Help me build my truck - What should I do?

[CountKrunk]

The end goal of my truck is family cruiser and hauler/towing as needed.

Don't want to worry about it breaking down on me and the fam.

 

[Hunter79764]

Added one more piece today, bought a set of secondhand ORD custom 4" front springs that were on a truck very similar to what mine will be, although I might have a little more front end weight with my heavy grill guard on there. I think I'll install them with the factory shackles, see what length I need based on actual height with the new setup, then purchase new shackles at that point. Seem like the right plan?

 

[chief_shotts]

I don't have a calculator here in front of me, but 37's with 3.73's and no overdrive is probably very comparable to stock tires, 3.73's and an overdrive trans.

It would also be a slug off the line

 

[chief_shotts]

For what it's worth my setup is 4.10, no overdrive and 35s. Cruising on the freeway is somewhere between 2500 and 3000 depends on traffic and my mood Ofcourse. That puts me somewhere between 60-70 mph. Aslong as your cab is sound proofed somwhat and you exhaust is done right there's nothing uncomfortable about cruising like this.

 

[Hunter79764]

It would also be a slug off the line

With 500 ft lbs and a 6.34 1st gear, I dont think it will be TOO sluggish...

Stock 3.73s and a TH400 with no overdrive and 32" tires with a 5.7 TBI is the baseline and highway is about the same as yours from the sound of it. Take off and cruising with this setup is "acceptable", and I'm pretty sure any axle with the 5 speed and the big block will improve off the line and trail driving, especially if I keep the doubler. I think I'm convinced that any of the available ratios will be OK, in dont need to specifically seek out 3.54's or 4.56's. Keeping 3.73 with 37s basically is a double overdrive with the 5 speed, at the expense of 1st gear being less of a granny gear and more of a true 1st gear. 4.56 pushes it back to a single overdrive and keeps 1st as a true granny gear. 4.10 is of course right in the middle, and I will be content with any of those 3...

 

[bucket]

Iirc, the 8.1l makes around 350lbs just off idle. It won't be ideal at all with that combo, but it should work.

I doubt you'll end up wanting to use granny gear all the time, for normal street driving.

 

[chief_shotts]

With 500 ft lbs and a 6.34 1st gear, I dont think it will be TOO sluggish...

Stock 3.73s and a TH400 with no overdrive and 32" tires with a 5.7 TBI is the baseline and highway is about the same as yours from the sound of it. Take off and cruising with this setup is "acceptable", and I'm pretty sure any axle with the 5 speed and the big block will improve off the line and trail driving, especially if I keep the doubler. I think I'm convinced that any of the available ratios will be OK, in dont need to specifically seek out 3.54's or 4.56's. Keeping 3.73 with 37s basically is a double overdrive with the 5 speed, at the expense of 1st gear being less of a granny gear and more of a true 1st gear. 4.56 pushes it back to a single overdrive and keeps 1st as a true granny gear. 4.10 is of course right in the middle, and I will be content with any of those 3...

My bad I was thinking turbo 400 first gear. You'll be more than fine with that.. infact you'll more than likely be shifting gears and passing Qs

 

[chief_shotts]

The shackle flip in the rear is a great upgrade btw. Just did it on my truck and I swear it rides a lot better over rough stuff now...

 

[Hunter79764]

The shackle flip in the rear is a great upgrade btw. Just did it on my truck and I swear it rides a lot better over rough stuff now...

What lift on the flip, and what shackle length? I just saw that they don't recommend the 4" lift with certain shackle combinations. I'll probably call when I'm ready and hear it direct from them, but it looks like I can do a 4" shackle flip and the standard length shackle, or the 2.5" flip and the 6" shackle and have the same overall height (I'm looking for about 4"), not sure which is preferable...

 

[Hunter79764]

Iirc, the 8.1l makes around 350lbs just off idle. It won't be ideal at all with that combo, but it should work.

I doubt you'll end up wanting to use granny gear all the time, for normal street driving.

I know you have some experience and have a pretty good handle on what I'm trying to accomplish... If I have my pick with the NV4500 and 37's, what ratio would you go for, assuming all else is equal?

I am leaning towards leaving the stock axles in place for now, getting it all running with the new drivetrain and lift, then swapping axles. I hate spending money twice, but I think the only cost will be possible driveshaft modifications and the larger U bolts? I can live with that if it means I'm up and running quicker, then I'll upgrade if/when I break something or find a screaming deal on a set.

 

[Grit dog]

The shackle flip in the rear is a great upgrade btw. Just did it on my truck and I swear it rides a lot better over rough stuff now...

I believe you. I’m about 90% sure that the short ass shackles on the front springs and the original everything on the rear springs minus a lift block are contributing a bunch to the buckboard ride of the K20.
I blame the springs because the rears are obviously stout (camper special) and the fronts appear to be rough country springs. But the fact that the front springs have a fair bit of sag with all the weight on them tells me they should be at least a little better than they feel over every pebble and acorn.

 

[chief_shotts]

What lift on the flip, and what shackle length? I just saw that they don't recommend the 4" lift with certain shackle combinations. I'll probably call when I'm ready and hear it direct from them, but it looks like I can do a 4" shackle flip and the standard length shackle, or the 2.5" flip and the 6" shackle and have the same overall height (I'm looking for about 4"), not sure which is preferable...

I have 2.5 flip. Stock shackles. 6in springs. Rides okay. Eventually I want to switch to 4 in springs and 6in shackles.


I've talked to ORD on the phone and read up on their literature available online.

What I've found is:

1. high arch (8in lift or more springs) will likely require the use of 6in shackles to prevent shackle inversion.

2. 4in shackle flip are used with standard sized shackles. And probably not a good idea to use the longer 6in shackles because it will cause excess body roll.

3. 2.5 in flip can be used with standard shackles for a 2.5 in lift or in conjunction with 6in shackles to gain roughly 3.5 -3.75 ish inches of lift (flip lift=2.5 in and shackle lift= [new shackle length- old shackle length] divided by 2)

4. 6 in shackles will allow more articulation of springs... especially if you have flatter springs

5. You are going to need the axle relocation plate that ORD sells because the shackle flip will move your axle forward they sell a 1/4 plate or a 1 inch zero rate that both do the same thing also. So that also factors into your lift height.

6. You probably need to shim axle for pinion angle.. I ended up needing 6 deg shims which probably add 1/8-1/4 in of additional lift maybe less idk for sure.

7. Shackle angle matters and ORD has it figured out for squarebodys so aslong as you buy from them everything should work nicely.

From the sounds of it I would think you should do 2.5 shackle flip and 6 inch shackles and then add in the 1in zero rate or 1/4 in relocation plate and you'll be hovering around 4in of lift with stock springs. I would probably do the 1 inch zero rate so you'd have a total of 4.5 in rear lift which in conjunction with 4 in front springs will either level or give you a tiny bit of rake ( depending on how squatted your suburban suspension currently is)

 

[chief_shotts]

I believe you. I’m about 90% sure that the short ass shackles on the front springs and the original everything on the rear springs minus a lift block are contributing a bunch to the buckboard ride of the K20.
I blame the springs because the rears are obviously stout (camper special) and the fronts appear to be rough country springs. But the fact that the front springs have a fair bit of sag with all the weight on them tells me they should be at least a little better than they feel over every pebble and acorn.

I believe ord front shackles are a bit longer to help stop the frame bashing that the really short og ones will do.

My truck had 6in shackles in the front when I bought it and they work nicely.. whoever did it shimmed the axle aswell to correct the pinion angle.

 

[bucket]

I know you have some experience and have a pretty good handle on what I'm trying to accomplish... If I have my pick with the NV4500 and 37's, what ratio would you go for, assuming all else is equal?

I am leaning towards leaving the stock axles in place for now, getting it all running with the new drivetrain and lift, then swapping axles. I hate spending money twice, but I think the only cost will be possible driveshaft modifications and the larger U bolts? I can live with that if it means I'm up and running quicker, then I'll upgrade if/when I break something or find a screaming deal on a set.

I like gearing for power. With overdrive and 37's, I personally would go with 4.88 or 5.13 gears. With no overdrive, I'd still go with 4.56 gears... maybe (just maybe) 4.10 if I wanted to attempt a little more economy. If you gear for economy with a big block, you loose more power than you gain in economy.

 

[Frankenchevy]

I believe ord front shackles are a bit longer to help stop the frame bashing that the really short og ones will do.

They are longer than most years. Either 87 or 88 the factory front shackles grew in length and are actually the same length as the ORD front shackles. So the OP may have longer front shackles, or he may’ve missed it by a year.