C-20 Drop Spindles

[jjdowney]

Ok, so I've seen a bunch of threads about C-20 drop spindles and the differences and disc brakes, etc. I might be a little dense and not getting it exactly, so I'm asking again.

I have a '72 C-20 with disc brakes on the front (drums in the rear) but its an 8 lug still. Is that possible? I haven't seen many with disc brakes and 8 lugs. I want to drop the front. I just bought the 3/4 ton drop springs from GMCPauls for 2" and I've seen C-20 drop spindles for like $400, where the C-10 drop spindles are only ~$250 and they both say something like "disc brake application only". I only bought the truck about 6 months ago so I don't know everything that has been done to it. If it has disc brakes in front, what has been done? Do I still need the C-20 spindles or can I do the C-10 spindles? I don't know of any other options to drop to front another couple inches, is there?

[viking427]

GM's 1/2 ton (C10/K10), 3/4 ton (C20/K20) and 1 ton (C30/K30) trucks got front disc brakes starting in 1971, so your 72 C20 has disc brakes, assuming its been left mostly stock (few people would replace front discs with drums). You can swap out your 3/4 ton spindles (same as 1 ton) for 1/2 ton spindles if you have no desire, use or need for the capabilities of a 3/4 ton truck. You would also need the 1/2 ton lower control arm that the 1/2 ton (10 series)spindles require, since the 20 & 30 series use a larger ball joint in the lower control arm than the 10 series. This would allow you to use 5 or 6 lug rotors for more/better wheel selection availability for the 1/2 tons. However, if you think you might have a need for the capabilities of a 3/4 ton truck, you already have the 3/4 ton drop spindles, so you can just pop them onto your existing C20 control arms, pick a set of 8 lug wheels and youre all set. The 1971-87 C20 used a 1.25" thick rotor with a single piston, floating/sliding pin caliper design, similar to the 1/2 ton caliper design, just a little larger.

[jjdowney]

I was planning on leaving it a 3/4 ton, I'm not sure that I need it to be, but its nice to know that I could use it if i needed. Plus, that way I dont have to change out the control arm and rotors. I have a set of the 2500 HD stock 8 lug wheels already. I am planning on flipping the leaf springs under the axle to drop the rear (I assume I'll need a C-notch) and I have 2" drop shackles if I decide I need more.

It might be completely worthless to try to stay 3/4 ton but that's my plan for now.

[jjdowney]

So I've been searching a bunch and just now saw these. Am I missing something or would these "theoretically" work?

http://www.streetbeatcustoms.com/Hot...D_S_18/872217/

[viking427]

Originally Posted by jjdowney

So I've been searching a bunch and just now saw these. Am I missing something or would these "theoretically" work?

http://www.streetbeatcustoms.com/Hot...D_S_18/872217/

I see this aftermarket supplier offers these drop spindles in both a "clip on" style caliper and a "floating pin" style caliper for the C20. I can't speak for whats available in the aftermarket these days, but original GM issue "clip on" ..also known as "wedge" style.. calipers and their required spindles, were issued on C/K30 1 ton trucks only, starting in 1974, which used a 1.50" thick rotor. Your 1972 C20 ..if original.. has the "floating pin" style calipers and spindles, which used a 1.25" thick rotor. Both style rotors are same diameter and 8 lug, so both will work - but you must keep the spindle/caliper/rotor styles packaged together for whichever style you choose.

I suspect the aftermarket suppliers are marketing the C/K30 1 ton "wedge" caliper drop spindles to C/K20 owners (larger target market), but not informing them they'll also need to change their rotors to the 1 ton rotor to use those larger calipers. The "throat" of the 30 series wedge style caliper where the brake pads sit is wider than the 20 series pin calipers, to accomodate the 1/4" wider rotor. More possibiities are someone is offering thicker brake pads to take up that 1/4" gap, allowing use of 20 series 1.25" thick rotors with wedge calipers, or some later model GM application allowed mixing and matching the three components. Again, Im not up on aftermarket offerings.

http://www.streetbeatcustoms.com/197...sion/Spindles/