67-72 vs. 73-87 crossmember

[68blazer]

Hello all, i have been lurking around this site for years doing homework and studing all sorts of different topics. I have had a 1968 SWB in my back yard for years and i've recently disassembled it and i'm currently doing a frame off. I also bought a 1975 Long bed for the front cross member / disc brakes and suspension. i've heard that using the newer front end has greater benefits, does anyone know for sure?
here is the pic of the stud from the 75 cross member.

it was so rusted and wore down i cut if off and started to drill it out. i have spent way too much time trying to drill it out. here is the pic of the punch stuck in the crossmember stud hole, any other ideas?



for arguements sake i still have the one from the 68 and as far as i can tell all the measurements of the crossmember itself are the same. The Studs look a heck of a lot better on the 68 then the 75, obviously i'm not talking about using the upper and lower control arms, but in this next pic i put the newer upper control arm rod from the 75 on the studs of the 68 to see if they fit.
if you have stayed with me this far, Thank You! and hopefully you can answer my question. what would be the good/bad/ugly of putting the 75 suspension on a 68 crossmember??
here is a pic of both years together

any info or opinions or comments will be appreciated

[steelhorse]

I am using the 73-up control arms on my 67. I believe the switch to rubber bushings was the biggest difference on the newer models

[wreckedchevy]

http://67-72chevytrucks.com/vboard/s...+brake+install

[68blazer]

thanks so far for the replies!

Wrecked: Is your 63 crossmember the same as a 67-72?

[67chevy1series]

I would like to add a question?.......
Why would switching to rubber bushings in 73 be better? Does it help with handling or the comfort in the ride? It is it just a part that's easier to service?

[C10_ustacould]

I did this swap on my 68 using the entire crossmember, control arms and steering components. if I ever do it again I will leave the original crossmember in place and simply swap over the control arms and steering components. The reason is that the '68 crossmember has brake hardline tabs where the hard lines terminate and the rubber hoses begin. The 73 and later brake lines terminate in the frame forward of the crossmember. If you use the original crossmember you can use factory hard lines and conversion rubber hoses from companies like Early Classic Enterprises. The biggest advantage, outside of the brake hoses, is the rest of the parts are readily available at your local part store. Just my 2 cents...

[68blazer]

thanks bucks thats what i was needing/wanting to hear. i was just making sure using the 68 crossmember with the entire rest of the 75 suspension wasn't going to throw my alignment off, or change the dynamics of the ride for the worst. not to mention everyone talks about drilling a new hole, what i didn't understand is that if you used the old c-member w/ newer components then you don't need to deal with it.

ok pressing on, i'm using the 68 cross member with the rest of the front end from the 75. i have already bought all new moog components (thanks to many members builds on here!) and i will complete that soon.

thanks again guys, and thanks to all the builds i have been reviewing

speaking of posting a build, i'm going to start a new thread about whether or not to post my build so i don't hyjack my own thread. i'm on the fence about it

[RichardJ]

Originally Posted by Bucks68

I did this swap on my 68 using the entire crossmember, control arms and steering components. if I ever do it again I will leave the original crossmember in place and simply swap over the control arms and steering components. The reason is that the '68 crossmember has brake hardline tabs where the hard lines terminate and the rubber hoses begin. The 73 and later brake lines terminate in the frame forward of the crossmember. If you use the original crossmember you can use factory hard lines and conversion rubber hoses from companies like Early Classic Enterprises. The biggest advantage, outside of the brake hoses, is the rest of the parts are readily available at your local part store. Just my 2 cents...

Why would you want to use conversion rubber hoses from an aftermarket company?
Using the newer hard lines allows you to route the rubber hoses correctly for the disc calipers. Everything is factory, even if it is a different year and you can get replacement parts from any flaps.
The newer hard lines also places the combination valve forward, under the radiator and eliminates the clutter around the master cylinder.

I did use the '67 crossmember with '75 arms and disc spindles, but for a different reason. In 68blazer's 2nd and 3rd picture, you see the steel mounting plates that are riveted to the crossmember. The '67 3/4T had forged steel mounting plates. The '75 3/4T had the steel mounting plates plus a steel reinforcing plate in the inside of the frame rail. I liked the forged steel mounting plate and added the '75 reinforcing plate, inside the rail.

[C10_ustacould]

Originally Posted by RichardJ

Why would you want to use conversion rubber hoses from an aftermarket company?
Using the newer hard lines allows you to route the rubber hoses correctly for the disc calipers. Everything is factory, even if it is a different year and you can get replacement parts from any flaps.
The newer hard lines also places the combination valve forward, under the radiator and eliminates the clutter around the master cylinder.

I did use the '67 crossmember with '75 arms and disc spindles, but for a different reason. In 68blazer's 2nd and 3rd picture, you see the steel mounting plates that are riveted to the crossmember. The '67 3/4T had forged steel mounting plates. The '75 3/4T had the steel mounting plates plus a steel reinforcing plate in the inside of the frame rail. I liked the forged steel mounting plate and added the '75 reinforcing plate, inside the rail.

They are easier to deal with than building custom hard lines to match up to the 73-87 setup. It's about convenience.

[Tx Firefighter]

Richards method doesn't require any hard line fabrication. It's all bolt in with unmodified factory GM 73-87 hard lines. That's how I do them too. You're left with 100 percent original GM stuff that can be bought anywhere, now or twenty years from now. No aftermarket adapter hoses or hassle with making new hard lines.

[RichardJ]

The image below is from the LMC web catalog. In the middle of the picture you see "Brake Line Union". That coupling is the same on '67, up through the '70s and is located in the passenger side frame rail, just past the firewall.

You remove it from the donor truck with the disc brakes and slip it into your truck. You have to drill two holes and small pilot holes were already there on my truck.

[Tx Firefighter]

Originally Posted by RichardJ

The image below is from the LMC web catalog. In the middle of the picture you see "Brake Line Union". That coupling is the same on '67, up through the '70s and is located in the passenger side frame rail, just past the firewall.

You remove it from the donor truck with the disc brakes and slip it into your truck. You have to drill two holes and small pilot holes were already there on my truck.

The holes were in the frame rails for the brake hoses on my 63 truck even. I'm behind you on this one. After doing it this way, I haven't ever wanted to go back to building new lines and using adapter hoses and such. Every 73-87 truck I part out I carefully remove the entire spaghetti and save it for the next early truck I build.