6 lug to 5 lug

[ready2go69]

I know there has to be a cheap way to convert my 70 gmc to a 5 lug. Can some one give me the best way to get this done?

[67ChevyRedneck]

Junkyard. Find a 71/72 truck and take the complete front suspension including the power booster/MC/proportioing vale, and power steering set up while you're at it too, and rear axle, or keep your eye out for a complete frame, they're sometimes as little as a couple hundred bucks, especially for a longbed. You just need to check the rear end to make sure it's a ratio that you want. Cut up what's left of the frame, bring in your old stuff and the frame and get a good chunk of money back in scrap.

Even that route will cost some good $ to do it "right." With 40+ year old parts you should at least get new bushings, ball joints, tie rod ends, shocks, rear trailing arm bushings and panhard bushings too. Plus new pads, rubber front brake lines, maybe new rotors, new rear shoes...

[Richard8971]

Originally Posted by 67ChevyRedneck

With 40+ year old parts you should at least get new bushings, ball joints, tie rod ends, shocks, rear trailing arm bushings and panhard bushings too. Plus new pads, rubber front brake lines, maybe new rotors, new rear shoes...

Yeah tell me about it. Thats a good idea Jessie. I have been wanting to do that to my truck as well and also to convert my front drums to discs. Will this work for doing that as well? I already have a booster that can handle front discs. I thought a '72 was the only year they had disc brakes up front.

D

[my67chevytruck]

71-72 had discs, Richard as long as you have a disc/drum proportioning valve your golden if you swap in a 71/72 xmember. to add more confusion, you could also swap in a 73-87 front xmember. for the rear you could get a 71/72 and it will bolt right in, if you dont want to mess with changing the rear, they make conversion axles that will give you the 5 lug rear...

we went the '72 route for my son's truck after speaking with Jesse on the subject.....

best of luck.

[Sublvr72]

It's just about the same as converting a C-20 over. I did my 72 suburban from 8 lug to 5 lug, and I had to find a 71-72 rear end, and 71-72 front end.

I could have saved some money if I thought about it, but at the time I didn't realize. Instead of buying a 71-72 complete front end I could have just bought the spindles, upper/lower ball joint, and the tie rod end.

The only difference in going from drum to disk, as others have said is to get the brake booster, proportioning valve, and the calipers that go with them.

[michael bustamante]

check your rear axle width, you might have the longer rear end. if you do you can swap axles instead of the whole rear end. (cheaper) But if you have leaf rear end you can use any rear end out a 73 and up truck I believe. as for the front end, you HAVE to change out your front brakes lines as wellas the prop valve. the threads are different

[67ChevyRedneck]

Originally Posted by Richard8971

Yeah tell me about it. Thats a good idea Jessie. I have been wanting to do that to my truck as well and also to convert my front drums to discs. Will this work for doing that as well? I already have a booster that can handle front discs. I thought a '72 was the only year they had disc brakes up front.

D

71&72. Make sure you have the right proportioning valve for disc trucks.

If you use the ENTIRE front suspension, you need to buy everything for a 71/72 truck. If you only swap the spindles, you need the 71/72 ball joints, 71/72 OUTER tie rod ends (if you keep the 67-70 center link, you need to use 67-70 inner tie rod ends) and I think you may need the 71/72 pitman arm, but for my truck I just used the 71 steering box I got with the truck. Also, the little "tit" on the back of the spindle to stop the wheels from turning too far needs to be ground down if you use 67-70 lower control arms. The bump stops on them are different. Before taking the truck apart, count the number of times the wheel turns from center so you can slowly grind the tit down until the 71/72 spindles with the 67-70 lower control arms will turn properly from lock to lock...

long story short, using the whole damn thing is way easier

...and obviously, if you buy an ECE or similar kit made for your year truck, it comes with everything to "make it work" with what you have.

[mrein3]

Originally Posted by michael bustamante

check your rear axle width, you might have the longer rear end. if you do you can swap axles instead of the whole rear end. (cheaper) But if you have leaf rear end you can use any rear end out a 73 and up truck I believe. as for the front end, you HAVE to change out your front brakes lines as wellas the prop valve. the threads are different

Way, way, way back in the early days of this forum, knowledge was passed around on how to swap 1970s to 5 lug by just swapping out the axels in your half ton. You needed to know if you had the wider or narrower rear in your 1970 as that was a transition year.

I never paid attention because I have a 4x4. Perhaps one of the 'old timers' on this board that have done this will chime in.

FWIW, I know a crazy old guy that has two eights lugs on the rear, a six lug on one side of the front and a 5 lug on the other side of the front. And you think my truck is a mutt.

[1-PU70]

I did my 70. Its a coil rear. Its true there were 2 different rears in a 70 one being wider then the other. I was lucky and had a wid one. I dont know any way to tell other then pulling the axels out. I got a set of axels from a 77. They fit perfect. I dident even change seals. For the front it just so happens I used another 77. You can go the the mid 80s but they went to metric in the early in the 80s. Some will say you need the entire front end including the sadel. I used everything except the sadel. Upper and lower controll arms with ball joints, shafts and spindals. All the stering linkage. Cant remember if I used the 77 pitman arme or not. I did this about 15 years ago so its hard to remember. The only other thing is the the proporting valve from a 71 or 72. You could use a 73 and up but they have 2 ports for the front so you would have to plug one. And a master from a 71 and up but I dont think is mandatory. As for front springs you coud use what you have or go up to 87 I think. NAPA has a good web site that will give you the load range of the front springs. I just went with 73 front springs HD for a BB. almost leveld out the truck and rids firm but not harsh. Good luck.