How can I level?

[3/4ton72heavychevy]

I have a 72 c20 and want to level out the front with the back by lifting it a couple inches. Any ideas? Could I buy some bigger shocks? or coil spring spacers?

[Tx Firefighter]

I had a 72 C20 a few years ago and used new springs spec'd for an 80s era diesel crew cab truck. Got them at O Reillys.

[SS Tim]

How much rebound travel was left after replacing the springs?

[Tx Firefighter]

It didn't come near to topping out the suspension. When you let it off jack stands the suspension compressed plenty. Basically it raised my front end 2 inches.
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[SS Tim]

Thanks that is a good data point to have.

[bollybib]

I was of a mind to lower the rear to level rather than raise the front, but I really like the way raising the front looks. I'll add this to my "I might do this someday" list.

Tx: Very sharp looking and level C20.

[3/4ton72heavychevy]

Looks great TX, any idea the specifics of what model springs you used?

[Tx Firefighter]

Originally Posted by 3/4ton72heavychevy

Looks great TX, any idea the specifics of what model springs you used?

I used R30 diesel crew cab springs. I couldn't think of any heavier factory application than that. The springs came from O Reilly. I don't remember what brand they were, but if O Reilly gives you a choice, I guarantee you I chose the most expensive of the choices to get the best brand. Probably Moog...

[3/4ton72heavychevy]

Thank you sir.

[72 K20]

TX
That is a sharp truck !!

How did that truck ride with those heavy springs ?


I want to level up my 72 but try to get a decent ride. I'm hoping to get some lift when I change the BB for a SB but, have also considered air bags. I found some tapered sleeve bags that I think will work,, the dimensions and travel dimensions seem to be correct.

[Tx Firefighter]

Originally Posted by 72 K20

TX
That is a sharp truck !!

How did that truck ride with those heavy springs ?


I want to level up my 72 but try to get a decent ride. I'm hoping to get some lift when I change the BB for a SB but, have also considered air bags. I found some tapered sleeve bags that I think will work,, the dimensions and travel dimensions seem to be correct.

The truck drove and rode real well. It was a factory big block truck with 3.54 rear end and pretty much all options. Even with the big tires, it was a real pleasant truck.

[72 K20]

TX
The truck I'm working with sounds like it's pretty similar,, BB,AC,AT,PS PB. From what I have determined it still has the original 3:54 rear gears,,,,, one of the reasons I bought it.

Did you keep the BB and automatic ? What kind of mileage did you get ?

I will be using this as a daily driver so want the best mileage.

Thank You ! Tom

[cleansquare]

Wanting to do this to my 85 c20. I'm guessing same springs should work on my truck right?

[Tx Firefighter]

Yes.

[BlacklandCamper]

Originally Posted by Tx Firefighter

I used R30 diesel crew cab springs. I couldn't think of any heavier factory application than that. The springs came from O Reilly. I don't remember what brand they were, but if O Reilly gives you a choice, I guarantee you I chose the most expensive of the choices to get the best brand. Probably Moog...

Moog part #6560S.
13.59in free height.
11in installed height.
1464lb spring rate.
3788lb load.

Compare to the stock springs on a '71 C20.

12.94in free height.
10in installed height.
1016lb spring rate.
2950lb load.

[Aruba1]

Aight, I am about to order a set of 6560S for my 1972 GMC C20 converted to 1 ton. I also will need to order some front shocks and would rather go with KYB gas-a-just. Do I get stock length or do I need to get shocks for a different model truck to compensate for the longer springs? Thanks

[GCncsuHD]

Originally Posted by Aruba1

Aight, I am about to order a set of 6560S for my 1972 GMC C20 converted to 1 ton. I also will need to order some front shocks and would rather go with KYB gas-a-just. Do I get stock length or do I need to get shocks for a different model truck to compensate for the longer springs? Thanks

Stock length, it is still limited to the stock travel constraints, it is just now riding in the upper area of that limit.

[BlacklandCamper]

It's really a non-issue. The KYB part numbers are the same for a 71-72 C20, and the 88 R30.
The 88 R30 is the original application for the 6560S coil spring.

[Aruba1]

Thank you so much!!

[derotoreut]

When I did a front disc conversion, I installed some HD springs (P/N 2772074) bought from NAPA for a front lift. Tires do not rub at all. They are 285/70-17 tires with H2 Hummer wheels. The ride is a bit stiff, but hey it's a 3/4 ton truck. Here's a comparison of the springs:

The stock HD C20 springs are as follows:

http://www.napaonline.com/Catalog/Ca...752_0162319756

Part No.: 2771752
No. of Coils: 7.92
Free Height: 12.94"
Spring ID: 3.68"
Spring Load Height: 10"
Design Load: 2950
Spring Rate: 1016
Wire Diameter: 0.812"

The springs I put on from C10, C20, C30 from 1973-83. They are as follows:

http://www.napaonline.com/Catalog/Ca...074_0162301536

Part No.: 2772074
No. of Coils: 8
Free Height: 13.61"
Spring ID: 3.676"
Spring Load Height: 10"
Design Load: 3841
Spring Rate: 1060
Wire Diameter: 0.83"

You could also use C30 mid '80's 1-ton springs, but I thought they would be too stiff. Those are:

http://www.napaonline.com/Catalog/Ca...085_0162304063

Part No.: 2773085
No. of Coils: 7.93
Free Height: 13.34"
Spring ID: 3.65"
Spring Load Height: 11"
Design Load: 3289
Spring Rate: 1318
Wire Diameter: 0.906"

[GCncsuHD]

Originally Posted by derotoreut

When I did a front disc conversion, I installed some HD springs....

[Aruba1]

How in the world did you guys fit this shocks under that truck? I have the truck fully jacked under the a-arm and the a-arm needs another 1 inch to compress so I can install the ball joint nut. It ain't happening, lol. Am I suppose to use some spring compression, it doesn't look like there is enough space.

Another thing is that I can is use my back hoe to just put some weight on the wheel axle (or whatever its called) so it will compress enough to install the bolt.

[Aruba1]

DO NOT USE THE 6560-S. DO NOT USE THE 6560-S. DO NOT USE THE 6560-S.

When installing the springs, it would barely sit right as it's too long. Also the front did not have enough weight for the ball joint to sit properly to tight the nut, I had to use my backhoe to put some weight on the front of the truck in order to jack the a-arm and tight the nut. Now I have probably between 1/2 to 1 inch suspension travel. Going about 1-4 MPH on my flat gravel driveway feels like I was in a Cheech & Chong episode. The suspension is excessively too tight and I was lucky that it has not busted anything yet, it's just bouncing all over the plate. Yes, I did gain 3" height but what good does it do if I can't drive the truck. Is it even worth putting picture online? Brhhhhhhhhh. You have been warned about the 6560S springs! The journey is not complete yet though, I may be trying the 6560 next and see if those work.

[derotoreut]

Sorry to hear about this. That seems to be a pretty massive spring. I was skeptical when I installed my springs so I went with one that wasn't too drastic. I was concerned about the installed height and spring rate. When you compare the springs I installed to these, you basically have the same free height. However, the greater the spring rate, the stiffer the spring and thus stiffer ride. Yes the design load may be lower, but the spring rate is much greater. That is why you gain an extra inch of installed height over the ones I used. Plus with an extra inch of installed height you're going to have ride stiffness issues. The bottom line is that you have a tall stiff spring that you can't compress much.

Look at the specs on the springs that I installed compared to those 6560-S springs:

Part No.: 2772074
No. of Coils: 8
Free Height: 13.61"
Spring ID: 3.676"
Spring Load Height: 10"
Design Load: 3841
Spring Rate: 1060
Wire Diameter: 0.83"

VERSUS

Moog part #6560S.
13.59in free height.
11in installed height.
1464lb spring rate.
3788lb load.

[Aruba1]

Thanks Dan,

The HD springs from NAPA sounds like a better fit. I hope they have some in stock so I can installed them tonight. I need to get the front-end of the truck ready for this weekend as I will be buying some Supersprings on Saturday and the truck will go for an alignment on Monday.