Suspension/chassis options for this Longhorn to K30 Big Block conversion.
Our goals are keeping a low ride height, factory look and we do not want to modify the firewall for clearance. Doing it right the first time and not having to redo anything priceless!
What would be the general consensus on engine mount and front & rear spring hangers?
Additional info:
Longhorn 133” frame, K3500 CC dually chassis parts donor
Torquey 454/496 (TBD) mounted in forward 2wd position running stock exhaust manifolds
T 400 w/205 transfer case (w/possible GV overdrive?)
D60 & CC 14Bolt DRW axles
Here are some of our options:
Front option #1
Complete 67-72 K1, 2 setup (motor cross member may need to be modified for frame fitment, BB pan & front pumpkin clearance?). You couldn’t look more factory than this so it’s high on my list but might not be practical due to clearance issues.
Front option #2
Complete K3500 mounts (clamshell style motor mounts will need to be reworked to fit the Longhorn frame) cross members & hangers complete.
Front option #3
Combination of option’s 1 & 2
Use the K3500 motor mounts/cross member with K1,2 front spring hangers.
Front option #4
I’ve got a 73 only (according to GM parts book) set of mounts (clamshell style) w/cross member (not as heavy duty as the K3500 stuff). We also have some front spring hangers that I was told came from the same application and they are a little different than the later square bodies.
All front options will include adding the front sway bar from the K3500. We’re going to need new front springs. The only front springs we have are from the K3500 and are too long for this build. Also we want to use the factory automatic linkage, so thinking 67-72 length front springs and hangers are a must to leave room for the frame mounted linkage pivot (mounts left side rail close to the front rear hanger and front body mount on that side (I have both T400 & T350 pivot styles))? Also we do have both a 67-72 and the later square body style trans/transfer case mount. I’m a little concerned about the additional weight a GV overdrive might create. Wondering if a 205 right side bracket might help with this? Thinking some would suggest we go with a 4l80e and a standalone controller. This was my thoughts originally as well, we even acquired a core trans from forum member mjensen. As this build project got closer I remembered how many newer OD type transmissions I’ve smoked in the past.
Rear option #1
Complete 71-72 K1,2 hangers w/new springs.
Rear option #2
Complete K3500 springs & hangers. JJorgensen52 did this in his 72 GMC K30 build and it looked like it worked quite well.
Rear option #3
Complete C30 springs and hangers. Pretty sure we have enough parts left over from the motor home chassis to pull this off. We would need to use additional blocks to get the ride height level.
Either rear option 2 or 3 we have spring packs that can be refurbished and shouldn’t need new rear springs.