TTB Long Travel Question

[Scott B.]

In an effort to increase the wheel travel of my TTB, I am about to change the shock mounts to F-250 towers and longer Bilstein shocks.

I also plan to change the (old, tired) Rancho spring for one with a lower, 300 - 325 lb. rating.

The question is, while I am at it, should I raise (or replace) the coil bucket to allow a longer spring to fit?

Will a longer coil spring yield more wheel travel?

 

[martin]

I believe you will have other interference issues before you need to be worried about higher spring buckets.

 

[Scott B.]

I believe you will have other interference issues before you need to be worried about higher spring buckets.

I understand this. Most of those have already been fixed.

I am asking specifically about longer springs.

 

[martin]

If you're putting in lighter springs they'll have to be longer to retain the same ride height so I guess the short answer is yes. whether you need to move the spring buckets or not depends on how much longer the springs are and how much they compress when the weight of the vehicle is on them.

 

[4x4junkie]

I raised the coil buckets on mine 2 inches.

I think a longer spring that is otherwise of the same rating would have a better fatigue life (you would be working the spring over a lesser percentage of it's overall length).

 

[Str8sixfan]

To me this has always been the pinnacle of the long-travel TTB, this one on an explorer, if you haven't already run across it yourself:

http://www.4x4central.com/zims.htm

I guess point is, I can't answer your direct question, but maybe some of your answers lie within that build.

 

[Scott B.]

To me this has always been the pinnacle of the long-travel TTB, this one on an explorer, if you haven't already run across it yourself:

http://www.4x4central.com/zims.htm

I guess point is, I can't answer your direct question, but maybe some of your answers lie within that build.

Yes, I've read about the Zimmerman truck. They were a very early adapter of the cut-and-turn, though they cut the beams in a different location than is popular today.

Unfortunately, I have not seen that truck person - I sure would like to.

 

[4x4junkie]

To me this has always been the pinnacle of the long-travel TTB, this one on an explorer, if you haven't already run across it yourself:

http://www.4x4central.com/zims.htm

I cringe every time i see that thing...

That guy no doubt had some great ideas (especially given as long ago as that was), however his execution had some issues. Not just that he cut the beams next to the pivots (his likely would've been better not having cut-&-turn beams at all), he, like some who've come along since, also failed to set the steering up properly (the result of which is clearly visible in the bottom pic on that link).
I seem to recall reading somewhere that he wound up giving up on it and swapped to a solid axle (likely because it was too scary to drive on the street and him not attributing it to the steering). May be why there hasn't been anything further on it since that article made it's initial rounds some 17 years ago.

 

[bobbywalter]

To me this has always been the pinnacle of the long-travel TTB, this one on an explorer, if you haven't already run across it yourself:

http://www.4x4central.com/zims.htm

I guess point is, I can't answer your direct question, but maybe some of your answers lie within that build.

that is the example of what NOT TO DO.


with that in mind study of it has merits.


its not a matter of what is now popular, because the right way to do long travel was in practice long before that abortion was built. a good decade before iirc...maybe more. the trs truck colors are based on the rough rider trucks that ran various versions of it.

 

[bobbywalter]

I cringe every time i see that thing...

That guy no doubt had some great ideas (especially given as long ago as that was), however his execution had some issues. Not just that he cut the beams next to the pivots (his likely would've been better not having cut-&-turn beams at all), he, like some who've come along since, also failed to set the steering up properly (the result of which is clearly visible in the bottom pic on that link).
I seem to recall reading somewhere that he wound up giving up on it and swapped to a solid axle (likely because it was too scary to drive on the street and him not attributing it to the steering). May be why there hasn't been anything further on it since that article made it's initial rounds some 17 years ago.

i have had shit tons of questions over the years based on discussion threads of that in various forums that yourself myself and several regulars participated in....that were years old at the time looking for clarifications.

its crazy.

 

[Will]

The problems are enormous. I broke a lot of parts getting the TTB to work. Longer springs--what does that mean? Tall springs don't matter. The length of the coil wire does matter. You need what you need. A coil that fits in the bucket and is the right thickness and number of loops to use all of the mechanical limits that the suspension has while supporting the truck at the correct height. When that is accomplished, the yokes have to be ground out so they don't bind and break, and the window in the axle has to be ground out so the shaft doesn't interfere with it. The shocks have to be positions, and selected, so they can work. The travel is different dynamically than statically. Even if it works on a ramp, it doesn't necessarily clear when you come bouncing down off of the bank of a creek.

Steering is a matter of lift more than floppiness of springs. It's a geometry thing. With just 3" lift brackets I got a ton of travel out of my suspension and made no modifications to steering. I ran my truck over 80mph with no problems on stock steering, and had other TRS people here that rode with me that will verify that. Our beloved administrator Ryan rode in my truck with 3 of my kids when I picked him up from the airport in Indy 10 years ago and we certainly hit 80. n9emz, though he might not be around anymore, did more than that with me in the truck more than once. More than 3", though, I would go with whatever advice 4x4junkie gives. I know for a fact things go rotten quickly on these trucks. Many, many steering problems we have seen over the years.

 

[Scott B.]

The problems are enormous. I broke a lot of parts getting the TTB to work. Longer springs--what does that mean? Tall springs don't matter. The length of the coil wire does matter. You need what you need. A coil that fits in the bucket and is the right thickness and number of loops to use all of the mechanical limits that the suspension has while supporting the truck at the correct height. When that is accomplished, the yokes have to be ground out so they don't bind and break, and the window in the axle has to be ground out so the shaft doesn't interfere with it. The shocks have to be positions, and selected, so they can work. The travel is different dynamically than statically. Even if it works on a ramp, it doesn't necessarily clear when you come bouncing down off of the bank of a creek.

Steering is a matter of lift more than floppiness of springs. It's a geometry thing. With just 3" lift brackets I got a ton of travel out of my suspension and made no modifications to steering. I ran my truck over 80mph with no problems on stock steering, and had other TRS people here that rode with me that will verify that. Our beloved administrator Ryan rode in my truck with 3 of my kids when I picked him up from the airport in Indy 10 years ago and we certainly hit 80. n9emz, though he might not be around anymore, did more than that with me in the truck more than once. More than 3", though, I would go with whatever advice 4x4junkie gives. I know for a fact things go rotten quickly on these trucks. Many, many steering problems we have seen over the years.

I was asking specifically about spring length, but since you expanded the discussion, I will talk more about my setup.

I am running Rancho drop brackets - 2 1/2" drop IIRC. They have been on the truck since 1995, have close to 300K miles on them, and have not given me the slightest problem (other than interfering with the oil drain plug on the 302 - but that is another discussion.) I am keeping these.

I will be replacing the Rancho radius arms and mounting brackets. The arms are fine, but I have reinforced both brackets. Unfortunately, they have a tendency to bend. And, I do not know where to get replacement urethane bushings (I think they are different than factory.) The plan is buy or build a set of arms with either Johnny or Heim joins, and mounts that incorporate a transmission crossmember.

I plan to keep the Rancho crossmember/passenger-side-drop-bracket-support, but will need to modify it to handle the additional front driveshaft movement.

I will open the passenger side axle opening in the beam, modify the axle yokes to allow for additional angular movement, and probably reinforce the beams.

I currently run extended brake lines (put new ones in when I did the '95 knuckle/brake conversion.)

And, longer shocks. Some flavor of Bilsteins. I would like to run the remote reservoir ones, but not sure the benefits for my situation warrant the cost.

Steering - not sure yet. Currently running stock TREs with a 2" drop pittman arm. This setup has worked well for me over the years. I know I need to improve it.

Let me know if I've forgotten anything (this came from memory, not my written notes.)

I think I will increase the loaded spring length. Doing so will give me longer coil wire, allowing more droop travel. Raising the upper mounting point should also allow a little more compression travel.

I don't plan on jumping this truck. I don't usually do as hard-core wheeling as I used to. But, the tough stuff is still fun, and increased wheel travel makes it even better!

 

[Scott B.]

I cringe every time i see that thing...

That guy no doubt had some great ideas (especially given as long ago as that was), however his execution had some issues. Not just that he cut the beams next to the pivots (his likely would've been better not having cut-&-turn beams at all), he, like some who've come along since, also failed to set the steering up properly (the result of which is clearly visible in the bottom pic on that link).
I seem to recall reading somewhere that he wound up giving up on it and swapped to a solid axle (likely because it was too scary to drive on the street and him not attributing it to the steering). May be why there hasn't been anything further on it since that article made it's initial rounds some 17 years ago.

In my effort to further my understanding of the TTB, can you elaborate on something?

Why is cutting the beams next to the pivots a bad idea? It looks to me that doing would require a longer center axle, and you could wind up with a narrower wheel track. But, won't the center u-joint run a factory (almost zero degree) angle when the truck is level?

I am thinking you need a much longer slip joint, since the pivot points have changed and the axle travel will change. But, will the u-joints bind since the angle of axle travel has changed?

Thanks.

 

[bobbywalter]

In my effort to further my understanding of the TTB, can you elaborate on something?

Why is cutting the beams next to the pivots a bad idea? It looks to me that doing would require a longer center axle, and you could wind up with a narrower wheel track. But, won't the center u-joint run a factory (almost zero degree) angle when the truck is level?

I am thinking you need a much longer slip joint, since the pivot points have changed and the axle travel will change. But, will the u-joints bind since the angle of axle travel has changed?

Thanks.

if i read that right, you answered your own question.


yes, changing the arc of travel in the manner of the zim thing you create a problem with axleshaft bind and slip engagement that was not there before, but it does leave static ride height pretty well unchanged, where the balljoint extension and no pivot drop method at 4 in of lift puts the inner joint at an angle from the start along with the outers. but these are well with-in operation limits.

but a balljoint ext with 3 in drop pivots and good radius arms and drop pitman will work much better at any speed with the 7 in of lift and stock steering linkages then that thing will. it was a great experiment, but with predictable results. more importantly, while predictable, they were also known and proven many many years prior to this....but that sort of development runs in a small circle pre internet.

this was just someone that took time to document a setup that was internet savvy, and its like a crater on the moon now. its just there....and wont go away.

of course there is a total separate debate that may as well be ford/chevy argument in many circles to this design.

 

[bobbywalter]

I was asking specifically about spring length, but since you expanded the discussion, I will talk more about my setup.

I am running Rancho drop brackets - 2 1/2" drop IIRC. They have been on the truck since 1995, have close to 300K miles on them, and have not given me the slightest problem (other than interfering with the oil drain plug on the 302 - but that is another discussion.) I am keeping these.

I will be replacing the Rancho radius arms and mounting brackets. The arms are fine, but I have reinforced both brackets. Unfortunately, they have a tendency to bend. And, I do not know where to get replacement urethane bushings (I think they are different than factory.) The plan is buy or build a set of arms with either Johnny or Heim joins, and mounts that incorporate a transmission crossmember.

I plan to keep the Rancho crossmember/passenger-side-drop-bracket-support, but will need to modify it to handle the additional front driveshaft movement.

I will open the passenger side axle opening in the beam, modify the axle yokes to allow for additional angular movement, and probably reinforce the beams.

I currently run extended brake lines (put new ones in when I did the '95 knuckle/brake conversion.)

And, longer shocks. Some flavor of Bilsteins. I would like to run the remote reservoir ones, but not sure the benefits for my situation warrant the cost.

Steering - not sure yet. Currently running stock TREs with a 2" drop pittman arm. This setup has worked well for me over the years. I know I need to improve it.

Let me know if I've forgotten anything (this came from memory, not my written notes.)

I think I will increase the loaded spring length. Doing so will give me longer coil wire, allowing more droop travel. Raising the upper mounting point should also allow a little more compression travel.

I don't plan on jumping this truck. I don't usually do as hard-core wheeling as I used to. But, the tough stuff is still fun, and increased wheel travel makes it even better!

your setup is well matched drop pit to pivot.


i disagree with Will because of the spring height comment has huge context needs. you seem to understand this clearly, loaded spring height is a key factor. BUT...you can increase loaded spring height and lower travel if your not paying attention. if the wire diameter is beefed you can actually have a two inch taller loaded spring with the same or less active coils that wont allow as much travel as a smaller diameter spring with more turns. but it will do a stout job at loaded ride height.


generally speaking, a 275-350 ppi coil is great for your proposed setup, and the longer the better if increased travel is the goal for both up and down. the longer the loaded rate the higher the bucket will have to be at ride height at a given load rate.

for this type of work, going with a mild rate is best done with single rate coils. the softer the spring the shorter its life in general for obvious reasons of wire diameter vs active coils.

there is a bit of trickery involved as well due to the different working lengths of the beams and the normal canted orientation of the ttb beam seats and coil buckets.

if you go too soft you will have to address it with some bags and custom spring seats to aim the springs in a manner they wont bow and pop out of position if you get too long of a spring. i was able to pull off travel that rivaled cut beams with uncut beams because i was willing to run the bags for a controlled variable rate.


so loaded ride height has to be balanced with wire diameter and coil count.

trust me, my e250 springs wont flex as well as my 4 in rc xj springs, even know they have almost a 1 in higher ride height at load.