How light of springs can I get away with up front?
I am putting together a 2nd set of coil overs for the off season. My 700/500 Koni's will jolt your teeth out hitting a bridge bump at 70mph. Looking for smooth but not bouncy, I got a set of older Pro shocks the rears are 250 and I am looking at 450, 400, or 350's for the front.
This setup is just for street driving Nov through March what Pro Shock rates are being run?
What springs do you have in the rear? The front and rear should go down in roughly the same proportions. For an FFR that seems to be about 55-60 percent rear to front and whatever it takes to keep the suspension from bottoming. My read is around 450 front and 225-250 rear would be a good start for a compliant ride. A big front sway bar will keep the car flat in cornering and still not knock your fillings out on bumps.
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I would say check to see if you are bottoming. I have had the same problem and put the 500# springs I took off the front onto the rear (8.8, 3-link, FFR Koni). I then placed a small zip tie on the rear shock. Even after a short drive on fairly smooth roads the zip tie showed that the shock had bottomed.
I then jacked up the rear using the axle housing and removed the tire. The shock measures right around 2" of travel remaining with weight on it. I then placed blocks under the frame and let the shock fully extend and it has around 7" of travel. So I am using 2" out of 7" available with a rear ride height of 3 3/4". No wonder it is bottoming so badly.
I have the same zip ties in the front and those shocks never bottom out. I would like to move the shocks mounts about 1.5" to get some more travel out of the 7" shocks. You can't go much more than 3.5" of travel as the frame would hit about the same time the shock bottoms. I guess an easier way would be to jack the rear up to 6" and just live with it looking like a dragster.
Why not throw just some 15" tires on it? Larger sidewalls are very forgiving on bumps.
I run the standard 500-350 Koni's, with 15" tires, and the ride is wonderful. Stiff enough to still handle great, and soft enough to not jar the heck out of you.
My MKII 3-link came with 250R 450F and it was quite nice, firm, but not harsh.
FFR5148K MkII Roadster, FRP 306 345HP w/ carb, 3-link, disc brakes, Still Gel-Coat Grey! Now with roll cage and more track stuff, wrecked, beaten, man-handled, cut up, butchered, Freaky body mods, sat on by HOOTERS girls, still barely street legal.
JoeE I have a few thoughts for you based on my experience w/ a MkI and MkII. They both came w/ Proshocks but the MkI had 2.5 ID front springs and mustang rear stuff. Both had 450 front springs and were fine in the ride department. The MkI was soft in the rear and was slowly upgraded, but the MkII was quite stiff in the rear. The difference was that the MkII had the smaller diameter rear coilovers. I was surprised how stiff it rode w/ 250 springs compared to what I had upgraded the MkI w/ Levy DA konis and 250 springs. So same spring rates but different shocks. Long story short here, especially in the rear, shocks can have a tremendous effect on ride. If I were doing this over again (the DA konis are 5 yrs old and the Breeze setup wasn't available then) I would go w/ the Breeze DA coilovers w/ the two knobs for adjustment. My konis require that the coilover be partially disassembled to adjust the bump rate which is a heck of a lot more work then turning a knob one click on the Breeze units.HTH
FFR 5353K,351/400hp,TKO 500, 3-link w/3.08 and Truetrac, Koni DA coilovers front and rear,APE hardtop,Forte front and VPM rear swaybars
I found a set of Proshocks added a set of QA-1 400lb springs in front and left the 250lb springs in the rear. The combination is just was I wanted to achieve ride comfort wise. No more getting abruptly jarred over significant bumps.
The one noticeable downside is the rear end is loose, now I can see why owners with 400+hp would need to be really careful with a stock setup. I still can hammer it in second but the tires are breaking loose all through the acceleration. With my other setup 700/500 once I got through the initial spinning it would hook up and run straight and predictable I could even bang hard into 3rd and mash the go fast pedal and she would pull hard in a straight line. I don't think I would be comfortable running a 1/4 mile with the soft setup as I have yet to really get on it in 3rd for the above reasons.
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