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52" compared to 56" springs

J

Jester1

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Ok I know this has been discussed to death in one way or another. But I am looking for more of the math side of this.

This is a 73 k5 with stock drivetrain 350/350/203 44 front 12 bolt rear.

What I am using is a 2 1/2" shackle flip (Ord) and have access to both 52 (74 pickup) and 56 (89 suburban) springs. I am also installing 3" tuff country's up front. May do a zero rate (most likely) or 1 body pucks for a true 4" lift. This will not be a crawler or a purpose built. It will only have 33/35" tires on it. This is an all around for weekend fun trail riding, going to the lake with the boat, getting into back country fishing spots, hunting, top off sunshine summer time cruiser/expo type rig that will have dirt and gravel under the chassis 50% of the time. Right now it rides like a lumber wagon (broken stock springs wore out frozen shocks) and I want a better ride, but I also want better travel and articulation out of the rear. I do not want to lose towablity with the boat or my light travel trailer 24/26'.

What say you as far as ride, to towability, backcountry travel. How much more articulation travel will I get with the 56 swap and what can I expect for shock length if I relocate the mounting for possible up travel? Worth it or not? What lenght of shackles can I expect to need for both?
 
I'm running 56" rear springs with Ord flip
Significantly more axle droop and articulation.
Brake line next next extension, CV shaft, bumpstop need to be addressed.
Limit straps, antiwrap may be needed as well
 
Was considering anti wrap for sure after a few test runs. And knew about brake lines but didn't consider a cv shaft. So there is that much change? If you could give it a number for change would you say twice as much droop 1/3 more.

I kind of have the mechanics of the swap I am looking for some numbers.to get a better feel for it before I tear it apart.

Did you change shakle length at all for the swap and what length are you running.

How about towability?
 
From what it sounds like, I would stick with the 52"s. I have 56"s and I don't feel as comfortable towing as I did before. Too much body roll and sway. This is using a 7 leaf pack + overload flipped over out of a Burb. Running 6" shackles. I also have a rear sway bar, which helps with drive-ability when it's connected.

This is an off road truck first, cruiser second, and towing if it's something my S10 can't tow. I can still fly past most people and can easily get speeding tickets on any street/freeway/mountain road/etc. But I don't see it being stable enough to tow. Maybe it's just me and somethings wrong, dunno.
 
When I talked to Chris at Ord he said towing would be affected by the shackle flip but nothing to major or unsafe, but that was when it was just 52's. I know it just the nature of the beast when you start changing the geometry of suspension. I was hoping it would not be amplified by longer springs. I am still trying to maintain a lower cog by keeping it to a true 4" with3" spring and zero rates. I have had lifted trucks in the past that towed fine, but this is my first go with flip and longer springs.


I would say the most I would tow is the rv fully loaded 3000 lbs (water, food, gear, gen set, yada). My boat may be all of 1500 lbs. So not a bunch. If it gets heavier than that I would hook up with one of my 1 tons.
 
I'd use the 52s at first. The old bushings being froze up and hard can limit your travel and give a harsh ride. Use the greaseable bushings when you change the springs. If your still not happy with it after that it shouldn't be that hard to change to 56s. Good shocks will play a big part in keeping it stable while towing too. Gm went from 52s to 56s then 64s on there trucks and tow just fine.
 
Subscribed as you are doing what my long time plan has been with my 78! Im planning on just running some half ton 56's without the shackle flip and just using 3" bolcks. THink about towing something with a 93ish pickup. It would be fine right? so why wouldnt it be fine to sap them onto our older trucks. I think the stability problem comes when you do the shackle flip. And i know that even my 90 3/4 ton suburban with the 56 rears, all stock, flexes like a mofo!

I do think that a better ride could be had with the shackle flip.I had also considered just doing the 56's, 2.5" shackle flip, and adding a rear sway bar but i plan on almost never really towing with mine.

FWIW, My '12 GMC has the 63's. It has only 2 main leafs and an overload leaf. It tows great and rides like a caddy.
 
my 56's in Mutt ride amazing... it needs an anti-wrap tho.... it'll pound the wheels thru the flatbed if I really get into it...
 
Yeah, tension shackle vs compression shackle.

My 56s are nearly flat. 5100 Bilstein shocks. 6" shackle with 4" flip. 38" Toyo, rear sway bar, and locker. Blazer wheelbase :/

When I get the itch to change, I will got 2.5" flip, 2.5" lift 56" springs, repositioned centering pin. (I run 0rates and moved both axles) Total of 5", to match existing.
 
Yep rears. I am planning on diy heavy shackles 1. Cause I like them and 2. With the flip I know they are stout and want to make sure the side to side movement is as secure as possible. I know the standard tied shackles are good but I have seen the twisted factory one and the standard strap ones tear twist or break.

I knew the 56" would ride well (thanks Paul) but on trucks the fulcrum to lever location is different. Trucks having the longer adventage to counter squat or waggle for pivot point while towing.

Also planning on geasable rear bushings but not sure up front yet with having new rubber ones in the tuff country's. I know it will take out some flex but a not yet needed expense.

Also planning on bilstiens all around and doing something like the ford towers or hoops for travel not hardcore. And possibly shock centering crossmember in rear more stiff.

There are of course some trucks on here I am using as mentors and I am happy to say the guys that are giving me ideas are chiming in.
 
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I guess I am really trying to figure out the actual distance gained by 56" compared to 52".

If say on 52" your droop is 8" and up travel is 6" then how much more is it with 56's. I run a lot of gravel roads and love the rear in my dmax and 90 3500 but have owned a76 and 78 truck with 52's that I had to put sandbags in the keep from rattling your teeth out on gravel and for traction on snow cause the rear end felt light.

Also taking into account trucks are spung heavier for load but as of now that's how the k5 feels because it was ordered factory with the HD rear end (6 leaves w/overload) and 12 bolt.

I am probably being a bit OCD with this, but math and numbers make sense to me as compared to "it's way more flexy". To many years setting up dirt bike suspension I guess.
 
I think the main problem is that 56s aren't all the same between years, weight ratings etc etc. No one can tell you exactly what they'll do, especially since truck weight will also come into play. They'll flex more in theory, but I can't tell you how much more
 
Good point. Since I have both I think that I may try the 56's as long as I can stabilize them. Read flexy not floppy. When I get closer I will call on the awsome all knowing Ord and diy as to how best maximize my plans with there products.

Although with 56's I may want to stay with 33's as not to stuff a tread into the tub. Then again I am not above some tasteful trimming. I can always slide the axle aft 1.5" with zero rates.

Next question brought up in this thread was a cv rear shaft. Is it absolutely necessary with the longer springs or a might be. I know when you go to the 6" lift it can be but a 4" I wouldn't think. Any opinions on this? My intrest it more to mellow out the stutter effect on long gravel roads. Any obstacles wont be taken at speed, my understanding was the cv was for vibes from pinion angle after lift. I dont see how longer springs will vary pinion.
 
Some people get away with regular driveshafts @ 4" lift and some don't. 6" lifts for sure unless you're willing to drop the T-case and hassle with other stuff.

The issue isn't the 56s, it's the shackle flip. With the flip, the axle yoke tends to rotate upwards. So....you either shim the hell out of it or run a CV and leave it be. I am not running any shims in the rear as the yoke points perfectly at the T-case. I'm also running 0rates with the axle back 1.5". Looks much better in the wheel well.
 
So you have a standard driveshaft octane?

That sounds like it is going to work out then. I may plan to change the 203 tc for something else down the road so if I can get through a couple years with this setup it will work.

I tend to take way more time thinking and getting info and parts together for a project than I takes me to do it. Works well as I rarely ever have to stop for lack of parts or problems.
 
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