69 GMC 6 lug drop questions.

[NCannon]

Hate to start a new thread here but I just can’t quite find what I’m looking for. If I’ve missed something where this is discussed, any pointing in the right direction is appreciated.
Truck is a 69 GMC fenderside long bed with 6 lug wheels and the I6 (if that matters).
I’d like to keep 6 lugs, and drop it roughly 3.5-4” in the front and back. As it sits now, it’s about 1/2“ lower in the back.

Front:
I don’t think I can (nor do I want to) cut the coils in the front to get the 4” of drop, so I’ll need to go with drop spindles. As I understand I’ll need to go to discs if I go to those drop spindles. I’d prefer to maintain consistency with my lugs and not have ½ of them be ½” and the other have be 7/16”. I’m also comfortable buying new rotors and just knowing they haven’t been turned excessively, they aren’t warped, or anything else I can’t check at the junk yard. Meanwhile, I’m trying to keep costs reasonable, so I’d like to pick up as much as I can from the local pull n’ save. The problem I’ve run into is that so many of the trucks here in the Denver area are 4wd, or the lugs are the wrong size, or they aren’t 6 lug, or any number of issues. I’d like to know if I can pick up the drop spindles and rotors from a supplier, and then get calipers/lines/proportioning valve/MC from a truck in the junk yard that didn’t quite match the lug specs for a direct swap. If so what fits that description?

Once that’s done, I’ll probably just go 2”-3” drop spindles and cut a coil (or get 2” drop springs and new shocks). Can I still keep my 15” rally wheels if I go to discs?

Rear:
I want to just go spring under in the rear, but from what I’ve read it looks like it’s usually more than the 4ish inches of drop I’m looking for. I’d be perfectly happy with a little rake since I use this truck as a truck (I just had 1000lbs of concrete and wood in it last weekend, which lowered it about as much as I’d like). I’m thinking a decent option would be to go spring under but get some heavy duty springs. I’d see the 4.5-5ish lower from the spring flip, but then gain a little back from the non-old/clapped out springs. Again, new shocks as well. For the rear, I just don’t know if there are good donor trucks out there for these springs? I guess I’m okay buying new leafs, but I’d rather just pick up something that will work from the junk yard.

Any help is appreciated, again, sorry if I couldn’t find these answers in a search. Thank you.
-Nate

[lolife99]

Look at this thread:
http://67-72chevytrucks.com/vboard/s...68&postcount=4

Read the parts that apply to you.
When I wrote it, I was trying to think of EVERY possible combination, which is almost impossible.

6-Lug Drum to 6-Lug Disc Conversions:
1) This 6-lug disc brake swap will include all of the above 5-lug information.

2) The only difference is the use of an aftermarket 6-lug rotor.
* These rotors are new castings.
* These rotors have been drilled with the correct 6x5.5" 6-lug pattern.
* These rotors have the correct 7/16" lug studs that match the original drum brake lug studs.

3) Several aftermarket suspension vendors sell these rotors,... such as:
* ECE (Early Classic Enterprises).
* POL (Performance OnLine).
* CPP (Classic Performance Products).

4) All 63-70 "conversion" stock height and drop spindles will work with these 6-lug rotors.

5) All 71-72 stock oem and drop spindles will work with these 6-lug rotors.

6) If using a 73-87 spindle,... it must be the HD spindle, that works with the 1-1/4" wide rotors.
* The 81-87 LD spindles will not work with these 6-lug rotors.

[lolife99]

Also look at Nate's "Blank Slate" thread.
Good 6-lug disc info here.
http://67-72chevytrucks.com/vboard/s...d.php?t=353633

[lolife99]

Truck is a 69 GMC fenderside long bed with 6 lug wheels and the I6 (if that matters).
I’d like to keep 6 lugs, and drop it roughly 3.5-4” in the front and back.
As it sits now, it’s about 1/2“ lower in the back.

Front:
I don’t think I can (nor do I want to) cut the coils in the front to get the 4” of drop, so I’ll need to go with drop spindles.
CORRECT. YOU NEED DROP SPINDLES.

As I understand I’ll need to go to discs if I go to those drop spindles.
I’d prefer to maintain consistency with my lugs and not have ½ of them be ½” and the other have be 7/16”.
AFTERMARKET ROTORS HAVE 7/16 LUG STUDS.

I’m also comfortable buying new rotors and just knowing they haven’t been turned excessively, they aren’t warped, or anything else I can’t check at the junk yard. Meanwhile, I’m trying to keep costs reasonable, so I’d like to pick up as much as I can from the local pull n’ save.
The problem I’ve run into is that so many of the trucks here in the Denver area are 4wd, or the lugs are the wrong size, or they aren’t 6 lug, or any number of issues. I’d like to know if I can pick up the drop spindles and rotors from a supplier, and then get calipers/lines/proportioning valve/MC from a truck in the junk yard that didn’t quite match the lug specs for a direct swap.
If so what fits that description?
BUY 63-70 DROP SPINDLES AND 6-LUG ROTORS.
EVERYTHING ELSE NEEDS TO BE NEW FROM YOUR LOCAL PARTS STORE.
SCREW JUNKYARD PARTS.
THEY ARE WORE OUT!

Once that’s done, I’ll probably just go 2”-3” drop spindles and cut a coil (or get 2” drop springs and new shocks).
Can I still keep my 15” rally wheels if I go to discs?
YES.
KEEP YOUR 15'' WHEEL BACKSPACING TO NO MORE THAN 4''.
YOU MIGHT HAVE TO TRIM YOUR LOWER A-ARM BALLJOINT AREA ON WHEELS WITH MORE THAN 3.5'' OF BACKSPACING.

Rear:
I want to just go spring under in the rear, but from what I’ve read it looks like it’s usually more than the 4ish inches of drop I’m looking for.
I’d be perfectly happy with a little rake since I use this truck as a truck (I just had 1000lbs of concrete and wood in it last weekend, which lowered it about as much as I’d like). I’m thinking a decent option would be to go spring under but get some heavy duty springs.
I’d see the 4.5-5ish lower from the spring flip, but then gain a little back from the non-old/clapped out springs.
YOU NEED A FLIP KIT OR NEW DROP LEAF SPRINGS.

Again, new shocks as well.
For the rear, I just don’t know if there are good donor trucks out there for these springs?
BUY DROP SPRINGS.
WWW.PERFORMANCEONLINE.COM SELLS 3", 4", AND 5" DROP SPRINGS.

I guess I’m okay buying new leafs, but I’d rather just pick up something that will work from the junk yard.

[NCannon]

Thank you, thank you, thank you!

I'd read the thread linked first and found it pretty valuable.

I'd prefer to go spring under in the rear, and I'm pretty comfortable just welding new perches on there instead of a flip kit, I was more just looking to see if there was some kind of heavy duty truck spring instead of the soft floppy ones back there now and if it would put me more in the range I was looking for lowing wise. Either way, it could just be simpler to just get replacements. Thank you again for the info. This sounds like it can be a good project for me over the winter.
-Nate

[lolife99]

Just remember if you install your own spring perches on the rearend,... you need to verify that the pinion angle is correct prior to welding.

[Tx Firefighter]

I agree with all Keith has said with the exception of one thing.....

Other than the new spindles and rotors, get all of the brake parts as a set from the junkyard. You're gonna want the master cylinder and brake calipers to turn in as cores when you get reman stuff. Reman calipers run about 15 each exchange and master cylinder 20 exchange so always replace rather than use junkyard parts. You got to have those cores though to turn in.

As far as used stuff goes, you can certainly run used junkyard brake lines and prop valve. Get new hoses though. You don't want to use 40 year old rubber hoses on your brakes. But the metal lines can be reused indefinitely if they aren't corroded. You'll also want the dust shields that go behind the rotors and banjo bolts for brake lines, wheel bearing grease caps, castle nuts, washers, brake line clips and all that. Used is fine for that stuff. You pay a lot to buy all that new and there's no safety or reliability reason to not go with used stuff.

I've done this swap a lot of times. My formula that works slick and pain free is

-new 6 lug rotors
-new drop spindles. Order for your truck year, a 69, and they will bolt right on.
-find a 73-87 donor at the junkyard. Make sure it has 1.25 inch thick rotors. From that donor, rob everything from the master cylinder out to the spindles and brakes as a whole. Yes, you're gonna scrap the spindles and rotors themselves, but its easier to buy big chunks and disassemble at your leisure at home to harvest what you need. Take all the brake lines and everything associated with them like clamps, clips etc.

73-87 brake lines will all bolt right into your truck in place of the old drum brake ones. GM bent some nice lines and they fit as well as anything you can bend up yourself. Quicker and cheaper too.
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[NCannon]

Sweet, thanks for the tips.

Yeah, pinion angle is something you only have to do wrong once to realize it's certainly worth the time to just get it right the first time. I want this to be a daily driver and I will be pretty unhappy blowing through u-joints and dealing with driveline vibes.

I suppose my main question was... could i pull the calipers, lines, master cylinder, etc from a 4wd (obviously not spindles) or a 2wd 5 lug set up (assuming they had the 1.25" rotors)? There are SO MANY 4wd chevy's in the pull n' save, but very few 2wds, and even fewer (none that I saw last time) 6 lug 2wd ones.
-Nate

[Tx Firefighter]

Your donor should be a 71-87 2 wheel drive truck. It will have 5 lug bolt pattern.
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[NCannon]

I've read a bit about how much a swaybar helps, will the donor truck have one I can poach as well?
-Nate