'67 drum to '72 disc swap - advice?

[Truckstr]

I'm about to embark on a new project and would appreciate any advice from the old hands here. Experience is the best teacher, so I want to learn from those with it.

Here's what I have:

'67 Chevy swb with drums on all four wheels to change to power disc.

'72 Chevy lwb with power front disc as a donor truck.

ECE drop spindles
new '72 power disc brake master cylinder
new front end rebuild kit for the '72 (procured before I had the '67) - ball joints, tie rod ends, etc.
ECE front anti-sway bar with drop brackets.

I plan on installing the rear end from the '72 later to get it to 5-lug all around.

What will I need, besides what I have, to get before I starting? New front brake hoses will be one thing on the list. What else?

I want to have the '67 down for as little time as possible. I can even take the complete cross-member assembly out from under the '72 and rebuild it, I suppose. That would mean that I'd need to pull the engine in the '67 to ease installation. Right?

Again, any advice before I get started (and after) will be appreciated. I'll try to take pictures as I go if I can swipe the digi-cam from work.

Thanks,
Jeff

[1971Stepside]

My advice would be to rebuild the 72 front end and pull the whole thing out and put it in your 67. I can't think of why you would need to pull the engine for that...other than the tight fit to the bolts, but you should be able to just pull your exhaust manifolds to have enough room.

[Truckstr]

Well, It was a six-cylinder truck originally, but now it's a 350 (destined to be a 406) installed in the six-cylinder position with headers.

The end of the motor mounts mounted on the cross-member is what I was concerned with. I guess that I'm just a little apprehensive about pulling the cross-member out from under it with the engine still in. I don't even mind removing the headers. They aren't "that" hard to get in and out. LOL

You should see the way the previous owner rigged up the brake lines. One of the lines (for the rear brakes ) is right up against one of the header tubes. That has GOT to be changed. I "think" all of the fittings are original. But who really knows? Not me.

Thanks for the reply. Keep 'em comin'.

Jeff

[1971Stepside]

Yeah, I was just thinkin you could support the engine with a cherry picker from the top to keep the weight up or support it under the back of the oil pan. I should have been more clear. Point is I wouldn't think you would have to pull it out completely since downtime was an issue.

[Truckstr]

Thanks.

I have a cherry picker, but thought that I might need it to move the cross member assembly around. I don't usually have much (if any) help on my projects . My 16 year old son is either in school, at work or chasing girls (oh to be 16 again!) - and he hates to get his hands dirty anyway .

I guess that I could get it to work out somehow, though.

Any other thoughts?

Thanks,
Jeff

[crazy longhorn]

you dont need to pull the crossmember, if you use the 71-72 lower a arms you will get around the steering stop issues. the only difference on the crossmembers will be mounting brackets for the brake hoses,& you can cut them off & weld them on the orig crossmember. If you have 71-72 dropped spindles,you need the balljoints, tierods assy (inner ,outer ,& sleeves) for the 71-72. Also, use the center link from the 72,as well as the lines, hoses, master & prop valve. Good luck....crazyL

[Truckstr]

Originally posted by crazy longhorn
you dont need to pull the crossmember, if you use the 71-72 lower a arms you will get around the steering stop issues. the only difference on the crossmembers will be mounting brackets for the brake hoses,& you can cut them off & weld them on the orig crossmember. If you have 71-72 dropped spindles,you need the balljoints, tierods assy (inner ,outer ,& sleeves) for the 71-72. Also, use the center link from the 72,as well as the lines, hoses, master & prop valve. Good luck....crazyL

Sorry crazyL, I wasn't aware that there were/are any steering stop issues. It does seem, however, that the steering on my '67 doesn't travel as far (turn as "tightly") as my '72.

I have a set of '69 GMC (I think) spindles that I had already sandblasted and readied for install. So, I take it that they won't work. Right?

Thanks,
Jeff

[Southpa]

I did a complete front end swap a few years ago. Donor was a 71 1/2 ton into my 70 1/2 ton. You can leave the engine in while doing the swap. The motor mount tower bases are bolted down in two places. 2 upper bolts to the frame (leave those) and 2 lower bolts to the x-member. I used a small jack with a chunk of 12" X12" plywood for support under the oilpan and just unbolted the lower tower bolts. I pretty much did it all by myself. The only help I needed was getting my neighbor to shake the old x-member (also supported on a jack) so I could get that very last bolt out. He got a bit of a surprise when the rotten bracket finally let go and the spring popped out at him.

[Truckstr]

Sounds simple enough, southpa, but I'm still unclear about the difference between the different year lower A-arms (or upper ones for that matter).

What gives?

Thanks,
Jeff

[crazy longhorn]

Truckstr, the steer stops are different on the 67-70 lower arms, & while the71-72 ball joints will press in , using the later spindles on the early arms will shorten the turning raduis. There are many way to go here, but the best way is what fits your time frame/ budget ,ect! my 69 has 71 arms (bottom), stock uppers, & 75 spindles & matching balljoints, tierods. All of the brake lines , hoses ,master , prop valve are also 75 pcs....the cradle is still original. there isnt enough info on the center link(boneyard pc only), but the general rule is 71 up is the same. Good luck...crazyL

[rayville body]

thinking about just swapping the x-member too since reading this post! would it be a wise idea to weld the x-member to the frame also? for extra support (i have a fear of somthing falling apart while i'm driving down the road)?

[Southpa]

Yeah, its only an issue if you want to mix 'n match parts. No problemo if you are doing an entire front end swap. NONONONONO NO to welding! The frames and adjacent parts on these trucks are designed for flexing. Welding will only cause internal stresses, which will result in snap, crackle POP!

[crazy longhorn]

Oops, I missed part of that post. The 69 lower a arms can be made to work, you will probably just have to grind a little off the steer stops on the spindles.......or modify the stops on the arms(whatever you are more comfortable with) to get the steering radius where it should be....crazyL

[crazy longhorn]

rayville body, I wouldnt weld that crossmember to the frame......mine has been there since 1969, & hasnt caused any problems.....

[Southpa]

Yeah, I can remember taking my truck to a front end specialist to figure out whatall I needed to get it back in shape. Both xmember to frame brackets were cracked and rotten. The guy took it for a spin around the block and then tells me, "this is the only kind of truck I know of that you can still drive in this condition". Kinda makes me think I made the right choice in vehicles.

[crazy longhorn]

Southpa, my longhorn is just a "pup" with a 1/4 million miles on her! One thing that helps is that Z in the in the serial #....the old gal came from So Cal, so rust or scale i havent seen. I can remember a few Illinois trucks that had a lot of scale up front(the ones that didnt leak oil!). At any rate , those are some beefy brackets from frame to crossmember, but it would be sure worth a look......if it looks like trouble, it probably will be(if it has tits, it will be for sure trouble) crazyl

[Southpa]

You got that right, its something I will definitely look at next time I check out another truck. Those brackets are natural "cups" for holding water. I think I have a pic of the old xmember somewhere, hard to make out the damage tho. But the brackets not only hold the frame onto the xmember, they also hold the pinions of your upper A-arms down, lol.

[67/72junkie]

Swap the entire crossmember.Its not hard at all and you can clean & paint everything alot better out of the truck before you install.Also 72 tie rods are larger diameter and stronger.

[Truckstr]

Alright, let's take this one step further.

I have another "spare" front cross member from a chassis that I salvaged a while back. That's where the '69 GMC A-arms came from. (At least I "think" it was a '69 GMC. Actually, all I know is that it was a short bed {still have the frame} that had six lug hubs, rear heavy duty leaf springs (7 per side!), 3.54 single spin Dana and lots of rust )

What if my "practice" notching the front cross member on the "spare" works out better than I expect?

What are the differences between the various '67-'72 (Chevy and GMC) crossmembers other than a few minor brackets?

The lower A-arms all have holes drilled for a front sway bar, right? Or do they?

I guess that what I'm trying to figure out is what I can practically and effectively piece together from what I have. What's different?

Help me out fellas. Edumacate me !