Help with my front leaf springs. (76 FJ40)

[SMG]

So I finally got enough courage to remove my front axle and take apart my my front leaf packs.

You guys were correct!!!! The military wrap had been redrilled 4" inches off center and flipped 180 degrees. I guess the original owner did this to try and keep the wheelbase around stock 90 inches or so.

My plans are to flip the military wrap 180 which will increase my wheelbase by 4"
By extending my wheelbase 4" this will dramatically help straighten my drag link to be more inline with tie rod. I realize I will need a custom driveshaft, but that was in my plans all along.

So here are some questions:

1. Will I have to trim my fenders and move my shocks to the front side of the shock towers?

2. Can I purchase aftermarket shock towers that move the shocks forward?

3. Will I have to cut off the shock mounting pads on the axle and flip them 180?

4. Were can I purchase the teflon disc to help with the friction?

5. Do any of the major auto stores sell new center pins?

 

[Cruiserdrew]

1-Maybe, but for sure if you get new shock towers.

2-Yes-May of us have used Ford shock towers which work great and are not expensive

3-Unknown but once it's in place you'll know. New shock mounts from RuffStuff work well too in this application

4-No idea. Not sure it's worth it.

5-NAPA has a good selection in the bins in the back. At least 3 different sizes. Cruiseroutfitters also sells good ones.

 

[SMG]

1-Maybe, but for sure if you get new shock towers.

2-Yes-May of us have used Ford shock towers which work great and are not expensive

3-Unknown but once it's in place you'll know. New shock mounts from RuffStuff work well too in this application

4-No idea. Not sure it's worth it.

5-NAPA has a good selection in the bins in the back. At least 3 different sizes. Cruiseroutfitters also sells good ones.

Thanks for your input,

Can you tell if my springs are stock Toyota by looking at my picture of the military wrap?

 

[SMG]

Here's a pic of my shock axle tab. I think I'm gonna have to cut these off and flip them or buy new.

 

[Cruiserdrew]

Thanks for your input,

Can you tell if my springs are stock Toyota by looking at my picture of the military wrap?

Looking at the simple keepers and small eyes I *think* they are stock FJ40 springs.

 

[SMG]

Looking at the simple keepers and small eyes I *think* they are stock FJ40 springs.

Ok, thanks!

 

[White Stripe]

For center pins I typically just use grade 8 bolts and round the head off, if the head is too short I just add some washers. But if u can find new center pins that works too. I think you could keep your shock towers stock if you wanted and just weld the shock mounts on the back side of the axle tube like people typically do shock mounts on the rear axle of a soa truck maybe. The steering stop may get in the way though so not sure. I moved my axle forward 2 inches and all I had to do was cut the shock mounts off the axle and flip them 180. More than 2" and I would have had to move my bump stops. You may get away with f250 shock towers and doing the shock mount flip. The ford towers bolt the shock in the center of the mount with double shear rather than to one side of the mount like stock and single shear.

 

[SMG]

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

Dave,

While I have my leafs apart I would like to add these friction disc you speak of.
What keeps the Teflon disc inplace? It seems like they would work there way out over time. Do you know of anyone that is selling these?


White stripe,

Thanks for the input. Im gonna try and find some Ford towers. Do you think moving the axle forward 4 inches is too much? Will it look out of place/weird?

Thanks

 

[White Stripe]

It's a matter of opinion as far as looks. At 4 inches u will likely have issues with the tire hitting the front fender lip. So u may have to trim them or adjust the bump stops. I would think,more than 3 inches will look funny. But I could be wrong. If u have adjustable leaf spring perches u can move it around and see what u think at 2 3 or 4 inches. So now would be a good time to swap in some adjustable perches. Just solidly mount your axle on something like tack weld it to some jack stands, measure the angle and mark position of old perches, cut off, and install new ones in same spot.

 

[pb4ugo]

Spring center pins are usually available at any auto parts store. I know because I've broken many of them. I now use socket head cap screws and have no more failures. You'll have to clamp the springs b4 removing the current center pin or compress the springs together if the springs leaves are apart, b4 installing the shcs.

 

[65swb45]

Having decided to move the axle forward, now would be an excellent time to consider not just reorienting the shocks, but also going with something taller to accommodate the longer travel of the SOA. I will post more shortly.

 

[lcwizard]

Dave,

While I have my leafs apart I would like to add these friction disc you speak of.
What keeps the Teflon disc inplace? It seems like they would work there way out over time. Do you know of anyone that is selling these?


White stripe,

Thanks for the input. Im gonna try and find some Ford towers. Do you think moving the axle forward 4 inches is too much? Will it look out of place/weird?

Thanks

Most spring shops keep them around. A hole is punched in the end of the leaf. The pads have a nipple that snaps in and secures them
They are common enough that even Jegs carrier them

Trail Gear 110120-1-KIT: Leaf Spring Slip Pad | JEGS

 

[SMG]

Thanks again for everyone's input. I think I will go ahead and drill the leafs for a 2" move.

I think 2" along with moving my Saginaw gear box back 1.5"
should put my my steering link pretty much parallel to the axle.

My plans are to run 35" tires. I really don't want my wheelbase or front end sticking to far out and looking abnormal. Also, I am hoping not to trim the fenders.

I placed an order for some Ford shock towers this morning.
They must have really gone up in price at $24.50 a piece.

Thanks
Steve

 

[lcwizard]

And while you're working the springs , enlarge the center pin to 3/8 throughout the pack.
The 40 has an incredibly weak 5/16 pin. The 60 series was upgraded by Toyota to the larger size. In that event , center pin spacers, to
increase the height of the pins are easier to build. 1/2" x .065 steel tubing is easy to acquire and is what spring builders use. It's a little less cumbersome than stacking washers. You can still break a 3/8 but it has 50% more shear strength than a 5/16 so it will happen less often.
Most center pin failures come from inadequate clamping from the u-bolts ( under torqued). 9/16 ( 14mm ) should be torqued to 100 ft/lbs
+ or - 5-ish. Make sure you u-bolt plates are heavy enough to sustain the torque without deflecting. The u bolt skid plates marketed
widely for suo won't hold up. Most are made from flat 1/4". They deform about 80 ft/lbs and if you get them to the 100ft/lb mark they will
deform slowly while driving and settle in at that point where the material can support the load.
We started with 1/2" top plates on flip kits about 20 years ago for our ARCA trucks. After a season we noticed very slight deformation at
the ears around the nuts. We went to 5/8" plate which is what we still use. The extra 1.00 is well worth the security. We bored one set out to 5/8 to test higher torque limits and ran a season with 5/8 u-bolts at 130 ft/lbs without any ill effects.
Typically 9/16 and smaller u-bolts are grade 5. Only 5/8 and larger are grade 8. This is true with every commercial u-bolt builder I've found .
Something to consider while you're doing everything as a one off anyway.
..and please do some reinforcement on the radiator core support where the steering passes through

 

[SMG]

Most spring shops keep them around. A hole is punched in the end of the leaf. The pads have a nipple that snaps in and secures them
They are common enough that even Jegs carrier them

Trail Gear 110120-1-KIT: Leaf Spring Slip Pad | JEGS

Dave,

How would 2"x4" thin pieces of stainless sheet work for in the U bolt area and then these disc on the outboards?

Should I put these between every leaf or just the top 3 or so?

Thanks

 

[lcwizard]

They would work fine. Between every leaf is best. Wherever the leaves touch is a friction point

 

[SMG]

They would work fine. Between every leaf is best. Wherever the leaves touch is a friction point

Ok, Thanks

 

[65swb45]

Well, under the category of better late than never...

This qualifies as my most under-promoted part ever. I've had these stock shock tower extensions for about 10 years now, and have never done a formal promotion for them, or even listed them on my website.

First disclaimer. Most of the credit for this design goes to @Downey . I think Jim originally developed this product around 2002. A rough prototype went onto Ruftoys, clearance issues were discovered and mostly resolved, and he put them to market. I really didn't see the point until 2004 when I got on Pirate 4x4 and started reading esoteric discussions from @wngrog and @Mace about SOA articulation. After I ordered my 5" Alcans for the LWB in 2005 and wheeled the piss out of the truck at Katemcy in 2006, I finally saw the light. I took a set of extensions from Jim, worked out a few more bugs, and had my own batch made...which promptly went into mothballs.

First and foremost, I thought Jim had a better idea from the standpoint that while the Ford tower option had more flexibility fore and aft, It was limited 1) in height by staying under the fender, and 2) because it moved the shock out towards the tire, which increased the chance of contact under flex. Jim's bracket didn't offer the latitude front to back, but it allowed the shock to come up further into the engine compartment (FIVE INCHES!) and it kept the stock shock geometry (away from the tire)

The lower brace gets welded to the stock tower. The upper brace bolts into the stock tower and meets the lower brace at a point 5" above the stock pin height. The brackets are handed left and right, which means they can also be flipped to the front of the tower for flipped spring applications. A quick eyeball tells me that the center of the shock would sit 3.5 inches forward of where it is in the pic if it were on the other side of the stock tower.

Here's a couple of pics from the 45 I just snapped. Like I said, no formal write up, but I have at least 20 sets of these on the shelf.

 

[SMG]

And while you're working the springs , enlarge the center pin to 3/8 throughout the pack.
The 40 has an incredibly weak 5/16 pin. The 60 series was upgraded by Toyota to the larger size. In that event , center pin spacers, to
increase the height of the pins are easier to build. 1/2" x .065 steel tubing is easy to acquire and is what spring builders use. It's a little less cumbersome than stacking washers. You can still break a 3/8 but it has 50% more shear strength than a 5/16 so it will happen less often.
Most center pin failures come from inadequate clamping from the u-bolts ( under torqued). 9/16 ( 14mm ) should be torqued to 100 ft/lbs
+ or - 5-ish. Make sure you u-bolt plates are heavy enough to sustain the torque without deflecting. The u bolt skid plates marketed
widely for suo won't hold up. Most are made from flat 1/4". They deform about 80 ft/lbs and if you get them to the 100ft/lb mark they will
deform slowly while driving and settle in at that point where the material can support the load.
We started with 1/2" top plates on flip kits about 20 years ago for our ARCA trucks. After a season we noticed very slight deformation at
the ears around the nuts. We went to 5/8" plate which is what we still use. The extra 1.00 is well worth the security. We bored one set out to 5/8 to test higher torque limits and ran a season with 5/8 u-bolts at 130 ft/lbs without any ill effects.
Typically 9/16 and smaller u-bolts are grade 5. Only 5/8 and larger are grade 8. This is true with every commercial u-bolt builder I've found .
Something to consider while you're doing everything as a one off anyway.
..and please do some reinforcement on the radiator core support where the steering passes through

Dave,

I took you advice and enlarged my center pin hole to 3/8"s. I also fabbed up some new beefier U-bolt skid plades.

I didn't go with 1/2" or 5/8" but I did beef them up to 3/8"
These are made out of stainless so I won't have to worry about rust.

My question is, do I have to worry about the jogle that is in the stock one?

Should I machine a trough in the new skid?

Thanks for your advice.

 

[65swb45]

The 'trough' is just a stiffener; it sits perpendicular to the spring when installed.