33 hotrod - Spring Rate

[kemper.s@sbcglobal.net]

My 10+ year old Hot Rod Rides Rough. Front hits hard, and Rear absorbs/travels little . Too stiff!
I have installed 275# rear coils (from 350#) currently untested.
Have other builders reduced front coil # PLEASE ADVISE
car is currently on jackstands for Radiator Repair (blew lower tank), oil leak, exh leak, repl coil springs ,tune up, bi yearly maint, and a cleanup.
PLEASE ADVISE MY SPRING RATE ISSUE
Steve

[33fromSD]

I switched to different spring rates & adjustable QA1 shocks on the 33 a couple years back and do not regret it at all. I'm running 9" 300# springs in the front with dual adjustable (rebound & compression) PromaStar shocks in the front (inverted for easy adjustment) and in the rear I'm running 12" 150# springs (recently chnaged from the 12" 300# I was running) with single adjustable (compression) PromaStar shocks.

The ride is awesome. Still a little stiffer than a normal passenger car but I do not get the jolt/rough ride over bumps like I did with FFR supplied Konis & coils.
Jim

[Dgc333]

Interesting, my 33 came with 400 lb springs on the front and 250 lb springs on the back. I find the front to be stiff but acceptable but the rear is harsh and is jarring over bumps. I am considering going down to 200 lb springs or maybe even 175 lb springs for the rear. BTW, it is a three link out back.

[TxMike64]

I switched to different spring rates & adjustable QA1 shocks on the 33 a couple years back and do not regret it at all. I'm running 9" 300# springs in the front with dual adjustable (rebound & compression) PromaStar shocks in the front (inverted for easy adjustment) and in the rear I'm running 12" 150# springs (recently chnaged from the 12" 300# I was running) with single adjustable (compression) PromaStar shocks.

The ride is awesome. Still a little stiffer than a normal passenger car but I do not get the jolt/rough ride over bumps like I did with FFR supplied Konis & coils.
Jim

Jim, you have the '15 IRS, correct?

[FF33rod]

NOTE: the rear springs are different depending on your rear end choice so might be a good idea to add your rear end type to your answers....

I have the IRS and have left the rear springs stock, believe they are 300... Also, I have the upgraded FFR dual rate shocks...

The front was stupid stiff so I went down to 250s. Really happy with the result for cruising.

Steve

[33fromSD]

Jim, you have the '15 IRS, correct?

No, I'm running 8" Moser rear-end with 4-link

Jim

[Tom Veale]

Hi Steve, Re: Spring Rates................

I also have experimented with lots of spring rates. I was using the car a lot for Track Days when it was first roadworthy, but don't do that any more (I'm getting OLD!) I have a solid rear axle with the 3 Link kit. For the track I used 450lbs/in on the front and 175- 350lbs/in variable rates on the rear. That was fine, but when I decided to go on the Hot Rod Power Tour in 2022 I knew I needed to soften things up for that Long Haul (2600 miles round trip!).

I dropped to 350lbs/in for the fronts and down to 250lbs/in on the rear springs. It's pretty civilized with these rates. I'm using QA1 single adjustable shocks on all four corners. Those I keep at 4 clicks from full soft for street driving. (a possible 18 clicks from full soft to full hard) When I'm going to exercise the car at the track, I change the shock settings to around 8 clicks for high speed stability.

I hope this helps,
Tom Veale
#007 FFR Hot Rod, 18K miles since 2009