stiff ride

[jwhit]

anybody change to differnt springs ? my car is small block with straight axle and ffr supplied with my kit 500 lb front and 300 lb rear springs
car drives good but it seems stiff as board.im not sure that springs even compress at all while driving.just seeing if anybody has same results


thanks

[CraigS]

While a coupe is a little different from the roadster there have been plenty of roadster guys who have gone to 200# rear springs for a softer ride. Two other thoughts. 1- If you have Koni shocks did you verify they are on their softest setting before you installed them. 2- Tire pressure should be around 22#

[JohnMac]

We’ve been building a gen 1 coupe. My friend and co-owner has a lot of experience in racing and setting up cars and felt that the supplied rear springs for the KONI rear shocks were way too stiff- they measured out at about 480lbs. We ended up installing a much lighter spring from his collection of parts... I think they are somewhere around 250lbs. We haven’t completed the car having just received the eng, trans, clutch etc.

[jwhit]

While a coupe is a little different from the roadster there have been plenty of roadster guys who have gone to 200# rear springs for a softer ride. Two other thoughts. 1- If you have Koni shocks did you verify they are on their softest setting before you installed them. 2- Tire pressure should be around 22#

i change rear springs to 275lbs and stayed with 500lbs up front this helped a lot and i did check to make sure all shocks were on soft settings .you are probaly right i think car could go with even less spring in back but i didnt want to go to far

[GoDadGo]

i change rear springs to 275lbs and stayed with 500lbs up front this helped a lot and i did check to make sure all shocks were on soft settings .you are probaly right i think car could go with even less spring in back but i didnt want to go to far

Remember that as you soften the rear springs, this change may cause the car to push or understeer.
Stiffen the rear while leaving the front alone can conversely create oversteer.
Finding the balance that suits your driving style is priority #1.
Also, the Coupes are significantly stiffer than the Roadsters.
Please keep the group informed of your findings.

[NAZ]

jwhit, dropping the spring rate by 75 lbs/in is not much more than a fine tuning adjustment. Keep in mind that stiffer spring rates not only make for a firmer ride but can result in less traction and poor handling. Besides ride quality, the suspension needs to keep the tires planted on the road and allow for sufficient weight transfer. When spring rates become stiff to the extreme it will degrade traction and weight transfer. Many times you will get better weight transfer (and traction) by using a softer spring and adding more pre-load to maintain ride height. Yes, you can go too far in either direction but from what I've seen with FFR, they start out with way too much spring rate and that coupled with poor instant center adjustment, roll center/couple not optimized, and ride height adjustments that disregard lower control arm angles, and too much tire air pressure all help make a car handle poorly.

[jwhit]

jwhit, dropping the spring rate by 75 lbs/in is not much more than a fine tuning adjustment. Keep in mind that stiffer spring rates not only make for a firmer ride but can result in less traction and poor handling. Besides ride quality, the suspension needs to keep the tires planted on the road and allow for sufficient weight transfer. When spring rates become stiff to the extreme it will degrade traction and weight transfer. Many times you will get better weight transfer (and traction) by using a softer spring and adding more pre-load to maintain ride height. Yes, you can go too far in either direction but from what I've seen with FFR, they start out with way too much spring rate and that coupled with poor instant center adjustment, roll center/couple not optimized, and ride height adjustments that disregard lower control arm angles, and too much tire air pressure all help make a car handle poorly.

i will try these for awhile car is still stiff but the spring change in rear is big help car seems to respond better to me ,also my ride height is little higher than ffr ask for in book i am around 4 7/8 in front and 5 1/4 rear this helps me deal with
all the speed bumps around our town and a few stiff drive ways.i had trie pressure around 26 and dropped it to 22 could not tell any differnce but i will will it at 22 since that seems to be a number i have heard from several guys

[NAZ]

Sorry, I should have said that 25 lb/in is just a fine tuning adjustment. And most folks likely would not "feel" much from such a minor change. Don't be afraid to tune your suspension with spring rates but you should be cognizant that you are also changing the suspension frequency and too much imbalance between front and rear can cause a condition known as porpoising, where the front and rear end oscillate at or near the same frequency when going over a bump. Gives you a ride like a tuna boat.

Here's some info on spring frequency. When I set up my cars I run the calculations to determine a starting point for spring rates so I get very close from the get-go and fine tune from there.


http://downloads.optimumg.com/Technical_Papers/Springs%26Dampers_Tech_Tip_1.pdf (https://www.drtuned.com/tech-ramblings/2017/10/2/spring-rates-suspension-frequencies)