Abubaca

iTrader: (3)

I put this in Suspension/Chassis, but it is very much a product/vendor review as well. Figured it'd reach more people here. ....I had lots of questions when I searched, some I had answered, some were answered by GC customer service, some I figured out on my own.

Vendor Review- Ground Control was great. Donovan took a good bit of time even before I was committed. Asked lots of questions about my car, and answered all of mine. Had a few email questions too, and they were answered promptly. I had also called another company selling weight jack kits for our cars and twice (on the phone) i felt as if my question were a burden, and they had better things to do. ....but all is well as my money went to Ground Control!!!!! They were awesome.

Product Review. Kit was well packaged well. Powder and ano is beautiful. Spanner wrench and allen key for set screw was included as well as "basic" instructions and a few decals. Front weight jack rod includes a grease fitting, and was lubed and ready to go when unboxed. Install was easy and the ride is MUCH better than my Eibach Pro-Kit.

Details. Guys, I took measurements of EVERYTHING, so hit me up if you have a specific question. Kit was for the 850# springs up front and 175# out back. Fronts are 9.5" (not 8") and are linear. GC said the 850's are 9.5" springs, and the stiffer springs are 8". (this came up a lot in other threads) Rears appeared to be NOT progressive as I expected. I think most thirdgen rears ARE progressive right??? These don't appear to be.

Obviously this isn't black and white as there are a gazillion variables, but here are my fender measurements. With the stock Eibach Prokit, fenders were at about 26.5" in front, and about 27.25" in the back. Knowing the GC kit was on deck, I cut the eibachs as last ditch "maybe it'll work" option. Had fenders at 25.5" and 26.25. Ride didn't change much, which is to say it was still "ok". Bottomed out, the GC kit was at about 25.375" and 25.5". ....I have it adjusted to 26" and 26.5", which to me is a good balance of looks, ride, and ground clearance.

Front adjustment was easy with the car on the ground. Lying on the ground, one hand on the tire for the leverage, the other on a 1/2" ratched with a 3" extension. (see pic) Very easy, just takes a little patience to pay attention and keep em even.

Rears I found were easiest to adjust by putting a jack under the SFC and jacking up 'til the spring was just a tad loose, then twisting the adjuster by hand. Didn't use the Spanner. Took too long.

Guys I have lots of pics and lots of measurement. Just lemme know if you specifically need something I didn't mention.

Abubaca

iTrader: (3)

That last pic shows it at 26" to the fender lip up front, 26.5" out back. I'm sure they'll settle a little, but so far so good.

....almost forgot, -the ride is awesome!!!!!!!! ....I have the Eibach Prokit for over 10 years while it wasn't bad, it certainly wasn't as good as it could've been. These springs feel great! Technically rated higher than the Prokit, yet so much smoother. ...and they seem to handle just fine, although I haven't pushed them yet.

t/aws61985

iTrader: (2)

Thanks for this post. I haven't installed my set yet. I bought my set used so Thanks for posting the small Info sheet.

Citation X

Thx Abubaca just got mine yesterday and can't wait to install them. After telling them about my car they suggested 950 front 175 rear so I went with it. I agree that the customer service and quality is second to none.

SilverChicken

iTrader: (1)

Thanks for putting up fairly detailed pics. I've been thinking about piecing together something similar out of circle track parts and a better designed adjustable rear spring cup for conventional springs.

Citation X

I found when putting on my rears with the shocks connected and the adjustment all the way up I still had quite a bit of gap between the isolator and the body of the car. About a hands width (2.5-3 inches maybe). Did you have this? I hope the shorter spring in the front wont cause any issues. I wanted to drop the front about 2 inches anyways. Will hopefully put the fronts on soon.

QwkTrip

iTrader: (22)

I have been using the Ground Control weight jacks about a year. They don't move around or rattle. These are high spring rates and the suspension doesn't move enough for the pieces to fall out. I haven't done any Dukes of Hazzard style railroad crossings to find out what happens when suspension goes full droop.

The springs are far too stiff and the ride is terrible. Car follows every little bump in the road instead of the suspension. And it gets worse the faster you go. Car gets no weight transfer whatsoever so traction is hard to find under throttle. In my opinion those springs are for smooth race tracks, not for the road.

Citation X

Ya I was worried about the fronts being too stiff. I guess I will find out. If I have to go lighter I will. I did drive it for about 30 mins with the rears installed and was actually happy with the way it drove. I was "breaking in" a new gear so I was taking it easy but as far as normal driving it did great. As soon as the rain stops I will take it out again to see what a little more aggressive driving does. I don't plan on any Dukes of Hazard jumps either hah. Just was asking to see if anyone had experienced any issues with it.

Going to order some struts before I do the front since it will have to be aligned. I would like to go koni's but I don't think it is in the budget right now. The kyb agx will be quite a bit better than whats on there so it will have to work for now.

QwkTrip

iTrader: (22)

The rear is much more compliant than the front. The lowest front spring rate offered is 750 lb/inch, and the lowest in the rear is 150 lb/inch. (I just looked in to this recently)

Citation X

I think if the 950 in front is too much I will go 850. Not sure how much noticable difference that will be since I am no expert on suspension. I see a few people happy with 850 though. I need to get my SFC's bolted up so I can take them to be welded before I get to crazy with it anyways. I should have done those years ago.

QwkTrip

iTrader: (22)

As a reference point,

My comments are with 800 lb/inch
Hotchkis front springs come in at 600 lb/inch
Stock front springs (V8) come in around 350 , 425 , 700 , or 750 lb/inch
Moroso Trick Springs are 220 lb/inch

Abubaca

iTrader: (3)

QwkTrip, which springs are you using??? ...can't speak to the 950s, but the 850 are really nice. I was pretty impressed. A track car would probably want more, but for the street, the 850s are perfect, imho.

Citation X

Thanks for the info. Ya if I don't like the 950's I will try the 850's for sure.

QwkTrip

iTrader: (22)

I have 800 lb/inch. Feels okay if the road is smooth or driving below 45 mph. Otherwise it is too harsh, so much so that I avoid driving on the freeway. That means I won't take the car on trips out of town, which is a shame because I want to enjoy the car more in that way.

Right now my car is a mess and I need to find the right balance of traction and handling for how I like to drive. I initially set up the car for handling but it turns out I make too much power for low profile performance tires. Problem is the tight suspension doesn't work with the drag radials either. I need to change things to achieve a better balance and improve ride quality as well.

TEDSgrad

iTrader: (4)

QwkTrip,
I'm not familiar with how your car is set-up, but this sounds backwards - at speed it should be smoother. Low profile tires will make it more harsh, though.
I have #850/36mm and #250/19mm and I like it. What bars do you have?

Can I assume you have Koni Yellows? And quality strut mounts? These are most critical. Next, if you have heavy wheel assemblies and brakes to increase unsprung weight which makes the rebound control more harsh. Everyone uses words differently, but when I hear "harsh" that usually indicates the damper, not the spring (especially at #850).

I have raised the front RC and lowered the rear RC, though. This helps to flatten out the roll axis inclination. Our cars are always lower front RC and higher rear RC leaving an incline angle. This worsens when car is lowered - roll axis inclination is increased. This definitely affects weight transfer and diagonal weight transfer (outside front to inside rear).

Front grip is limiting factor, so we figure out the front then match the rear to it.

You're a smart guy and I might not have anything to add - just trying to understand.

Brian

QwkTrip

iTrader: (22)

Thanks for the reply. Definitely appreciate your thoughts.

I have Bilstein yellow front struts and Koni red rear shocks. Do you think the Bilstein struts could be part of the problem?

TEDSgrad

iTrader: (4)

QwkTrip,
I do think they are part of the problem (most , if not all), but they are not bad struts per se (2nd to Koni Yellow), and you have reds on the back (not as good as yellows). There has been a lot of technology improvements since Bilstein and Koni yellows were develped. But Koni yellows are cost effective and good. The symptoms you are describing definitely points to the dampers. More than any other component on the car, they are critical for performance and comfort. They do go together - performance and comfort.

Harsh or jarring comes from the damper, or damper not doing it's job and transferring jarring motions through the chassis so that it is "felt." Front spring will control suspension travel and should not contribute to harsh or jarring per se. Especially at #850!

I'm assuming you have SFC and wonderbar. You never mentioned your strut mounts - they keep the strut in place so it does its' job. If there is weakness around the strut (bearings), those jarring motions will be transferred into the chassis and not absorbed by the damper because it is not forced to do it's job. I have also added a plate underneath the tower to help distribute force - anything to strengthen!



We use weight jacks to lower our cars and have minute adjustments. When lowering say 2", we lower the CG 2" and the front RC 2". The rear RC only goes down say 1/2". I'm just giving numbers for conceptual understanding. We are trying to reduce the distance between the CG point and the roll axis (a line from front RC to rear RC). The smaller the distance between the two, the less leverage exerted - very good for handling. This distance or lever is called the moment arm. If you look at the attached crude pic, I have original ride height in pink, and lowered amount in yellow. Again, the pic is just to help understand the concept. The CG point is above the roll axis line. You should also see that the incline (front to back) is greater for the yellow lowered line (roll axis inclination). That's what I was talking about above. The yellow CG point is also closer to the yellow roll axis line - the good benefit of lowering. The roll axis inclination of the yellow line harms weight transfer. So by lowering, you gain some benefits, and loose some.
When we lower 2", we loose 2" of travel on the strut and we are out of the designed shock curve. Aftermarket strut mounts are usually taller, which restores some or all of the 2" of strut travel lost. I like Spohn's design. If you don't have the taller strut mounts, you are not operating the strut in its' designed shock curve and it will be harsh or jarring; or even damaged over time.

Once you have lowered, you should address the yellow roll axis inclination by: extended ball joints in front, and by PHB axle side extension bracket (lower the axle side attachment point). This will raise the front RC and lower the rear RC so that the yellow roll axis inclination becomes more flat. This way you get both the shorter moment arm (CG and roll axis closer together) and you get a flatter roll axis (helps weight transfer).

More than anything, we need good struts and good strut mounts - so they absorb and don't transfer force. Then, when we have weight jacks for lowering, we need the ex.t BJ and PHB ext. bracket to flatten back out the roll axis inclination.

Brian

QwkTrip

iTrader: (22)

Thanks again!

I have Founders strut tower mounts.

Does panhard bar position have any effect on front-rear weight transfer?
What are my choices for panhard bar adjustment? (who makes products) Or is it just a matter of fabricating something?

TEDSgrad

iTrader: (4)

http://umiperformance.com/catalog/in...oducts_id=1036

$89. Weld-in; don't go with their bolt-in. There's a good amount of stress on it. Be careful and make small changes until you get it where you want it. It will aid front to rear weight transfer a little. It helps the diagonal weight transfer more as we are talking about roll. You will need to up rear spring rate when lowering rear RC.
DSE uses #950 front and #275 rear - I tend to use them as a benchmark. I'm 850/250. You have more power so 200-225 or so, but every car is it's own animal.
I'm a believer in RideTech (HQ 6110) coil-overs. On their site they have a vehicle weight database and suggested wheel rates. They have the right range for a 2" drop. Much better shock. I'm waiting for their strut to come out to replace the Koni's.
Founder's will work, but they don't secure the bearing as well as Spohn. DSE's are the best, but the cost is also.

QwkTrip

iTrader: (22)

Alright, TEDSgrad, you talked me out of $500 for a pair of Koni struts. Parts will ship tomorrow.

TEDSgrad

iTrader: (4)

Wise purchase.
Waiting is the hardest part.
Now, you'll enjoy the Koni's, and you'll have restored confidence in the GC weight jacks, too. Win-win.

Don't forget to post pics and let us know your opinion.

Brian

Citation X

ok TEDSgrad talk him outta some koni's for me now haha.

Citation X

Hey Abubaca how does the ride height in the front treat you on the road? Gonna try to finally get the fronts jacks on my car this weekend and don't want to thrash my air dam.

Abubaca

iTrader: (3)

I think it really depends on your roads. I'm at 25 7/8" at the front fender, and with good roads in this area,I don't ever really hit. I gotta take it slow out of my driveway, and certain shopping centers, but I can see it coming and I just pick my angle accordingly. Every now and then I'll scrape the air dam, but few and far between.

Citation X

Thanks Abubaca. I just went and measured and I am at 27.5 front and 27 7/8 out back. I will probably go to 26 in the front and leave the back for now as it is hitting somewhere on big bumps. Not hard so I can't tell just yet. Probably need to do some massaging somewhere. With my wheels being staggered I may leave the back anyhow.

Zach/90\irocZ

iTrader: (6)

Late in posting but what Ted says is spot on I had 1000lb front and 200 rear with largest sway bar in front and adjustable rear one and koni yellows and had no jarring and drove daily and more than 2 hours on weekends on long trips etc but there are far better strut shocks options out there but dampening is key

QwkTrip

iTrader: (22)

I just dropped from 175 lb/in rear springs to 150 lb/in and the car is already more poised and better driving. Less jarring and jittery over bumps. Haven't even touched the front struts yet but I like what I'm feeling already.

Zach/90\irocZ

iTrader: (6)

Question do you have stock bumpstops skim thru thread but getting shorter ones hellps with the jarring any amount of lowering and bumpstops will be hitting constantly but depending on how you like the car and drive it no to suspension especially springs and roll bar are the same but getting and or trimming bump stops help slot giving suspension more travel

rgauder

iTrader: (1)

I'm going to be running extended height lower balljoints. Do you think that will negate having to trim the bumpstops?

Zach/90\irocZ

iTrader: (6)

No because only thing your shifting is spindle height and raising it like a drop spindle doesn't Change but the height of the wheel hub

Citation X

Got the front weight jacks on and set to 26 in the front. I am pretty happy with how it rides and looks. I have yet to put on the struts and founders mounts so it should only get better.

Abubaca

iTrader: (3)

Looks sharp!

Citation X

Thank you.