Rear coils to leafs frame ?

[1-PU70]

Is the frame for rear coils the same as the frame for rear leafs? I have a 70 with rear coils and It dont quite cut it when its loaded and towing. It has HD coils, shocks with coils on them and the factory overload spring. According to the NAPA web site the HD rear coils are rated at 2900lbs each. If I went to leafs I could go to 3500lb springs and then add a top helper rated at 1050. I know the coils ride way better then the leafs and I hate to give up my coil ride. If you have any other ideas just pipe in. Thanks. Oh ya no air ride. Dont want to spend the coin. The only other idea was to get the air bags that go inside the coils but i wanted something that was real simple.

[glock35ipsc]

What about adding a set of factory auxiliary leaf springs for the trailing arm suspension? They seem to pop up used every once in a while

[1-PU70]

Already have them.

[SCOTI]

....Oh ya no air ride. Dont want to spend the coin.

How much for the leaf swap?

Manual fill air bags meet your capacity needs & could be cheaper than swapping to leafs. Install the bags in place of the existing coils. Run two separate airlines to two schrader valves (one for each bag). Bags w/fittings = $170, schrader valves = 2@ $5; 20' of .250" DOT airline = $20. Better ride while meeting or beating capacity.... priceless.

[fly-n-j]

To answer your question about the differance in the two frames- Yes they are drasticly different. The coil rear frame is about 6-8" wider over the axle to accommodate the coils. It starts getting bigger just behind the rear cab mounts and reaches it's widest point just over the axle and then it tows back in as it heads toward the rear bumper. The leaf spring is a strait shot viewed from the top down, from cab mounts back. The only way, in my opinion, you could switch to leafs, is to cut the coil frame out and replace it. I did the reverse of this (leafs to coils) to mine to gain the ride of the trailing arm rear end.

[SCOTI]

Originally Posted by fly-n-j

To answer your question about the differance in the two frames- Yes they are drasticly different. The coil rear frame is about 6-8" wider over the axle to accommodate the coils. It starts getting bigger just behind the rear cab mounts and reaches it's widest point just over the axle and then it tows back in as it heads toward the rear bumper. The leaf spring is a strait shot viewed from the top down, from cab mounts back. The only way, in my opinion, you could switch to leafs, is to cut the coil frame out and replace it. I did the reverse of this (leafs to coils) to mine to gain the ride of the trailing arm rear end.

While I suppose anything is possible, I know 2x4 vs. 4x4 frames are different. 2wd leaf vs. coil frames are the same (I'm basing this statement on the fact that I've had one of each sitting in my driveway @ the same time).

The leaf spring frame got wider above the rear axle just like the coil frame. It also had beads in the frame where the leaf hangers were placed where as the coil did not. The leaf frame has different shock mounts & did not have the c.member that mounted the shocks & reinforced the coil mounting area of the frame.

[69 longhorn]

Originally Posted by SCOTI

While I suppose anything is possible, I know 2x4 vs. 4x4 frames are different. 2wd leaf vs. coil frames are the same (I'm basing this statement on the fact that I've had one of each sitting in my driveway @ the same time).

The leaf spring frame got wider above the rear axle just like the coil frame. It also had beads in the frame where the leaf hangers were placed where as the coil did not. The leaf frame has different shock mounts & did not have the c.member that mounted the shocks & reinforced the coil mounting area of the frame.

X2,the 2wd frames were the same ,leaf or coil. 4wd,Longhorn,or cab /chassis(dually), had straight rails that measured 34 " rail to rail. The only difference is in the crossmembers & brackets on the run of the mill 2wd trucks. You can swap the pcs over on your 1/2 or 34 ton 2wd to leaf.......yes it will ride a little stiffer, but it will be more stable with a heavy load. Best of fun,crazyAL

[mike16]

3/4 ton trucks are nice too, they got leaf spring rears

[69 longhorn]

Originally Posted by mike16

3/4 ton trucks are nice too, they got leaf spring rears

No, not ALL of them.....leaf seemed to be standard on the GMC, with coil as an option. On the CHEVY, coil was standard, with leaf as an option. 4wd,longhorn, & cab /chassis only came with leaf springs. crazyAL

[capev86]

you are telling me that the 3/4ton HD option coils are not good enough? what are you carrying.....lead bricks? or the biggest pickup camper ever made? the HD coils are practically one ton springs. 3500 pound rated springs are what they sell for trucks that carry heavy loads all the time. i'd suggest some air springs or something less drastic than changing your entire chassis unless all you ever do is haul a load with your truck. how old are the coils in your truck and do you actually have the HD coils or the standard 3/4 ton coils?. maybe it would be easier to trade with a guy with a 1 ton and upgrade that truck.

i have the standard rear coils in the back of my 72 burb 3/4 ton. they are in great shape for 38 years old but i do plan to upgrade to the HD coils for towing super big loads. when i hear your problems with the HD units, i think it weird that anyone complains about the optional (2000lb rated) rear coils in 1/2 ton trucks being too stiff.

[mike16]

I was suggesting he could buy a 3/4 ton....with leaf springs and add more as needed.be carefull overloading your truck.Just cause thesprings can hang, remember theres other components to that are upgraded also just cause your truck can handle the extra load does not make it leagal. If you get in an accident and your truckis loaded beyond the rating placard you may find your self in the dog house.


I know they made coil jobs as I have owned several. I had 1 tone coils rated springs and 500# factory helper springs. rode pretty hard without a load. I had a wood bed and that kinda limited what all I could put in the back.

Capev86 brings up a good point ...at some point the suspention no longer becomes the issue. I would start to worry about axle bearing or shaft failure.

You could also just get a trailer

My coil spring fram has a braket for the trac bar. do the leaf frams have that?

[capev86]

no.....leaf springs provide lateral stability, whereas trailing arms will flex side to side. the 3/4 ton with coils has a much beefier track bar as well as a rugged axle. you might be able to have a spring shop make some coil springs with more lift and increased capacity, but it is mind boggling to think the HD coils are not stiff enough. i'd put them on a 3/4 ton truck like why i like the 1/2 ton HD (standard 3/4t) on the back of a 1/2 ton.....the extra cargo capacity in the back for hauling loads, trailers, etc and not having rear end sag. my dad put 3/4 ton coils on the back of his 72 1/2 ton and the overload springs never engaged after that, even with our 71 holiday hitched up (800 lb tongue weight). the truck sat like a drag racer unloaded and still have a slight rake with the trailer on!