I'm going to Grattan raceway on May 11 http://www.grattanraceway.com/ . Grattan is about a 2 mile road course in south west MI. If you are interested in going, we may have some spots open for you. It will cost $125 and I would be thrilled if I got some thirdgen boys there. Last year I was the only camaro. so sad. Email me if you're interested, or go to http://events.kzoorice.com/ to register. Anyways, on to my question.

My car was pushing bad at Gingerman last year. I know the rules, stiffen the rear if you have a push etc. I want to balance the car out using softer springs in the front since Detroit roads are not very friendly. Which ones should I use? Which ones will get me closer to being balanced? I want to cut them to drop the car about 1-1.5" all around. I don't want to buy Eibach's etc, they are overpriced. I want to balance the car using some regular springs maybe from a z28, v6, s10, or g-body.

I have an 87 IROC with all of the stock springs. All poly bushings front and rear everywhere. boxed rear panhard and control arms. Srut tower brace up front. Weld in SFC's. Relocation brackets in the rear. I will be installing a fiberglass z28 hood to reduce the weight.

I'm looking for recomendations for softer front springs that will balance my car. I can use the relocation brackets to fine tune.

Thanks for your help. Austin

 

Well, that will depend on exactly what springs you had. That may also not be the cure. Where is it pushing at? Turn-in, mid-corner, on exit? Did it happen only on high speed, or low speed corners?

You might be able to get away with just dropping down a size or two in the front sway bar. It could also be your driving (no offense).

 

No offense taken.

Definately do not rule that out, but I know that I got a hell of a lot better at driving by the end of the day.

There was a long high speed turn ~70 mph, where there was no line to take, it was just a long turn, where all you do is regulate the gas to go as fast as the car will turn ya. It was definately a push. I had to give it a lot of gas to move the back end.

I have the stock IROC springs. They have to be the stiffest ones availble from the factory, the 706 lb/in ones, i'm sure of it. The car drives like absolute crap on bumpy roads. I've lost teeth from it.

So how drastic should I go? Anybody have experience with this?

Most people probably go stiffer on the rear, what have you guys done to balance your cars? 7/8 rear sway bar? I'm even considering making some heim joint rear end links.

 

it really depends on exactly what the car is doing. You could try going down one size in the front sway bar, or maybe up to a 24mm in the rear (or both), and see if it gives you a little balance.

I'll add, that it is really hard to advise on this, without driving the car. You seem to know the dynamics, the best solution, is probably trial and testing. You may need to change the sway-bar, maybe try some slightly diffrent alignment settings, and some air-pressure changes. Our cars in stock form do tend to plow a bit. But it also doesn't take drastic changes, to make it much more nuetral.

 

What kind of springs and sway bars do you use and what kind of track do you race at?

I'm going to put the front camber at -1 before I go. I'd rather not fork over the money for new sway bars, but maybe a smaller bar from salvage would work good. That would be something that I can change at the track.

I'm also thinking about making some heim joint end links to play with.

 

I would take a sway bar or two, from teh junk yard with you next time. It is easy enough to change a sway bar, between run sessions.

I run 750# front springs / 175# rear, with 1LE sway bars. But, my car is also not at stock ride height, so my roll centers are going to be diffrent than yours.

Also, what tires do you run at the lapping days? The stock cars that I have driven, with R compound tires, understeer less, than when they are on street tires. especialy if you get the alignment, and tire pressure dialed in.

 

I have 18 x 9.5 in z06 wheels with dunlop dierezza tires 275/35/18. Just street tires.

I want to drop the car 1-1.5" before I go. I'll cut springs.

What front allignment specs do you use? I realize they probably won't be right for my steet tires.

Right now I'm thinking that I'll find a regular z28 front bar, whatever dia they are, and maybe some z28 springs. I'll cut them to give me an 1-1.5 drop. I'll start off with my stock sway bar and swap it if I still push. Do you know what the z28 spring rate is?

I can play with my relocation brackets adjust the push/pull in/out of turns if I ever get this far.

 

Before you do a thing with springs or swaybars, But some Koni Yellows (About 2 clicks on the rear{3rd setting stiffness out of 4}, and mid firmness dail setting on front rebound)and move your battery to the rear compartment of the car. That alone WILL help you, just how much needs to be tested.

You are just getting too much body movement through the corner and the heavy nose weight combined with the roll movement is causing the push.

Dean

 

It would be real nice to have a set of Koni yellow, but it looks like they are way out of my price range. Ebay showed $450 for just the fronts. No can do.

I'm defiantly going to move the battery to the trunk. I also have a fiberglass hood that I'm going to put on.

 

I was not aware that stock springs were as stiff as 700#. If they are that stiff I would leave springs alone. Get a set of good shocks on the car and start from there. You may be amazed at how much of a difference the shocks will make. Good shocks will also improve how the car feels on a bumby road. Shocks and tires are the basis for tuning a car. Going at the springs and sway bars without touching the shocks is really just a work around. If the front springs are 700# what are the rear springs? If you are going to leave the panhar rod in the stock location you would want ~150# rear springs and a 36/24 or 21 swaybar combo. Softer springs will hurt the track performance of the car. Also if you cut your springs they are going to be stiffer than they are now. There is a formula that demonstrates this but I am not sure what it is. Normpeterson and 83crossfire have discuseed it several times on this board. It has to do with reducing the number of free coils.

 

Yeah I agree with that, as far as mods go I would do strut/shocks first. It makes the biggest difference. But as far as balancing the car out, I think Dewey has some good ideas. Playing with the swaybars is much easier than changing front springs and could be done at the track between rounds. Bottom line is that you're gonna have to experiment at the track to see how it feels. I would try either a stock RS front swaybar, or a bigger rear swaybar like a 1LE or aftermarket. You can also play with the tire pressures when running but be sure to keep an eye on the tread wear (or if you wanted to get really technical about it get one of those heat meters). If you wanted to play with the rear spring rate too I think this would be do-able at the track between rounds, rear spring swaps on our cars are easy. But you'll have to determine what spring rates you have now so you know what to buy. When buying new springs I would look for circle track springs like Suspension Spring Specialists or something similar you'll find at a speed shop related to oval track racing and/or maybe even dirt track racing. These types of places will allow you to specify spring OD, height, and static spring rate. You also might want to consider height adjusters (weight jacks) when going this route so you can control ride height too.

 

The Federal Mogul website shows that the rear springs are 107 lb/in.

I'm almost positive that the fronts are the heavy duty 748 lb/in springs since it says "Front Heavy Duty Coil Springs Iroc z28". There is no way that this car could ride more harsh.

It looks like Moog has 3 different front spring rates to offer: 347, 424, and 748 lb/in (atleast for camaros). Here is the website http://www.federalmogul.com/aftermar...ml?Country=USA

When I get time I'll dig out a book and make a spreadsheet to calculate the spring rates after I cut a coil or half a coil etc. If I cut the rear, it might put me up to about 150#. Then maybe get a softer front, and cut it to lower the height and raise the spring rate. I don't know think that a softer spring will necessary hurt track performace. I think the most important thing is to be balanced. I was using the **** out of the front tires last year because that was the only thing turning the car.

You guys got me interested in the struts / shocks. Are Koni Yellows the only adjustable ones out there? What do you guys run? Do I need adjustable struts/shocks or just "good ones". I don't know much about dampers.

 

Adjustable shocks are not needed, but if you are going to be playing around with your setup it is nice to be able to switch your settings. I am not currently using my adjustability. I am set at one click from full soft rear and full stiff front and they have been that way for 2.5 years. Tokico Illuminas are pretty good adjustable shocks from what I hear but they are not that much cheaper. If the rears are that soft you will need to stiffen the rear. Balance is important, but you also need to maximize the potential of your tires. You can not do that with soft springs.
So enough of what I think is best and on to tuning your car the way you would like it. What size are the swaybars that are on the car now? The problem with using stock springs is that there is really no way to be absolutely sure of what the spring rate is. Add to that mix the idea of cutting the springs and it just gets a bit messy. As Hawaiian mentioned Suspension Spring Specialists sells springs in various lengths and spring rates and they are only about 55 plus shipping each (just ordered new 800# front springs). Our front springs are 5.5" diameter. Not sure what length you would need cause I am using Ground Control Weight Jackers. I will measure my factory WS6 springs for length if you are interested. When you mention relocation brackets are you talking about LCA or PHB? You have poly bushings in the rear of the car which is not optimal because of binding.

I know you dont want to buy the Eibach springs but your stated objectives fit the prokit nicely.
Here is a good start point for our cars. http://www.frrax.com/rrforum/index.php?showtopic=5255

 

I went to the Moog site that you linked but I could not find anything that showed spring rates. Could you link to where you got your spring rate info? I found part numbers but that is about it. I compared your car to my car as far as listed spring part numbers and they were the same (I have a WS6). Again there were no spring rates listed but when I went from the stock springs to 775# springs it was noticably stiffer.

 

[QUOTE=Souseless]I went to the Moog site that you linked but I could not find anything that showed spring rates. Could you link to where you got your spring rate info? I found part numbers but that is about it. QUOTE]

go to http://www.federalmogul.com/aftermar...ml?Country=USA , then click on catalogs / make model look up. then put in your year, car, engine (select 5.0), part etc. It will bring you to the part number list. There is an "I" that you can click on that will give you the information on that particular spring. the free height for the 748# springs is 13.01".

 

I have the stock sway IROC sway bars. The front is either the 34mm hollow or the 31 solid (i think that those were the sizes offered). Not sure what the IROC rears are, maybe 3/4 or 7/8", not sure.

The relocation brackets are the LCA.

I understand how the rear suspension with out have the endlinks could "bind", but wouldn't that just add to the spring rate? Is that really a big deal?

Thanks for the link, I will do some searching on that site.

 

When I mentioned the problem with the Poly Bushings I was talking about LCA and PHB. Yes this does increase wheel rate but it is not a constant. The rear will bind and then snap loose. OK for straight lines not so good for turning. When you are at operating at the edge of adhesion sudden changes are a bad thing. The poly is OK for the swayar endlinks though. Heim joints are better but that should not be your current focus. You need to get rid of your push and buy GOOD shocks/struts. The cheapest way to get rid of the push is to use stock swaybars. They came in many sizes and they make a significant impact on how the car handles. They are also cheap. Sometimes they are free. If you go looking for a rear bar the 3rd and 4th gen bars are the same fit so you have 20 yrs worth of cars to choose from. Measure yours and then buy some used ones to balance the car. The harsh ride is your shocks/struts.

 

A set of Tokico Illuminas are on Ebay buy-it-now fow $424. That seems like a good deal for as long as I have been looking (1 day).

So I have a decision to make. Tokico shocks and struts or C5 brakes? I planned on doing the brake upgrade, lower, and spring change before the 5/11 track day, but you guys got me sold on these struts now. I can't afford both unless I take out a Home Equity loan.

 

Figure out how to make the brackets and get LS1 brakes from this guy. http://www.frrax.com/rrforum/index.php?showtopic=7096 It looks like he will sell his calipers for cheap and they are almost the same as C5. Also make sure that they are the Illumina shocks/struts. www.shox.com has them for 540 so your ebay price sounds like a good deal. If you are stuck with the stock brakes for the track day try to add vents to the car. I have the crappy stock brakes still and I can only get about 3 good 30 minute sessions before I start having problems. Try using Hawk HP+ pads they have great grip and ATE Blue brake fluid. I have been using DOT 4 but it just isn't good enough. Also on the shocks try calling Sam Strano from www.stranoparts.com I am not sure what his price for the shocks will be but he is very knowledgable about our cars and can help with setup when your trying to tune the car after the install. As you can imagine the advice is easier to come by if you buy the parts from him.
----------
I just noticed that you have an auto tranny. You may want to add a tranny cooler befor you hit the track again.

 

I'm already somewhat committed to the C5 brakes since I already have the brackets.

Never thought much about adding a tranny cooler, but I suppose it won't hurt. Have you heard of inccidents with auto's on the track?

 

Awesome link. Tons of good info. I went thru and searched for every spring overed in third gens heres a word document listing all the springs that they list as stock replacement. I didnt break them down...but theres quite the variety.

 

Double check this but you may be able to use that bracket with the LS! brakes as well. I have heard of auto trannys having trouble on road courses. I have no first hand info, but I know the fluid will get damn hot. You may be able to find some info in the tranny board that is not related to drag racing or go to FRRAX and check there. You may also find something at www.nasaproracing.com

 

Hey man, thanks for putting that together. That was something that I wanted to do but didn't get to yet. Now I don't have too. Thanks again.

 

Big_Mods,

I don't think you need to make drastic changes, like changing springs. You would really be suprised at how far small chances go, towards making everything balance better.

 

Dewey316, Souseless, Crazy Hawaiian, thanks for your help.

I'm going forward with the C5 brakes. I got a good deal on used calipers which will save me about $130. The rest of the parts will come from gmpartsdirect and I'm going to get the Hawk HPS pads.

I now agree that the dampers will probably help the most of any single mod for my car. I have to see if the budget can fit it in though.. (house needs roof, Detroit's economy sucks, I'm making less than I did the past 2 years etc waaah waah). Right now I'm thinking yes, but we will have to see. I need to make a decision here in the next week or so.

Let me tell you the coolest part about this track.. a 1/2 mile straight away coming out of a 50 mph turn!! How awesome is that!

 

Two of them. . And one of them comes into a 90* chicane, the other goes into a very high speed, left/right combo.

 

It may sound odd but I am glad to hear that you decided to go with the brakes. Reason is that you were going to settle for what would be my 3rd choice in dampners and I am a big fan of buying top notch go fast parts. You can still fix the push for cheap with a sway bar. You never posted the size of your bars, you posted a guess but not anything that you measured. One size up in the rear bar would likely do it. You should be able to get a bar for less than 75.00.

BigMods
I may make it out to that track some day. I've been going to Watkins Glen which is about 3.5hrs from home (Buffalo; so I understand bad roads). There I get near the top of 3rd just before turn two so I short shift into fourth and put the pedal to the floor through turn 3 and 4. I keep it down until about 450 feet before the bus stop (or inner loop) (or turn 5 for NASCAR fans). Not sure how long that is but I can usually have a nice conversation with the instructor during that time.
https://www.trackmasters.com/Images/Elevation1.jpg
I will be there again on July 5th + 6th.

 

It sounds like your not a fan of the Tokico shocks and struts? Why, and which brand do you prefer?

I got under the car and measured the bars and front springs:

front sway bar: 34 mm
Rear sway bar: 23mm (I've never head of it either)
Front spring bar diameter: .76" which makes it the 748 lb/in spring (the stiffest one offered)

Where can I find a bigger bar than 24mm for $75? To my knowlege 24 mm is the biggest factory bar available, so I'd have to go aftermarket.

How fast to you get up on that watkins glen? I'm hoping to hit 130 - 140. I'm going to give my trans the full throttle upshift into 4th mod.

Dewey316, that track looks awesome.

 

It is not that I am not a fan of them it is just that they are the second best choice for an off the shelf adjustable dampner. I have not used them I went with Koni because that is what the national champion autcrossers are using in our cars so I figured there must be a reason. I talked to people that had used both and was told Koni was better. The improvement in handling was dramatic with the Koni's. My second choice for shocks would be revalved Biltiens from Strano's if you know about what spring rate you will stay with. On the Moog website they list bushings for a 23mm bar as a stock replacement so that must have been an available size. That being the case a 24mm bar would be ideal. The aftermarket bars wil run over 200 so I would not go that route either. Start checking the junk yards and ebay for the bar I see them alot. you can buy a bar from a 1982 through a 2002 so there are a bunch of bars out there. Or you can buy some rear springs for 55 each; I just dont know what free length you would need. I wish I had known about the true stock spring rates as I also have the 748# springs. Last year I spent a bunch of cash to put in the springs that I have and the net change in rate was small in front but I did get the ability to adjust height and to one day corner weight my car.

Watkins Glenn is starting to haunt my day dreams as the weather is starting to finally break here in Buffalo. My car has a stock 305 so the best I can do is around 125 on the back straight. If you look at the elevation map in the link you can see that there is a 90' elevation change between turn 2 and the inner loop. Climbing the hill sucks up a lot of the power I have available. and the 3.23 gears are not doing me any favors either. I just get to the top of 4th gear when it is time to start slowing down for the turn. After 100mph my car is just out of power. My car is a work in progress; l am almost done tweaking the suspension ( I should "finish" this year) and then I will work on power.

 

[QUOTE=Watkins Glenn is starting to haunt my day dreams as the weather is starting to finally break here in Buffalo.... l am almost done tweaking the suspension ( I should "finish" this year) and then I will work on power.[/QUOTE]

You should take a day off work and come to Grattan on 5/11. That way you can finish tweeking your suspension before you go to Watkins Glenn.

What is the cheapest you have ever seen the Koni Yellow's for a thirdgen? What did the people that you talked to say that they didn't like about the Tokico's?

I'm just asking because I don't need the absolute best shock out there since I only go to the track once a year, and I don't race competitvely, but I don't want to buy something that I'm not going to be happy with. If the difference is small I'll just buy the Tokico's. My car is mostly steet driven, and I'll go to the drag strip as much as I'll go to the track.

 

The biggest issue with Tokico, is that their adjustment adjusts both rebound and compression. To get a good rebound valve setting, you end up with much more compression valving than you really want to run.

Koni Yellows will run about $650 for all 4 corners.

 

http://cgi.ebay.com/ebaymotors/82-92...QQcmdZViewItem

this is a 24mm swaybar. The shipping price is nice and low too.

I autocross 2-3 times per month, so that is how I decide if my latest changes were helpful.

When you are ready to spend money on shocks call Sam Strano; he will go over the shocks and why one is better for a given application than another. He really knows his stuff. As for what I remember they either have too much rebound or too much compression. After reading Deweys post I understand why. Bilstiens (possibly revalved) are supposed to be the next best choice.

 

There is a 24mm rear bar for sale on FRRAX right now also. The person selling them is also a member here. I think his username here is SlowTA.

 

I just registered at that FRRAX site. Seems like I could get in to it.

How are the Koni's different? Can you adjust rebound and compression individually?

 

The Koni's have a fixed compression setting and you adjust only the rebound.

 

Souless nailed it.

Here is a graph of the koni shocks, and their adjustment. Notice that the bump has no adjustment, only the rebound.



Here is a a graph of Tokico shocks.



Notice how the adjustment is very linier, and adjust both bump and rebound. You will also notice that in the koni graph, the rebound adjustment is greater at slow-speed rebound valving, much so compared to the high-speed rebound valving.

 

I also found this gem of information, well searching some posts on another board. This graph data is for mustang rear shocks. But the information should translate, as they are all going to use similar adjusment system for their valving.

KONI Mustang presentation slide 15

Click thru the slides, it compares, Koni Sport, OE, Tokico Illumina, Bilstein Sport, and KYB AGX.

Really good info, and you can see how the valving is diffrent between the diffrent brands, and also the differing ranges of adjustment.

 

I think the biggest conclusion to make is that the koni has the highest forces at low velocities (which will keep your car flat in turns), and the damping at higher velocities (bumps) somewhat flattens out (it doesn't go linearly). I didn't gather that conclusion myself, I didn't some reading on the Koni site last night and another TGO post. If that data that they publish is true, then I 100% agree with you guys that koni does have the best shock out there. Premium product at a premium price. My 20 hour damper education tells me that the Tokico's don't look to good when graphed by koni KONI Mustang presentation slide 10

The koni shocks/sttuts are out of the question for this year, but at the minimum I want to balance the springs this year (sway bars and springs) since that won't cost much and I'll save the loot for next year. If you throw the dampers out of the picture I know that I have an imbalance because during the long sweeping turn at Gingerman last year the car pushed pretty bad. If I can fix that, I think that is a significant step in the right direction. Shocks and struts will help with the transition in and out of turns. Springs rates for the middle of turns.

I figured out that a 36mm hollow bar is about 5% less stiff than a 34mm solid (what I have), and a 24 mm solid rear bar is 16% stiffer than a 23mm solid bar (what I have) believe it or not. It suprised me at first, but it makes sense because the stiffness of the bar is proportional to the diameter^4. So I'm going to try and get the 36/24 set.

Crazy Hawaiian, I PM'd you about your 1LE bars.

 

I applaud your use of the mathmatical equations that are available. I never ran the calcs but I always thought that the 36 was the stiffest bar available. Based on the amount of research you have been doing the last couple of days you are now officially hooked; congratulations and good luck.

 

Haha thanks. Mostly I'm just a dweeb. It's friday and what am I doing??? Math!

 

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