I ordered a TRW design 355lb FG spring to replace my damaged stock spring in the '81. Before I put it on, is 355 going to be toooo stiff? I'm replacing the original FG spring which seemed way too soft. I thought the original was 340 lbs (just by seeing what's available), but now I'm told it was around 315 lbs. That's a pretty big jump. Should I continue or reconsider? I was also told it wouldn't affect the ride height.. Is this right?

 

it shouldnt be to big of a jolt... a few guys on here are running 550's on all four corners, that is definately to much if you have any wripples in the pavement nere by

ZD

 

Two thoughts:
1. Paul Lisinsky - sales manager for Vette Brakes told me last year that 80% of a C3's ride quality is determined by the rear spring. So the proper rate is VERY important.
2. The balance or ratio between the front and rear springs is also very important. If the front is too soft or the rear too stiff, ride quality and control will suffer.

For street driving, many seem to prefer slightly stiffer springs and larger anti sway bars. This way, you get a comfortable ride and better cornering.

On my 71, I have tried stock steel, VB 315, VB custom 345 and TRW 315.
Overall the TRW 315 gave the best combo of ride and performance. Its curvature also makes it easier to adjust ride height.

Shock selection is also very important with FG springs. Rebound rate is so much faster (esp with VB springs) that you need to invest in good shocks. Ater trying KYB, Carerra, Koni, Delco and Bilstein Xtreme, I have settled on Bilstein Sports.

It goes without saying that the above discussion assumes that all other components of your 20 year old suspension have been rebuilt or replaced. Poly recommended. If not, do this first.......

 

Tnx for the info. I installed the new spring (along with other new suspension parts) today. The spring is the TRW design 355 lb and I've got to say that the ride is not as stiff as I thought it would be. The repairs are in a series of other damages caused when a u-joint sheared off, and it also damaged the left shock, which I noticed after removing everything. In haste, I went to Auto Zone and purchased some Gabriel Gas vbs shocks. The ride is kinda springy compared to what is was with the old spring. Not bad, but, for example, when you shove down on the front end it recovers fast with one rebound and it's tough to shove down. The rear end shoves easily and bounces 2 or a bit more times before stopping. The handling seems better though, but I haven't really taken it through the paces yet. I may have to try those Bilstein Sports.

Also, the ride height is now elevated in the rear, by maybe an inch. I still have some play left on those longer bolts they supplied, but I didn't really want to extend it past the cotter pin holes. I thought I'd give it a few days to see if it settles down. Anybody else have this problem?

Might as well throw this in.... When replacing the side yoke (yep, there was lots of damage), I noticed wear on the rod that the side yoke tips come close to (no idea what that thing is called). Looks like the tips rubbed against it and made some grooves on it. Could this have been caused from the old suspension or spring allowing too much movement of the yokes, or perhaps (my guess) when the u-joint snapped and beat up the yoke it caused it to jam into that rod? it looks like it'll be ok, but those grooves (more like dents) make me a tad nervous.

I'll be taking some pics of all the damages soon and will post them on here. The worst part of all of this is receiving the wifey 'lecture' about how I wasn't going to the strip again. :nono: Arghh...

 

flynhi,

Did you see a significant improvement when you went from the VB 315 spring to the TRW 315 spring? I currently have VB's monospring's front and back. They handle great on flat roads, but the roads around my house are not in very good shape and the back end tends to bounce a lot and get out of control when trying to go through some of the curves. Did the TRW improve things. I already have the specially valved bilsteins which helped, but I'm still looking for some improvement. The VB rear is adjustable, but I always keep it on the softest setting so going with a non adjustable spring wouldn't be a big concern for me. :confused: :cheers:

 

The main difference I observed is that the TRW seemed to respond more smoothly than the VB. If you have the right shocks, the diff should not be too noticeable.
I really found a diffference in stabar response. If your problems are in curves, perhaps a change in stabar sizes would help. I use 1 1/8" front and 5/8" rear. A change from #/4" to 5/8" in the rear made a BIG difference. I checked the formula and found that the resistance of a 3/4" is twice that of a 5/8". My rear end really settled down after switching to 5/8".
Also check four wheel alignment and the condition of trainilg arm bushings.