Potomac-Greg

What would be a good "rough" spring rate setup for coilovers (all four corners) for street use? Maybe somewhat firmer than stock, but truly livable for daily use. Could you go as soft as:

F: 200#--------------200#
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R: 250#--------------250#

thirdgenbird

last night i dove my car 230 miles on a 350/450# setup.

it was rough on some roads, but liveable.

JohnKoaWood

Yes, but that setup MIGHT present issues to get the torsion bars indexed correctly.... but it could be done.. and would be slightly stiffer than stock on a N/A, but not too harsh for street use...

My 951 currently wears 300s in the front and I will soon be installing 550s in the rear to rid myself of the TBs all together... I use it 100% street to date, and have no regrets..

I have always felt it is easier to delete the torsion bars and go full coil over, but that IS just my oppinion. I just don't understand WHY you would keep the torsion bars while installing coil overs when it is teh same price to get rid of the torsion bar setup all together.

Potomac-Greg

To clarify -- These rates are with t-bars removed.

I guess the question becomes whether 250# in the rear with no t-bars is enough rate, or enough increase over 200# up front. I don't know whether teh front-to-rear split should be based on weight or proportion. For example, a 50# split seems like very little, but it's a 25% differential. Using the same proportion, if I had 400# up front, the rears would be 500# in the rear, proportionally.

One confession: I'm influenced by the fact that I already have 250# springs left over from when I had coilovers and t-bars together; so I'm wondering if I can use them in the back and match them with springs up front. (Can't use the 250s up front b/c they're different diameter).

JohnKoaWood

https://rennlist.com/forums/924-931-...ive-rates.html

looks to me like 250 would get you close to having a nice corner ballance as long as you have 23.5mm effective torsion bars...

Now that I go through it again, maybe I'll stick to 400 lb rears...

Potomac-Greg

Even though I have looked at that table a dozen times, I just noticed that the left side translates coilover spring rates to effective rates, but refers to the coilover rate as being in millimeters, not spring rate. Coilover springs are sold by ft/lb rate, not mm. So is that a typo in the chart?

thirdgenbird

my 350/450 is without torsion bars. jason at paragon recomended about a 100lb split. he said 300/400 is great for street use. i gambled with 350/450 and so far i like it.

thirdgenbird

keep in mind jasons 300/400 recomendation should oversteer more than my 350/450 but my 924s limits my rear tire size.

PorscheDoc

I would not go higher than a 300/400 (TB's removed) for street use.

Potomac-Greg

Thanks. Now, how low (spring rate) would you go (or not go)?

vt951

When you factor in the motion ratio of rear coilovers, a 250 lb/in spring rate equates to only 103 lb/in at the wheel (if t-bars are deleted). That is softer than the stock t-bars, and with 200 lb/in springs in front (about 166 lb/in at the front wheel assuming .91 motion ratio). So, with 166 at the front and 103 rear, I think the car will probably understeer quite a bit.

xsboost90

im running 450/525r and it handles beautifully- but its quite stiff on the street. I think a good street N/A setup would be 300f/400r no torsions.