In my search for 2"-3" lifts for my 79 Bronco, I
discovered a bunch of specifications for front springs and other lift info that I decided should be ingrained into history. So here it is.
MOOG springs from 79, F-250, 2WD. (GVWR 8100 lb. with 460)
Part number CC8646. Right side 430 lb/in
and Left side 485 lb/in as truck is supposedly heavier on that
side??
Installed height on the F-250 was 14-1/4" (15" seems reasonable on
a Bronco). NOTE: I don't think the F-250 springs are going to work.
Probably way too stiff and the truck won't be level after you are
done.
SUPERLIFT 2" spring
Spring rate 320 lb/in, installed height of
14.4". Spring rate 415 lb/in, installed height of 16.5" (3.5"
lift). NOTE: I've had Superlift's 4" springs and it
rode firm, but not harsh. Nice and "travely" offroad. I would
definitely not want to go over that spring rate.
TRAILMASTER 2" spring
Variable spring rate of 330-400 lb/in.
Guarantees a 1.5-2" lift.
SKYJACKER 2-3" Spring
2" spring variable rate from 330-366
lb/in, guaranteed 2" lift
3" spring variable rate from 330-380
lb/in, guaranteed 3" lift.
REAR SPRING/LIFT INFORMATION
Most major companies offer an add-a-leaf that is rated for
1.5-2 inches of lift. Since most Broncos are 1.5-3 inches higher in
the back then than front, an add-a-leaf would compliment a 2-3"
spring nicely.
Another method of lifting the rear of any Bronco is lift
blocks. Lift blocks are usually regarded as inferior to any type of
suspension lift for the rear. Lift blocks can induce spring wrap
causing drivetrain problems and don't really offer any additional
suspension travel. The maximum lift block I recommend is 2 inches.
A quality lift block and U-bolts is not even cheaper than an
add-a-leaf. The only benefit I could see from lift blocks over an
add-a-leaf might be ride quality, as the spring pack/spring rate is
not disturbed at all. Add-a-leafs do not usually increase ride
harshness at all.
Another method of getting a small rear lift is doing the
shackle flip. This requires grinding off both rear shackle mounts
and flipping them upside down (left to right and vice-versa). The
most lift you can get AT the shackle would be 3.75 inches. This
means the most AXLE lift you may get would be 1.5 inches.
Realistically, you may get .75-1 inches lift. If you are going with
2" front springs, this would make a nice, virtually no cost
addition to the front. It will also help in wheel travel providing
more droop from the rear shackles than could be provided by the
stock configuration.
Other rear lift options/comments covered by John Blanchet
I was talking specifically about the Rancho add-a-leaves that come
with their 3" and 4" lifts. There are two per side with the lift
and were meant to replace the longer leaves in the spring pack.
They aren't like those big fat add-a-leaves that fit at the bottom
of the spring pack. They were like regular leaves but had a lot
more arch than the stock springs. My truck had six leaves. Had I
not removed them, I would have had 8 leaves. It was Rancho's intent
to remove one or two leaves per side depending on which stock
springs were underneath. Would it have sat any higher in the back?
Just from the fact that the two leaves combined probably were 1/2"
thick and the axle is below them, yes it would have sat a little
higher. I had also posted something from an article on a 2"
Skyjacker rear spring set that when used in a Bronco lifted it
around 3". The article indicated a leaf was removed to get the rear
lower since they were only using 1 1/2" - 2" leveling coils in the
front. Comments about small rear lifts. When I had 1 1/2" - 2"
leveling coils in the front, I needed something to lift the rear. I
cut a couple of pieces of 3/8" plate the width of the spring and
long enough to cover the factory wedge. I drilled a hole in middle
of the plate and bolted two of them per side together with the rest
of the leaves with new center pins. Viola, a cheap 3/4" rear lift
that leveled out the Bronco. Only reason I used 3/8" plate was
because I had some scrap laying around and was easier to work
with.
OTHER SUSPENSION COMPONENTS
Lifting 1-2 inches will not require any other suspension
components.
Lifting 3" or more may require an adjustable track bar or drop
down bracket. If the track bar is not moved or lengthened, you may
end up egging out the holes in the upper frame bracket.
Also when you get to 3" lifts, you may need slightly lengthened
shocks. Driveshafts should be OK up to 3" of lift. Degreed "C"
bushings may be required for 3" lifts to enable the front
suspension caster to remain the same. Otherwise, the truck may
wander on-road with the reduced caster.
