Thufir

I just took my 1967 Cutlass Turnpike Cruiser out for a spin with my two daughters on the back seat. When I drove through a depression in the street the left rear wheel bottomed out, hit the quarter panel with a loud screeching noise and the tire got cut badly. I was sure there is a technical issue since my juvenile girls seem to feed on salad only. I checked and noticed the old (original?) air shock system lost pressure but only the left side lost height - 1 inch in relation to the right side.

This leaves me with a couple of questions:
1) Am I guessing right that the air pressure is lost on both shocks simultaneously since there is only one valve to fill them?
2) Is the assumption correct that the left side coil spring must be worn out because the car is sagging only on one side?
3) Since even very old European cars have bump stops - what is limiting the wheel travel - is it just the coil spring? Really?
4) And if so: when I swap the air shocks with regular shocks and the coil springs also, how can I figure out which springs are correct and will limit the travel sufficiently without jacking up the car too much?

The rims the previous owner put on the car are Centerline Auto Drag 9,5 / 15 with 265/50 R15 tires. Will I be fine with the regular 442 springs? (it's not a 442 but a Turnpike Cruiser with 400 BB - same suspension if I'm correct)

Any advice and help is very much appreciated since I have to import the springs to Germany and trial and error is not an option.
Cheers - Thufir

lemoldsnut

Often the tire size is not the issue. The wheel offset is. If the wheel is very offset it can interfere with the wheel opening/lip.

Yes 442 springs would be the same as Turnpike cruiser. I have had several of both. If you plan to haul people in the back often maybe consider cargo coil or variable rate springs. They get firmer as they get more load. They stay pretty ride comfortable when in a normal load condition.

A very common mistake is that people think shocks are to hold up a car. Springs hold a car up and shocks keep the tire to the ground.

never rely on air shocks to hold up a car to clear tires. They can and will fail.

Just my two cents.

Thufir

Thank you very much for the quick response lemoldsnut!

The wheel offset (backspace) is definitely not well chosen by the previous owner. It's way negative with the side of the tire in line with the outer rim of the quarter panel. But since I can't afford new rims right now, I have to cope with that by going with new and tighter coil springs.

Now I've searched the forum here and internetshops and the result is a wide range of suggestions:

Rockauto
Moog 5385 HD Height 12,60in Inner Dia. 5,57 Installed Height 9,00 wire: 0,59 Load rate 168
Moog 6321 Height 14,29 Inner Dia. 5,58 Installed Height 8,50 wire 0,53 Load rate 119

Summit
Moog 6319 Height 14,17 Inner Dia. 5,58 Installed Height 9,00 wire 0,53 Load rate 119

forum Run to Rund:
Moog 5413 HD Height 12,93 Inner Dia. 5,53 Installed Height 8,50 Wire: 0,59 Load rate 167

forum oldcutlass
Moog cc507 HD Height 15,38 Inner Dia. 5,53 Installed Height 10,00 Wire 0,61 Load rate 158

forum droldsmorland
Moog 5415 HD Height 14,62 Inner Dia. Installed Height 9,0 Wire 0,61 Load rate 169

Could you give me a hint, which coil springs to choose? I listed only Moogs because they are pretty easy to get here in Germany.

Many thanks in advance!
Cheers - Thufir