Flipping Shackles

[Hap_Hazard]

Ok, I admit that this question is going to prove that after nearly 50 years we guys never really grow up.

While repacking my wheel bearings on my ’05 WW FSC2800 I was inspecting my springs and axle mounts for wear or damage and noticed (for the first time) the position of the middle spring mounts and shackles. Now my terminology is lacking here so I’ll describe what I see and then ask my question.

The middle mount of my twin axle set up has a welded upper connection to the frame (I’ll call this the frame mount). On the lower portion of this mount is a drilled and bolted triangular shackle (cast iron) which mounts the front and rear leaf springs (I’ll call this the middle shackle attaching point).

The forward mounting hole of this triangle shackle is the rear leaf spring mounting shackle for the rear of the front spring. The rearward hole of the middle triangular attaching mount is the location point of the front of the rear spring mounting shackle. Both spring mounting shackles travel upwards from the middle triangular mount to the spring eyelets on a 30 degree angle. I assume this is for balance between the two axles and to allow indepentant movement).

I know many of you are aware of the configuration I’m trying to describe and I apologize for using 100 words when 10 should have done the trick. Anyway, to my question?

To gain additional tire to wheel well clearance (Height) what would stop me from just re-positioning these shackles downward.

From the old hot rod days we frequently took the pry bar to stock rear shackles and flipped them down to gain 2”-3” in the wheel wells. I believe this would be much less effort then flipping the whole axles.

Any comments (especially from anyone that’s tried this) would be appreciated.

Thanks,
Hap

[mapguy]

Crude picture but if you are talking about a double set of holes in the spring hangers and equalizer hanger as shown -yes this is a valid way to adust height on a trailer. Nets about 2" typically.

[big_buford]

Yep going out of a drive way where front axle gets unloaded and rear is loaded heavy it would snap back in place and vise versa. Would be great if it did work though. Had a boat trailer that would do that on occasion, pain in the rump.

[retired-tech]

doing what you are suggesting would drastically change the geometry of the axles converting the camber that is built into the axle to make it tow better into toe in/out which would cause tire wear. there are legitimate reasons this has never been mentioned as an option.

[Hap_Hazard]

Thanks folks for the rapid reply.

Camp-n-family: As a member of this site for just about seven years I have never mastered the photo up load system. I wish there was a direct up load feature but there isn’t so I’ll just live with my limited abilities.

Nayther: Thanks again for your input. As it turns out, on my unit the very front spring mount on the front leaf and the very back mount on the rear spring are fixed, welded, and bolted. This location can’t move (only pivot).

However, I think you may be correct as that middle pivot could travel forward or backward far enough to let one spring shackle move and return to its original position.

If that were to happen then the two axles would be clearly out of balance with one higher than the other. Your comment helped me to re-examine my thinking and avoid a possible very unpleasant situation.

We do need to get together for that adult beverage. Now that I’m retired I should be around the same time as you’re in town. Just get me a shout.
Hap

[ScottG]

My TT actually had extra holes to do just as you describe. I lowered the bracket to the next hole because sometimes the tire would rub on the plastic fender. That was 4 years ago and it has worked out great. The trailer sits more level too.

[BobWanderer]

aemedic wrote:
When I was flipping my axles, I had the entire 5th wheel up on jack stands. While the axles were suspended above the ground all the shackles and springs settled in the lower position you described. When I put the 5th wheel on the ground they all moved back into the original position.

YEP

From someone who has worked on brakes and suspension for ~45 years.

Works on some cars & trucks, not on MOST trailers.

[aemedic]

When I was flipping my axles, I had the entire 5th wheel up on jack stands. While the axles were suspended above the ground all the shackles and springs settled in the lower position you described. When I put the 5th wheel on the ground they all moved back into the original position.

[nayther]

I don't think they would remain "flipped" Hap. I am aware of what you are talking about on a leaf sprung car/truck, I've done that before but the front of those leaf springs attach to a fixed location, trailers have shackles on both ends. Once the spring compresses far enough the shackle will "snap" back to where it was I believe. Mabye BobWanderer can confirm or offer advice as he's worked on a ton of heavy duty trailers.

We still need to get together for a cold beverage some day, heading up your way to Brown's on the Owens for the Fourth of July week.

[camp-n-family]

^This is why they say "a picture is worth a thousand words" 😉