Leaf to Coil Swap

[mas09ts]

Anyone got a how to or info on how to do this, any pics?

[my67chevytruck]

I have seen some leaf spring trucks that had the trailing arm crossmember in place. Is this the case on your truck?

[lofly'a]

i'll take a stab since i will be swapping my 71 gmc over soon, but with air ride. i know that on my swb the trailing arm crossmember is there, but the brackets for the trailing arms are not. also, the the crossmember that the rear shocks are attached to on the leaf suspension is different. then theres the panhard bar, brackets, and hardware that have to be addressed. the rearend does not have the cast in mount (hole) for the panhard bar, but that is'nt a show stopper unless you want it stock looking. early classic or CPP can help with that issue. at the least you'll need a panhard setup, rearend with lower shock mounts, trailing arms and brackets, and the coils, bags or whatever...... this is what i know about swb trucks, i have no idea what you have if your is a lwb.

[glock35ipsc]

Other than swapping parts from a coil truck (like mentioned above), one of the biggest things to address are the coil springs themselves.

The frame rails on the leaf truck are practically straight/parallel over the axle, where the coil spring frame bends out. The coil springs attach to the underside of the frame. (See pic) So when converting a leaf truck to coils, a bracket needs to be made to bolt/weld to the outside of the frame to give the coils something to attach to. I have seen these for sale (don't remember where), but they would be super easy to fab.

Use ECE's super track bar. It mounts to the frame on the drivers side (will need the OEM bracket, or fab one) then to the right side trailing arm.

You will need the trailing arms saddles off of a coil spring rearend. Or just find a complete coil spring rear end.

Shock crossmember (upper), shock brackets off of a coil rearend (lower).

Front trailing arm brackets.

LWB, SWB, it's all the same back there.

[lofly'a]

thanks Glock i forgot about the upper coil mounts. i went back and looked at the frames and compared the 71 gmc to my 72 chevrolet with coils and the frames are exactly the same.

[mas09ts]

Originally Posted by my67chevytruck

I have seen some leaf spring trucks that had the trailing arm crossmember in place. Is this the case on your truck?

It has these holes so....

[glock35ipsc]

Compare your pic to mine, and you can see where the trailing arm brackets go. The holes closer to the hole for the driveshaft are for the carrier bearing bracket to mount to.

[SCOTI]

Originally Posted by glock35ipsc

The frame rails on the leaf truck are practically straight/parallel over the axle, where the coil spring frame bends out. The coil springs attach to the underside of the frame. (See pic) So when converting a leaf truck to coils, a bracket needs to be made to bolt/weld to the outside of the frame to give the coils something to attach to.

I had both, a short leaf (67 GMC) & short coil (68 Chevy) rolling chassis side by side in my driveway @ the end of '07. My experience is the frame rails were the same on both trucks. The 'curve' where the springs mount is there for both & they do utilize different bracketry. The 'curve' is not there on 4x4's (frame is straighter as described above).

The leaf frame did have some structural 'beads' in the steel around the spring hanger areas that the coil frames don't have.

[mas09ts]

So what would i need if my crossmember will work?

[powerbench]

The frames are the same except for a few reinforcing dipples that are stamped right where the leafs supports go..I just finished doing this swap , and got a lot of help from everybody here.I found the best way was to do it with the box off , and have a coil truck handy for all the brackets you need...and for measuring all the bolt hole locations...i'll try to resize some pics of how mine came out.

[mas09ts]

Originally Posted by powerbench

The frames are the same except for a few reinforcing dipples that are stamped right where the leafs supports go..I just finished doing this swap , and got a lot of help from everybody here.I found the best way was to do it with the box off , and have a coil truck handy for all the brackets you need...and for measuring all the bolt hole locations...i'll try to resize some pics of how mine came out.

thanks man pics would help

[powerbench]

i love pics so here i go.....

[powerbench]

more

[powerbench]

hope i don't over load the server.... hope these help

[mas09ts]

Now thats step by step great dude!! thanks

[ERASER5]

And what are you guys doing with the old leaf springs? There are some people who do the exact opposite swap. Brackets, hangers and such are hard to come by. We do have a sale forum here. That's all I'm say'n.

(Mine was born with leaves)

[glock35ipsc]

Originally Posted by SCOTI

I had both, a short leaf (67 GMC) & short coil (68 Chevy) rolling chassis side by side in my driveway @ the end of '07. My experience is the frame rails were the same on both trucks. The 'curve' where the springs mount is there for both & they do utilize different bracketry. The 'curve' is not there on 4x4's (frame is straighter as described above).

The leaf frame did have some structural 'beads' in the steel around the spring hanger areas that the coil frames don't have.

Ah-ha, you got me! The only leaf trucks I have been looking at for reference are my two 4x4 frames out back. My 67 GMC 2wd was leaf, but I never paid it any attention. I wonder what the Blazers frames are like. I have a 72 and have been kicking around the idea of converting it to a 2wd.

powerbench - Great pics!!

[14U2NV]

Originally Posted by mas09ts

It has these holes so....

I parted a LWB GMC many years ago and it had leafs and the trailing arm crossmember sans the brackets. It does have the carrier bearing support bracket. My question is that I can see the two larger holes to the outside have the parking brake cables running through it, what are the other two holes of the same size for? I plan to run my exhaust through there on the blazer. I think I can get by with leaving the brake cable holes but not the other two.

Chad

[glock35ipsc]

Originally Posted by 14U2NV

My question is that I can see the two larger holes to the outside have the parking brake cables running through it, what are the other two holes of the same size for? I plan to run my exhaust through there on the blazer. I think I can get by with leaving the brake cable holes but not the other two.

Chad

Here is mine. This is the drivers side, from the rear. The lower left hole is for the e-brake cable. Don't know what the others are for, but I don't need them, and I haven't seen anything ran through the others on any of the other 67-72's I have/had.

[mas09ts]

So all i need are trailing arms, coil rearend, and crossmembers that i need? I think i can get a whole coil spring truck for about 200 bucks.