Rear Suspension Mod's For Big Blue?

[Gary Lewis]

Evan - The springs were replaced by the previous owner, and I don't know exactly what they are.  However, my measurements say they are the right size for the GVWR of the truck.  But, that doesn't mean that I like the ride.  So, I'm wanting to pull some leafs out, but then either install overloads or air bags.

Bill - I fully agree that Blue Jeans is softly sprung.  In fact, it really needs air bags in the rear to do the best job of towing, but it gets the job done.  But it isn't a serious truck like Big Blue is.

MOPAR flathead six?  I grew up driving one of those in a '54 Plymouth.  Not too strong, but you couldn't hurt it no matter what you did to it.

Poly 318?  You are the only one I know that would build one of those.

[85lebaront2]

MOPAR built some pretty big flat head 6s, you have to remember prior to 1951, most MOPARS were flat head 6s. a few 8s, but mostly 6s and Chrysler had a 265 ci one through 1954, Plymouth's biggest was a 230 ci. The bigger 6s were longer head length. and can be built, not like a stovebolt or Ford 240/300 and not quite to the Hudson Hornet level either, but can be built for some power.

[Gary Lewis]

Why not the Slant-6?

[82F100SWB]

Even with the same spring count, those leaves are going to be stiffer than the stock ones as they don't taper out at the end like the factory ones do, and the individual leaves look to be thicker as well.
Pull leaves until the ride suits you and then use airbags or the likes for carrying capacity.
Bags are good but absolutely make sure you keep 10-15 psi in them or they will eat themselves.

I've often contemplated building something along the lines of a Peterbilt low air leaf for my truck, and I do believe there is/was a company building a similar setup that wasn't a small fortune.

[85lebaront2]

Width of it, M37 hood is pretty narrow at best, even the Poly motor might be pushing it, BTW they were built in up to 354 ci in the 1957 lower line Chryslers, sold as the Spitfire with the Hemi being the Firepower in either 354 or 392 ci. As far as I can find, the blocks were pretty much the same, just the heads were different. The Poly engine was to save some of the cost of the Hemi by eliminating the second rocker shaft, it also is narrower than the Hemi as the exhaust valves are near vertical.

[Gary Lewis]

Evan - That's basically my plan when I can get to it - pull leafs until I like the ride, and then go back with overloads or air bags.  I'll still have the capacity when needed, but will have a much more reasonable ride all the time.  (I don't understand - Ford used the same spring pack in the F350's and just added overloads.  Why not use a lighter spring pack in the F250's with overloads?)

Bill - Early Hemi's are WIDE!  I remember seeing an early Dodge pickup at Carlisle many years ago that had an early Hemi sticking way out of the engine compartment and they had to leave the side panels off the hood to clear the valve covers.  So I can understand not getting them in.  But I don't remember my Slant 6 being that wide in the Valiant, although I guess it was.

As for the flathead six, did the Spitfires have an aluminum head?  Something tells me they did.

[85lebaront2]

The Spitfire 6 I believe did, the Spitfire V8, no.

[82F100SWB]

The over 8500GVW F250's were pretty much F350's rear suspension wise, minus 2" of block. My 96 F250 and 350 have the identical spring code, both trucks have overloads.
The overloads however were an option on both models.
Really missing my literature right now. Lost all of my brochures and manuals in a fire back in March.

[Gary Lewis]

The loss of the literature is a pity.  Glad I have the majority of mine on line.

As said in a previous post, we have the following trucks with the same "K" spring code:

'85 F250HD regular cab rated at 5922 lb GAWR w/a 6250 lb axle and LT 235/85R16E tires (Gary's)

'86 F350 crew cab rated at 6084 lbs GAWR and with a 6250 lb axle and LT 235/85R16E tyres  (Jonathan's)

'86 F350 crew cab DRW rated at 7400 GAWR and with a 7400 lb axle and 4 215/85R/16D tyres  (Bill's)

The '83 dealers facts book shows the F250HD as having the same frame as an F350.  So the only difference in the rear would have been the 7400# axle vs the 6250# axle on the F250 and the overloads.  But with the additional weight of the crew cab and heavier axle the F350 probably rode better than the F250.  Or, said another way, the F250HD rides the worst of all the trucks.  

Oh, and mine has the 2" block shown below.

[82F100SWB]

I did have a considerable amount of my stuff scanned and online, but alas, when the server, your desktop and all three laptops burn you really wish you had of opted not to host things yourself.

The 84+ F250 extended cab 4x4 is essentially identically speced as an 80-85 F350 with a shorter rear block, extended cab of course automatically made it a HD.

I can tell you without a doubt my crew cab F350 does for the most part ride better than my extended cab F250, and the ex cab really doesn't ride much different than my regular cabs did, but the solid axle doesn't handle short sharp bumps and washboard nearly as well as the TTB due to the front shackle setup being designed for the TTB's inverted leafs.
 A set of super duty front leafs and a shackle reversal alleviates that problem.

Another option for the rear is to go to 08+ Super Duty springs. They are 8" longer than our stock ones and a longer leaf is going to ride and handle sharp bumps much better.
We won't even talk about how I have my Dodge sprung so soft I had to put the sway bar back on, but it will still bounce you out of the seat on washboard because the 48" long front springs just can't handle it.

[Gary Lewis]

I'm happy hosting this forum and the website elsewhere.  I do back up my machines routinely, but it would be devastating to lose the website or forum.  

I've wondered about doing the shackle reversal on Big Blue, but want to get the rear sorted before I worry about the front.  Maybe I'll get to try the rear mod's in a few weeks.

[Nothing Special]

Gary Lewis wrote

.... I've wondered about doing the shackle reversal on Big Blue, but want to get the rear sorted before I worry about the front.  Maybe I'll get to try the rear mod's in a few weeks.

I haven't really heard of anyone doing a shackle reversal on a leaf spring TTB.  As I understand it was designed for the solid axle F-350 (which, as 82F100SWB noted, had shackles that were designed for the TTB anyway).  And originally the kit manufacturers said that their kits shouldn't be used on TTBs.  Later on they started saying that the kits could go with TTB, but no one seems to know what changed that made it now a good idea (speculation I've heard is that what changed is the kit manufacturers desire to increase sales began to outweigh their desire to sell a good product, but that's just internet speculation).

And on a solid axle at least a shackle reversal lifts it about 2".  So keep that in mind before swapping if ride height matters to you.

[Gary Lewis]

Interesting.  Hadn't heard/seen that they didn't recommend it early on.  Maybe I don't want to do it.

But, I wouldn't mind another 2" of height in front - unless my leaf-removal exercise drops the rear quite a bit it is much higher in the rear than the front.  But, as noted, I can remove the 2" spacer block in the rear to drop it some if needed for air bags.

[Ford F834]

My understanding of the RSK is that the monobeam F350 have positive arch leaves. When they flex, they extend in length. With the hinging shackle in front, it has to pivot against the direction of travel (=direction of impact) and results in a harsher ride. Moving the hinged shackle to the rear makes the flex smoother as it pivots with the direction of impact). TTB on the other hand have negative arch springs. When they flex, they shorten in length. This pulls the hinged shackle toward the rear, which is already the correct direction when traveling forward to achieve the best ride. There may be more to it than my simplistic understanding, but I would not do RSK on a TTB. Even if it ~did improve the ride, the lift would need to be compensated by a drop of the beam ends, and the springs are not symmetrical. I wonder how moving the shackle could affect the geometry and alignment of the axles? If I really hated the leaf spring TTB ride, I would probably do a SAS with reverse shackle. Independent suspension with leaf springs is rather self defeating in my opinion, and you would probably get a better ride out of a RSK’d monobeam. That said, I never had any complaints about the ride of my stock F350, and I don’t have any immediate plans to RSK it.

[Gary Lewis]

Good explanation, Jonathan.  Thanks.  I'll leave well-enough alone.

[82F100SWB]

Another reason not to change the shackle design on a TTB truck is the stock A frame shackle; which on a solid axle truck defeats the side to side axle locating inherent to a normal leaf spring design and requires a panhard bar, is designed to allow the spring to twist and follow the arc of the axle beam during suspension travel.
I'm not sure how a standard shackle setup would ride with a TTB.

[Gary Lewis]

I'm sold.    It is what it is in the front, and while it is stiff, with the sway bar end link off it doesn't hurt your teeth.  Prior to that you saw bumps coming and got prepared.

But the rear, even with that link disconnected, hurts your neck.  And a trip to Colorado from here to Ouray, which will be 1700 miles w/o the side trips, doesn't sound like as much fun as it would be with a bit less spring.  Plus, the stiffness can't help traction when traversing the mountain backroads.