75 C30 leaf spring hanger replacement/relocation queries.

[AyWoSch Motors]

Hello all, I have some questions about my latest toy.
I recently picked up a 75 C30 dually flatbed, and it has some quirks with the rear axle.
I noticed the other day, that it sorta crab walks a bit, so I peaked underneath and noticed that rear leaf spring hanger had previously been cut off/broke off/rusted off, and very poorly booger welded back together in the wrong place.

So I'm now into cutting those off, and buying new ones. My questions are: are hangers from a C10 or C20 the same? Could I potentially get them from a junkyard or do I have to get them new? Do I have to get chevy C30 hangers, or can I get a generic universal fit? Is there a way to tell exactly where they should should go back to factory, without a ton of measuring and figuring? And should I weld them on, or bokt them on?

Also, as another wrench in the spokes...
The truck has its original 1975 1 ton rearend and springs, but I have a set of chevy 5500 extra heavy duty leaf springs of a 2000 chevy box truck that I would like to use as an upgrade.
My plan for it is to make a tow truck, so much heavier spring would be a good idea.

What accommodations do I have to make ro accept those bigger springs? Should I even do it, is it a bad idea? And what changes would that make to my leaf spring hangers issues?

I also wouldnt mind making it sit a little higher, so should I mount the hangers lower to raise it up, or is that a bad idea?

Lots of questions, but any insight would be helpful. I've never messed with modifying/fixing suspension issues like this. Thank you

 

[AyWoSch Motors]

Truck in question...

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And 5500 springs I have...

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[75gmck25]

Original springs were either 52” or 56” length, and a C30 would have the longer springs. There are specs online that show where the stock spring perches were mounted. I’ve seen 30 series in the yard with a 10,000 GVW, but I’m not sure if there were higher load ratings available.

Trying to reuse springs from another truck might work, but it’s always easier to stick with actual squarebody parts. RockAuto has ‘75 C30 leaf springs with up to 4650 lb rating, and you can add a helper spring for another 1000 lbs.

 

[AuroraGirl]

Truck in question...

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And 5500 springs I have...

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you may reconsider using a 2wd c30 as your tow rig with such a short wheel base(C&C?) it may not provide what you seek =================

 

[AyWoSch Motors]

you may reconsider using a 2wd c30 as your tow rig with such a short wheel base(C&C?) it may not provide what you seek =================

Well every wrecker I've ever seen has been a single cab long bed dually, so I don't see the issue.

When I say tow truck, I mean tow other trucks tow truck, not tow rig like hauling trailers.

 

[AyWoSch Motors]

Original springs were either 52” or 56” length, and a C30 would have the longer springs. There are specs online that show where the stock spring perches were mounted. I’ve seen 30 series in the yard with a 10,000 GVW, but I’m not sure if there were higher load ratings available.

Trying to reuse springs from another truck might work, but it’s always easier to stick with actual squarebody parts. RockAuto has ‘75 C30 leaf springs with up to 4650 lb rating, and you can add a helper spring for another 1000 lbs.

If the spring width and length are the same, should be a simple swap, just need longer u bolts.
Either way, I wouldn't mind using the stock springs, just figured I have these, maybe I could use them.

 

[RaisedK5]

Rear spring hangers are different on one ton. The spring perch width of a one ton is narrower than a 1/2 or 3/4 ton. You'll need to find new hangers from a c/k 30.

 

[AuroraGirl]

Well every wrecker I've ever seen has been a single cab long bed dually, so I don't see the issue.

When I say tow truck, I mean tow other trucks tow truck, not tow rig like hauling trailers.

Oh I gotcha, but you dont have a long bed dually you have a short wheel base which shouldnt hurt yoor situation I just want to clarify my post was about the length back that axle is. its too short to be LWB

 

[AyWoSch Motors]

Oh I gotcha, but you dont have a long bed dually you have a short wheel base which shouldnt hurt yoor situation I just want to clarify my post was about the length back that axle is. its too short to be LWB

Well that bed is 8 and a half feet long, so I'd say it's a long bed.
They didnt make short bed duallys from the factory.
But if you mean longer than a long bed, no, it's not a 12foot, its 8.

 

[AyWoSch Motors]

Are these the right parts I'm looking for?
For a stock C30 square.

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And these are off a late model, but they're cheap, and also, the springs I have are off a late model too. Would these work too?

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[AuroraGirl]

Well that bed is 8 and a half feet long, so I'd say it's a long bed.
They didnt make short bed duallys from the factory.
But if you mean longer than a long bed, no, it's not a 12foot, its 8.

Is this a cab and chassis or a pickup? Im looking again and Im leaning more toward truck, but I guess The flatbed made the rear wheels appear closer. I was not saying anything about the bed length, I was talking about the wheel base. but I compared and it looks like it can be normal. is it a 14 bolt or a dana 70

also here is @Craig 85 k30 pic for good ref

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[bucket]

C30 hangers are their own design. Set up for narrower perch width and shorter height than K30 hangers.

It aught to be real easy to find a rear C30 frame section out you way? Then remove the good factory hangers to use on yours.

 

[AyWoSch Motors]

Is this a cab and chassis or a pickup? Im looking again and Im leaning more toward truck, but I guess The flatbed made the rear wheels appear closer. I was not saying anything about the bed length, I was talking about the wheel base. but I compared and it looks like it can be normal. is it a 14 bolt or a dana 70

also here is @Craig 85 k30 pic for good ref

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Vin and dash says it's a Silverado pickup, not a factory chassis model. I would assume at one point in its life it originally had a standard bed with dually fenders. Its has a 14 bolt I believe.

I distance from the back of cab to the axle looks weird, because the back end of the bed hags over the rear farther that a standard looking bed would, it looks funky.

 

[AyWoSch Motors]

C30 hangers are their own design. Set up for narrower perch width and shorter height than K30 hangers.

It aught to be real easy to find a rear C30 frame section out you way? Then remove the good factory hangers to use on yours.

Right now at my junkyard, there are 4 c20s, a c10, and a c30, but it's a big 14 foot bed. Would hangers from that truck be the same? And also, they're riveted on, correct? How would you get them off?

 

[wanderinthru]

Right now at my junkyard, there are 4 c20s, a c10, and a c30, but it's a big 14 foot bed. Would hangers from that truck be the same? And also, they're riveted on, correct? How would you get them off?

I would guess they are the same. If the frame is scrap, get on the inside with a torch. If it aint scrap get at them with a grinder. Your truck appears to be a cab and chassis, looks to narrow to be a dulley.