I've seen a couple threads talking about moving your rear springs to the front and using 63" Chevy springs with the 5th leaf in the back, but I haven't really seen why this is preferred over stock springs. Is it something you really only see any benefit out of when going SOA? Whatever the answer to that question; is it something that'd be good for a DD rig? I assume that both the rear spring AND shackle mounts would have to be moved to allow for a spring that's 16" longer than what's originally there.
Just something else new (to me) that's got me intrigued....
Kling-on is right; the springs are a lot longer, the move or flex more, which results in a LOT more movement of the axle whcih provides for a much softer ride....maybe too soft in some situations, but the articulation is awesome!
When set up well, it should be good for most conditions including DD'ing. Kling-on's plan to add air bags to his rears would only be another plus, too.
That's what I've gathered. LONG springs under the axle can add to clearance issues. I'd like to see in on a SUA rig though before I ruled it out. Pave the way Spook!
My buds that rock crawl with 63" Chevys have to buy them 10 pair at a time. Either my buds are playing too hard, or 63" Chevys are on the frail side of life?????
My buds that rock crawl with 63" Chevys have to buy them 10 pair at a time. Either my buds are playing too hard, or 63" Chevys are on the frail side of life?????
Do you know if they're using the 5th leaf in their packs? I would imagine not since for crawling I would think they'd want the most flex they can get.
Butt, that's exactly what I was thinking. If it's something I'm going to want when I go SOA (which it sounds worth it), I'd like to go ahead and do it (if possible) while still SUA, just to save myself another step when SOA time comes.
I run a set on the rear of my Mini. I used the longest 4 leaves of a 5 leaf pack. Second best mod that I ever made to that truck. (First was dumping the Rancho shocks and going to mono-tubes.)
I'm guessing that if they are rock crawling with them that they are allowing them to go negative arch. In the case of the GM's their leaves are flexible enough that it is easy for them to kink at the spring perch. Nothing kills a leaf spring faster than a combo of allowing them to go negative arch and allowing them to kink. Max spring life is when you limit the travel such that the spring has at least 1 inch of positive arch remaining in it.
I used the GM O/L leaf under the GM pack, placed upside down. Now the spring 'rolls' down onto the O/L leaf and can't kink at the perch, but the O/L really doesn't ramp up the spring rate in the process. A local 4x4 shop owning friend taught me that one.
Something that I've never seen mentioned about the GM 63's is that they have an unusual feature in their assembly. There are shims between each pair of leaves. Those shims make sure that the leaves don't touch except at the tips and create friction. The tips have anti-friction plastic sliders as do the keepers. I had to go up from Bilstein 255/70 valving in the rear to 275/78 valving just due to the reduction in spring internal friction.
I run a set on the rear of my Mini. I used the longest 3 leaves of a 5 leaf pack. Second best mod that I ever made to that truck. (First was dumping the Rancho shocks and going to mono-tubes.)
I'm guessing that if they are rock crawling with them that they are allowing them to go negative arch. In the case of the GM's their leaves are flexible enough that it is easy for them to kink at the spring perch. Nothing kills a leaf spring faster than a combo of allowing them to go negative arch and allowing them to kink. Max spring life is when you limit the travel such that the spring has at least 1 inch of positive arch remaining in it.
I used the GM O/L leaf under the GM pack, placed upside down. Now the spring 'rolls' down onto the O/L leaf and can't kink at the perch, but the O/L really doesn't ramp up the spring rate in the process. A local 4x4 shop owning friend taught me that one.
Something that I've never seen mentioned about the GM 63's is that they have an unusual feature in their assembly. There are shims between each pair of leaves. Those shims make sure that the leaves don't touch except at the tips and create friction. The tips have anti-friction plastic sliders as do the keepers. I had to go up from Bilstein 255/70 valving in the rear to 275/78 valving just due to the reduction in spring internal friction.
So you took your packs down to a 3-leaf setup plus the O/L leaf upside-down on the perch? I assume you went 3-leaf for more flex? I'm thinking that with the weight of my 62 (plus whatever gets put on it) and the fact that mine's not a crawler, the 5-leaf pack would work just fine for me. Which GMs commonly had the 5-leaf 63" packs?
Also I'm wondering if I put a 5-leaf pack on the back of my rig, if I should keep the Add-A-Leaf in my rear spring packs when I move them up front. I would expect yes, given the weight of my engine plus aftermarket bumper and winch when they're installed.
they are long... I have a feeling I will be adding aals or some more springs after she hits the road for a bit. The front perch is mounted close to the stock location:
So you took your packs down to a 3-leaf setup plus the O/L leaf upside-down on the perch? I assume you went 3-leaf for more flex? I'm thinking that with the weight of my 62 (plus whatever gets put on it) and the fact that mine's not a crawler, the 5-leaf pack would work just fine for me. Which GMs commonly had the 5-leaf 63" packs?
Also I'm wondering if I put a 5-leaf pack on the back of my rig, if I should keep the Add-A-Leaf in my rear spring packs when I move them up front. I would expect yes, given the weight of my engine plus aftermarket bumper and winch when they're installed.
No, I removed the short leaves to get the total spring rate down to what worked with the truck. They're just right when I have the shell on it and a bit stiff when I do not and have nothing in the bed. I don't use the Mini as a crawler, I use it for chasing desert racers and going exploring.
Not sure that it makes any difference, but mine were sourced from a 3/4t Chevy truck.
For under a 60 I'd start out with all 5, but plan on possibly needing to tune them a bit. I think that the O/L leaf is a very important thing for spring life - particularly if the short leaves are removed in tuning the ride, but I don't see it working well for SUA.
For axle wrap you can also chop the back half of a leaf (after the perch). This gives you more resistence to wrap without adding as much to the spring rate as the full leaf would. At least according to one of my chassis books, no first hand experience with this.
For under a 60 I'd start out with all 5, but plan on possibly needing to tune them a bit. I think that the O/L leaf is a very important thing for spring life - particularly if the short leaves are removed in tuning the ride, but I don't see it working well for SUA.
Yeah I don't see removing the short leaves making much of a difference when still SUA. I'm gong to finish some pressing maintenance first and tackle this project this winter to see how much of a difference the different leaves make when SOA.
Knowing the stock rears are 3" longer than the fronts, I wonder if it'd be necessary to move the front shackle (or spring) mount to directly swap the springs. I'm also wondering if swapping the fronts out for rears will change my caster angle as well. Hopefully not because if I don't have to worry about those two issues, it'd be a simple bolt-off, bolt-on to move the rears up front.
brokenparts, GOD DAMN that's alot of cutting! I definitely don't want to do any cutting on my rig. Hopefully I won't have to cut anything to get 35" tires to fit at full stuff...
some of that cutting was by design... not because of the springs. Its an attempt to disguise the 60's large behind and make it nearly impossible to negotiate the tight trees here in the northwest. Should climb like a mo'fo' though.
Okay, the plan is in the works again. I have one thing to finish on my Duster to make is usable as a DD until the roads freeze, so I'm going to take advantage of the downtime that'll afford my 62. I still have some maintenance to prioritize before I can tackle this project, and when I get around to it will depend on when I'm able to complete the tcase rebuild and H55 conversion (priority is new tires first. My mudders have gnarly flat spots that make driving a bitch).
My plan is to install 63" springs in place of my rears, set up for my current ride height (stock plus full length AALs). I'm hoping stock GM 63" springs will do the job. If not, I'll look for a set of 2" lifted ones. I'll leave the AALs in my rears and move them up front, then "tune" them as necessary as I drive around so that I can find the best combination of comfort, sag resistance and flexibility on the logging roads in the mountains. I'm trying to find a couple local guys to help me out with the measuring and fab work, with pizza and beer provided, of course
Edit: Looking around it seems everything I find for a 3/4ton Chevy rear is a 52" spring. Old and new alike, stock and lifted.
Also from what I've been searching through on Mud, it looks like I'm going to want 3" lift springs for the rears once I find the right length, and when I move my OEM rears to the front I'll want to beef those up. I'm wondering if doubling up on the AALs in my OEM rears will be good or bad for the front, or if I should take leaves out of my front springs to beef up the OEM rears in order to allow for a bit of flex and stand up to extra weight in the front (keeping in mind I'll have the extra weight of a second battery, bumper and winch hopefully sooner rather than later in the future).
Should climb like a mo'fo' though.