Suspension advice please; 2,400 lbs., street legal

[LAP1DOUG]

Originally Posted by Hasbro

Fwiw, was comfortable with 2.35 - 2.5 hz. suspension and RA1s on last street project, could go a little bit higher with proper dampers.

Hasbro:

With the low weight that you are going to, you are looking at a corner weight of about 540 lb on each front wheel, and 660 lb on each rear wheel.

With these corner weights on the 986 suspension geometry, you only need about 330 lb/in springs in front for a 2.40 Hz frequency, and 430 lb/in rear springs for a 2.56 Hz frequency in the rear.

If you are going to autocross at AMS, I would not go much over a 2.5 Hz frequency as there are some surface changes where you need compliance to avoid upsetting the balance.

If you know what natural frequency you are going to run, you really don't need multi adjustable dampers. Just get some high quality single adjustable dampers set up at around 70% of critical damping force, and you are good to go.

That said, the biggest bang for your buck is going to be camber control. For that, you need either GT3 LCA's or camber plates (or both) along with an adjustable front bar. These McStrut suspensions have awful camber curves, and you must add front bar to stop the dynamic camber change that makes the stock configuration understeer like a pig.

Good luck.

[Hasbro]

Originally Posted by LAP1DOUG

Hasbro:

With the low weight that you are going to, you are looking at a corner weight of about 540 lb on each front wheel, and 660 lb on each rear wheel.

With these corner weights on the 986 suspension geometry, you only need about 330 lb/in springs in front for a 2.40 Hz frequency, and 430 lb/in rear springs for a 2.56 Hz frequency in the rear.

If you are going to autocross at AMS, I would not go much over a 2.5 Hz frequency as there are some surface changes where you need compliance to avoid upsetting the balance.

If you know what natural frequency you are going to run, you really don't need multi adjustable dampers. Just get some high quality single adjustable dampers set up at around 70% of critical damping force, and you are good to go.

That said, the biggest bang for your buck is going to be camber control. For that, you need either GT3 LCA's or camber plates (or both) along with an adjustable front bar. These McStrut suspensions have awful camber curves, and you must add front bar to stop the dynamic camber change that makes the stock configuration understeer like a pig.

Good luck.

Thanks, LAP1DOUG. In November I spoke with Chuck at Elephant re. their Vonn's non adjustable coilovers. With my budget requiring a drawn out time line I would have to save up for a good while. Not a horrible situation but it would delay some of my other concurrent projects such as bodywork and a ton of refreshing. An economical route would allow me to move on, however, down the line, higher quality parts would be desired. I guess I need to determine my priorities! Therein lies the rub.
I really like tinkering with suspension adjustments so with non adjustables there would still be adjustable bars front and rear?, tire pressure, yada, yada. Maybe go with even lighter springs?

I appreciate your weighing in. My last project involved struts and an engineer on that forum made a wonderful suspension program for that specific model. It was the best tool ever and it taught me a lot so I still want to think in Hertz for starters.

[bcrdukes]

Consider the Vorshlag camber plates. They allow for both camber and castor adjustment. They were great to work with and turnaround time was super quick.

[Hasbro]

Wow, time has flown!

Thanks to everyone's input I have pretty much narrowed suspension parts down (to start out with) and should be ready to get going here soon. Been saving my pennies in the meantime.

To review, this is for a 2,400 lb. "street rat", for cornering, don't care about top end or fitting into a sanctioned group. On the street, can go into corners fast, not as much emphasis on mph coming out of corners. I'm anticipating a lot of adjusting with the square setup. I'm concerned there won't be enough tread.

- Tires; Toyo Ra1s, 235/40/17, squared. 24.4" diameter, 9" tread (wish I could go wider). Lower gearing, a little lighter in the rear, warm up fast, don't cycle out and handling keeps improving as it wears to the end. Will lower car at least 3/10" without suspension adjustment to help with McPherson's camber problem the more it compresses. They handle a smaller width wheel very well.

- Coilovers; Feals, stock springs for now until weight is attained. Do I need the adjustable bump stops?

- Lower GT# adjustable arms for front for now rears later.

- Adjustable front bar.

- Adjustable rear toe links, front and rear thrust arms, rear control arm links.

- I will also replace tranny, motor mounts.

Sound good?

edit; I also have a paved 1/6 mile "track" that I can play on after hours. Just need to lock the gate. Lots of different cambers and elevation changes.

[Javi Cooper]

BUMP!

Anyone try the RaceWorks coilovers yet?

They do have an option for 986s now, and you can select different valving, spring rates and spring brands, and adjustable camber plate or pillowball mounts. Prices start at $1,300. I was going to rebuild my H&R's but this is starting to look like a great option.