Rear shock length question

Martin

Well-Known Member
Pretty much done the chassis on the 58 suburban and everything that needs to be attached to it is there except frame extensions for the front brake hoses.

Question is, how do I gauge the length of the rear shocks required and when should I be measuring for size required.

At the moment, as above, its a complete chassis with all the bits attached, no body or anything else mounted, gas tank dry ect.

The upper shock frame mounts are in the same position as original and the lower original shock mounts have been used although a 1980 Camaro axle is now in place but they are pretty much in the same place.
The distance between the bottom shock mount and the top shock mount is presently 20"
If the vehicle was jacked up using the axle pumpkin and stands placed on the frame, the axle would drop more once the jack (using the axle to jack it up) was released so would a shock be required to cater for this extra drop/axle sag/spring pressure release, so that a shorter shock would not actually be holding or restricting the axle from dropping down when the vehicle is suspend by the frame on stands or a jack to change wheels ect.

Do I need to wait till the vehicle is fully assembled before deciding on shock length.

Reading back that looks like a lot of words to a simple question, what can I say, its 0 degrees, I've been out in the shop with no heat drinking too many beers?
Fank goudniss faw spill chock, hic?
 
Hahaha Martin!
I will jump in with my uneducated opinion, but will be looking forward to seeing the experts come forward and set us straight :)
I would be waiting for the unit to be assembled before worrying/attempting about the right length shock. Its job is to dampen the spring (action), not add any height to the rig; with it assembled (rig) you will then know the static height which should be the middle (or there-about) of the stroke.

Good to here you being so productive in your shop....and still no heat after all these years of proving to your good Lady that you are getting things built?
Cheers,
Greg
 
I'll take a shot at answering. Since your new setup is pretty well identical to the factory original, then a original shock should work fine. You don't want a shock to bottom out before the diff hits the snubbers so it needs at least a little more room to travel down than the bottom out distance. And going up it needs 1-2 " at least to drop the axle . If a vehicle has coils then you don't want it to open up too much cause the coil can fly out. Some vehicles like newer GM 4x4's the shock hardly travells on the front axle cause basically you have to compress the suspension to install the shock....thus why so many of them break cause no room to bounce.
 
Guessums I'll wait till its all together then. Least that's a spend on shocks I won't have to make for a good few months.
I did get to painting some of the underside today, two heaters going while I was doing it and now the body is wearing a skirt to keep heat in while the paint dry's. Not sure if I'll leave it painted or put paintable underseal on and paint it again though.
The wood underside cleaned up nicely so that will see some kind of varithane.
 
rear shocks

Set up chassis at ride height on a level surface with rear axle at desired distance from ground to suit your tyre wheel combination. Shocks are set up at 1/3 downstroke to determine required length from eye to eye.