customblackbird

iTrader: (15)

I'm making a custom coil over kit for my 87 Fordiac… or 87 formula 350. I bought part of a spohn kit, 12" 300lb springs, adjusters, thrust bearings and support plates. I bought a 2nd set of plates and Im integrating a STB with the plates sandwiching the strut tower for a stronger more solid setup. I had some top spring isolators made for the top of the spring so I could run my hot part caster/camber plates… not a fan of spohns caster plates and I already had mine.

Now as we all know the coil over spring takes up 90% of the strut tower opening and kills your ability to make considerable changes to the front suspension. Now I was wondering… if I were to lower the top of the spring by using a tube spacer between the caster plate and the top spring cup could then be below the strut tower opening and would then give me a lot more adjustment. My question is… going from a 12" spring to a 9" spring, then using a 3" spacer will that cause the front suspension to bottom out? I have 6" of space from the bottom coil over spring adjuster to the top of the strut (seal area) that would contact the top spring cup. That leaves me with 6" of space from the top of the spring to the seal as well. If I remove about 3" of that it leaves me with 3" of free space between the spring cup and the strut (unloaded). Does this mean I would have to increase spring rate to compensate? Im not after road racing or anything… just a fun street car to take to shows and such.

If I have to increase spring rate to compensate for only 3" of spring travel… how high would It have to be? Also that is having the adjuster bottomed out (lowest point)… if I raise the setting I might be able to go with a 8" spring with the 3" spacer which would give me more space between the spring cup and strut. I would think that would be best… Plus I would get more adjustment of the front strut. If I run a 6 - 8" spring, the 3" spacer, then adjust the spring adjuster like 1/2" way up that would give me more clearance between the cup and strut no?

Figure 12" total height max, this gives me 6" free space unloaded between the top spring cup and strut. I believe the adjuster has 4 - 4.5" of adjustment.
9" spring = 3" spacer = 12": adjuster bottomed out: 3" of free space unloaded
8" spring + 3" spacer =11": so I can move the adjuster up 1": 4" of free space
7" spring + 3" spacer = 10": adjuster moves 2": 5" of free space
6" spring + 3" spacer = 9": adjuster moves 3": 6" free space

let me know what you guys think? If I decided to go with a 6" or 7" spring does that mean I need to increase spring rate?

here are some pics.

This is what the 300lb 12" spring looks like


This is how far it sticks past the strut tower surface… its about 3"… If I can get that spring cup below the strut tower it increases my adjustments like 3 fold.


Here is the underside.


It bolted down.

customblackbird

iTrader: (15)

Actually Now that I think of it... I can never gain back the length of the spacer on the strut. Unless I'm thinking of it wrong.

plum92_camaro

I would have just used weight jacks. All the pluses of coil overs, none of the issues.

AlkyIROC

I don't run front coil overs but I've played with spring rates on the rear. I've had as heavy as 150 pound but currently run 110 pound. The 150 and 130's I tried didn't allow enough suspension travel.

With the 110 pound, I move the adjuster to get the ride height I want.

Springs hold the car up and you adjust them to get the proper ride height providing they're not so light to produce coil bind. Shocks do all the work. Too heavy a spring and the shocks don't work properly.

customblackbird

iTrader: (15)

You mean besides drilling a large hole in the front subframe, welding a plate to the Kmember? The coil overs would work just fine but I needed a lot of adjustment before the coil overs to get my front end in the correct alignment… and the coil over spring takes up 90% of the strut tower opening… so that doesn't give me a lot of options.

I didn't want to cut and weld my brand new powder coated race craft moly Kmember honestly…

I might go front weight jacks tho… since everything is out of the engine bay… gotta figure it all out. what is a good front spring rate with a 150lb rear coil over? I had cut moog 5664s before… so I figure 800ish with the weight jacks might be a good match?

customblackbird

iTrader: (15)

Thats exactly what I have going into my rear… a 150lb rear coil over setup with QA1 single adjustable shocks, Its a spohn kit.

Do you run the 110's bc your a drag car? Mine is a street car that might see some track time once in a while. Ive heard that 150 is kinda soft (drag racing and street)… 175-200 for serious cornering or auto X. What do you run in the front?

Depending on how it feel I might go with a variable rate once I get a feel for how it rides this summer.

plum92_camaro

I have Ground Control Weight Jacks (850# fronts, going to get 1000#), there was no cutting or welding involved. They go in stock location and adjust through the bottom of the a-arm.

What plate do you have to weld to the k member? Do you mean you'd have to add the upper spring cup to your aftermarket k member that is set up for coil overs?

Btw, I apologize for my first post not sounding very polite.

customblackbird

iTrader: (15)

You going to sell the springs? I might be interested in the springs. Most people run the weight jacks by cutting the spring pocket out of the Kmember and welding in the stop weight jack plate with nut. They cut a hole through the front subframe to allow the bolt to pass through. This means no crawling under the car to adjust the height. This Can not work tho for me as I have a a Moly Kmember with upper spring perches. The Kmember I got and my old UMI Aarms are both stock coil spring ready its just adapting the weight jacks to my Kmember and not really wanting to drill through the front subframe. I wasn't sold on the coil overs as I thought they might not ride as nice or adjust. Which is why this thread was getting them to adjust more. I see that GC WG's are adjusted through the bottom which I like better. Im putting together a kit which is about $150 for the complete front setup (need to mod it alittle) and that includes 800lb 9.5" springs.

AlkyIROC

I've considered dropping down to 90# springs. With the 4-link suspension in a drag car, you want the suspension to move. Like I already said, the springs hold up the weight of the car. With double adjustable shocks, you can control how the diff reacts.

My suspension is set up to drive the tires down into the ground quickly and slowly allow the force pressing down to release. This keeps the tires planted until the car gets momentum. If they're forced down hard and kept there too long, you can go into tire shake. If they are not driven down enough or not kept down there long enough, you get wheel spin.

That's why you use double adjustable. You change the compression and extension settings depending on the track condition. There is no single setting that will work perfectly in all conditions.

Although the front coil overs look nice on a street car, a third gen isn't really designed for them as you've found out when you're trying to play with and adjust a custom setup. My Moroso Trick springs in the stock location and some Koni SPA1 struts work just fine. My problem is keeping the front end down and I like the big springs under the frame to absorb the landings.

plum92_camaro

I've seen the ones that go through the frame. that's fine for them but I've only adjusted mine twice. Once when i installed them to set ride height and once again when I realized it was too low. My tires had rubbed holes in the fender liners from the hard cornering i was doing in autoX. I believe in the "set it and forget it" rule because every time you adjust them it messes up the alignment. I'm going to 1000# in the front because I'm still burying the tires up into the wheel wells.

I thought about hanging on to 850's for after the LS1 swap. Around 100 lbs off the front of the car they say. Not sure I'll still like the 1000 pounders then. Ground Control springs are $120 a pair and come in 25 or 50 lb increments. Give them a call, their website doesn't have all the springs they sell listed.

With the Ground Control set up I'd like to make you aware that there are two lengths of springs available. I have the shorter option. When I first installed them they were loose in the spring pocket until adjusted (extended). You many want the longer springs if you will be drag racing, fully extending the front suspension then dropping it. A longer spring will also have more travel before coil bind right?

customblackbird

iTrader: (15)

Yea I understand, for a drag setup… a taller softer rate spring helps with weight transfer and has more stored energy. I guess your setup is apples to oranges with how I want mine to react.

I like the coil over and would only cost me $25 to get spacers made but I loose too much strut travel and Im not fan of wearing parts out quickly. My driving style has calmed down over the past 5 years or so where I don't run it at the track as often and Don't want a harsh ride or a super mushy one.

customblackbird

iTrader: (15)

How did the 850s ride on the street? stiff bumpy ride or smooth but not mushy and bouncy? Im looking at the 850 as I think I have a 600lb BB over my Kmember… but now my Kmember only weighs half as much lol. I was running cut moog 5664s (1.5 coil cut) coil i think for a 12" free height for the past couple of years and the car had very little front suspension travel. THats a 750# spring at stock height… the cut coils put it in the 900lb range if I remember correctly. I thought the 800 would be stiffer than the profit and softer than my cut moogs but I think an 850 might suit me better. I had sport lines on it a while ago with the OEM 350TPI and it was better than the stock WS6 in the beginning but got rid of them for the stiffer cut moogs.

I dont drag race much anymore, 1 time a year maybe! Even with my cut moogs I was pulling 1.8 60' on 295/65r15 MT drag radials… which isn't the best but it had a 900lb front spring and a 200lb rear spring with a good bit of rake. I can raise the fronts up now even with a 800-850 spring rate and hopefully my 150 rears will allow alittle more weight transfer. But Im not looking for the best 60' just a fun mild mannered street car.

The way I see it is if I make my own weight jacks I get a full WG height of 1.875" if I make it to the GC style. Then add my 9.5" free height spring and that puts me at 11.375" which is almost .75" lower than my cut moog 12" free height already and that was as low as I would want to go. Plus the slightly softer rate would work out for slightly lower as well and then I have my 2.5" of adjustment up with the WG. Im worried about having an unbalanced front and rear spring rate.

plum92_camaro

I like the ride, very firm and stiff like a sports car should be. A bump that would be harsh on any car (or even my Dakota 4x4) is harsher than normal but I can't confirm if thats the springs or the combination of parts I have like, no spring isolators, GW Del-a-lum bushings, koni yellows and CC plates. All things that eliminate deflection that the stock rubber absorbed before. I went from worn out stock to upgraded new.

I know with that extra weight of the big block you will need a higher spring rate than me with my little 305 to get the same ride and performance, but I'm not sure how it will effect the harshness going over bumps. Also the extra weight of the big block vs a sbc, even with the tubular k-member will throw off the balance of the car. They say a 5:1 ratio for spring rates in these cars but I can't imagine that is true for ALL cars. You have extra weight in the front so of course you'll need a higher spring rate, but the rear of your car shouldn't be significantly heavier so you shouldn't need higher rear rates than if you still had the 350 right? I haven't installed the rear springs in my car yet so I can't comment on how they ride but Ground Control set me up with 250# rears because I have extra weight in the rear (dynamat from firewall to the hatch release, and 2 subs and amps). From what I've seen, anywhere from 150-200 rear rate is a good rate for a street car. 200 might be a little firm but A lot of people say they like a soft rear and you can tune it with sway bars. If launch is important to you listen to Alky, he knows drag racing.

Here is a picture of my 850s in a hard left. This photo is why I'm going to 1000# front springs. Rear is stock and somewhat worn out but i'll get to it.
[IMG][/IMG]

customblackbird

iTrader: (15)

Well all mine is upgrade as of now… not one piece of stock suspension left lol. my rear suspension is all tubular with double rod ends. The front is now fully tubular, Aarms (have poly bushings in them) even my motor mounts are solid now. Im not worried about stiff as I only put 500miles on the car in 3 years but I don't want like "jarring" etc. Firm is good. Just like a trans shift… firm and quick is good but a hard bang shift is not. I have some poly isolators I ran on the back and thinking I'd try them on the front to absorb some road noise.

My weights are a crap shoot lol. Mostly all OEM except I have aftermarket 5pt harness racing seats, 8pt roll bar (added 100lbs easy), adding full GFX, BBF up front (weighs a tad more than a fully dressed iron SBC), STB, Wonder bar, Going to have Front weight jacks, and this is all added weight.

Now Ive deleted all these… Rear seats, AC, Smog, Whipers and motor, Brake booster, Stock Kmember, OEM Rear LCAs, Panhard bar, panhard bar support, Tq arm, Front Aarms, CC plates, and my hood (now I have 4" cowl bolt on glasstek hood). I would say Ive Broken even… but can't say for sure. Ive def lost weight over the nose due to the 600lb motor, but Ive dumped hood weight, AC weight, Smog weight, Kmember, cuise control, coolant and whipper fluid tenks etc. That easily makes up for the extra 55-75lbs my BBF weighs over the iron 305/350.

I had 200lb rear weight jacks and it was a bit stiff for me. Im hoping the 150lb coil overs soften it up alittle.

Your pic you got some lean! lol. Looks like you have the car lowered a good bit tho. I can't run that low with my dual 3" exhaust with Xpipe so I will prob actually raise it alittle this year which i hope helps with the ride comfort alittle.

Thanks for your recommendations, I think a 850 would work well as It should support the BBF but hopefully its alittle softer than the 1.5 coils I cut off my moog 5664s.

plum92_camaro

Its lowered some about an inch from where it had sagged at stock. Rear is stock (for now) and the amount of gas in the tank effects rear height. Here is the most recent photo I got of it's normal ride height. Had to move it from one side of the shop the other so I took picture of it since it's the only time it's seen snow in the 15 years i've owned it.


I think your right, 850, maybe 800 front with 150 rears would be a real nice combo. I figured the BBF would make a bigger weight difference. DBLTKE has 800/200 on his car. He is REALLY low and like me carries some extra weight in the back. Do an advanced search with his user name and check out his ride. There are several threads where he talks about his set up.