Coil Overs or Not

[trink408]

I put an AJE k-member in my 1988 HB last year, and now the front end seems to stick up higher than it used to. I would like to lower it down, but I'm not sure on the best way to do that.

I was thinking about just buying lowering springs for the front, but then I thought maybe I should just go with coil-overs. This car is mainly for strip use, but I will drive it on the street now and again.

What do you guys recommend?

[Feature Pony]

If you are going to mainly do strip used I would go with the eibach drag springs and take out the factory rubber mounts which will drop the front end down.. Springs will transfer the weight better than coil overs but its your call, I'm going tubular k member with stock arms and the drag springs..

[SMOKD U]

will im switching over to coil overs an i also just bougth a AJE k member

im interested also in finding out the 60ft time diff with coil overs? VS drag springs

[93GT]

I think I responded to this question somewhere else. :D
The Eibach drag springs do work better than coilovers. But taking the spring isolator out is not enough IMO. You need to cut them a little. I put them in my car uncut and the ride height looked pretty terrible in front. They worked great though. If you want the coilovers to work, you are going to have to run something very light. The 14" 150's I have now don't tranfer the weight as well as those Eibachs.

[1slo5.0]

I have Eibach springs in my blue car and I hate them. The front of the car sits too damn high and they are stiffer than ****. I have coil overs on my red car and they work much better. There is also a small weight savings with coil overs.

[dave bandt]

A coil over system will work better than anything if the everything is set up right.....and you can adjust your ride height with them and still maintain the same preload on the wheel.

[93GT]

It's nicer to be able adjust them, but supposedly they just don't have the stored energy like the stock springs do I have heard, and there is less suspension travel with them. This is an old thread, but that Kevin guy posted before that it would take a 19" long coilover at 90lb rate to equal the stock spring. http://bbs.hardcore50.com/vbulletin/showthread.php?t=5934 Do you think there is any truth to that? On a car with a light front end and using the 130s it probably dosn't need too much weight transfer I would guess. The front end of my car was pretty heavy which is why I'm guessing the Eibachs worked so well. I put 175lb 14" coilovers in and car car wouldn't transfer weight worth a damn. Then I put the 150s in and it was much better. I have some 130s to try out this year too for the hell of it, but they look so thin I'm wondering if they will bind on the street. Dave and Darrell, what rate of springs did you guys use?

[1slo5.0]

I'm running 175 lb springs Mike but I'm wondering if they might be too stiff. I might have to change them this year.

[93GT]

I'm running 175 lb springs Mike but I'm wondering if they might be too stiff. I might have to change them this year.
Hmm I couldn't even get the ride height low enough with the 175s adjusted all the way down.

[1slo5.0]

Hmm I couldn't even get the ride height low enough with the 175s adjusted all the way down.


That's odd......my car sat pretty low in the front. There wasn't much preload set on the springs though.

[93GT]

That's odd......my car sat pretty low in the front. There wasn't much preload set on the springs though.
Your car should be quite a bit lighter than mine was in front too. I'm assuming they were 14"? Do you have coilover struts, maybe that is the difference? Mine is just a coilover conversion on lakewoods. The turbo crap weighs at least 50lbs more on the driver side now, and the C6 should weigh pretty close to the tremec with safety bell so I'm hoping it doesn't bind on that side on the street with 130s. Then I'll have to drive with the hood off lol.

[1slo5.0]

Your car should be quite a bit lighter than mine was in front too. I'm assuming they were 14"? Do you have coilover struts, maybe that is the difference? Mine is just a coilover conversion on lakewoods. The turbo crap weighs at least 50lbs more on the driver side now, and the C6 should weigh pretty close to the tremec with safety bell so I'm hoping it doesn't bind on that side on the street with 130s. Then I'll have to drive with the hood off lol.


I honestly don't know the length of my springs. I know they are 175 pounders because there is a tag on them. Everything on the car is QA1 (K-member, control arms, coil over kit, caster camber plates. I am also using Lakewood 90/10 struts. What caster/camber plates are you using? If you don't have the plates specific for a coil over kit you might have some issues. I know QA1 caster/camber plates have a seat for the coil spring. Using the coil over kit with out them could cause a ride height variation and could be dangerous.

[93GT]

My k member and arms are both QA1. The caster camber plates were Pro3i or whatever it is that stangnet sells. The coilover kit was from X2C. I bought the front and rear and decided to just keep the Eibach springs in the rear and sold that part. The fronts do have plates that locate the top of the spring if I remember right, that came with the X2C kit. The lakewoods I have are only 70/30, and everything worked great launching on drag radials with the stick, but I don't know how great it's going to be with an auto and such a low stall with no transbrake which is why I'm going to try the 130 springs.

[1slo5.0]

With a low stall, no transbrake auto it will launch lazy so you should be ok with the set up that you have now since it worked hitting the tires hard with a 5 speed.

[93GT]

With a low stall, no transbrake auto it will launch lazy so you should be ok with the set up that you have now since it worked hitting the tires hard with a 5 speed.I know the gearing is worse in the auto too and I'm putting in 3.27 gears in the rear. Hopefully the thing even moves off the line at all.
:thud: It probably won't be near as fun as the stick, but at least it should be consitant I'm hoping.

[1slo5.0]

I know the gearing is worse in the auto too and I'm putting in 3.27 gears in the rear. Hopefully the thing even moves off the line at all.
:thud: It probably won't be near as fun as the stick, but at least it should be consitant I'm hoping.


You might have to get out, push it thru the 60 foot beams and hop back in :D

[BBATCO1]

I run 130# 14 inch qa1 springs on lakewood 90-10s. They work great. There is alot more to suspension tune than just springs. A low horsepower car may benifit from the stored energy of a drag spring if traction is even an issue. The better you get the rear suspension to work(which I would concentrate on first) the less you need that stored energy. There is alot of science here. How fast will the car be anyway? If its a turbo car without a break it will be way lazy 60' anyhow.....

[93GT]

I run 130# 14 inch qa1 springs on lakewood 90-10s. They work great. There is alot more to suspension tune than just springs. A low horsepower car may benifit from the stored energy of a drag spring if traction is even an issue. The better you get the rear suspension to work(which I would concentrate on first) the less you need that stored energy. There is alot of science here. How fast will the car be anyway? If its a turbo car without a break it will be way lazy 60' anyhow.....
I don't really know how fast it will be since I am changing so much. It is a fairly small turbo and should see full boost by 3000rpm though, so I'm hoping to be able to build a little boost to launch with. The suspension worked great with the stick. I only was able to go out once at the end of the year with nitrous on it, and it was getting 1.6 60's with a best of 1.57 onr 275/50 BFGs. It just pulled the tires a couple inches people told me and hooked. :thumbs_up I was only running 11.7-11.9@117 on most passes.

[BBATCO1]

Sounds like a fun street car. Your suspension works nice, you are 60' good on those tires for sure. I personally would go coilovers and try a 150# spring I bet the 130# will be to thin with all the turbo stuff up front. It will be a little trial and error though. Other then that i think your car works well....

[93GT]

Sounds like a fun street car. Your suspension works nice, you are 60' good on those tires for sure. I personally would go coilovers and try a 150# spring I bet the 130# will be to thin with all the turbo stuff up front. It will be a little trial and error though. Other then that i think your car works well....I already have coilovers in there.
:D I think the post got too sidetracked from the original guy asking if he should use them. :D I have the 150s in there now which is what I've been using, but have some 130s now too, so I figure it can't hurt to try. Here is a pic of how low the 150 was before the turbo, so I'm hoping with the 130s I can get it toward the middle of the adjustment. I want the car sitting a little higher now too so the intercooler doesn't scrape. :D If the 130 only works as well as the 150, I will keep the 150 for sure as it will probably feel more stable driving around.

[trink408]

:D I think the post got too sidetracked from the original guy asking if he should use them. :D


NO problem. I'm learning from all of this.

I'm looking to continue using my lakewood 90/10's and I have a 408 in the car with nitrous.

What springs do you think I need, 150s or 170s?

Do all coil over kits work with any kind of struts and caster/camber plates?

[93GT]

NO problem. I'm learning from all of this.

I'm looking to continue using my lakewood 90/10's and I have a 408 in the car with nitrous.

What springs do you think I need, 150s or 170s?

Do all coil over kits work with any kind of struts and caster/camber plates?
No, some kits only fit certain struts. I have Lakewood 70/30s I wish I would have got something adjustable, but they are quite a bit more $ that I didn't have. I had a strut go out with less than 1,000 miles on it, so I don't have much faith in the Lakewoods as far as reliability any more.
You need to find out how heavy the front of your car is as it could be a couple hundred lbs different than another car. I would order 150 first and go from there, as I'm sure you will not want a higher spring rate than 170 unless the car is really heavy. The coilovers springs are only about $70, so it doesn't cost a lot to switch, and the 150s would be easy to sell if you wanted to as from what I've seen a lot of people start with 175s and then find they are too stiff. I've heard of people using any kind of cc plate, just make sure they are not the poly bushing kind as all the weight of the car will be supported by them, and those weren't designed for that.
I haven't checked out any kits recently, so I don't know what the cheapest or best parts for coilovers is out there now.

[dave bandt]

NO problem. I'm learning from all of this.

I'm looking to continue using my lakewood 90/10's and I have a 408 in the car with nitrous.

What springs do you think I need, 150s or 170s?

Do all coil over kits work with any kind of struts and caster/camber plates?

If you weren't going to be spraying the car then I would say to start at 140-150. Since you're gonna run juice the 175's will be the ticket.


As far as springs go....let's think about this for a minute. Let's look at your typical street Mustang at 3200 pounds with a 54/46 weight distribution. In this instance there would be 1728#'s up front and 1472# in the back. Let's forget about the rear. And because there are two springs up front the load each "sees" is 1/2 of what i listed, or 864#. Now I have no idea what the rate is for stock front springs but i seem to remember reading that they are variable rates and i also remember 300 or so pounds/inch. Maybe i'm way off base here but we'll run with it for now. We're going to assume that they have a linear rate and that it is 300 lb/inch. Now let's look at some different springs.

90#/in 864/90=9.6

175#/in 864/175=4.9

Stock(300#/in) 864/300=2.88

The numbers above represent how much the springs will compress in response to 864 lbs of force being appied to each. Notice that going from stock to 175/in will drop the nose of the car a tad over 2". Going from stock to 90#/in will drop it almost 6 1/4"!

Now let's dispell a myth here. A stiffer spring does not store more energy. It has the POTENTIAL to store more energy than a smaller spring. However, unless the smaller spring goes into coil bind it doesn't matter if the spring is rate is 100 or 10,000....all that changes is how much it compresses and the rate that the energy is released. According to the laws of physics......a spring compresses X distance in response to Y weight.....PERIOD. And the larger the spring constant (rate) the less they deflect in response to a force.

Now, with all this said....the rate at which a spring RELEASES energy is what we are manipulating when racers play with spring rates. Sure, ride height is important....but coil overs give you the ability to adjust that without changing spring rates. What a lot of people don't think about is what the spring does in tension....i.e. as the car is launching and the front end is rising. Think about this for little bit....a low rate in the front of the car will deflect a lot when the car is sitting there. However, it will also stretch a lot when the front end comes up off the ground. Conversely, a very high rate will start applying force sooner and more rapidly once the front end starts rising.

So to sum things up.....if you don't make a lot of power or your chassis is marginal light springs in the front will allow you to "throw the weight" to the back tires more quickly and pull the front end up higher. The down side of this is that the car is using the engine power to do this instead of moving it foreward. If you make a lot of power running stiffer spring can help to keep the front end down on launch. You just have to be "on your game" with respect to chassis tuning.

[trink408]

Thanks for the INFO Dave.

Have any of you guys tried UPR products?

I was looking at their coil over kits, they will work with my Lakewood struts.

[dave bandt]

UPR makes decent stuff and is a big supporter of the NMRA. I wouldn't hesitate to use them. Of course, Anthony Jones is one of my sponsors and his company is known for making the best K members in the business.....but you pay for that. Jason Smith over at PA Racing is another big NMRA supporter that makes a nice K member. You won't go wrong with any of these if you get the right one for your application/budget.

[trink408]

UPR makes decent stuff and is a big supporter of the NMRA. I wouldn't hesitate to use them. Of course, Anthony Jones is one of my sponsors and his company is known for making the best K members in the business.....but you pay for that. Jason Smith over at PA Racing is another big NMRA supporter that makes a nice K member. You won't go wrong with any of these if you get the right one for your application/budget.


I already have an AJE K-member, and it was a very nice product. I will have to check and see if AJE sells coil-over kits, I would definitely buy from that company again.

[trink408]

Are you guys running bump steer kits since the car is lowered?

[dave bandt]

I didn't use one on my 87 coupe but i didn't need one. Then again, my car wasn't lowered much.

[93GT]

Are you guys running bump steer kits since the car is lowered?
I don't have my car that low either. It would be a good idea if you want it low though. :beer: