Modifying the Chev 63's

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May 24, 2015
I have the height I want with a 3+1 chev 63, a 2" lift block, and an 8" shackle. The truck has a fairly weighty tube deck. I want to ditch the block but keep the height. Not sure if I need it stiffer or not.

What is an "'add a leaf"? Is it different than going to my local spring shop and getting a couple 2.5" leafs cut at appropriately fanned lengths and slipping them in there?

What are my options for keeping an acceptable ride quality, compression, and droop?
I had several sets of 63" Chevy springs to play with so one day I used my HF 20 ton hydraulic press to "re arch" them. Not really the correct term since spring shops properly heat and cool them. I did it cold. It worked great. I ran them for several years.....hard. They're still good to go. They flex great. I did have some wheel hop with the 3.4 and low gearing so I built an anti wrap bar.

I did it on a NEW set factory OEM Chevy springs. Some guy took them off his brand new 2017 because he lifted it. They must be fairly ductile because I tried to do the same to my sagged out TG front springs and they just snapped. On the first push. Very brittle.

I made a simple jig with scrap just to try it and I got lucky I guess. I can take a pic when I get out in the garage.

I used a square and soap stone to make marks every two inches "I think" across the leaf. I pressed on each mark for a little bend. Checked it by laying it on the floor and measuring from the floor to the arch. Lots of checking. Then you have to make the other leaves the same. Takes a while.

I think I got the idea on Pirate. I remember a youtube video of a spring shop doing it. Except it was on a press with the leaves laying on their side in a jig. Press was pushing horizontally. The springs are still on my 88 so I'll get some pics.

I'm not saying it's a proper mod so do it at your own risk. Steel flying out of a press can kill you.

To answer your question. An add a leaf is just that. An extra leaf stuck in the pack to increase load carrying capacity. Not really to add lift. It will ride stiffer without weight also.

Some spring shops can make a custom set of springs for you. Not cheap. They would be done right though.
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Sounds pretty do-able, altho a bit more involved. Id like to see the jig you made.

I think if I was going to get totally carried away/custom I'd look into deavers.

How would I determine if I needed more or less spring rate in the rear? I suppose that might be the deciding factor if I can add leafs or not.
Basically, if you're hitting the bump stops and too soft, you need stiffer springs or add a leaf to stiffen it.

Here's my truck right now. It's high and the shackle angle is bad because there's no weight in it. No engine, transmission or t cases.



Here's my jig. It doesn't look like it but, I buffed the pointed edges smooth. The soft angle just flattened back out against the harder springs.

It was a quickie experiment so I didn't put a lot of time in the design. It was scrap. It just happened to work out for me.



Looks simple enough. I'll keep that in the back of my mind. Mounting a dial indicator on there might make it pretty easy/consistent.

I might try and find another set of 63's and do some shortening on some of the leafs and slip them in and see what happens. Then I'd end up with a second set of main leafs to stall the press out on if adding leafs doesnt pan out.

I dont have bump stops yet but I dont think its that soft. Not sure if its too stiff though, lol. The truck rides pretty good, but packs up in the rear end when im cruising and hit multiple dips and bumps in a row. Its on 5100's and they were mounted at about 45 degs.

Probably going to take some trial and error to get it dialed in.
Yep, I played around with different sets I put together. All you can do when your working with used parts.

I put them in the press to get the lift without blocks. The number of leaves gives you spring rate. Soft, stiff or just right.

Thinner leaves are a plus. I used what I had. Maybe some from an F150 or others would be good to have to make up your perfect (for you) pack.

These I did worked out great for my ride.

Good luck with whatever you decide to do.
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How flat is flat? Set the bump here or flatten the spring out more? I measured 17 1/2" from top of leaf to bottom of the frame rail with the leaf sitting at natural droop (although I think it was bound a bit from the shackles and frame mounts being torqued at ride height, rubber bushes holding it up a bit) and then jacked it up to pictured and measured 11 3/4. Thought thered be more than 5 3/4" travel there.

Driver side has about 1" more of free arc.

Do the rubber bushes tear off the sleeve in short order? Wonder if I should put poly bushes in for free-er range of movement.

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Kind of getting back around to this.

I'm going to ditch the 2" lift block I had... the lift block had hollow centers and didnt properly fit the perch pad. It etched itself into the perch pretty decently and probably wasnt doing me any favours in stability and holding the axle solid.. by the time I ground the perches flat there wasnt much thickness left. Ended up just bucking the perch off and making an 8" long perch out of 1/4" wall. Allegedly theyre supposed to help with axle wrap... dunno about that, we'll see.

Will burning these perches on with 1" stitches and cool to the touch between stitches pull the housing? Seems theres all sorts of opinions and ideas on the internet ranging from just burn em in to theyre going to pull no matter what. I dont really have a way to check the housing afterwards other than eyeballs and if the axle slides in nice. Altho I may have to rig some tooling up.

I found a set of 4+1 chev 63's... I did a crude spring rate measurement of measuring the arch upside down, then standing on it and measuring the deflection. Then did my bodyweight/deflection and came up with 185lbs/inch for the 4+1's and 135lbs/inch for the 3+1's. That doesnt seem quite right? What is the proper way to determine spring rate?

I'm tossing the idea around of running a 4+1 or sticking another leaf in there and running 5 leafs. I'm thinking the 3 leaf was definitely too soft, and if my spring rate calculation is even close, 4 leafs is probably still too soft but might be a good compromise. Will 5 make it ride like a haywagon? Lol


I think things move less when it's assembled. I just welded mine in but the diff and axles/brakes were in place. The tubes are pretty thin.

I think you're going to have to just take a guess and assemble a spring pack and see how you like it.

The longer perches are supposed to help with spring wrap but I never ran them so I can't say.

I think the factory Chevy rubber bushings are better than poly. I've never had to replace them.
I have the axle dry assembled so I can determine where I need the perches angle wise..... I wasnt planning on leaving the 3rd or axles in but youre probably onto something there. I'll leave it together when i burn it in.

Ideally I'd like to determine the perch angle for the spring set up I'm going to run, I dont really want to end up having to run a shim, but it might come down to that. Kind of doing this backwards I guess.
If you haven't even made your spring pack I would wait on final welding.

I would have the axle installed, wheels on the ground before final welding. Just tack it good and in places you can easily reach to cut if necessary.
I had thought about doing that, just wasnt sure if tacks would keep the perches solid enough while I was test hitting the spring configuration.

The truck is going to see a healthy amount of highway driving and medium speed FSR's, so thats why I'm leaning more towards thinking I need a stiffer spring vs a soft spring set up.
I did drive the truck for years on the highway and FSR's etc. And the truck had tons of flex with the 3+1 pack and blocks but there was lots of sway and pretty soft handling characteristics. Id like to make it a bit more solid, even if I lose a bit of the purely wheeling articulation.
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I wouldn't drive it on tack welds. Just meant for you to wait to make sure of pinon angle before you fully weld the perches.

You sound like you have a good plan for what you want. Just would suck if you have to cut perches back off.

Good luck with your build. Looking forward to seeing it.
Yeah, it would suck to have to redo the perches. It would be sweet to test hit the truck before final burn in, but would be playing with fire on that one. A custom long 1 or 2° angle shim probably wouldnt be the end of the world if a spring pack cofiguration change makes an appreciable change to the driveline. Just gotta try my best to avoid needing a shim and work with what I got and get it as close as I can for a range of conditions...

Somethin to be said about the factory averages... they already had it all worked out then we take and change it all, lol.

I should make a build thread, one day I'll take and compile some pics.
assemble it with weight. set perches and go.
i learned my lesson by eyeballing it before and it sucked.
a tape measure is your friend.
measure 17 times burn once
Thx. Ive already worn out a tape measure on this truck. I have only seen the truck with the 4+1's without the trans, fuel tank or flat deck installed. It sits with a bit of rake. Hoping it doesnt totally sag out when its back to running weight. If it does I may have to add a smidge of arch to the springs. I'm 100% not going to run blocks, I know that much, lol

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