Question about rear leaf springs

[ABINIDI]

I inherited a 1984 C30 crew cab dually, and was wanting now that we have fixed most of the things that were wrong with it, was to see about doing a 3" drop on it, shackles on the rear. I didnt want to do bags on it, just something simple. Looking underneath it, I have a few questions:

is this an add-a-leaf , aftermarket or factory? and would/should I take it out if i was to lower it?

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Also It appears to already have drop shackles on it? or is that factory? Could I remove it and add a longer drop shackle and remove the add-a-leaf to get the 3"?

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Any advise would be appreciated.. been a follower here now for some time since getting the truck, learned alot from you guys.

 

[HotRodPC]

I won't swear to it, but I'm 90% certain those are going to be the OEM rear springs set up just as pictured. It's possible it's one of a few different factory options as far as spring pack. Known to some as a 2 stage spring pack. It's purpose isn't to lift or raise ride height. It's purpose is for ride comfort so that when there is no load on the truck you're not having to feel the stiffness of the entire spring pack but just a portion of it. As weight is added more springs carry the load. In this case, you're only 1 spring in the secondary pack.

As far as lowering, I'm NOT your guy. I was hoping someone would have popped in here by now to help you. @Old77 knows a little about lowering on a 3/4 ton, not sure of his experience on a 1 ton.

 

[74propu]

Those are OEM 1 ton springs and shackle . the one on top is a over load spring. If you look at the frame above that spring there is 2 brackets that will contact the over load spring when you put a lot of tonnage in the bed ( 2 maybe 3 fat girl's ) lol You can do a shackle drop on it BUT the over load brackets will have to come off the frame . and I think there is a brake load valve on that truck (just left of center of the rear axel ) steel line in rubber flex line out to rear axel that will need to be removed (bypassed) So the back brakes don't think you have a hole heard of fat girl's in the bed

 

[HotRodPC]

See, and that's why you lower a truck. So the fat girls can get in and then they mess everything up. So much easier just to lift'em since fat girls can't jump then you don't have those problems.

 

[Charlie]

 

[Craig 85]

Those are factory overloads. You can see in the picture of my K30 it has the same set up. What I do notice is that the bottom overload has already been removed from your spring pack. Your truck may have been a Camper Special. It looks like you have the remains of the rear factory sway bar mount under the spring pack. Does the glove box tag have "G52" as one of the codes? If that's the case, you had 9 leaves in the pack, plus the bottom overload. If not, it would be like mine which had 8 leaves plus the bottom overload.

Bell Tech still makes a lowering like for that truck. 3" front/4" rear. Their kit replaces the front spring hanger on the rear suspension to get that low. You can probably buy just the lengthened shackle to get yours lower and then adjust the pinion angle. You will probably have to cut a bed cross member to install the shackle. Your truck is already lower since you have leaves missing. I don't think I would get rid of the top overload. It does not impact ride until the spring hits the pads. If they make contact too soon once its lowered, you can have a new flatter spring made for it if needed.

If you have the weight sensing proportioning valve (picture #2) you may not have to remove it. By lowering it, you will get more rear brake bias which is the opposite problem I run into when I've lifted trucks with this. If I don't adjust or remove it, I will have little or no rear brakes.

http://www.belltech.com/belltech-75-91-gm-c30-1-ton-crew-cab-dually-only-3-f-4-r-w-o-shocks-728.html

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[ABINIDI]

Thanks for the info. Glove box doesnt have a G52 code, so its just like yours Craig. and the pic of yours looks exactly like my whole rear end, brake proportioning valve as well.
Truck used to be my father-in-laws and he used it for hauling around a 5th wheel, which i have no intentions of doing that nor do i own a 5th wheel, just own a simple open flat trailer that this truck more and likely just tow full of camping gear.

So technically i could remove that overload spring, get the new shackle kit and it should still ride well, taking out the factor of the fat girls in the back?
Do the new front shackle brackets get welded in, or just bolt in after grinding off the old bracket rivets?

 

[Craig 85]

So technically i could remove that overload spring, get the new shackle kit and it should still ride well, taking out the factor of the fat girls in the back?
Do the new front shackle brackets get welded in, or just bolt in after grinding off the old bracket rivets?

The front brackets are bolted in after the rivets are drilled/chiselled out. You may have to open the holes for larger bolts. There are instructions at the bottom of the original page I linked. If you remove the top overloads you will need to replace the spring center pin and get shorter u-bolts. The center pin is part of the the overload an the main pack. If you want more ground clearance, you can switch the the 3/4 ton style u-bolts. ORD sells the u-bolts and upper plates.

http://offroaddesign.com/catalog/Rear U-Bolts.htm

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[HotRodPC]

Thanks for the info. Glove box doesnt have a G52 code, so its just like yours Craig. and the pic of yours looks exactly like my whole rear end, brake proportioning valve as well.
Truck used to be my father-in-laws and he used it for hauling around a 5th wheel, which i have no intentions of doing that nor do i own a 5th wheel, just own a simple open flat trailer that this truck more and likely just tow full of camping gear.

So technically i could remove that overload spring, get the new shackle kit and it should still ride well, taking out the factor of the fat girls in the back?
Do the new front shackle brackets get welded in, or just bolt in after grinding off the old bracket rivets?

The fat girls in the back will make it ride even smoother and even offer better traction in certain conditions. Of course it doesn't help the mpg much not to mention all the Twinkies you'll have to buy to keep the fat girls quiet.

 

[Frankenchevy]

The front brackets are bolted in after the rivets are drilled/chiselled out. You may have to open the holes for larger bolts. There are instructions at the bottom of the original page I linked. If you remove the top overloads you will need to replace the spring center pin and get shorter u-bolts. The center pin is part of the the overload an the main pack. If you want more ground clearance, you can switch the the 3/4 ton style u-bolts. ORD sells the u-bolts and upper plates.

http://offroaddesign.com/catalog/Rear U-Bolts.htm

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The ORD website says to not get the u-bolt flip on a 1 ton frame without a lift. The spring perch being closer to the frame on a 1 ton can make the u-bolt plate hit the bump stop bracket. I wanted to get the kit, but didn’t want to lift my truck just yet.

 

[ABINIDI]

The front brackets are bolted in after the rivets are drilled/chiselled out. You may have to open the holes for larger bolts. There are instructions at the bottom of the original page I linked. If you remove the top overloads you will need to replace the spring center pin and get shorter u-bolts. The center pin is part of the the overload an the main pack. If you want more ground clearance, you can switch the the 3/4 ton style u-bolts. ORD sells the u-bolts and upper plates.

http://offroaddesign.com/catalog/Rear U-Bolts.htm

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My truck still have the bottom mount anti-sway bar, so the bolts have the bottom bracket setup for the UBolts. I assume the sway bar goes, or I find shorter ubolts that work with the bottom bracket?

 

[Craig 85]

My truck still have the bottom mount anti-sway bar, so the bolts have the bottom bracket setup for the UBolts. I assume the sway bar goes, or I find shorter ubolts that work with the bottom bracket?

I recently had my rear springs rebuilt. I removed one of the lower leaves to soften the ride, it was broken anyways. The shop made up some new U-bolts for me while I waited. I did have to cut about a 1/2" off the bottom so they weren't too long.