'63 front end swap and drop

[PLYONS11]

More guidance is needed! In the middle of my 3/4t to 1/2t conversion on my 63 1500. The rear end is done except for decisions on disk brakes and a parking brake. (Currently a trans mounted brake)

I am however struggling with the front end swap. I have read tons of material and just cant decide what to trust and/or what direction to go. I am looking for the easiest way to convert to 1/2t and 5lug disk. My wants are the ability to bag it some day and the ability to use tubular control arms with polly bushings and a sway bar. My needs are lowering it 3-4" and disk brakes.

I understand that CPP and ECE make drop spindles for the 3/4t that retain the same ball joints and end links, but then I am limited on options. Furthermore I already need to replace the ball joints, links, and cross shaft bushings. As far as I can tell from my research there is no a arms that are tubular that will work with the 3/4t. CPP did however say that they sell saddles that bolt to the 3/4t x-member that will allow for the u bolt style 1/2t a arms. Can anyone validate this? Seems to me that if this were possible I would have read it on one of these forums already.

I have found a few 80-87 total front ends at a local junk yard for $350 and I am fully equipped and capable of doing this swap, but I hesitate to go this route because I want to retain the factory 305 V6 and I cant find anyone who can confirm that the 305 will mount to the later x-member without fabrication.

[FetchMeAPepsi]

Originally Posted by PLYONS11

More guidance is needed! In the middle of my 3/4t to 1/2t conversion on my 63 1500. The rear end is done except for decisions on disk brakes and a parking brake. (Currently a trans mounted brake)

I am however struggling with the front end swap. I have read tons of material and just cant decide what to trust and/or what direction to go. I am looking for the easiest way to convert to 1/2t and 5lug disk. My wants are the ability to bag it some day and the ability to use tubular control arms with polly bushings and a sway bar. My needs are lowering it 3-4" and disk brakes.

I understand that CPP and ECE make drop spindles for the 3/4t that retain the same ball joints and end links, but then I am limited on options. Furthermore I already need to replace the ball joints, links, and cross shaft bushings. As far as I can tell from my research there is no a arms that are tubular that will work with the 3/4t. CPP did however say that they sell saddles that bolt to the 3/4t x-member that will allow for the u bolt style 1/2t a arms. Can anyone validate this? Seems to me that if this were possible I would have read it on one of these forums already.

I have found a few 80-87 total front ends at a local junk yard for $350 and I am fully equipped and capable of doing this swap, but I hesitate to go this route because I want to retain the factory 305 V6 and I cant find anyone who can confirm that the 305 will mount to the later x-member without fabrication.

Problem is you're getting into territory that alot of us don't drive down. Some guys mod them up and change everything, others prefer to keep the stock look and feel. Most of the members here are the second group, but I like to see both, but really prefer chevys for mods. Parts are easier to come by and there aren't many GMCs left.

If you figure it out though start a build thread and let us see what you do. A little modernization can be a good thing.

[PLYONS11]

Originally Posted by FetchMeAPepsi

Problem is you're getting into territory that alot of us don't drive down. Some guys mod them up and change everything, others prefer to keep the stock look and feel. Most of the members here are the second group, but I like to see both, but really prefer chevys for mods. Parts are easier to come by and there aren't many GMCs left.

If you figure it out though start a build thread and let us see what you do. A little modernization can be a good thing.

I love the original thing, and considered this for quite some time, but it just didn't work for me. This is my grandfathers truck and I want it to stay in the family. I want to be able to drive my son around in it. It just didn't ride or stop they way I wanted it to. I plan to basically keep everything as close to original as possible except for the suspension, brakes, and handling.

I sure hope someone can chime in and give some insight into my dilemma. Thanks!

[Clyde]

This is my 1969 GMC Suburban which has air bags and disc brakes all around.

[WDShaffer]

The crew at ECE are great. My '61 was actually in their shop for review and measurement of the factory stock frame before I modified it. They indicated at the time a "late model" front cross member - '80 - '87 - would bolt into the frame at the same location of factory rivets. Regarding the engine mounts, what is a little fabrication at that point?

[Cchill]

Below is the link for the writeup I used for mine. I don't have the bb v6 anymore, but I hope this helps. Also if you are capable of doing this swap, then the motor mount work would not be to much more.





http://67-72chevytrucks.com/vboard/s...d.php?t=366850

[jimjaz]

Hey PLYONS11,

Swapping out a 63 GMC front end to acquire 5 lug disc? I think I can help you out here with some specifics and thoughts for you to contemplate. I have done this swap on my 65 GMC Sub which was pretty straightforward since my 65 has a mechanical clutch linkage and bell crank. Your 63 uses a hydraulic clutch, right?, so you have two lines off your master- one for the brakes to all 4 wheels, and the other for the clutch. To me, this will most likely be your biggest hurdle. If you can convert your hydraulic clutch to a mechanical setup as is used in 64-66 GMC trucks, then this will make things a whole lot easier for you.
I used a 79 GMC (or Chevy front end- it doesn't matter)- all 73-87 GMC and Chevy trucks are all 5-lug for the 1/2 ton, which is what you are after.
Go out to your truck and take a peek at what is hanging down the lowest on your truck. Is it the oil pan? Doing a drop spindle thing like 4 inches won't work- you will wind up tearing a hole in your pan, and if you don't know, the big V6 can be very expensive to repair/rebuild/machine/buy parts for. Don't go here, please! A guy in Chandler AZ was going to do this and was saved by Chris out in Apache Junction AZ who told him, "You can't drop slam your truck from 1/2T stock with a GMC BB V6. Your oil pan will then be the lowest thing under your truck." The V6 weighs in at 825 pounds carb to pan with exhaust manifolds. A SB V8 is about 500, BB V8 only adds about 50 pounds. You need to think on this as well. 825 lbs over a half-ton conversion kit from CPP or ECE or wherever with or without a 4-inch drop will most likely make you very unhappy due to bottoming out even on bumps and road divots that a stock suspension would more or less glide right over. The aftermarket houses job is to sell you their kits, their parts, and they are probably not going to tell you that their stuff is just not built to take on an 825 pound engine over the front wheels. Bottoming out is REALLY hard on front-end stuff.

My conversion on my 65 was a 1/2T to 1/2T, kept my original springs and marked them side specific (they have the natural 53 year drop on them), and I like the ride height and use mine as a truck to do truck stuff like going off road to camp, fish, haul firewood, and what-not. Doing any drop spindles is rather permanent and you are most definitely going to limit where you can go; road humps and street to parking lot curbs will be your enemy, even the moderate ones. Air bags are out, since you would need to change a whole ton of stuff for the rear that you say is pretty much done, and then there's the oil pan thing. I just mention this so you can think about this "down the road" (excuse the pun) before you take the plunge and have many regrets. Nobody wants regrets.... On to the meat and potatoes....
- both my 63 GMC Sub cross member (came with V6) and my (now) 79 cross member in my 65 (came with an I-6) have the same mounting hole pattern for engine mounts in the cradle between the frame rails, and both have 3 holes on the top of the frame rails, each having 2 and 5/8th inches center-to-center spacing. Yours should be no different. In essence, these 73-87 cross members are the same as 60's stock which makes them very versatile.
Here is the skinny on my findings when I did my 65 (factory drum front) to 79 factory disc front) conversion;

First, the bad news- you will have to drill one hole on each side of the frame to accept the later year cross member, and you will also need to elongate one hole on each side that do not line up directly, sort of like a half-moon affair. Your template to do this is already there, since there are already holes in both the cross member and your frame that DO line up directly. Just put in the bolts that line up, then drill one and elongate the other.
Also, kit parts are only available from kit vendors, so you are basically married to them as long as they manage to stay in business. I do not recommend a kit from anybody for this reason- everybody and their mother sells OEM stuff for GM/Chevy trucks. In other words, your options are pretty limited.

Now, for the good news, and there is lots of it (using OEM);
- 73 to 87 cross member is compatible with the same engines that 60-66 GMC and Chevy use. The V6, V8, or I6.
- the 1/2T donor truck will also come with coil springs already broken in. They are going to get you a softer ride than your current 3/4T setup. The V6 being 325 pounds heavier than a 73-87 with V8 will probably get you a 2-inch drop up front just from the mass of the V6. If you happen to remove the springs, mark one and put it back on the same side it came out of. Springs are funny and don't "wear" the same. If you get them put in backwards, then your truck could be listing to one side.
- donor truck comes with 5 lug spindles that you want.
- bigger, beefier upper and lower ball joints. The ball joints on our 60's 1/2T trucks are wimpy in comparison.
- OEM 73-87 spindles are far superior to any aftermarket "kit" that adapts front disc using your 60's factory wimpy ball joints if you were going with a "kit". You will not be happy with a kit, in my own humble opinion.
- if your 63 truck happens to have factory front anti-sway installed, then good! A lot more 73-87 GMC/Chevy trucks already have this. Much thicker bar, so much better resiliency to sway. Get the anti-sway from the donor truck anyway, but be sure to get the frame cradles as well.
- factory A-arms (zerk greaseable) would be a better idea than going with the poly bushings for A-arms. They will creak and squeak over time. This alone causes folks to stop going to car/truck shows from the weird noises it makes over time. Tubular A-arms? Why? Nobody looks at them anyway.... is there a benefit? I go back to the V6 sheer mass and weight to say probably not a good idea.

My 1965 GMC Suburban swap is all OEM using a 79 non-power brake front end and all the associated components that drop out with the cross member (A-arms, springs, spindles, rotors, and front spindle soft brake lines that come off the outside of the frame), and got the front hard brake lines along with the master cylinder, prop valve, and anti-sway bar. I did not want a power brake setup for reasons of the potential to lock up your brakes during a panic stop ((( oops! Too late, you are already headed sideways...))). The exception would be to have anti-lock brakes installed, and that is just crazy expensive and a whole different ball game. 75 to 80 percent of your braking is done up front on the disc rotors anyway, so doing my all OEM conversion to disc/drum was easy since the 73-87 trucks are all this way. Have you thought about this at all? Power brakes are simply not needed if the disc/drum braking system is designed properly, and GM has done tons of design, testing, and engineering on braking systems, and this is the main reason for me going with OEM versus aftermarket since GM already did the work. My conversion was kind of a no-brainer- yours is going to be a challenge because of the hydraulic clutch you currently have. In your case, you cannot, to my knowledge, use a master cylinder except for the one that came on your truck. Have you mentioned this little factoid to CPP or ECE regarding the kits they sell and compatibility for your hydraulic clutch? This is uncharted waters for me. This would require a 3rd output line off the master since 73-87 disc/drum braking systems use a master with two reservoirs- one for the front and the other to the proportioning valve for the rear, or you could potentially find the 64-66 GMC mechanical clutch linkage stuff with bell crank from somebody on the site or salvage yard that just happens to have all the stuff which would solve this problem for you. And just remember you would need the frame side piece as well for the bell crank. This is factory riveted in place on the donor truck and not just bolted on. This is a critical component if you are changing from hydraulic clutch to a mechanical linkage and you must have this part for your frame rail as well, otherwise you got nothing that will actually work. I can't imagine that the block on your V6 would not accept a bell crank adaptation, but you would need to verify this before proceeding.

My advice to you is to seriously think about staying with OEM using a 1/2 ton donor truck 73-87 that will have almost everything you need, and start out with the stock spindles. Do the swap with everything you can get off a single donor 1/2T GMC or Chevy truck for one cheap price- the entire front suspension that drops out via 6 or 8 bolts that hold the cross member in place, and the other stuff already mentioned. This is ALL based on you being able to find the parts to convert your hydraulic clutch to mechanical linkage, and (more bad news) THIS WOULD INCLUDE THE BELL HOUSING off of a 64-66 GMC that would need to be changed out as well. The hydraulic is passenger side for release bearing pivot fork, and mechanical is driver side. You could get everything you need from just one truck if it were a 64-66 GMC with a BB V6 in a wrecking yard. This is going to be easier said than done.
I know this is very windy and long (and boring?), but I do hope that it may give you some better direction or a different way to go. My way is most certainly not the only way....

Regards,
Jim

[Chuck78]

I saw this thread and was interested as I have had an 89 Suburban 1/2 ton disc brake front crossmember in the garage for a decade now, awaiting me getting settled into my life with enough time to perform the swap. I have already dealt with the hydraulic clutch setup a decade ago before I got sidetracked with life.
I added a small diameter but thicker power booster from Pirate Jack's I believe it was, used a 67 1 ton master cylinder as it had what I then calculated as the correct bores for a rear drum/front disc setup once removing the front proportioning valve from the master (turned out my slight initial fears were worse, this was calculated for front disc fluid leverage ratios, and gives the rear far too much power if still 4 wheel drum, 45mph panic stop locked up the rears to avoid crushing an idiot that cut me off doing 10mph & I slid sideways through a road sign post...).
I used I believe a standard mechanical clutch gmc brake master cylinder for the clutch (memory is foggy here, search the old archived Yahoo posts for my info under Chuck or Chuck78). Finding an appropriate clutch line to replace mine was the most difficult part, but a hydraulic shop custom line would be simple.
I fabbed up my own power booster bracket to space the booster in front of the clutch master. I used what I recall being two different power booster brackets MIG welded together in the middle to give me the extra distance, & the pedal to booster rod was a piece ir two that I assembled from parts from Pirate Jack's catalog.

I wish I could find my fresh install pics. I'll snap a pic of 10+ years later, nice rusty master cylinders from sitting outside...

[Chuck78]

The front 5 lug disc concerns that I wanted to poke around this forum for were more along the lines of what front springs to use, as I'm going from torsion bar setup to coils. I really like the torsion bars and their adjustable ride height, but I still found them to not be quite stiff enough. I will miss that setup, but getting 73-91 Suburban / 73-87 truck interchange on replacement parts is AWESOME and worth the tradeoff. My ball joints are shot, and all 4 priced out 10 yrs ago cost more (nearly double!) than replacing every single ball joint, tie rod, idler arm, & bushing on the 73-87pu/91burb front end!!! Plus as noted, a better & more stout ball joint design...

Back to springs... the 89 suburban I had rode pretty soft up front with a heavier 700r4 trans and a much lighter and excellent 350tbi engine. I will be adding at least 250 lbs to the front end vs the 89 burb drivetrain. However I recall seeing the weight of a 60-66 1/2 ton 1000 panel being listed as 4,000lbs, & the 89 Suburban I had was listed as 5,000lb if I recall correctly.
(I NEED TO RE-VERIFY THESE #'s)

Let's assume that may have been a Chevy 1/2 ton panel weight, & say 4,300lbs on the panel. The 89 burb is much longer and has more interior trim and back seats. So 65% of that weight difference may be biased toward the rear. If all these figures are in the ballpark, that would mean the 89 burb springs are spec for about 245 lbs more weight than if ran in the 62 gmc 1000 panel.
This would seem like everything should work out fine, but I am very skeptical and I'm thinking that the much heavier GMC big block v6 engine directly over the springs is going to require heavier springs than the 1989 Suburban front crossmember has equipped stock.

I can drive the truck onto the scales at the scrapyard, & then get 2 additional measurements with the front wheels only on the scale and the rear wheels only on the scale, & likely could go to an aftermarket spring/suspension supplier and get a good spec.
For my prior 70-81 Camaro/Firebird hobby, I came across a chart of moog spring diameters/coils/wire thicknesses/heights/etc and picked some random oem replacement springs that were very close to the height I wanted and the rate of choice. That may take some research for the truck, or else find a 1/2 ton suburban 454 big block spec spring. Maybe even a small block 3/4 ton Suburban spring.

[jimjaz]

Chuck, My memory is no steel trap any more, but I seem to remember that a front-end suspension crossmember is good from trucks (Chev or GMC) from 73 thru 87. Maybe I got my wires crossed up and a '89 as you have will work. The one I snuck in under my '65 GMC Sub was from a '79, and it was pretty much a piece of cake.

R/
Jim