Gathering parts for drop and front suspension rebuild...

[r8rs4lf]

So I heard if our trucks have the original suspension parts, we should assume that there's already 1" of sag. Is that a safe assumption?

Looking to do a 2/4 but I'm thinking maybe I should add another inch.

Looking to do 2.5" drop spindles with 2" drop springs
Rear would be 5" drop leaf springs.

Should I do 6" in the rear to account for the 1" of sag?

Not looking to notch the frame.

All suspension components are going to be changed up front at the same time.

[71CHEVYSHORTBED402]

I installed 4/2.5 in my SWB, the drop levels the truck. If I remember right original C10 front coil springs are 13 inches. First time doing this - a reputable sent me two coil springs that were powdered at some point, and much of the finish had worn out. New?☺ They were the same springs as my originals, nice shape otherwise so what the heck, slapped them on with new powder coat - My finish guy, who finishes parts with must be 10 or so types says powder coat is ideal for springs BTW, because it's flexes so well.

Can say with only my BBC drive-train and control arms on the frame, and with my 220 lb son sat on the intake, my frame's rear lifted off the floor trying to install 2.5 drop spindles with 13" c-10 coil springs - Secured springs of course, yikes!.........Be nice if I had BA hooks in the floor, but I'm not likely to do it again, but if I do I'm bringing BA hardware, at least a full 6" thick of lumber, and cushions.

When we saw the rear off the ground, I thought hmm, try supporting the frame's front too? That did the trick somehow, with perhaps the weight of my 180 lb son on the top control arm too.

Should I have gotten 12"ish tall springs? I don't really know.

[r8rs4lf]

Did you notice the drop or was it more of level of the truck?

I'm afraid of that happening to my truck. I want it lower, not so low where it rides like crap or bottoms out, but I also want it to be a noticeable drop.

Just wondering if the talk of 1" of sag is truth.

[PowerdbyChevy79]

If using using new springs there will be no sag..

[r8rs4lf]

Originally Posted by PowerdbyChevy79

If using using new springs there will be no sag..

I understand that.

Let's start off with this, if all I wanted was to install factory height springs all the way around, will the truck actually be raised because of the 1" sag on the old parts? Yes?

Now let's say I take a measurement from the ground to the fender lip as it sits (54 year old suspension) right now. When I go to install a 2/4 drop, will I see a true 2/4 drop or will it be more of a 1/3 drop because of the 1" sag from the old parts when I took the measurement?

I'm assuming these companies manufacturing the drop springs are measuring against the stock height springs installed from the factory, but we are talking about a 54 year old suspension as it sits right now.

If the 1" sag on the old parts is true then I would actually need a 3/5 drop to get a true 2/4 right?

I edited the title to be more specific.

[MySons68C20]

I used new replacement front springs from ECE for my 2.5" spindle drop front & 4" spring drop in the back.
Once the front springs settled out I ended up adding an additional 1" drop block in the rear to get the 1" rake front to back I was looking for.

[r8rs4lf]

Originally Posted by MySons68C20

I used new replacement front springs from ECE for my 2.5" spindle drop front & 4" spring drop in the back.
Once the front springs settled out I ended up adding an additional 1" drop block in the rear to get the 1" rake front to back I was looking for.

Can you post a pic please?

[CC69Rat]

This is going to be goofy. -- but please bear with me.

300 pound guy, jumps and bounces off a 12' diving board. Boing, splash .. into the pool.

How much did the board flex? Now cut off 2". Same guy, boing .. Does it flex the same? It would be stiffer, correct? I understand there are different spring rates available, but just conceptually, stock vs stock. It's still just torsional rigidity. Over time, this will get weaker, for sure. It really all depends on how hard your truck was used / not used during it's life ( so far ). But in my experience, I usually would assume if the truck is sitting on the stock suspension parts now, Id assume 2" lower than it was when it was new.

2.5" Spindles, + 2" springs up front. Then I usually do a 4" rear spring, and adjust with drop blocks to my liking. Why? Remember the fella on the diving board. If you can keep that spring a little longer, the truck will ride better ( less stiff in the back ) If you buy a 5" spring, and it's too low, youre stuck. Blocks are cheaper than springs too..

But, I wouldnt go over a 2" block. Just me. For example if you want 6" total, do a 4" spring, and 2" block. Or, if you want 5" total, do 3" spring, 2" block. Or 3" spring, 1.5" block. But keeping the spring longer will improve the ride quality overall and doesnt lock you in. You can dial it in perfectly that way.

Id highly recommend McGaughys, or Hotchkis springs. I use them a lot, and have had great luck with their parts. Just my .02.

[r8rs4lf]

Originally Posted by CC69Rat

This is going to be goofy. -- but please bear with me.

300 pound guy, jumps and bounces off a 12' diving board. Boing, splash .. into the pool.

How much did the board flex? Now cut off 2". Same guy, boing .. Does it flex the same? It would be stiffer, correct? I understand there are different spring rates available, but just conceptually, stock vs stock. It's still just torsional rigidity. Over time, this will get weaker, for sure. It really all depends on how hard your truck was used / not used during it's life ( so far ). But in my experience, I usually would assume if the truck is sitting on the stock suspension parts now, Id assume 2" lower than it was when it was new.

2.5" Spindles, + 2" springs up front. Then I usually do a 4" rear spring, and adjust with drop blocks to my liking. Why? Remember the fella on the diving board. If you can keep that spring a little longer, the truck will ride better ( less stiff in the back ) If you buy a 5" spring, and it's too low, youre stuck. Blocks are cheaper than springs too..

But, I wouldnt go over a 2" block. Just me. For example if you want 6" total, do a 4" spring, and 2" block. Or, if you want 5" total, do 3" spring, 2" block. Or 3" spring, 1.5" block. But keeping the spring longer will improve the ride quality overall and doesnt lock you in. You can dial it in perfectly that way.

Id highly recommend McGaughys, or Hotchkis springs. I use them a lot, and have had great luck with their parts. Just my .02.

I have a leaf spring suspension in the rear so as I understand it, for me to use lowering blocks I would need to do an axle flip correct?

I get what you're saying though. I could go with a 4" drop in the rear and if I need a bit more, I could go with a 1" lowering shackle.

[MySons68C20]

I have a coil spring rear (C20) so not apples to apples as applies to your leaf spring rear suspension.

[CC69Rat]

Originally Posted by r8rs4lf

I have a leaf spring suspension in the rear so as I understand it, for me to use lowering blocks I would need to do an axle flip correct?

I get what you're saying though. I could go with a 4" drop in the rear and if I need a bit more, I could go with a 1" lowering shackle.

Correct, yes. But i will say, an Axle flip is going to drop it quite a bit. I usually do a flip on Square bodies, but Ive never dropped a leaf sprung 67-72. I would plan on around 6" drop in the rear if you flip it. Someone that has done it will likely chime in.

But yeah, similar concept you'll just have a few more variables to deal with.

[PowerdbyChevy79]

Ok , I see what your saying...
First i would say that 1" sag is a guestimate....there's actually no way to truly know how much a stock 54 year old suspension has actually "sagged" without installing stock springs and then comparing the difference. So I wouldn't worry about it... concentrate on what drop you want. Then work from there.
What I would do is use 2" drop spindles for the front... then if you want more drop you can add a drop spring..
for the rear most flip kits give you either a "5 or "6 drop.. for a "4 drop, Shackles and hangers is what you want to do..... if you're using original leafs they may sag some but a shackle/hanger kit should give you a true 4" drop even with the original leafs. The main problem you're gonna run into is there's not alot of parts available for rear drops on 67-72 gmc. Thats why most people convert over to coil springs.

[HO455]

If you are particular about an exact height plan on buying several springs to get the look you want. Most spring manufacturers don't do testing of their springs to see how much drop their springs provide for every model. Most of the time they make the drop estimates based on mathematic calculations, not by installing them on the vehicle.

You're asking for drop amount information without providing us information on your truck.
Is it a c10 or a c20? Long bed, short bed, or a Longhorn? I6, SBC, BBC, LS? Does it have AC?

All these things will make one truck sit differently than the next one with the exact spring set installed. My experience leads me to believe spring manufacturers do not have QA programs to assure that each spring part number maintains less than a 3 or 5 percent difference in spring rate. At best they might try to match a pair so the vehicle sits level but that's probably it.

Here is a photo of my SBC, non-AC, Burban with stock spindles and Hotchkiss 1 inch drop springs. I can hit the bump stops on speed bumps if I'm going 20 mph in a 25 mph speed zone.

I would expect the exact same springs to sit higher in a pickup due to the lighter weight of the pickup.

Unless you are the original owner of the truck you don't know how it was abused over its life which would affect how much sag has occurred. Not only sagging of the springs but of the frame and control arms. As such there is only a generalization as to how much the average truck may have sagged. That may or not apply to any specific truck.

As always this is just my opinion which along with a sawbuck will get you a steaming hot cup of Joe just about anywhere.

[r8rs4lf]

Originally Posted by HO455

You're asking for drop amount information without providing us information on your truck.
Is it a c10 or a c20? Long bed, short bed, or a Longhorn? I6, SBC, BBC, LS? Does it have AC?

1972 C10
SWB
350/350
Factory AC
PS, PB, Factory front disk brakes

[71CHEVYSHORTBED402]

Originally Posted by r8rs4lf

Did you notice the drop or was it more of level of the truck?

I'm afraid of that happening to my truck. I want it lower, not so low where it rides like crap or bottoms out, but I also want it to be a noticeable drop.

Just wondering if the talk of 1" of sag is truth.

It feels more like a car, and looks more like a toy. Mixed emotions, I hear I can't put my 8/15 Rally on, was looking forward to those as an option.

I don't know about any 1" sag.

[r8rs4lf]

Ok so I purchased all parts for the front end rebuild.

Upper and lower ball joints
Inner and outer tie rod ends
Tie rod adjustment sleeves
Upper and lower A arm bushing kits
Pitman arm
Idler arm

Now on to the drop.....

I can safely say that 2.5" drop spindles will be purchased.

The problem I'm having is where to go from there?

I have a rear leaf spring suspension and I don't want to alter that so drop leaf springs will be ordered. Ride quality means more to me than being in the weeds. I understand a rear trailing arm suspension conversion would be optimal and I've considered it, but my truck is a 'Highlander" with the leaf spring option on the SPID so I don't want to stray too far from that by adding a C notch.

I've done a ton of searching with different titles concerning drops and have come up with old threads.

My truck will be a driver, no hauling or towing. Nothing more than a chair and cooler in the bed. No track days, not looking to run 8's in the 1/4 mile.

From your experience, what drop combo can I go with:

1. Without having to do a C notch
2. Will net me the best ride quality without bottoming out

All options are on the table.

From what I've read here it looks like a 3.5/5 which will be achieved with 2.5" drop spindles with a 1" drop coil up front and 5" drop leaf spring pack in the rear. Will I need shock relocaters?

As for tires, I just ordered some 235/75/15 Coker WW tires for now. I plan on going this way for a bit until I make the decision to go with aftermarket wheels, I'll tackle that later. This will give me time to think about it.

What you say?

[ullose272]

if it was me, id look for examples of how you wanted your truck to look and figure out how much it was lowered, and go from there. also wheel and tire diameter make a big difference on not only how low your truck is but how well it fills out the wheel well, which affects overall appearance.

[ullose272]

if it was me, id look for examples of how you wanted your truck to look and figure out how much it was lowered, and go from there. also wheel and tire diameter make a big difference on not only how low your truck is but how well it fills out the wheel well, which affects overall appearance.

[cj847]

The squarebody guys lower the rear with drop shackles and relocated front hanger (ie not drop springs). You might want to look into their builds.

On the "sag". I recently replaced the front springs in my 67. I purchased new stock height springs. My before and after measurements were almost identical. The ride? Might be a little better? Not sure. Anyway, my conclusion from this experiment was something I had heard years ago. A spring doesn't "wear out" over time, it was either overload or overextended at some time during its life if it sags.


PS> The stock front spring is 13" free length. It is 10" when installed.