I have a dual spring rate / lift height puzzle for you...

[alwaysFlOoReD]

Pretty good information, but it gave me a motion ratio of 0.70.

Beam mount to spring mount / Beam mount to wheel center

So I still have to dive more into this 1.5 leverage issue.

If you flip the ratio it works pretty close. I'm guessing that is what is happening to get the 1.5 ratio.

 

[Jim Oaks]

I got it...

Leverage = Beam mount to wheel center / Beam mount to spring mount.

 

[Jim Oaks]

If you flip the ratio it works pretty close. I'm guessing that is what is happening to get the 1.5 ratio.

Ya, I went outside and took a measurement. Pivot to spring mount is 30 and it looks like pivot to wheel center is 43, so it calculated out to 1.43.

 

[alwaysFlOoReD]

And if you measure the other side, I bet you get slightly different numbers...

 

[lil_Blue_Ford]

Whoa… alright, you all have my interest… especially because I’m gonna be dealing with springs again before long… definitely interested in seeing how this all goes.

So, my F-150, back when I built it up, I bought progressive coils for an F-350 for the front. I even ran load shocks that had a coil spring on the outside until they blew out, but like @bobbywalter mentioned, it didn’t seem to take super long before the close windings were in contact all the time. I was really disappointed with that. But maybe just indiscriminately buying progressive F-350 coils wasn’t the right answer.

Also, @Jim Oaks , I remember the brackets. I was toying with the idea of seeing if they were available not too long ago actually. I wouldn’t mind seeing them reproduced again, give me some time to scrape up money. I forgot about the diff cover actually. I’m also actually in the market for a diff cover for the 8.8 in my Choptop because I now have a locker to stuff in there and I don’t really want to put the factory tin foil cover back on. Any chance some could be produced soon?

 

[Jim Oaks]

I don't know. I'd have to find a shop willing to cut them from the drawings. If I did this, it would probably be a weld them yourself thing. Most serious off-roaders can either weld or has a buddy that can weld. So, it makes this stuff a lot cheaper than paying for me to have someone weld them. And I assure you, you don't want me welding them. I need a lot more practice. I'd like to get the set that @alwaysFlOoReD has so I can compare the individual pieces to the drawings to see what if anything Joel changed.

I just found this thread of him showing the brackets:

CopyKat's Copy Cat B4 | Page 19 | Ford Explorer Forums - Serious Explorations

I have to admit, it kind of annoys me that he took all of the credit for the design. I designed the drivers beam bracket around the Skyjacker bracket but beefed it up.

EDIT: Nope, strike that. Those are his D44 brackets. I didn't have anything to do with those.

 

[4x4junkie]

There's been many times I've searched the internet for something, and it brought me right back to here. I just saw a post where a guy was talking about TTB and said he found the information on another site, and he as quoting @4x4junkie article HERE.


@alwaysFlOoReD I actually posed this question to ChatGPT but didn't ask it as well as you did. So, garbage in, garbage out. LOL. Maybe you should ask it to explain the 1.5 leverage of the TTB and what effect it has on spring rate.


The point in all of this is trying to give people some guidance when trying to figure out how much lift their going to get from a coil spring and what to expect. But I didn't know how to address progressive rate springs.


I have to admit, I was a bit surprised when JD told me their springs were 385/650. 650 seems like a really high rate.


Ok @4x4junkie I'm going to throw a few more questions at you:


1) Why would the second rate be so high for a Ranger?

You had me going for a bit there Jim, I couldn't remember writing an article titled "Is The Ford TTB Suspension Really That Bad?"... But I see now that it is the forum Sticky "Is a SAS the only option?" lol. Nicely done transferring it to the Tech articles (title change seems appropriate too).

As for the rates, I'm a little surprised JD told you at all... I remember they once were real tight about their stuff, even to the point of refusing to sell you individual lift components unless you could prove that you had previously purchased one of their kits.

The best guess I have is the higher rate is a leftover relic from when common shock absorber technologies were what they were 25-30 years ago (twin-tube dampers, none of which had reservoirs, many not even gas-charged, clunky dual & triple-shock kits being the way to get more damping). Compared to the shocks of today (Fox, King, and even cheaper offerings such as Skyjacker ADX and Rough Country Vertex) they offered little damping control, especially during fast compression. A progressively stiff spring likely was the answer back then if you wanted to go fast and/or catch a little air.

2) I'm trying to understand why we're only using the lower rate. Is it because the section of coil with the 650 PPI rate won't compress at all because the weight is being absorbed by the coils rated at 385 PPI? Is that weight not transferred through the whole coil?

The weight is transferred through the entire length of the coil. The different spacings between the windings is irrelevant to the spring rate up until only that point when the closer-spaced windings begin to touch. At that point the spring is then working at the higher of the two ratings.

Back in 2006, glfredrick posted on Pirate4x4 (HERE) "Before you just go throwing a bunch of springs at the TTB suspension, you have to know a little bit about the geometry of that suspension. Each different type of suspension has a different amount of leverage needed to support the weight of the vehicle. An SAS (full width axle) is a "longer lever" than a TTB. That means that the carrying capacity for the springs needs to be less on an SAS than on the TTB."


I looked at coil spring rates between a Ford F-150 Dana 44 and Dana 44 TTB and didn't see any big differences between spring rates. I went back and looked at the load rates, and a 1985 Ford F-150 coil spring has a load rating of 1,428 and a 1979 Ford F-150 coil spring has a load rating of 1,700.

A 1428 load rate for a TTB coil vs 1700 for SA does seems backward to me also. Load rate was something I never did fully quite grasp... I came to the conclusion that it was simply a number used for the suspension to be set to a certain ride height, had nothing to do with what the maximum the spring could actually support was (I may be wrong on that).

But if you look at the specifications you have for spring rates on your coil spring chart (assuming they are directly from the manufacturer), it infact does show a Skyjacker F-150 6" TTB coil (623PPI) is 171PPI stiffer than the F-150 6" SA coil (452PPI). Interestingly, that number for the TTB coil is almost exactly 1.4× higher than the number for the SA coil... It was 1.4:1 that I had figured for the fullsize (F-150/Bronco) TTB leverage ratio (this due to the longer beams and the spring being slightly closer to the wheel relative to the pivot).
I'd check for the same for TTB Ranger coils at 1.5×, but alas, no SA Ranger to compare it to lol.

Junkie, you replied in that conversation with "Multiply the sprung weight by 1.5 (TTB beam leverage), then divide by 2 (this will be the amount of weight each coil will be supporting)." But I haven't been able to support that by finding Dana 44 TTB coil springs with higher spring rates than a Dana 44 live axle. I'm not saying you're wrong, I was just looking for a reference to 'show me' so that I could actually understand it.

I would really like to understand this more and what importance or effect that it has.

That had nothing to do with determining the leverage ratio itself.
What that was, was a set of equations to be able to find the amount of weight the coil spring itself would be subjected to based off your vehicle's weight, so you could then select a suitable spring based on it's free length & spring rate.

Determining the leverage ratio is (like you stated, post #48) simply finding the mid-point along the TTB "lever arm" where the spring is mounted in relation to the pivot axis, and the tire's contact patch.
In actuality, it goes a bit deeper than that because the pivot axis actually runs diagonally from the beam pivot over to the radius arm bushing (and this is where that diagram I once had would've come in handy). It's been forever & a day, but I seem to recall the ratio might've been closer to around 1.48 or so (just barely under 1.5).

With stock radius arms, both sides of the suspension (pivot axes) actually are symmetrical with each other (so there would not be a leverage ratio difference between the passenger & driver sides). The passenger beam being shorter was mostly to account for the fact the beam pivot was located further rearward along its diagonal pivot axis than the driver side (well, and differential pumpkin clearance too). Extended radius arms actually distorted this symmetry slightly, but not by enough to be significant.

(hopefully you were able to follow all that... The TTB certainly was an engineering marvel )

 

[Curious Hound]

Wow! What a discussion. Some day, i'll need to read all this again and take notes. As I mentioned above, I had become aware if how the ttb parts related. But I never figured out exactly how to put the math to it. This is great.

 

[lil_Blue_Ford]

I don't know. I'd have to find a shop willing to cut them from the drawings. If I did this, it would probably be a weld them yourself thing. Most serious off-roaders can either weld or has a buddy that can weld. So, it makes this stuff a lot cheaper than paying for me to have someone weld them. And I assure you, you don't want me welding them. I need a lot more practice. I'd like to get the set that @alwaysFlOoReD has so I can compare the individual pieces to the drawings to see what if anything Joel changed.

I just found this thread of him showing the brackets:

CopyKat's Copy Cat B4 | Page 19 | Ford Explorer Forums - Serious Explorations

I have to admit, it kind of annoys me that he took all of the credit for the design. I designed the drivers beam bracket around the Skyjacker bracket but beefed it up.

EDIT: Nope, strike that. Those are his D44 brackets. I didn't have anything to do with those.

I’m fine with welding my own. Let me know if you decide to go for it. Maybe there’s a member on here with a plasma table that would cut them out for members?

 

[Jim Oaks]

I’m fine with welding my own. Let me know if you decide to go for it. Maybe there’s a member on here with a plasma table that would cut them out for members?

Honestly if I did it would probably be a while. The thought of it literally just entered my head. I just dug up the drawings and would have to build a set for myself to make sure they work ok first.

 

[Jim Oaks]

Wow! What a discussion. Some day, i'll need to read all this again and take notes. As I mentioned above, I had become aware if how the ttb parts related. But I never figured out exactly how to put the math to it. This is great.

This topic has literally created four new tech pages that I'll be posting links to tomorrow.

But while we're brainstorming.... we need to dive into the coilover suspensions on the new Ranger, and for anyone that might want to replace coil springs with coilovers on on the old Rangers.

 

[Jim Oaks]

As for the rates, I'm a little surprised JD told you at all... I remember they once were real tight about their stuff, even to the point of refusing to sell you individual lift components unless you could prove that you had previously purchased one of their kits.

I emailed them and asked them the free length and spring rate. They replied with the length. I replied back and asked them the spring rate and they sent it to me.


Here's something interesting I've found in my research:

A 2005-2023 Ford F-250 coil spring has an O.D of 4.764" which is pretty damn close to the Rangers 4.840" and smaller than the F-150's 5.44" and early Bronco 5.25". Its free length is 16.00" which is 2.25" taller than the Ranger's 13.75" free length.

Obviously, the downside is that it's got a higher rate of 589 ppi (I had trouble finding rates, but that was a stock rate I found) which is higher than the Ranger's 430 - 485 ppi, but that might be OK if you've done a V8 swap.

Factoring in the increased spring rate, I could see where a stock F-250 coil would give someone a 3.50"-3.75" lift. You might end up with a 5.5"-6" lift using a 1.5-inch lift coil.

Also discovered that the 1980-1996 Ford F-150 coil had a lower spring rate than the Ranger, but the extra 2.25" in length gave it a higher load weight to support the truck.

 

[SenorNoob]

Does that mean lift coils for the 80-96 F150 would be softer than Ranger coils?

 

[Jim Oaks]

Does that mean lift coils for the 80-96 F150 would be softer than Ranger coils?

The numbers say yes. Providing the numbers I've found is right.

Below is a F-150 coil and Bronco II coil (similar to Ranger). They appear to have the same number of coils with the difference being that the F-150 coil is a little wider and a little thicker.

​

Ranger Coil:
0.67 wire diameter
4.17" mean (width center wire to center wire)
8 coils
= 488 ppi

F-150 Coil:
0.71" wire diameter
4.73" mean
8 coils
= 422 ppi

So why is the bigger coil softer?

If we change the mean of the F-150 coil from 4.73" to 4.17" it changes the spring rate to 616 ppi.

The F-150 coil has a lower spring rate because the coils are spaced out wider than the Ranger coil.

Now, I don't know any of this from experience. I'm just going by the numbers.

EDIT: Lift coils are different. From what I found, a Skyjacker 6-inch coil for a Ranger is 435 ppi, a 6-inch coil for a 1985 F-150 is 623 ppi, and a 6-inch coil for a 1979 F-150 is 452 ppi. @Curious Hound is using that 1979 6-inch skyjacker lift coil. There are clearly different numbers with the aftermarket coils over stock.

Maybe someone with F-150 coils will chime in.

 

[Jim Oaks]

New Articles:

1983-1997 Ford Ranger Coil Spring Guide

Understanding Leverage On A Ford TTB Suspension

How To Calculate Motion Ratio For A Ford TTB Suspension

Mounting Early Bronco Coils To Your Dana 35 TTB