• Forum membership has its advantages....

How to spring a heavy truck?

PeteRock

Well-Known Member
I am just having a hard time seeing that truck weigh over 8000, that's more than most tt, and even fully loaded luxo prerunners. My chevy with a cummins does not even weigh that, my dodge diesel long bed 4x4 weighs around that.
 

jon coleman

Well-Known Member
aren't air springs/ shox very progressive?, i mean if you dont get geometry right , it could be worse?, i would move coil over 'a' arm mount to get it closer to optimum, looks like you got some wiggle room? no??
 

partybarge_pilot

Well-Known Member
aren't air springs/ shox very progressive?
All depends on how much airspace you give them. If you bottom out the IFP when you assemble them, then they will not be all that progressive.If you add oil to the resi so that the IFP almost bottoms out at full bump, they will be super progressive. But even without making them super progressive, running 150PSI in them would be like taking 600#'s off the front of the truck to the coils.
 

Bert is my name

Well-Known Member
Seeing a stock steering rack , brakes, frame, I have a hard time believing 8000 pounds. I would be fearful of pushing the stock components of your truck any faster than you are going if it truly is over 4000 on the front. Especially with those steering extensions and stock tie rods. You are asking for problems at that weight . From What I see in the pictures you have a grotesquely overweight truck. You have a proven kit up front . But you might be asking too much.
 

osidepunker

Well-Known Member
I am just having a hard time seeing that truck weigh over 8000, that's more than most tt, and even fully loaded luxo prerunners. My chevy with a cummins does not even weigh that, my dodge diesel long bed 4x4 weighs around that.
Seeing a stock steering rack , brakes, frame, I have a hard time believing 8000 pounds. I would be fearful of pushing the stock components of your truck any faster than you are going if it truly is over 4000 on the front. Especially with those steering extensions and stock tie rods. You are asking for problems at that weight . From What I see in the pictures you have a grotesquely overweight truck. You have a proven kit up front . But you might be asking too much.
Thanks for all the comments guys, I sincerely appreciate the help and advice here.

My truck does weigh a lot. And recently I added a little over 100 lbs in additional weight by switching to steel skids. But you have to understand that a tundra really is built well. I mean, the damn axle is 10.5" gearset. Plus, I have modified the truck to handle the additional weight. I have boxed the rear half of the frame and added a very large bed cage. I have reinforced the front cross member and tied the frame ends together with a bumper that has double walled frame horns. In the rear, the stock toyota leafs were 2" wide, I redid the leaf hangers and switched to 3" wide leaf packs and had Jeff build me custom long travel packs for my specific weight. I have been beating on this truck hard for years now. Yes, I had to repair some misc things like the front diff mounts cracking, the trans crossmember cracking etc. But every time I break something, I fix it stronger. This truck has been VERY reliable and I have crossed miles and miles of extremely rugged terrain and I am NOT gentle on it. If you're curious you can check out my youtube, osidepunker (I don't care about followers). I have a few examples in there of exactly what I put this truck through. This is the weight before the new skids:

Screenshot_20190823-045018_Gallery.jpg


I'd try an 18" spring before considering an air-bypass.
So I thought about that. But I don't know how that will actually play out. If a 16" coil binds, does an 18" in the same rate bind as well?

So cut down a longer one and weld a uniball cup on the end.
hmmm That sounds very doable. I don't do welding, do you have a recommendation for a shop willing to try something like that?

Also, disregarded my spring rate estimate. You would need to use the spring rate spread sheet to really nail it down. 150psi=300 pounds of force. Rate will be determined by the air space.
Doesn't sound too hard. All I have to do is make sure I set the IFP properly and then just play with the pressures until I have the correct sag.

aren't air springs/ shox very progressive?, i mean if you dont get geometry right , it could be worse?, i would move coil over 'a' arm mount to get it closer to optimum, looks like you got some wiggle room? no??
Its probably a good thing that they are progressive since I have a large motion ratio.

I don't have room at the LCA, the lower mounts have to stay where they are. But I am playing with the idea of relocating the upper mounts and switching to a 10" shock. I'm just not sure if I should spend the money on that or go 3.5" over, full custom arms and redo the whole thing.
 

osidepunker

Well-Known Member
So I changed the coilover stacks to a single flutter, all 15s, 1.8, then 0.020 spacer, then 1.8, 1.6 etc I also added a 1.8x15 rate plate

Bypasses are 4.3.2 all 20s with a rate plate. I had to use red loctite on the stover nut because not enough threads, but I've done that in the past and it holds up.

So far its pretty soft on the street, a little bouncy but pretty comfortable and not something I can't live with. I haven't had a chance to get it in the dirt yet.

Question: I am looking at the eibach specs for my coils, 1600.300.0800. It lists block height as 8.15" With preload set for my ride height, at full extension the coil measures roughly 15". Does this mean that with a 7.5" travel shock I am going to bind these springs???

I'm going to Johnson Valley this weekend so I guess I'll find out haha
 

osidepunker

Well-Known Member
ok, thats good news lol

Should I do the same rate, 800lbs in an 18" or jump down to 700 lbs??

Current: 16" 800# block height 8.15"
18" 800# block height 9.76"
18" 700# block height 9.09
 

osidepunker

Well-Known Member
You have roughly 1" of preload now. So 18-8.5=9.5 if you had a block height of less than 9.5, you would be golden.
Well, but that one inch of preload is with 800# rate. So if I understand this correctly, minus 1" preload, minus 7.5" shock travel, means on an 18" 800# coil the block height of 9.76" is too much and I would still bind.

So I could consider jumping down to a 700# which has a 9.09 block height, but I would need more preload so I might still have the same problem

fml
 

partybarge_pilot

Well-Known Member
Exactly, like I keep saying, you are at the limit of what a 3" coil will do. If you went up to a 3.5" coil, you would be better off.
 

osidepunker

Well-Known Member
Exactly, like I keep saying, you are at the limit of what a 3" coil will do. If you went up to a 3.5" coil, you would be better off.
Ok, thanks for all the help man, I really appreciate it. We'll see how it goes this weekend and maybe I'll get serious about changing my bypass shaft. 3.5 coil wont fit, it'll interfere with the axle and tie rod
 

osidepunker

Well-Known Member
Exactly, like I keep saying, you are at the limit of what a 3" coil will do. If you went up to a 3.5" coil, you would be better off.
Ok, thanks for all the help man, I really appreciate it. We'll see how it goes this weekend and maybe I'll get serious about changing my bypass shaft. 3.5 coil wont fit, it'll interfere with the axle and tie rod
 

chatter_splatter

Well-Known Member
Just throwing this out there, but Viper makes a spring that is 17" tall and 900lb/in with a block height around 8.5". Could be the perfect spring for your truck.

I'm thinking with the 900lb spring you can pull some valving out of the coilovers and rely on the bypass and spring rate for bottoming control. Could soften up the small stuff.

Give Jim at FOA a call and ask about the 17" 900lb spring.
 

osidepunker

Well-Known Member
Just throwing this out there, but Viper makes a spring that is 17" tall and 900lb/in with a block height around 8.5". Could be the perfect spring for your truck.

I'm thinking with the 900lb spring you can pull some valving out of the coilovers and rely on the bypass and spring rate for bottoming control. Could soften up the small stuff.

Give Jim at FOA a call and ask about the 17" 900lb spring.
Actually they have lots of options! I don't think I should go up to 900# because when I switched to 800# thats when it got stiff. I really wanted 750#, but eibach didn't offer that. Viper shows a 750 but their website links are all broken. Where did you get the specs from??
 

chatter_splatter

Well-Known Member
Actually they have lots of options! I don't think I should go up to 900# because when I switched to 800# thats when it got stiff. I really wanted 750#, but eibach didn't offer that. Viper shows a 750 but their website links are all broken. Where did you get the specs from??
Gotta call Jim at FOA and he can look them up. Yeah the website isn't awesome haha.
 

osidepunker

Well-Known Member
Update: After tearing through Johnson Valley a couple weeks ago I took apart the coilovers and the coils are not binding. I think my uptravel was limited when the kit was installed so my coilovers are not bottoming out all the way. In any case, I'm not gonna fix what isn't broken. I'm on the right track with my valve stacks. I have a single flutter in the coilovers and I can feel them doing work in the whoops. The truck is much more controlled and feels much safer in the bigger stuff. The flutter is keeping soft on the streets and the bypasses are taking the big hits in the bump zone. I have a few minor tweaks and "experiments" I want to try, but I'm going to start working on the rear stacks now. I have a similar problem in the rear, the middle of the stroke isn't doing much. But the rear is different, I don't have a coilover to work with. I do have 3" air bumps. So my plan is to treat them like smooth bodies. I'm going to close the tubes all the way and put in some aggressive stacks with a single flutter. I'm going to start with a 3.2.2 with a 8 face shim. I am hoping it will be smooth on the street and stiff on the bigger stuff. Then I will start to open up the tubes juuust a little until it smooths out and feels controlled on the whoops. I will have the air bumps for bottom out control. I also changed the rebound stacks from a 70 to an 80. I have a little donkey kick that I am trying to eliminate:


Any comments criticism and help would be greatly appreciated. I am starting to feel more confident making these changes and I am closer to getting it truly dialed. I cant believe I waited all these years to start working on shim stacks haha
 
Top