Real Leaf Spring lowering options

[corndoggydogg]

Hello. I am getting ready to lower my 72 GMC and add some new wheels/tires. The challenge is, I have leaf springs in the rear. From what I read on the forum, my options are somewhat limited and not as flexible as coil rear springs.

Here is what I want to do:
1) Maintain a reasonable amount of hauling capacity (it is a truck after all).
2) NOT install a c-notch. Too much brain damage.
3) I definitely DO NOT want a "low rider". I just want a lower stance without going overboard.
4) Keep costs as reasonable as possible for the drop and spend most of the budget on wheels/tires. (Not interested in lowering leaf springs at $300-400)
5) I'm not opposed to flip kit, but I am concerned about bottoming out. Just something I don't want to have to deal with.

I am leaning towards the following, as a starting point:
1) 2.5" drop spindles in the front.
2) 3" drop shackles in the rear.
3) 17-20" wheels (possibly staggered: 17"/18" or 18"/20")

I have attached a photo of my truck (blue) and another one I found on line that has the general stance I am going for (black).

Considering all of the above, my questions for the forum are as follows:
1) What kind of drop set-up should I consider?
2) What size wheels would be a good complement to the drop?
3) I will probably do the drop and wheels in 2 phases. Which should I do first?

Thanks everyone!

[summitflier]

I guess, it comes down to $$$.

https://www.performanceonline.com/ch...springs-parts/

Extended shackles are reasonably cheap, and will help some.
Lowering and heavy loads don't mix real well. Especially without notching.

https://www.yearone.com/Product/1967...mc-truck/js025

Blocks also works. But then, like you said.. bottoming out becomes a concern.
If it was me, I would do the lowering first.. before the wheels.
I would hate to drop $1000 or more on some wheels just find out they don't fit.

With a 2" inch drop it probably won't matter too much, but if you go more
with 18 inch wheels, clearance becomes an issue.

[lolife99]

Here's my take on leaf spring lowering on 67-72 trucks:
1) blocks don't work without a flip kit, unless you are RAISING the truck.
2) Flip kits will get you a 5-6 inch drop or more.
3) Flip kits require a c-notch in my opinion on these year of trucks.
4) Flip kits require shorter rear shocks and fabbing a new upper shock mount to make the shocks more "vertical", so they actually work.
5) I don't know of a 3" drop shackle. (1-2" adjustable is all I have ever seen)

I think Drop leaf springs is your answer. (not what you want to hear)
Keep the rearend under the spring pack and use an aftermarket drop leaf spring pack.
I know www.performanceonline.com sells 3", 4", and 5" drop leaves.
Be prepared to deal with driveline issues with a two piece driveshaft.
Usually adjusting the location of the carrier bearing will solve your issues.

DEFINITELY do the drop before measuring for wheels!

https://www.performanceonline.com/19...AF-SPRING-SET/

[Mike C]

I dropped my 69 with 2 1/2" spindles and 2" springs in the front. I did an axle flip in the back and my truck has the HD rear leaf package. Not sure if that drops it less because they have more arch or more because more leafs, but the net effect was a 7" drop. I can haul 500# in the bed without hitting the frame...much. I cut the bumpstop pads off the axle housing and installed the urethane pads that came with the DJM flip kit. That made all the difference. I used front shocks all around and drilled the opposite side of the bracket in the rear and used new front shock studs to move the shock more vertical.

I see just 3 ways or combos to get there:

1) shackles get you 1 1/2" drop.

2) drop leaf springs with your choice of drop

3) axle flip = 7".

So if you want something between 1 1/2" and 7" you need to buy springs. I would do the 4" and keep the shackles in my back pocket as an option to go to 5-6" drop.

Big tires are what makes the drop work IMO. I went 27" tall front and 29" tall rear. 235 55 17 on 17x8 with 4.5" bs and 275 55 17 on 17x9 with 5" bs. That's the biggest tire that will fit on a step without modifying inner bed sides.

[corndoggydogg]

Thanks for all of the quick and detailed responses. So I hear you loud and clear: drop leaf springs. What about removing a few leaves? And maybe I'm over thinking the c-notch. How much work is that? Do I need a torch? Just exploring all options. Thanks again.

[Mike C]

Removing leaves changes ride and handling and load carrying. In additioin, the main leaf was designed to be supported by the other leaves. Don't do it. I did pul the overload off my spring pack though. No efffect on drop #, but I have CalTrac bars that were hitting it.

You can get 6" without notching, don't see a need. Buy the 4" springs. Buy the shackles. Put it together with just the new springs. If you want it lower, add the shackles.

You got some great advice from low life 99. One nice thing about the flip kit is it moves the rear axle back so no driveline issues. Not sure if the aftermarket spring pack has relocated pin location or not. Time to work the phone and I would call Early Classics and were I you, would use them as my vendor as well.
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[leadfoot067]

rightway spring in tacoma,or gitts spring in auburn may be able to help with a custom set of springs for less cost..

[sKnNyPpY]

I just hauled about 1000 lbs of mulch with my flipped leafs and no c-notch. I do have new leaf packs and relocated shocks, though.



A write up I did on my flip experience: http://67-72chevytrucks.com/vboard/s...d.php?t=577529

[lldjr05]

Originally Posted by lolife99

Here's my take on leaf spring lowering on 67-72 trucks:
1) blocks don't work without a flip kit, unless you are RAISING the truck.
2) Flip kits will get you a 5-6 inch drop or more.
3) Flip kits require a c-notch in my opinion on these year of trucks.
4) Flip kits require shorter rear shocks and fabbing a new upper shock mount to make the shocks more "vertical", so they actually work.
5) I don't know of a 3" drop shackle. (1-2" adjustable is all I have ever seen)

I think Drop leaf springs is your answer. (not what you want to hear)
Keep the rearend under the spring pack and use an aftermarket drop leaf spring pack.
I know www.performanceonline.com sells 3", 4", and 5" drop leaves.
Be prepared to deal with driveline issues with a two piece driveshaft.
Usually adjusting the location of the carrier bearing will solve your issues.

DEFINITELY do the drop before measuring for wheels!

https://www.performanceonline.com/19...AF-SPRING-SET/

What's the options for adjusting the carrier bearing to solve driveline issues?

[lolife99]

The best option is to use a 2-piece drive shaft with a "slip yoke" in the reare shaft.
Without the slip yoke, you would have to shorten the shaft to the correct length, or shim the carrier bearing up or down, depending on the way it's mounted.
The slip yoke version would be my first choice,...

[GASoline71]

I used 2.5" drop shackles and removed the overload leaves on my 1972 GMC. Getting the drop shackles in the upper pockets was a biotch...

One of these days I'm swapping out my bent 1972 leaf sprung frame for a nice and straight 1969 coil sprung frame. I will give you the drop shackles if you want them... but... if you plan on doing this soon... I can't guarantee I'll have them out anytime soon.

Gary

Gary

[lldjr05]

Originally Posted by lolife99

The best option is to use a 2-piece drive shaft with a "slip yoke" in the reare shaft.
Without the slip yoke, you would have to shorten the shaft to the correct length, or shim the carrier bearing up or down, depending on the way it's mounted.
The slip yoke version would be my first choice,...

Thanks for the info, I was planning on 2.5" drop spindles front and 3" drop shackles rear, I don't care about load capacity, I will never carry anything when the truck is done, I'm concerned with driveline angle and overall look. I'm would love advice and info, just started the frame up restoration of a 70 GMC with my son!

[lldjr05]

In the picture of the flat black truck posted by corndoggydog why does the rear wheel sit so close to the rear wheel well?

[Mike C]

1 1/2" is max for lowering shackle. Anything more would stick out the bed! But removing the overload leaf and the shackles gives you almost 2 1/2". But you will not regret buying springs and doing it right the first time, but you might regret NOT doing that. But in the case of the shackles, they can be sued with the 4" springs and you could add the overload back, so no rear loss except a new spring center pin.

[corndoggydogg]

Here's what I ended up doing.

2.5" drop spindles in front. 2.0" drop shackles in the rear.

Front wheels/tires: 18" x 8" with 235/65.

Rear wheels/tires: 18" x 9.5" with 275/60.

Very happy with the results.

[maybizel]

Originally Posted by mike c

i dropped my 69 with 2 1/2" spindles and 2" springs in the front. I did an axle flip in the back and my truck has the hd rear leaf package. Not sure if that drops it less because they have more arch or more because more leafs, but the net effect was a 7" drop. I can haul 500# in the bed without hitting the frame...much. I cut the bumpstop pads off the axle housing and installed the urethane pads that came with the djm flip kit. That made all the difference. I used front shocks all around and drilled the opposite side of the bracket in the rear and used new front shock studs to move the shock more vertical.

I see just 3 ways or combos to get there:

1) shackles get you 1 1/2" drop.

2) drop leaf springs with your choice of drop

3) axle flip = 7".

So if you want something between 1 1/2" and 7" you need to buy springs. I would do the 4" and keep the shackles in my back pocket as an option to go to 5-6" drop.

Big tires are what makes the drop work imo. I went 27" tall front and 29" tall rear. 235 55 17 on 17x8 with 4.5" bs and 275 55 17 on 17x9 with 5" bs. That's the biggest tire that will fit on a step without modifying inner bed sides.

i know this is an old post but did you use stock hight front shocks on the rear or did you get the lowered front shocks and put them on the rear? Thank you in advance

[corndoggydogg]

as far as I know they are standard. I did not do anything with the shocks.

[MDPotter]

Posting here for anyone else that is looking for info on lowering a leaf spring truck.

Mine is a 68 GMC C15 and it had the HD rear leaf setup - a total of 8 leafs. I bought the 4" drop leaves from Western Chassis (through Summit) and ended up with just over 3" of drop. All I can guess is that my factory springs had sagged a little bit over time. I was expecting more than 4" of drop because the leaf pack is so much slimmer than the HD leaf pack, but not the case. I could use more drop, maybe the flip kit is what I needed but it would require a c-notch in my opinion. I put the shocks back in the stock position and it's not too extreme. The measurement between top of the axle tube and the underside of the frame is 4.15", where I was 7.25" with the stock springs and shackles.

I have a set of small tires on this truck right now (26"), so keep that in mind. I cut 1 full coil off the factory front springs and probably dropped about 2".

Also, don't forget to order u-bolts because they do rot away over time, even in drier climates.

[cab4word67]

Originally Posted by MDPotter

Posting here for anyone else that is looking for info on lowering a leaf spring truck.

Mine is a 68 GMC C15 and it had the HD rear leaf setup - a total of 8 leafs. I bought the 4" drop leaves from Western Chassis (through Summit) and ended up with just over 3" of drop. All I can guess is that my factory springs had sagged a little bit over time. I was expecting more than 4" of drop because the leaf pack is so much slimmer than the HD leaf pack, but not the case. I could use more drop, maybe the flip kit is what I needed but it would require a c-notch in my opinion. I put the shocks back in the stock position and it's not too extreme. The measurement between top of the axle tube and the underside of the frame is 4.15", where I was 7.25" with the stock springs and shackles.

I have a set of small tires on this truck right now (26"), so keep that in mind. I cut 1 full coil off the factory front springs and probably dropped about 2".

Also, don't forget to order u-bolts because they do rot away over time, even in drier climates.

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How does your truck ride with the 3 leaf springs and what is the part number / where did you get them?

[cab4word67]

Also it looks like my blue before the Purple pearl was added.

[MDPotter]

Originally Posted by cab4word67

How does your truck ride with the 3 leaf springs and what is the part number / where did you get them?

Originally Posted by cab4word67

Also it looks like my blue before the Purple pearl was added.

It rides about as good as you can expect from leaf springs. A little stiff in my opinion. I don't haul anything so load bearing is not a need for me.

They are 4" drop leaves from Western Chassis. I can't remember where I found them cheapest - Western Chassis, POL, and Summit all sell them. Part # WST-661014 from Summit.

Voodoo Blue. Still happy with my choice.

[cab4word67]

Originally Posted by MDPotter

It rides about as good as you can expect from leaf springs. A little stiff in my opinion. I don't haul anything so load bearing is not a need for me.

They are 4" drop leaves from Western Chassis. I can't remember where I found them cheapest - Western Chassis, POL, and Summit all sell them. Part # WST-661014 from Summit.

Voodoo Blue. Still happy with my choice.

Mine is PPG Paradise Blue w/ Plumb Crazy Purple pearl, I call it Blurpl