Issues With Big Blue!?!?!

[Gary Lewis]

....

• Some guy that thinks he's Nothing Special: .... The beam won't let the axle end move front to back and the spring greatly resists right to left, so the suspension binds up.

One thing I had at least a little wrong back then is that the beam actually does let the axle move front-to-back. That's why coil spring TTBs still work so well, even with a radius arm. But a radius arm does allow the axle to move right-to-left, and I'm still confident I'm right about a leaf spring fighting that, so overall I still stand by what I said then.

....

• Diesel Brad: .... If you want a great ride with MINIMAL lift go Solid axle and RSK. It is unbelievable how smooth they ride And it adds 1.5" to the stock height of a F350 with the proper springs

Keep in mind that's adding 1.5" to a stock F-350, which already rides about 2" higher than a stock F-250. I think Big Blue might already have a front lift, so I'm not saying you'll be lifting him 3.5". Just trying to clarify.

Bob - I had assumed that there was some flex in the bushings, if not the TTB itself, that lets the axle move a bit. And I can see that the springs can act as torsion bars and twist. Plus there's flex in their bushings. But there's just no way to get around that the geometry of the 4wd F250's front suspension is just ... wonky.

I've frequently wondered why so many people bad-mouth the TTB's. But I was thinking of the F150's TTB's, not that of the F250's. And now that I have thought about the difference it is night and day. With coil springs TTB's make sense, but add a leaf spring and they just don't.

And then there's the ride. I was originally giddy about getting Big Blue and then getting him running. And even after driving him for a bit I assumed that the horrible ride was just the way "big trucks" ride. Then I rode in a later F350 and was blown away with the ride.

My mind is made up, so please don't confuse me with any more "facts".

As for the lift, I don't think BB has one. I really thing everything under it is stock. However, 3.5" in front will level him out with the current rear springs, so when I pull some leaves out I may have to bring the rear up a bit. But I'll wait to worry about that until I get everything together and find out how it sits.

Anyway, our plans for the day have changed. We are under a severe thunderstorm watch and the National Weather Service has just raised the threat level for us, with large hail, high winds, several inches of rain, and tornadoes likely. So, I'll be making my calls and will postpone the trip to 4wd Parts until tomorrow or even Wednesday.

[Steve83]

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

[ArdWrknTrk]

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

With the inverted leaf the wheel base change is negative.

Camber change is limited because of the lack of travel to the bump stop.

As is caster.

Because the rear of the spring is the pivot while the shackle up front allows the spring to retract.

(negative arch springs)

But those spring and pivot bushings take a real beating due to the twisting motion in both planes.

Where as the solid axle suspension of the 350 just acts on the bushings normal to their axis.

[Nothing Special]

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

Gary, if we should quit littering your thread now that you've made up your mind, feel free to let us know. Otherwise...

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

You're not wrong about the wonky steering geometry changes with a coil sprung TTB. But overall the changes don't tend to be significant, at least in terms of how they work in a street-driven truck (with minimal wheel motion) or in a desert racer (with lots of wheel motion, but driven on relatively forgiving surfaces as far as steering geometry is concerned.

But with the leaf-sprung TTB, the rear half of the leaf spring acts essentially like a radius arm, forcing the outer end of the axle to move fore-and-aft as it moves up-and-down. And with the essentially flat spring at ride height, that "radius arm" actually gets shorter as the wheel moves up or down, so it pulls the axle back even more than a radius arm would. So if anything, even just the rear half of the leaf spring is worse than a radius arm.

By even worse than that, the leaf spring also has a front half. As the axle moves up-and-down the axle swinging around its pivot makes the spring pad move right-to-left. The rear end of the spring is fixed to the frame so the front end of the spring tries to move right-to-left twice as much as the spring pad. But the front end of the spring is also tied to the frame through the shackle. That's why the leaf spring TTB is fighting itself, and why I believe it inherently can't give good wheel travel.

[Gary Lewis]

With the inverted leaf the wheel base change is negative.

Camber change is limited because of the lack of travel to the bump stop.

As is caster.

Because the rear of the spring is the pivot while the shackle up front allows the spring to retract.

(negative arch springs)

But those spring and pivot bushings take a real beating due to the twisting motion in both planes.

Where as the solid axle suspension of the 350 just acts on the bushings normal to their axis.

Yup, there's so little travel that nothing can change. I can't even slide my pointer finger between the bump stop and the spring as the knuckle is too large. And I've measured my knuckle at less than 3/4". While the bump stop isn't directly at the axle, so there's more movement at the axle, and there is twisting motion that may account for a bit more, I can't see more than 1 or 1 1/2" of wheel travel at most. I'm not a fan.

Anyway, here's the morning update:

• The lady at Mingo Salvage does not have any SuperDuty springs

• The D60 that I found on eBay, but which is close to me at Catoosa, is really a 4.10 instead of the 3.54 as advertised.

• The D60 in OKC that Shaun found is a 3.54 and has the tie rods on it, but there is nothing else with it.

  They do not have the track bar, the track bar bracket/mount, the driver's side u-bolt plate, nada. (So, what do they do? Pull an axle and crush the rest of the stuff that is absolutely necessary for a swap?)

So I think Jim's plan is the best: Work on what I have and keep my eyes open for a complete F350. Maybe one with a bad engine or tranny. Or that has been wrecked. That way I'll have all the parts and won't have to piece this thing together.

[ArdWrknTrk]

Yup, there's so little travel that nothing can change. I can't even slide my pointer finger between the bump stop and the spring as the knuckle is too large. And I've measured my knuckle at less than 3/4". While the bump stop isn't directly at the axle, so there's more movement at the axle, and there is twisting motion that may account for a bit more, I can't see more than 1 or 1 1/2" of wheel travel at most. I'm not a fan.

Anyway, here's the morning update:

• The lady at Mingo Salvage does not have any SuperDuty springs

• The D60 that I found on eBay, but which is close to me at Catoosa, is really a 4.10 instead of the 3.54 as advertised.

• The D60 in OKC that Shaun found is a 3.54 and has the tie rods on it, but there is nothing else with it.

  They do not have the track bar, the track bar bracket/mount, the driver's side u-bolt plate, nada. (So, what do they do? Pull an axle and crush the rest of the stuff that is absolutely necessary for a swap?)

So I think Jim's plan is the best: Work on what I have and keep my eyes open for a complete F350. Maybe one with a bad engine or tranny. Or that has been wrecked. That way I'll have all the parts and won't have to piece this thing together.

Gary,

Do you know anybody that goes to insurance auctions?

Does anyone in your church know anyone?

Usually vehicles that will be up for auction are listed.

So you could give them a model and year range and a bid cap, see what they turn up.

 

[Gary Lewis]

Gary, if we should quit littering your thread now that you've made up your mind, feel free to let us know. Otherwise...

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

You're not wrong about the wonky steering geometry changes with a coil sprung TTB. But overall the changes don't tend to be significant, at least in terms of how they work in a street-driven truck (with minimal wheel motion) or in a desert racer (with lots of wheel motion, but driven on relatively forgiving surfaces as far as steering geometry is concerned.

But with the leaf-sprung TTB, the rear half of the leaf spring acts essentially like a radius arm, forcing the outer end of the axle to move fore-and-aft as it moves up-and-down. And with the essentially flat spring at ride height, that "radius arm" actually gets shorter as the wheel moves up or down, so it pulls the axle back even more than a radius arm would. So if anything, even just the rear half of the leaf spring is worse than a radius arm.

By even worse than that, the leaf spring also has a front half. As the axle moves up-and-down the axle swinging around its pivot makes the spring pad move right-to-left. The rear end of the spring is fixed to the frame so the front end of the spring tries to move right-to-left twice as much as the spring pad. But the front end of the spring is also tied to the frame through the shackle. That's why the leaf spring TTB is fighting itself, and why I believe it inherently can't give good wheel travel.

Bob - There's no reason to quit talking about this. I'm not in the least worried about the thread, so please have at it.

However, let me say that your analysis is good theory. But, it is theory only since there isn't enough up/down movement of the axle to write home about.

Seriously, what I found in the spring/bump stop clearance boggled my mind. That is absolutely insane.

[Nothing Special]

.... However, let me say that your analysis is good theory. But, it is theory only since there isn't enough up/down movement of the axle to write home about.

Seriously, what I found in the spring/bump stop clearance boggled my mind. That is absolutely insane.

I think the lack of travel is because of what I'm theorizing about. Effectively the spring has to get a LOT stiffer as the axle tries to push it from side to side, so the "progressive" spring would stop moving pretty soon, even if the bump stop wasn't there. The bump stop might be as close as it is to prevent the spring from being stressed too much (but that's just speculation on my part).

I know that a very few people ('89F2urd being the only one I know of) have good experience with lifted leaf spring TTBs. And I know that my own experience with my '97 shows that they can be acceptable in stock form. But I still maintain that the design is terrible, even if it works well enough in some applications. (If Ford had only put coils springs and radius arms on the '80 F-250 and F-350 TTBs...)

 

[ArdWrknTrk]

Gary, if we should quit littering your thread now that you've made up your mind, feel free to let us know. Otherwise...

With coil springs TTB's make sense, but add a leaf spring and they just don't.

I think it's opposite, because they didn't just "add a leaf spring". They also deleted the radius arm, which is why the TTB's motion was so wonky to begin with. With radius arms, the hinge lines are diagonal (from the axle pivot through the RA bushing, but NOT along either's axis); with leaf packs, the hinge lines are parallel to the truck's axis (straight through the axle pivot bolt). So with leaves, there's almost no caster change through the wheel's travel; with radius arms, the caster, camber, toe, track width, and even WHEELBASE changes through the travel.

You're not wrong about the wonky steering geometry changes with a coil sprung TTB. But overall the changes don't tend to be significant, at least in terms of how they work in a street-driven truck (with minimal wheel motion) or in a desert racer (with lots of wheel motion, but driven on relatively forgiving surfaces as far as steering geometry is concerned.

But with the leaf-sprung TTB, the rear half of the leaf spring acts essentially like a radius arm, forcing the outer end of the axle to move fore-and-aft as it moves up-and-down. And with the essentially flat spring at ride height, that "radius arm" actually gets shorter as the wheel moves up or down, so it pulls the axle back even more than a radius arm would. So if anything, even just the rear half of the leaf spring is worse than a radius arm.

By even worse than that, the leaf spring also has a front half. As the axle moves up-and-down the axle swinging around its pivot makes the spring pad move right-to-left. The rear end of the spring is fixed to the frame so the front end of the spring tries to move right-to-left twice as much as the spring pad. But the front end of the spring is also tied to the frame through the shackle. That's why the leaf spring TTB is fighting itself, and why I believe it inherently can't give good wheel travel.

Gary already has an unlittered thread going with his thoughts and plans for what to do and how to do it.

[Gary Lewis]

Gary already has an unlittered thread going with his thoughts and plans for what to do and how to do it.

Jim - Yes, I have an unlittered thread, so I'm not worried whatsoever about continuing the conversation. In fact, it will probably help others who might be considering what to do. So, keep on truckin'!

As for someone in auctions, I don't know anyone. But, I do know someone at church that is an insurance salesman, and he would probably know. Good idea!

Bob - I agree that '89 is about the only person I've seen on any forum pushing the TTB's in an F250. F100's and F150's yes, but not F250's. And now I see why.