Issues With Big Blue!?!?!

[Steve83]

...the strange contortions the TTB geometry make it go through. As it moves it not only flexes like a normal leaf spring, but it also gets pulled sideways, a direction in which it is VERY stiff.

But it's really not moving much in that direction; the distance from the pivot to the spring center times (1- the cosine of the the travel angle). And none of that force affects the ride - it all gets applied between the pivot bushing & the 3 spring bushings (2 eyes & shackle). Without calculating any of it, I assume twisting the spring pack through the travel angle has a much-higher impact on effective spring rate than any lateral bending (which I don't think actually happens).

In any case... I'd say a coil spring suspension will always ride better than a leaf. I was working on a '97 F350 2WD duallie a few days ago; and I was shocked at how well it rode with a 4" lift & crappy mud tires (even before I did some repairs to the suspension).

https://supermotors.net/getfile/1149429/thumbnail/b4.jpg

https://supermotors.net/getfile/1149428/thumbnail/frsusp.jpg

[ArdWrknTrk]

Jim - Good point. Progressive springs is an aspect of the discussion that we've not covered, and which makes it more complicated. From what I remember of the 250 springs there are two full-length leaves. Do the 350 springs, and presumably the SD springs, have different length leaves?

I'm going to guess that the 250's lack of allowable travel forced Ford to use a single-rate spring. It had to be STIFF to ensure it doesn't hit the stop all the time. But with more allowable travel the 350 springs could be softer initially and then stiffen up as you near the stop....

Whether the F-250 spring rate is linear or progressive isn't easy to see at first glance. By the look of it it would seem to be not nearly as progressive as the F-350 spring. But keep in mind the strange contortions the TTB geometry make it go through. As it moves it not only flexes like a normal leaf spring, but it also gets pulled sideways, a direction in which it is VERY stiff. I don't have any equations to support this (thankfully!!!), but I think the effective spring rate has to get a lot higher as it gets pulled around. (Which probably explains why the stiffness I calculated seemed too high. I was thinking about the stiffness in the normal bending direction which is likely lower than I calculated. It's the actual stiffness that I calculated, and as I just hand-waved here, that must be significantly higher than the "normal" stiffness. So using an F-250 spring on a solid axle probably isn't as completely stupid as my first calculation indicated. But it's still likely significantly stiffer than an F-350 spring, just not 2.5 times stiffer.)

I have to agree with Steve here.

The springs are trying to twist but because of the thicker (relation to the 350) leafs, rubber bushings at each end of the spring and the pivot I doubt there is enough to enter the equation.

This is why I discounted it before.

[FoxFord33]

'97 F350 2WD duallie...4" lift & crappy mud tires...

I work at a tire and service shop, and I don't understand... Other than maybe "what a good deal on these mud tires," but to go through a lift to support said tires baffles me. Are they planning to convert to 4wd? Not trying to ridicule, but honestly discussing my feelings about it; I feel that a thing should be used in the way it was designed. I have had to swallow that feeling many times at work while putting M/T or A/T tires on a 2wd vehicle.

[ArdWrknTrk]

'97 F350 2WD duallie...4" lift & crappy mud tires...

I work at a tire and service shop, and I don't understand... Other than maybe "what a good deal on these mud tires," but to go through a lift to support said tires baffles me. Are they planning to convert to 4wd? Not trying to ridicule, but honestly discussing my feelings about it; I feel that a thing should be used in the way it was designed. I have had to swallow that feeling many times at work while putting M/T or A/T tires on a 2wd vehicle.

Duallie's are are often used to haul stock, hay or water trailers around.

They have a hard time moving even on damp grass, let alone cow slop.

I can understand the want for any traction available in a farm vehicle.

If it's used for a car or travel trailer then the owner is compensating for an endowment issue.

(Just want to clarify that that was in NO way meant as a dig at Steve, just an explanation as to why some of your customers may want AT or MT tires on a dually.)

[85lebaront2]

Duallie's are are often used to haul stock, hay or water trailers around.

They have a hard time moving even on damp grass, let alone cow slop.

I can understand the want for any traction available in a farm vehicle.

If it's used for a car or travel trailer then the owner is compensating for an endowment issue.

(Just want to clarify that that was in NO way meant as a dig at Steve, just an explanation as to why some of your customers may want AT or MT tires on a dually.)

I bought the same tires the counties here use on the school buses, they are Firestone Transforce 8 ply if I remember correctly and are capable of carrying more than Darth is rated for. Fronts are now 4 1/2 years old and still have excellent tread.

[Gary Lewis]

Duallie's are are often used to haul stock, hay or water trailers around.

They have a hard time moving even on damp grass, let alone cow slop.

I can understand the want for any traction available in a farm vehicle.

If it's used for a car or travel trailer then the owner is compensating for an endowment issue.

(Just want to clarify that that was in NO way meant as a dig at Steve, just an explanation as to why some of your customers may want AT or MT tires on a dually.)

I'm reading the mail, but spending most of my time on the phone. Here's the nid-day update:

• Brandon/Bruno2: Honda runs like a sewing machine. Call Richard at Axle Transmissions & Transfers.

  And talk to David at Harmon's.

• Axle Transmission & Transfers: No D60's. "They go as fast as they come in."

• Midway U-Pull: No trucks like that at present, but they think they recently bought an F350 like that and don't know if it is 4wd as it isn't in the inventory yet. But, I signed up to get a text if they get an '86-'97 F350 in stock.

• Harmon's: No D60's. But they may have a double-cardan yoke for the BW1345. Will check and call back.

• Big D: Boss man is out chasing 9" parts. Will have him call when he get's back.

• Midwest Expedition Outfitters: No Dana stuff. We usually do Toyotas. Call Big D. Told him 'bout the website and forum and he said "You don't have a 9" pumpkin in 3.55 do you?" Guess what my response was. But, as a clue, he thanked me.

• Jon Stittsworth/JStitts: Jon's in the insurance industry. Said to call George W. Smith Salvage City, Ada. And call Square Deal Auto Parts.

• George Smith: Don't think so, but will call back after checking.

• Square Deal: Don't have anything like that.

 

[1986F150Six]

I'm reading the mail, but spending most of my time on the phone. Here's the nid-day update:

• Brandon/Bruno2: Honda runs like a sewing machine. Call Richard at Axle Transmissions & Transfers.

  And talk to David at Harmon's.

• Axle Transmission & Transfers: No D60's. "They go as fast as they come in."

• Midway U-Pull: No trucks like that at present, but they think they recently bought an F350 like that and don't know if it is 4wd as it isn't in the inventory yet. But, I signed up to get a text if they get an '86-'97 F350 in stock.

• Harmon's: No D60's. But they may have a double-cardan yoke for the BW1345. Will check and call back.

• Big D: Boss man is out chasing 9" parts. Will have him call when he get's back.

• Midwest Expedition Outfitters: No Dana stuff. We usually do Toyotas. Call Big D. Told him 'bout the website and forum and he said "You don't have a 9" pumpkin in 3.55 do you?" Guess what my response was. But, as a clue, he thanked me.

• Jon Stittsworth/JStitts: Jon's in the insurance industry. Said to call George W. Smith Salvage City, Ada. And call Square Deal Auto Parts.

• George Smith: Don't think so, but will call back after checking.

• Square Deal: Don't have anything like that.

Time for a cup of Joe.

 

[Gary Lewis]

Time for a cup of Joe.

Lol! NO! I've had three cups of Joe today and my tummy is NOT happy. Just took a Tagamet and a "few" Tums.

The guy from George Smith called and they don't have a D60. But he said to call another outfit. And that guy said they have a few in C&C's with DRW's but they are "worn out". They want $650 for them. But, obviously, they'll have the wrong hubs and probably the wrong ratio.

However, he says they have an '88 F350 SRW w/TTB's and 3.54. We discussed that a bit with me saying it really should be a D60 as TTB's (he called them "the scissors suspension") were not used in the F350's. He's gone to look and is to call back.

[ArdWrknTrk]

Lol! NO! I've had three cups of Joe today and my tummy is NOT happy. Just took a Tagamet and a "few" Tums.

The guy from George Smith called and they don't have a D60. But he said to call another outfit. And that guy said they have a few in C&C's with DRW's but they are "worn out". They want $650 for them. But, obviously, they'll have the wrong hubs and probably the wrong ratio.

However, he says they have an '88 F350 SRW w/TTB's and 3.54. We discussed that a bit with me saying it really should be a D60 as TTB's (he called them "the scissors suspension") were not used in the F350's. He's gone to look and is to call back.

Maybe a cab swap on a rotten 250?

Otherwise,.

[Gary Lewis]

Maybe a cab swap on a rotten 250?

Otherwise,.

No more info. No returned calls. Just lots of robo calls.