Mongo

Hey guys I've been doing some calculations using Paragon Products' formula to achieve an effective rate without doing any re-indexing on the torsion bars of my 944.

The Koni rear coil over kit uses an 80 lbs. spring to prevent reindexing the bars. When plugged into their formula below:

(x-126)
--------- = 80
0.56

I will get x= 170.8 lbs. desired effective rate. not bad considering I am still keeping the stock torsion bars and that will be fairly stiff for the rear end. I'd like to upgrade to the front Adjustable Ride Height Kit for my 944 and use Koni yellows. I have narrowed the choice of springs down to 3 effective rates:

-250 lbs
-275 lbs
-300 lbs

My question is, will the car become more unbalanced and push if I used a heavier spring rate than 250 lbs with an approximate 171 lbs. rear rate? I am using M030 sway bars from the year 1987 with a 968 Clubsport Adjustable rear sway bar on the stiffest setting. The car currently does not understeer much, but has the slight tendency to oversteer (not a problem to me though and can EASILY be controlled) I'd like to hear some thoughts and experiences on getting this car stiffer for upcoming DE and Auto-X events. Thanks.

tifosiman

You are going to need to re-index, no matter what rate you choose. You need to pre-load the springs a little bit to keep them from clanging about. If you don't re-index, your rear coils clang/rattle around bumpy corners, and it's *** will be too high.

Before you go doinking with your suspension, I would suggest to actually do a few events with the stock set-up first so you improve your skills and get a baseline for comparison to future mods.

Geo

The other solution to keeping the springs from unseating and rattling is installing helper springs.

tifosiman

Agreed, but from personal experience on a couple of 944/968 cars, it doesn't work very well (still get clang on moderate to bad bumps, especially in the corners when one side is loaded and the other is at full extension) and adds yet even more height in the rear (another 1/4-1/2 inch when the helper spring is fully compressed).

M758

Even with helper springs you can't get a good rear ride height with out indexing.

Personally rear coilovers are false benefit to me.

Sure once you get into stiff springs or pull the bars and want to make quick adjustments they are great, but keeping to he more "lemming" spring rates most of us use it is just as easy to go with big t-bars. Folks think they can avoid the dreaded t-bar indexing using coilovers, but 90% of the time that is just not the case. Of course to re-index the t-bars and replace is the same work as installing new ones.

Mongo

Helper springs was something I was considering too Geo. Tifosi, I am considering my current setup to learn from up until the end of this year, that way I can analyze the suspension and see what other tweaks I need to do. At the same time I can save and expand my budget to include a torsion delete and go even more stiff in the back. However, keeping the torsions does save some time and money from tearing the rear arms from the car just to remove them (difficult little buggers)

I'll take your advice and definitely learn the car more as I'm still green when it comes to the track. BTW, how long have you both been doing events? I'll continue to update this on any suspension ideas, recommendations, findings, etc. Again other users are more than welcome to submit replies and posts on here to share ideas.

Mongo

To compromise that 1/4"-1/2" height increase, what if I were to adjust the rear arms via those nuts I see under there to lower the car? Would that reduce some of that height increase along wtih making an adjustment to the collars of the coil overs? (just more thoughts and questions I have)

Also what is re-indexing the torsion bars, and what does this involve?

M758

Andy you can make quite a competent car using big t-bars. Certainly one stiffer than is comfortable on the street.

I have been autocrossing since 98, Started DE in 1999, Started autcrossing my 944 NA in 2000. Started Racing in 2002.

Take some lessons from the 944-spec cars. The rules and the car set-up was based on cheap speed. It was a solution that myself and 944 guys with 20+ years of racing experience came-up with. While a 944-spec set-up may not be fastest in world, they are quite good when it comes to cost to build, speed and fun.

My advice is to keep on autocrossing and talk with 944-spec guys in you area. Hey maybe if Tim does one of those 944-spec rent-a-drives at an autocross you should drive his car. It will help you understand if like that basic set-up. I think you will find a 944-spec MUCH stiffer than you would expect and 10 times stiffer than a stock 944. That you remember was all done with a little weight redution and relativly soft spring rate with a basic set-up.

M758

http://www.944spec.com/944Tech.htm

1/4" rear ride height change also impact the balance of the car greatly. High rear end = oversteer.

If the rear spring plate is set to the center you might have 1/2" of lowering adjustment. This is some times enough to lower the car back to ok IF you go soft enough on the rear coil over. Basicly the added spring rate cannot raise the back end more than 1/2" for you to lower the car back to level.

Of course if the rear has already be turned or you want a lower than stock ride height or the rear spring raises the car too much you are SOL.

Geo

Tifo - The helpers should not require any more re-indexing than the main springs (you just adjust the coilovers lower to accomodate the height of the helper set-up). But I agree that virtually any coilver set-up that retains the stock t-bars will require re-indexing.

Joe - I agree with you that for a street car there is no real advantage over not going with bigger t-bars. The only real advantage for coilovers as I see it is for racers - quick change of spring rates. This would be especially important in the rain since I would not dream of changing t-bars for a wet race were I might consider changing main springs in a coilover set-up.

I would expect the helper springs would add more than 1/4-1/2" height in compression. I'd thnk the helpers would be at least 1/2-1" compressed, plus the ring between the main and the helper springs.

Mongo

Joe that link is amazing about suspension information and torsion re-indexing. The thought of taking the rear suspension off the car creeps me out! I'm always impressed by the knowledge of these cars from any 944-spec drivers. I'd like to switch to that class since in GS M030 sway bars and 220 lbs springs aren't cutting it, and my competition has MANY more mods that are borderline between GS and GP; I"m also not as good of a driver as they are either. Come to think of it, I wonder if I can be in GS/S even with M030 sways since technically they could be considered stock if M030 944s had them. i guess that's something I'll need to discuss with the officials in the Zone 8 Region.

tifosiman

My first autocross was back in 1989. In addition to autocross, over the years I have raced SCCA Pro Rally (Drove in Production Class and Group 2), SCCA Pro Solo, several Hill Climbs (including Pikes Peak and the now defunct Chinmey Rock event) and participated in DE's.

I have never done any door-to-door racing ala the 944Spec series.

I have also raced bicycles for many years-------Time Trials, Crits, Mountain Bikes, Road Races, Stage Races, Hill Climbs. Oops, too much info I guess...

Mongo

I kinda don't wanna do any door to door racing unless I have money for cosmetic repairs also....I hear Spec Miata (AKA Spec Pinata) likes to add their own body graphics to spec cars using their own paint off theres when doing wheel to wheel racing

joseph mitro

stig - just do a lot of DE right now. there is no point in racing when you're not ready for it and you have a lot to learn. i have about 5 or 6 track days under my belt and hope to drive once a month from now on.

to answer your original question, my current setup is:

front 350 lb springs on konis
rear 275 lb springs with torsion bars (total rate about 300-325lb)
27/19 mm sway bars

car handles pretty well except for pushing at times, but i think that's because i am still learning how to drive. in my DE yesterday, i was passing cars like the subara STI, corvettes, and S2K simply because i drive the line better and keep the car's momentum going better. not that i'm a good driver, but i'm learning how to be better. my point is.....don't even worry about racing or competition until you're a great driver, which takes a LOT of practice.

Geo

Hey Jeremy, when did you do Pro Rally? A guy I used to race karts with did Pro Rally in the mid 80s. He had a really cool photo of him at some rally that started downtown in some small town in Ohio and he was about 2' off the ground. That is the tires were 2' off the ground. With the full rally suspension at full droop! He was sailing. A friend told him only John Buffum (sp?) in his Sport Quattro got more air.