Help with my front leaf springs. (76 FJ40)

[SMG]

Ok, here's my dilemma. I picked up this partially built 76 FJ40 earlier this year. It has a spring over axle and a reverse shackle conversion.

I was able to track down one of the original owners who had all of the suspension modifications done.

He claimed that front leafs were swapped 180 degrees, but I wonder if they were put back sometime after his ownership.

I am wondering which direction is stock? Currently, the longer portion of the leaf spring is towards the front. (roughly 24" from center bolt to eyelet). The rear portion of the leaf is 19,1/2" from center to the rear eyelet.

What issues would I run into if I put the longer portion of the leaf to the rear? It looks as if it would gain me 4" of wheelbase and would help with the drag link angle to my Saginaw gear box.

Would I have to modify the front fenders?

I currently have no driveshafts and plan on having some custom ones made.

Here are some pics:

 

[Mace]

Generally when you do a Shackle reversal you flip the springs so that the military wrap is on the spring hanger side.

I would not think twice about flipping the springs 180*. But you may want to look and see what that does to your alignment.

 

[SMG]

Can you tell me what is stock?

Looks as if my military wrap is to the front(not on the shackle side).

My tie rods and drag link will be custom lengths.

Just wondering if I flip the springs, will I have to modify the front fenders?

 

[lcwizard]

The long side is the shackle side, short side is the fixed side. Mil wrap is intended to go at the fixed point. I think that pack was disassembled and rearranged. The mil wrap should be on the short side

 

[Mace]

Is there a mil wrap on both ends of your spring?

 

[ginmtb]

Here's what happened to mine when I installed the springs backwards:

Won a '74 40 on a coin toss... (post #234)

My drive shaft barely fit together. But with a reverse shackle that may not be an issue.

 

[Tysano]

With a shackle reversal long side go's to the back which means you have to lengthen you drive shaft also you should install a longer slip Yolk as your front axel can know move back and forward rather than just foward and up if you running stock steering linkage you won't have to cancel anything just
recenter your steering wheel. The pic look's like whoever did the reversal did a nice job.

 

[lcwizard]

There's no rule as to reversing your leaf pack, it would depend where you place the hangers but Toyota actually looked at leaf spring design
when they built their springs.
If you notice on the short side the step between each leaf is shorter than the long side. This creates a stiff leg that more resist spring wrap .
A leaf is intended to replace a couple things in a suspension system. The link or links that positions front to back and a compression component
like a coil, airbag etc. The forward half , done correctly, positions the axle through it's swing. It should be rigid enough to control wrap as not to need a torque arm or upper link as in a 4 link but not so rigid that it interferes with the spring as a whole. The rear half should be tuned to dictate compliance, deflection. Tighening the gaps between the points the leaves terminate adds stiffness. Small details like adding space between leaves, both at the centerpin and leaf ends reduces friction between leaves for faster response. Spacers at the centerpins should be
something that won't compress. The spacers at the leaf ends are usually teflon discs. At the center I use 2" x 4" galvanized 14 gauge rectangles with a hole punched in the middle for the centerpin to pass. Friction between the leaves is one of the biggest culprits of a terrible riding leafpack.
People will open the leaf clamps, spray WD40 on and between the leaves but spacers are the better solution

 

[Mace]

I have used graphite paint in the past to reduce friction as well.

 

[SMG]

Ok, thanks for all the comments.

After researching here on mud I believe what I have going on is:

When the shackle reversal was completed. The springs were reversed so the military wrap is now at the front.

From what I can tell, the front of the frame horns has been extended to compensate for the long side of the leafs pointing forward. This leads me to believe the wheelbase is back to stock.

Is there a good way to measure to tell if the front axle is sitting in the correct position?

I'm kinda worried because looking down from the top my drag link to Saginaw gearbox is at a pretty good angle and not parallel with my axle.


Thanks
Steve

 

[Mace]

This picture,

Looks like the shock is still angled back a bit.

What's the current WB?

 

[SMG]

This picture,

Looks like the shock is still angled back a bit.

What's the current WB?

Yes,

I will check when I get home from work.

 

[SMG]

Ok, just measured the wheelbase. Looks to be around 89.5" center axle to center axle.

Does anyone know what the stock wheelbase is?

Thanks
Steve

 

[Mace]

90 (ish)

 

[SMG]

Still debating on what to do with my front leaf packs. My wheelbase is currently around 89.5".

It's really bugging me that the long side of the leaf pack is toward the front.

If I were to flip them 180, my military wrap would then be on the shackle side.
Which I know isn't correct.

Should I separate the packs, re-drill the center pin on the top two leafs so the wrap is still towards the front (hard mount), then flip the lower rest of the leafs?
(I have a Bridgeport mill, so drilling them shouldn't be an issue.)

Again, my drive shafts and drag link have yet to be made so I don't mind the longer wheelbase.

Does anyone have some side shots of what the front would look like with an extended front wheelbase?

Thanks for everyone's help.

 

[too tall]

You would only have to re-drill the second leaf (military wrap) and flip it around . The rest of the pack stays the same . Then flip the entire pack .I bet if you take one of the packs apart you will find the hole is already there . Looks like you'd have to flip the shock as well to the rear of the tab on the axle and the pin on the tower would have to be flipped to the front . As mentioned , you should have a long slip type shaft in the front if possible . I have had some luck using early mini truck front d-shaft slip portion on the front w/reversal.

 

[SMG]

You would only have to re-drill the second leaf (military wrap) and flip it around . The rest of the pack stays the same . Then flip the entire pack .I bet if you take one of the packs apart you will find the hole is already there . Looks like you'd have to flip the shock as well to the rear of the tab on the axle and the pin on the tower would have to be flipped to the front . As mentioned , you should have a long slip type shaft in the front if possible . I have had some luck using early mini truck front d-shaft slip portion on the front w/reversal.

Ok, thanks for your advise. I will try and open the leaf packs tomorrow.

Is it hard to open the clips that hold the leafs straight?

Still asking for some pictures of a extended front wheelbase looks like.

Thanks for your help.

 

[lcwizard]

Here's 1 1/2" forward. It's a second gen shackle reversal. Our first design we sold through Man-a-Fre starting in 96. I never do a 4" or better lift without a cut and turn anymore so we don't market these kits. Man-a-Fre is currently having our older kits built. Because of failures from imported greaseable shackle pins we also adapted the late style 18mm pins rather than use the smaller stock early 40 pins.
Without control of the spring selection it's hard to market a suspension kit. People will look for the best deal on springs rather than go with the tested and recommended if they cost more. Although that's not the majority of buyers it is the majority of those writing the reviews. Geometry from one spring to the next varies enough that I couldn't absolutely guarantee a result without testing each brand and adding shim values based on each manufacturer. The original intent, back in the 90's was to use a stock front spring with a 2 1/2" rear lift spring. The stock springs are very predictable. One example I encountered recently, I installed a 2 1/2" aftermarket spring on a stock configuration ( shackle forward )that required an 10 degree caster shim to acquire 2 deg positive caster. The spring was built in a way that the spring seat was set at 8 deg neg. That is by far the worst I've seen and from a major manufacturer. Two degree variations are common.

 

[SMG]

Here's 1 1/2" forward. It's a second gen shackle reversal. Our first design we sold through Man-a-Fre starting in 96. I never do a 4" or better lift without a cut and turn anymore so we don't market these kits. Man-a-Fre is currently having our older kits built. Because of failures from imported greaseable shackle pins we also adapted the late style 18mm pins rather than use the smaller stock early 40 pins.
Without control of the spring selection it's hard to market a suspension kit. People will look for the best deal on springs rather than go with the tested and recommended if they cost more. Although that's not the majority of buyers it is the majority of those writing the reviews. Geometry from one spring to the next varies enough that I couldn't absolutely guarantee a result without testing each brand and adding shim values based on each manufacturer. The original intent, back in the 90's was to use a stock front spring with a 2 1/2" rear lift spring. The stock springs are very predictable. One example I encountered recently, I installed a 2 1/2" aftermarket spring on a stock configuration ( shackle forward )that required an 10 degree caster shim to acquire 2 deg positive caster. The spring was built in a way that the spring seat was set at 8 deg neg. That is by far the worst I've seen and from a major manufacturer. Two degree variations are common.

View attachment 1287643

View attachment 1287644

Dave,

Thanks for the info, My axle is a SOA and has had the cut and turn done some time in the past. (Prior to my ownership) Whoever did the work did a really nice job.
Do you think I should open the pack to see about turning the leafs around except the Military wrap?

Off topic,

I purchased your frame torque tube and was very happy with the quality and how it turned out. The fit was really good!
I made it so I can unbolt it if need be.
Check out the pics.

 

[lcwizard]

It seems the mil wrap leaf was spun 180 degrees. The PO either had a new mil wrap leaf made or spun it and repositioned the centerpin hole.
Like too tall said, chances are that the leaf is the original and the original hole is still there. That would be the simplest way to lengthen the
wheelbase. I would as he also mentioned replace the slip yoke. The front from an FJ80 or Tacoma. You can get the whole assembly new.

If you use this you'll need to drill a new pattern at the slip yoke end. It's the front FJ80/truck pattern

Driveshaft Kit