Spring Rate Suggestions for '68 Camaro

[Mkelcy]

I've finally got my '68 Camaro build on the street. It's got a 21st Century Street Machine subframe, a Lateral Dynamics 3 link rear, LS3 engine and T56 transmission. Because of the intrusion of the upper link into the rear seat area, I've elected to eliminate the back seat, so it will never carry more than two people. The car is Dynamatted but doesn't otherwise have weight added. The battery in in the trunk.

I've just gotten the car on the road. Although I've got very little seat time, my impression is that it's over sprung for my use, which is spirited local driving and long distance trips with little to no auto-cross or track time.

For the front I'm using 450 lb./in. springs, a 1.15" hollow sway bar that has a rate of 300lbs./5 degrees of twist and QA1 single adjustable coilover shocks dialed down to the softest setting. For the rear I'm using 200 lb./in. springs on AFCO double adjustable M2 coilover gas charged shocks with a remote reservoir, both compression and rebound dialed down to the softest settings and, having just checked, the former gas charge on the shocks has leaked away over the years, so they are not charged; no rear sway bar. As I said, I'm just starting to get miles on the car, so the shock settings are simply to get a baseline from which to make adjustments (and I'll throw a 50 lb./sq. in. nitrogen charge on them when I get my fill kit).

I'm thinking of stepping down to 400 lb./in. springs for the front and 175 lb./in. springs for the rear.

Anyone have any thoughts on whether that's enough of a step down (especially after I get a charge on the rear shocks) or too much; am I looking at the wrong part of the suspension (say the front sway bar, and/or adding bar for the rear if I go with softer springs); or should I get the rear shocks charged and get more seat time before doing anything?

Thoughts?

I'm looking for a little smoother ride while still allowing for excellent street handling.

[dhutton]

How much preload do you have on your coilovers? In my experience a lot of preload leads to a lousy ride on the street. The preload "fires off" when going over abrupt drops in the road which can make the ride seem harsh. I found a stiffer spring with less preload gave a better ride for me.

Just my two cents, not an expert by any means.

Don

[Mkelcy]

Originally Posted by dhutton

How much preload do you have on your coilovers? In my experience a lot of preload leads to a lousy ride on the street. The preload "fires off" when going over abrupt drops in the road which can make the ride seem harsh. I found a stiffer spring with less preload gave a better ride for me.

Just my two cents, not an expert by any means.

Don

At full extension, hardly any on the rear; I'll have to check the front, but my recollection is that I don't have much there, either. The car already rode a little high, and I didn't want to raise it more by preloading it a lot.

[dhutton]

I've got some 12" 175 pound springs if you want to try them. Just PM me your address and I can send them out this week.

Don

[Penny]

Post a pic, I am subscribing.

[Vegas69]

Twenty five pounds won't be noticeable in regards to ride. Those are light springs. I'd say it's shock valving or you need to buy a Cadillac.

[Sieg]

How many miles on the suspension? There is a break in period for springs, shock seals, and bushings. Subtle but still a factor. Another factor is personal perception, what are you used to driving or what are you comparing it too?

[Mkelcy]

Originally Posted by Sieg

How many miles on the suspension? There is a break in period for springs, shock seals, and bushings. Subtle but still a factor. Another factor is personal perception, what are you used to driving or what are you comparing it too?

Fair questions. Perhaps 200 miles on the suspension.

I'm comparing it to '68 Camaro with 550lb./in. front springs and 200 lb./in. composite rear leaf springs

[Sieg]

Originally Posted by Mkelcy

Fair questions. Perhaps 200 miles on the suspension.

I'm comparing it to '68 Camaro with 550lb./in. front springs and 200 lb./in. composite rear leaf springs

Lighter motor in this one?

Brake packages similar?

Overall car weights?

[Matt@BOS]

I would guess that it is more shock than spring related. If you start to drop rates you might end up with a car that wallows a bit and bottoms out over dips in the highway. I've upped rates 100-150 lbs all around on my DSE suspension, and upgraded shocks. It rides better than with softer springs and the original non adjustable Koni/Afco shocks.

My first suggestion would be to gas up the rear shocks in case the rear is getting rattled around over bumps, without much shock control.

If that doesn't fix things, you may want to swap shocks. Trust me, in the long run you will have less headaches. My Afcos always leaked down and the verishocks seem to blow seals, and, in my opinion, they don't ride amazingly well, either. Please don't take this as an agressive sales pitch, or attempt, (I have a small fortune worth of JRi shocks and work with JJ all the time) but the fastest way to get your car driving down the road with the ride you are looking for would be to call RideTech up and get a set of their shocks. Their Ride Quality and Handling Quality series of shocks (hope I got those names right) flat out work the way they should. The cars I've driven with them ride so well I don't even think about the suspension. The ride is smooth, solid and pretty composed without clunking over bumps.

Bret/Rod please don't ever let that end up as a testimonial on your website, accompanied by that picture of my car under the Fox awning at Laguna Seca. I will get in trouble.

Matt