Coilover conversion kits

[NDSP]

I tried searching the forum and Google for info/opinions on the conversion kits for track days/autocross type applications and didn't find anything, so I thought I'd ask the forum here first before asking the companies that have something to sell.

Basically, I'd like to be in the $2500 dollar range all in for some coilovers. I know that ground control has something in that range, but 40 year old shock design give me pause, probably more than it should but it does. And MCS once you add springs and cc plates are $3500. So that leave me with not allot to work with. One option that is available is to keep my bilstiens and use a conversion kit, since bilstien can't seem to get a true coilover out. It seems to me coilovers aren't much different than a standard strut with a machined housing, so how different could a conversion kit be?

Anyway I'd appreciate this forums opinion on the conversion kits as it applies to performance use and not appearance use.

Thanks,

James

Sent from my ASUS Transformer Pad TF700T using Tapatalk

 

[Vorshlag-Fair]

Converting an OEM style strut to a coilover is an old trick.... but not a very good one.

A long time ago we had a lot of customers asking us to make one of these kits, and we produced a short run of the silver "over collars" above. This would be used with an OEM style strut where you cut the lower perches off, slipped the collars on, and then switched to the appropriate diameter coilover spring (60mm or 2.5", depending on the diameter of the strut and collar). The problem was, the results are almost always terrible. Why? Because the struts are still always too long for lowered ride heights and the car bottoms out a LOT. The second problem was the shocks would never be valved properly for the SIGNIFICANTLY stiffer spring that you would want to use. Re-valving a Bilstein OEM style strut is TRICKY, too.

In 2010 we built a BMW E30 LSx for a budget restricted event where we had to build the car for $2010, and compete in a 3 event magazine sponsored challenge: drag race, autocross and concours. Its called the Grassroots Motorsports $20XX Challenge.

Since we couldn't use proper coilovers, we bought some old Koni OEM style struts for $25. Then we cut the lower perches off and bought some cheap threaded circle track collars.

With some used 2.5" ID coilover springs, we had a stiffer spring rate and "homemade coilovers" on the car. How bad could they bad, we figured? Oh they were awful... they rode like a jackhammer and were in the front bumpstops ALL THE TIME.

But for this extremely tight budget build, they worked well enough in competition (against other crap can cars), but I would never recommend this for the street.

We did "OK" that first year, but the car failed miserably in the drag race portion (355 whp + T5 transmission = BOOM!). We came back in 2011, after just doing some suspension set-up tuning, and won the event.

But when we weren't doing this ONE specialized, weirdly low budget magazine event, we swapped on AST 4100 coilovers and some CCW 18x11" wheels (in place of the 15x10" $50/each circle track wheels). Those AST struts had 2" shorter strut housings and that made for proper bump travel at the low ride heights we ran. They also had the proper valving for the much stiffer than stock spring rates we ran. We tracked it in NASA TTU and it was FAST! It rode 100 times better on the street, too.

So that's one of many horror stories I can share about "home brew coilovers."

Just like we have explained in the "OEM vs Coilover" discussions here, lowering a McPherson strut car requires both a shorter spring AND a shorter strut housing. Just putting lowering springs on an OEM style strut leads to a direct loss of bump travel. Doing the same thing with a coilover adapter sleeve and short coilover spring on the same OEM length housing does the exact same thing - no bump travel, and you are in the bumpstops after every bump.

As for other "low cost coilovers" designs.... you always get what you pay for. Some lower cost S197 coilovers use a Koni twin tube insert, and we've discussed the limitations of those in the past. A properly built, quality monotube shock is better in every performance metric, and in ride quality as well. The AST 4150 monotube single adjustable used to be the lowest cost proper monotube single adjustable coilover for the S197, but those are still in limbo for several more months as the new distributor gets set-up and inventory rolls in. But we did find out that the price of these 4150s has risen from $2200/set to $2650/set.

Which is the same price as the proven, reliable, and strong MCS TT1 coilovers. And yes, with springs (+200) and camber plates (+479) it approaches $3300. What can I say, it is what it is... but the only alternatives are Chinese made junk or twin tubes. We are working on some things to reduce the price of these kits, trying to get them closer to $3000.

We know that $3300 price tag is a bit steep for folks, and we already offer the shorter strut housing Bilstein Street Pro monotube inverted strut/shock + spring + camber plate combo for $1500. This works for good street ride, proper bump travel at a lowered ride height, and is strong as a tank. They are good for some autocross and track use, but aren't what we'd use on a serious competition autox or track car.

Vorshlag is working on another solution, using Bilstein motorsports parts, that could potentially get closer to the $2500 mark. We should have something this summer, if we can get time to develop and build this kit.

 

[NDSP]

Thanks Terry. I was wondering about the ability of a stock style strut to handle stiffer springs. So that answered that question. I "upgraded" my 2006 to a 2012 Brembo car last week and I'm in the process of swapping over suspension onto the new ride and unfortunately MCS's aren't in the budget after the car upgrade. I'll just go with the bilstiens until budget allows a good coil over setup.

 

[FR500GT]

Is anybody else running the Ground Control kit?

 

[RocketcarX]

Do you know what is Strange referring too when they say their strut is compatible with a coil over conversion? Or did I misunderstand what I read about the adjustable strut they offer?

 

[jmauld]

Vorshlag is working on another solution, using Bilstein motorsports parts, that could potentially get closer to the $2500 mark. We should have something this summer, if we can get time to develop and build this kit.

I'm looking to buy a set of shocks and springs in the next few weeks and this is exactly what I'm looking for. How likely are you to have this kit finished this summer?

Which bilstein are you using? Is it one of the parts that will be able to use the MDS pieces to be converted to an adjustable strut? Or is that an adjuster that I see on the bottom of those?

 

[claudermilk]

Is anybody else running the Ground Control kit?

I believe Whiskey is.

 

[Dubstep Shep]

My suggestion:

Up your budget and start looking at Griggs racing.

I currently have a watts link, torque arm, and LCAs from them and the rear end on my car just STICKS.

Next on my list is their SLA kit.

 

[Whiskey11]

Is anybody else running the Ground Control kit?

Which one? The conversion kit or the full kit?

I believe Whiskey is.

I'm running the full kit which is NOT a conversion kit for standard Koni Yellows (they offer that too). My GC kit includes custom made strut housings and custom valved Koni inserts. The rears are the same weight jackers as the conversion kit and the rear shock is a shortened Koni Yellow with custom valving. I have the valving curves if anyone wants to see them.

The GC full kit I have is a huge step up from a conversion kit for OEM style struts.

 

[Saleen304]

My suggestion:

Up your budget and start looking at Griggs racing.

I currently have a watts link, torque arm, and LCAs from them and the rear end on my car just STICKS.

Next on my list is their SLA kit.

I just installed a Griggs coilover kit recently and really like them. The only experience I have is comparing it to the stock Saleen suspension so take that with a grain of salt. They are in your price range and are true coilovers that put the spring on the rear shock (no weight jackers) for improved bump travel and control (or so I have read). The only issue is that you need to weld in shock supports. Griggs use custom valves and shortened Koni yellows which some may not like since they are twin tube.

 

[Dubstep Shep]

I just installed a Griggs coilover kit recently and really like them. The only experience I have is comparing it to the stock Saleen suspension so take that with a grain of salt. They are in your price range and are true coilovers that put the spring on the rear shock (no weight jackers) for improved bump travel and control (or so I have read). The only issue is that you need to weld in shock supports. Griggs use custom valves and shortened Koni yellows which some may not like since they are twin tube.

The coilovers that Griggs uses aren't mustang coilovers. They're actually Koni racing coilovers that Griggs revalves and adapts to our cars. Pretty badass stuff.

 

[csamsh]

The coilovers that Griggs uses aren't mustang coilovers. They're actually Koni racing coilovers that Griggs revalves and adapts to our cars. Pretty badass stuff.

Hmm. I believe they're still twin-tube "Koni Yellow" inserts. If I'm correct, the prices they want are highway robbery compared to something like a GC kit which has the (IMO) stock rear spring location w/ weight jacker, and some camber plates too. They don't say anything about being monotube, and I bet they're not Koni 28's, as Koni 28's are ~$1000 a shock. I could be wrong, but I don't think I'm wrong.

 

[Dubstep Shep]

Hmm. I believe they're still twin-tube "Koni Yellow" inserts. If I'm correct, the prices they want are highway robbery compared to something like a GC kit which has the (IMO) stock rear spring location w/ weight jacker, and some camber plates too. They don't say anything about being monotube, and I bet they're not Koni 28's, as Koni 28's are ~$1000 a shock. I could be wrong, but I don't think I'm wrong.

Maybe do some more research on them before forking over what they're asking?

You're welcome to go check out Griggs site.

Personally I'm not a fan of the factory spring locations. Further out is better for control and adjustability.

 

[Saleen304]

Hmm. I believe they're still twin-tube "Koni Yellow" inserts. If I'm correct, the prices they want are highway robbery compared to something like a GC kit which has the (IMO) stock rear spring location w/ weight jacker, and some camber plates too. They don't say anything about being monotube, and I bet they're not Koni 28's, as Koni 28's are ~$1000 a shock. I could be wrong, but I don't think I'm wrong.

The Griggs kit includes camber plates. The fronts from what I understand are re-valved ground control units.

 

[csamsh]

You're welcome to go check out Griggs site.

Personally I'm not a fan of the factory spring locations. Further out is better for control and adjustability.

I did, those were my findings after doing so. Lots of talk, not a whole lot of tech, which is surprising coming from them. (They actually have about zero tech/data...)

I still have yet to see any data on why further out is better, other than that it can cut into wheel clearance room, which is actually a point for worse. That would be an easy test- take a "true" coilover shock, run some laps, then put it in stock location, go run more laps, compare times. Change spring rates if you want to account for motion ratio differences. I doubt there's a difference, but I have no data that backs up this claim.

 

[csamsh]

The Griggs kit includes camber plates. The fronts from what I understand are re-valved ground control units.

Good! Now the price doesn't seem too crazy!

 

[FR500GT]

Which one? The conversion kit or the full kit?

.....The GC full kit I have is a huge step up from a conversion kit for OEM style struts.

Yeah I am looking at buying the full kit. My car gets daily driven and I just can't justify the cost for AST's (as badly as I want them). So the GC kit for $1600 should do just fine for my needs.

http://www.ground-control-store.com/products/description.php/II=822/CA=171

 

[jayman33]

Yeah I am looking at buying the full kit. My car gets daily driven and I just can't justify the cost for AST's (as badly as I want them). So the GC kit for $1600 should do just fine for my needs.

http://www.ground-control-store.com/products/description.php/II=822/CA=171

Yes, we've sold a lot of these kits. Great kit, especially for the cost and the customer service you get from ground control is top notch.

 

[Dubstep Shep]

The Griggs kit includes camber plates. The fronts from what I understand are re-valved ground control units.

If you get struts. If you go with the SLA kit they're no longer a strut.

 

[jayman33]

Which one? The conversion kit or the full kit?



I'm running the full kit which is NOT a conversion kit for standard Koni Yellows (they offer that too). My GC kit includes custom made strut housings and custom valved Koni inserts. The rears are the same weight jackers as the conversion kit and the rear shock is a shortened Koni Yellow with custom valving. I have the valving curves if anyone wants to see them.

The GC full kit I have is a huge step up from a conversion kit for OEM style struts.

I ran the exact same setup as whiskey on the ring here in Germany, they did just fine with suspension travel. We as well talked to bilstein on the potential possibility of a coilover system for our cars. Actually, there's multiple shops talking to them about this.