand your point as I am using tckline sa front struts

[vachss]

Originally Posted by Dubbedown

Also, the general consensus from GC users is that the ride is more harsh then oem, whereas HPA & TCK require stock comfort. So given similar prices between GC and HPA, I offer up the HPA kit to those who prefer the same performance benefits without sacrificing ride quality.

I'm really curious about this. Wouldn't ride comfort mostly be a function of spring rate and choice of damper? In other words, unless the Konis set on full soft are still stiffer than the TCK dampers couldn't you just choose a spring rate on the GC conversion kit to replicate the comfort of the TCK?

[3002 tii]

Originally Posted by vachss

I'm really curious about this. Wouldn't ride comfort mostly be a function of spring rate and choice of damper? In other words, unless the Konis set on full soft are still stiffer than the TCK dampers couldn't you just choose a spring rate on the GC conversion kit to replicate the comfort of the TCK?

To be honest, but seemed like every time I had read a TCK vs GC thread, TCK users reported back a ride comfort comparable to stock whereas GC owners warned the ride was slightly harsher. And this was also later confirmed when I initially spoke to that indy shop and he advised, if I had a choice I should go with TCK for that very same reason.

[Serious]

Just spend the extra cash and get a better damper. The koni based kits are fine (I ran tck's on my m3) but really if you're spending that much cash just spend a little more and get a kit with a better damper.

[The HACK]

TC Kline Single Adjustable COs uses the same Koni shocks. So unless TC Kline spec's out softer compression settings on the Konis, then ride comfort would come down to just spring rate/design.

I would have to assume, if you want more "stock" like ride quality, you can probably do the same with GC's kits but have the Koni's re-valved for a softer compression setting, or go with OEM like spring rate instead of the spring rates suggested in their kit.

I have my opinions as to coil-overs. The "height adjustability" portion of the kits are mainly only needed if you plan on corner balancing the car. Otherwise the BEST riding package out there is simply a better damper mated to OEM springs. Factory Z4 and MZ4 spring rates are actually quite a bit on the stiff side compared to their 3 series counterparts, on top of a very short wheelbase.

The 300f/450r springs on the GC kit is a bit on the harsh side for street only but is a good compromise for track and street use. Frankly if they had dialed it down to ~250f/300r it would be a perfect dual purpose vehicle for MY needs. But then it would be HARD for them to market and sell because that's only marginally higher than OEM spring rates.

As for HPA stuff, I've know Harold for a couple of years now and he's certainly put his time and effort into developing them, mostly on E9X but the same knowledge and knowhow mostly translates over to the Z4 platform well. If I didn't have my GC kit on the car I'd definitely go talk to him. In fact, if he needs my input for an MZ4 solution I'd be happy to help out.

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Originally Posted by The HACK

TC Kline Single Adjustable COs uses the same Koni shocks. So unless TC Kline spec's out softer compression settings on the Konis, then ride comfort would come down to just spring rate/design.

I would have to assume, if you want more "stock" like ride quality, you can probably do the same with GC's kits but have the Koni's re-valved for a softer compression setting, or go with OEM like spring rate instead of the spring rates suggested in their kit.

I have my opinions as to coil-overs. The "height adjustability" portion of the kits are mainly only needed if you plan on corner balancing the car. Otherwise the BEST riding package out there is simply a better damper mated to OEM springs. Factory Z4 and MZ4 spring rates are actually quite a bit on the stiff side compared to their 3 series counterparts, on top of a very short wheelbase.

The 300f/450r springs on the GC kit is a bit on the harsh side for street only but is a good compromise for track and street use. Frankly if they had dialed it down to ~250f/300r it would be a perfect dual purpose vehicle for MY needs. But then it would be HARD for them to market and sell because that's only marginally higher than OEM spring rates.

As for HPA stuff, I've know Harold for a couple of years now and he's certainly put his time and effort into developing them, mostly on E9X but the same knowledge and knowhow mostly translates over to the Z4 platform well. If I didn't have my GC kit on the car I'd definitely go talk to him. In fact, if he needs my input for an MZ4 solution I'd be happy to help out.

Hack - as always your input / feedback is appreciated. After confirming with Erik @ TCK that their setup for the Non-M Z4 is the SAME as the E46, I believe Harold is going off that info but I'm sure he'd welcome your expertise feedback. As of now, I've suggested 440f/550r which is what Erik advised for a street/auto-x setup but now I wonder if I should go softer...?

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Originally Posted by Serious

Just spend the extra cash and get a better damper. The koni based kits are fine (I ran tck's on my m3) but really if you're spending that much cash just spend a little more and get a kit with a better damper.

For some, the $1500 is already at the breakpoint especially when the initial option was just the conversion kit at approx $800. The $600 extra to get to AST's is 40% extra, not something I'd consider marginal or "little more."

[The HACK]

Originally Posted by Dubbedown

Hack - as always your input / feedback is appreciated. After confirming with Erik @ TCK that their setup for the Non-M Z4 is the SAME as the E46, I believe Harold is going off that info but I'm sure he'd welcome your expertise feedback. As of now, I've suggested 440f/550r which is what Erik advised for a street/auto-x setup but now I wonder if I should go softer...?

Depends on how often you drive the car on the street. And depends on your tolerance level to the ride.

I must be getting old(er), since I used to love tight, stiff rides. Not anymore. Now the relatively soft springs on the MZ4 Coupe GC package makes me weary, and prefer my ~150-200 lbs springs on the WRX for daily use. All things considered, I could probably use stiffer springs on the MZ4 Coupe if all I ever use it for is track and AX.

Another thing to keep in mind is, do you want to be competitive in AX? I can wring a ton of speed out of these relatively soft springs on the GC kit for the track. But for AX use? They're too soft and allow too much movement to be of any good.

So...My answer is, I don't know. Your BEST BET, is to get 2-3 sets of springs in various rates and experiment. From my experience? 440f/550r is what you'll typically find on west coast IP cars (I-Prepared in Club Racing) and work well for track use, but a little "stiff" for street. But it may work well for AX, but I've typically found that really competitive AX guys run a much higher spring rate. So if you're handy, you can swap out the multiple set of springs and find out which one is the best compromise.

Just my personal opinion.

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Originally Posted by The HACK

So...My answer is, I don't know. Your BEST BET, is to get 2-3 sets of springs in various rates and experiment. From my experience? 440f/550r is what you'll typically find on west coast IP cars (I-Prepared in Club Racing) and work well for track use, but a little "stiff" for street. But it may work well for AX, but I've typically found that really competitive AX guys run a much higher spring rate. So if you're handy, you can swap out the multiple set of springs and find out which one is the best compromise.

Just my personal opinion.

440/550 seems to be the going "initial" starting point recommendation. Little harsh for street works for me as I only drive the car mostly on weekends. In terms of AX competition, I completed my first season this year but I didn't attend as many events as I'd like. End of day, seems like it's more for fun than anything as I can't really commit all my weekends to it, but when doing so I would like to get close to placing as possible.

[nlink720]

I started with 440/550 and it was a great combination for the poor North Jersey roads and was much better handling than stock. It really depends on the shock stiffness as well.

Whatever springs you get, the common tendency is the suppliers recommend 6.5" rear springs. That is way too high. 6" and GC rear adjuster at minimum is about 1.5 fingers fender gap, or equivalent to the drop seen in the H&R springs. I suggest you go with rear 5.5" or 5" springs (these are 2.25" diameter in the rear), and run the rear adjuster up since it has over an inch and a half of adjustability. Coil bind has not been even close of an issue on the 5" rear springs for me, but my rears are 900# (not much compression), so perhaps a 5.5" rear might be better at a 550 rear spring if you can find a 5.5" length.

You seem not yet a hardcore autocross/track driver, so I would say any of the above options are good, but if you will track/auto-x heavily, just go straight to some ASTs.

You are still welcome to meet up with me and we can swap out some different springs and you can feel how the ride changes on Konis with conversion kit before I go to AST. I have 440/550/600/650/700/800/900, so you can run the gamit on how stiffness is affected by different rates.

Also, do some research on Swift springs. I have never used them, but have heard varying things. I use Hyperco and Eibach springs, and both are great.

[Serious]

Originally Posted by Dubbedown

For some, the $1500 is already at the breakpoint especially when the initial option was just the conversion kit at approx $800. The $600 extra to get to AST's is 40% extra, not something I'd consider marginal or "little more."

My response to that is that suspension is the most important aspect of the car, it's what you experience every single second over every inch of road... prioritizing money spent on other areas of the car such as engine mods or wheels and sacrificing suspension improvements is a bad decision IMO.

Basically my philosophy is to spend as much money as possible on suspension.

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Originally Posted by nlink720

Whatever springs you get, the common tendency is the suppliers recommend 6.5" rear springs. That is way too high. 6" and GC rear adjuster at minimum is about 1.5 fingers fender gap, or equivalent to the drop seen in the H&R springs. I suggest you go with rear 5.5" or 5" springs (these are 2.25" diameter in the rear), and run the rear adjuster up since it has over an inch and a half of adjustability. Coil bind has not been even close of an issue on the 5" rear springs for me, but my rears are 900# (not much compression), so perhaps a 5.5" rear might be better at a 550 rear spring if you can find a 5.5" length.

Also, do some research on Swift springs. I have never used them, but have heard varying things. I use Hyperco and Eibach springs, and both are great.

Thanks for the heads up. I know they have 6" but no 5.5"...

Originally Posted by Serious

My response to that is that suspension is the most important aspect of the car, it's what you experience every single second over every inch of road... prioritizing money spent on other areas of the car such as engine mods or wheels and sacrificing suspension improvements is a bad decision IMO.

Basically my philosophy is to spend as much money as possible on suspension.

Who's talking about sacrifice? This is obviously an upgrade over stock. Everything is relative and not everyone needs a full balls out race car. If this were a convo on springs only or some entry level off-the-shelf system I could see your point.... now back on topic please.