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Leaf spring lift height?

Lunar-tic

Sr. Member
Joined
Sep 28, 2009
Messages
629
Loc.
Brentsville
Got a question about which leaf springs to order. The PO lifted the Bronco about 2-2.5 inches I believe, I am not sure about the front but the rear has 2 inch blocks under the what appears to be stock leafs. The frame measures 24.5 inches at the front frame rails by the bumper and 22 at the rear. Actually the left side is at 21 and the right is at 22. The leafs are obviously worn out and need to be replaced, the question is how much lift to go with? I was originally thinking 3.5 inches out of some 11 pack springs, suggestions?

Thanks
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Measure from the top of the axle tube to the bottom of the frame. Stock measurement for the rear is about 6in Front 7in. Then pick the height of springs you like. You can jack up on the bumper to get a idea of the height. Its hard to take good measurements because tire size varies.
 
OP
OP
Lunar-tic

Lunar-tic

Sr. Member
Joined
Sep 28, 2009
Messages
629
Loc.
Brentsville
So, based on the front axle to frame measurements of 9.5 inches, I figure I need 2.5 inch rear leaf springs to match the front lift. I assume this will level the rear with the front, does this sound right or should I go with 3.5?
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
Depends on how fat the Bronco is.

A Bronco with no rear seat, no bumper, no spare, no tailgate will tend to sit higher then listed for a lift.
But add a hard top, seats, heavy bumper, spare, and a couple of tool boxes loaded, then you will not get the listed lift.

Call up the vender you are looking at getting the springs from. Talk to them about your needs. A set of soft ride crawler type springs can make for a nice ride (if the shocks are not too stiff), but they are sensitive to weight and if you carry varying payloads can be an issue. Then there are varous other types of springs that are more like stock, stiffer.

But in general a 2½" lift spring is about right.
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
8,980
Loc.
Memphis, TN, USA, Earth, Milky Way
Measure from the top of the axle tube to the bottom of the frame. Stock measurement for the rear is about 6in Front 7in.
Good info... Do you remember what the axle tubes' outside diameters are? In the back, is that measurement to the actual frame tube, or the bottom lip of the bracket welded on for the bumpstop?
 

Broncobowsher

Total hack
Joined
Jun 4, 2002
Messages
34,833
The clearance is the gap between the frame and the axle. Since bumpstops get mangled and replaced with aftermarket versions, that is removed from the equasion. Basicly remove the bumpstop, measure the gap where the axle would hit the frame, that is the 6/7" base measurements.

Not sure why the axle tube diameter would be a factor in this?
 

Steve83

Bronco Guru
Joined
Jul 16, 2003
Messages
8,980
Loc.
Memphis, TN, USA, Earth, Milky Way
It was sort of an off-topic question, but since broncnaz's measurement is from the top of the tube rather than center, I figured it was still relevant. Maybe not, though - is the tube of a big-bearing 9" the same diameter as a small-bearing? I'm asking because it applies to the frame diagram I'm working on. I'm trying to get enough detail into it to help people figuring body & suspension lifts. This is where I am now:



I've sketched in the axle tubes at 3" OD, and the rear is shown 6" down from the frame tube, and again from the bumpstop bracket that's welded to the frame tube. That's what I needed clarification about.
 
Last edited:

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
Im not positive but I think tube size was the same at 3in od for all years. I think they may have used thicker tubes in 76/77's but still retained 3in OD but I'm not 100% positive. But any differance will be minor 1/4" max and the 6/7" measurements are just a general area as it more than likely varies vehicle to vehicle due to manufacturing differances.
 

broncnaz

Bronco Guru
Joined
May 22, 2003
Messages
24,341
I believe they are all 2 3/4" diameter for the d44 unless you have a D44 out of a F250 which had 3in tubes. Not sure on the D30 dia. but from what I've seen they appear to be the same as the D44
 

Jeff10

Contributor
Bronco Guru
Joined
Feb 20, 2011
Messages
2,137
Loc.
Indianapolis
Hi,

I'm a little late to the discussion; but, I can share my experience.

James Duff thought my spring lift in the front was 3-1/2" based upon a 10-1/2" measurement between the bottom of the frame and the top of the axle housing.

I don't recall who it was; but, I believe a poster on this forum posted a link to the a B.C. Broncos document. That document is: http://www.bcbroncos.com/springheight.pdf . (File also attached.) It states the same thing.

The back end of the Bronco had a 5-pack when I bought it, and it looked way low in the rear. I bought a new pair of 3-1/2" 11-leaf springs and hardware and installed them last week. At first I thought it was still lower in the front that in the rear. With it on a trailer yesterday, I have to admit I'm pretty pleased with the way it leveled-out.

I hope this helps.

Jeff
 

Attachments

  • Spring Height Reference 051211.pdf
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