Rear Suspension Mod's For Big Blue?

[Gary Lewis]

I'm seriously considering modifying the rear suspension on Big Blue by removing some leafs out of the springs and adding air bags in an effort to get the ride a bit less harsh.  (Removing the sway bar links helped, but it is still quite harsh.)

I think Vernon may have had heavier than standard springs installed as these have 7 leafs and what I can find in the catalog says there should be 6.  And nothing I've put in the bed or on the trailer has dropped the rear ride height much at all.  So, while it is nice to have the ability to carry lots of extra weight, running around with that capability 100% of the time is getting old.

Air Lift has their LoadLifter 5000 system that is a bolt-on.  But with its 5000# capability it is a lot more than I need since the springs are supposed to have about that capability.  So, if I pull a few leafs out and get the springs down to ~3800#, which is the lightest spring set for an F250, I'd only need a max of 2000#.  I've written Air Lift to see if they have a lighter-duty set that will fit, but from what I can see they use this one for F100's through F350's, so I'm betting they'll say "This is it."

Anyway, what do y'all think of this plan?  How many leafs would you take out to start with?  (In theory I could take out almost all of them and use the air bags to get the load capacity.)

Also, what about take the spacer block out if the ride height doesn't come down enough?  The spacer block is circled in red, below.

[Ford F834]

Gary, 7 springs definitely seems excessive. My F350 has 5 plus the 6th factory overload that only contacts the extra brackets when squatting. The ‘81 F150 2wd springs are also 5, but only 2.5” wide. The donor 4x4 had 4 leafs that were 3” wide... and someone added overload leaf packs to it (probably for hauling firewood).

I really can’t speak to airbags, as I have never owned or used any. If it were me, I’d try 5 like my F350 and see if that improves the user experience without the airbags. I like how it rode, but it has a longer wheelbase. Still, it was quite smooth for a 1-ton. If it’s still too harsh go to 4 leafs like the 4x4 F150 and add the air bags if you need the capacity. I think you might be pleased, however, just going from 7 to 5. The F350 spring pack with the auxiliary 6th spring might be another option to air bags? Not to “bag” on them, but I’ve not heard anything good about air bags from guys who do off-road.

[Gary Lewis]

First, clarification: Big Blue has 6+1, meaning 6 leafs in the main pack and the 7th factory overload.

But, I could try 1 less in the main pack w/o the air bags, and then drop another if I think it is warranted.  And then add the air bags if needed.  Good idea.  

What about the air bags did the guys not like?

[Ford F834]

Okay, so big blue has the auxiliary factory overload? I’ve not noticed it on F250, but I’ve never really looked either. Do you know if subtracting springs acts the same as the next smaller set? They are not dynamically matched as a pack that needs to stay together?

On the air bags, the main complaint I’ve heard is ruptures from grit getting in the seams and rubbing through. Like I said, I have no first hand experience or knowledge of which products these were, but that’s what I have heard. The other complaint is restriction of articulation but on a 8 lug truck that hardly applies.

[Gary Lewis]

I don't know if subtracting springs in a pack is similar to a smaller or lighter set.  Here's BB's springs, and if I were to take two out I think I'd take the 2nd and 4th from the top.

As for the air bags rubbing, I can see that if they had no air in them they might rub.  But if they had some air in them then wouldn't the air keep them opened up so they wouldn't rub?

Thoughts?

[1986F150Six]

I am all about limiting expenses, so I vote for removing 1 or 2 leafs as a beginning. Your time and labor will be involved, but not your wallet!

[Gary Lewis]

I think that’s probably the best plan. Just pulling the u-bolts that hold the pack to the axle and then pulling the retaining bolt should let me slip a couple of leafs out. And that is I’ll let me know if it makes an appreciable difference.

[85lebaront2]

I may have to go look closely at Darth, I count 5 leaves + the extra short leaf on top from the pictures. Mine is supposed to be 7400 lb rear and I know it takes a bit to even get close to the overload spring. Maybe that's why I don't think Darth rides that bad.

[Gary Lewis]

I still see 7 leafs.  What am I missing?

[85lebaront2]

You can count! Amazing! I was saying what I have, if you want from the same angle it will have to wait probably until Thursday. But here are some when I was swapping rear axles.


As you can see, my overload springs are on top and the frame has a pair of angles with rubber pads that come down to sit on the overload leafs when needed I think if you go back and look at the spring chart for both Big Blue and Darth you will probably find Big Blue is way oversprung.

[Gary Lewis]

Oh, yours!  Ok, now I understand.  But, no need for further pics as I can see what you have quite well.  And it appears that Big Blue a bigger spring pack than Darth does.  But, I'll take some measurements tomorrow and maybe you can check my measurements against Darth's to help me understand if that is really the case.

[Ford F834]

Gary, mine has an upper overload like Darth. There is a spacerbetween the rest of the spring pack and the upper leaf which I do not see on Darth’s, but mine is 4x4. As mentioned it does take a LOT to squat it to where the extra leaf contacts the stops on the frame, and in my opinion it rides quite nice. Here is another horrible pic but you can see it if you look:



And a couple from google images in case any future reader needs clarification:

[Gary Lewis]

Interesting.  Yours doesn't have nearly as much spring as Big Blue has, but then he doesn't have the overload spring on top.  And I don't think he has the stops on the frame for the overload either.

I do have the stops from Dad's truck, which have already been powder coated but not installed as there's no overload spring on Dad's either. I've been thinking about not installing them and saving the weight as they are quite heavy.  So, if I decided I needed the overload and found the springs and spacers I could, potentially, use those stops.

[Rembrant]

Gary Lewis wrote

I am zero help with the springs, but that Trickflow diff cover is a nice piece! I was eyeing them up for my 8.8, and they get rave reviews from those who have installed them.

Carry on...I'll stay out of the spring discussion;).

[Gary Lewis]

Thanks!  That is just one of the many, many things that Vernon had installed on this truck.  

[85lebaront2]

Here are a couple more pictures, there is a block between the main spring pack and the overload. What it appears to be is a 3 stage spring. 4 of the 5 main leaves are used empty and light loads, either the 5th leaf or the upper overload (I would have to load the bed until one or the other made contact, but I believe the upper was first from towing the 5th wheel) finally the very stiff 5th leaf makes contact with the main pack.

[FuzzFace2]

Gary, what are the tires pumped up to?
Max PSI is for Max load I say lower the PSI for a good ride / handling and keep the springs.
Dave ----

[Gary Lewis]

Dave - The max pressure on these Load Range E tires is 80 psi, and I'm running them at 40 so I don't want to take them any lower.

Bill - Your pack is similar to Jonathan's with the overload on top.  That's a good approach and I might consider that if I were to find the overload spring and block.

As for what springs I have, I'm not sure.  I've measured what I have and they don't match up to any in the catalog.  Here are the oddities I've found:

Big Blue's rear GAWR is 5922, which would suggest the springs should be rated for ~2961 lbs.

His rear spring code is "K", and that means he should have E3TZ 5560-T springs, which were replaced by E7TZ 5560-A's.  But neither of those codes show in the catalog

His rear axle itself is rated at 6250 lbs

The current spring pack has 4 leafs that are 23/64" thick, 1 that is 5/16" thick, and then the bottom one that is 9/16" thick.  The whole stack is 2 5/8" tall and the springs are 3" wide.

General Spring says that Big Blue should have 3100 lb springs, and theirs have 6+1 leafs and are 3" wide and 2 5/8" tall.

So it would seem that I do have 3100 lb springs on the rear.  And while that is just right to load the rear axle up, I don't need to do that very often.  So I want to try pulling a couple of leafs out.  We'll see what that does.

[Ford F834]

Gary, I hope that works. I think it will take stiffness out of the ride. If you like the result, then consider going with the F350 set up and the extra spring on top. I think the only time mine contacted was when hauling gravel. It did squat easier than my old brown ‘81 F250 with overload springs, and that was reflected in the ride quality. That F250 was a rough riding son of a gun with that extra spring pack. The extra upper spring on the F350 is plenty. I once had the guy at the quarry load me up with crusher fines that were still fairly wet after a rain. As he tilted his loader bucket the whole scoop plopped out instead of gradually pouring in as intended. The truck had the full 8 foot bed filled to the bed rails and a peak in the middle that was higher than the cab 😬. And yeah, these were wet crusher fines that were fine enough to cake together. The springs didn’t look bad at all, it was the tires that I was worried about. They were flattened out pretty badly, but I only had a couple miles to go and I kept it under 20 mph.

[Gary Lewis]

I would like to find the overload setup for Big Blue as that should be just the right combo.

But your story reminded me of much the same experience.  Back in probably '73 we had a winter storm coming into Wichita, so I took my '72 F250 to the quarry to get sand.  It was cold enough that the sand had frozen together, and when it finally let loose the whole scoop dropped into the bed.  It wasn't as much as you got, but it was a lot and the suspension was well into the overloads.

This was in the days of 16" split rims with skinny tires.  I could twist the steering wheel back and forth and the sidewalls would take all the flex.  In other words, the truck would turn but the tire patches didn't, and we kept going down the road straight for a bit.