Disc Brake Upgrade Reference Thread

[old_1966_GMC]

i see what your saying the only way it would work is if i would switch crossmembers this will be the only way to remove the c20 lower arms and switch them to the correct c10 arms that would bolt rigth in. So in this case let say i did switch the cross member to a later model would i have any problem with the engine mounts as i tend to keep my stock 305.

[Captainfab]

I'm assuming you are referring to the 305 V6? I don't think you'll have any issues with using your existing engine mounts with the later model crossmember. As far as I know the later model cross members have the lower motor mount bracket holes in the same location.

Originally Posted by old_1966_GMC

i see what your saying the only way it would work is if i would switch crossmembers this will be the only way to remove the c20 lower arms and switch them to the correct c10 arms that would bolt rigth in. So in this case let say i did switch the cross member to a later model would i have any problem with the engine mounts as i tend to keep my stock 305.

[old_1966_GMC]

i think im ganna switch crossmember to make this a easy brake build oh yea its the 305 v6

[TheTurtleMan]

Ok, sorry I am sure this has been talked about somewhere in here but I couldn’t find it. Anyway I have a 66 short fleet, and I bought a 76 short step side to part out for my truck. I am really unsure what I want to do. Kinda wanna keep it 6 lug because I like my wheels and used 6 lug wheel are much easier to find. So what could I do to the 76 ft end to make it 6 lug? But if I go 5 lug anything weird with putting the 76 rear end in my truck. Sorry for the dumb questions. LOL

[raycow]

Originally Posted by TheTurtleMan

So what could I do to the 76 ft end to make it 6 lug? But if I go 5 lug anything weird with putting the 76 rear end in my truck. Sorry for the dumb questions. LOL

Not dumb questions at all.

6 lug rotors are available from CPP, Performance Online, and several other vendors. This is an aftermarket part that is a direct swap for the 5 lug. If your 66 has rear coil springs you can get a kit which contains weld-on brackets for the trailing arms and panhard bar. If you want 6 lug shafts for the 76 rear, you can use stock shafts for a 71-87 4WD. Your 66 shafts are too short for the 76 rear.

Ray

[jmlcolorado]

Originally Posted by raycow

Not dumb questions at all.

6 lug rotors are available from CPP, Performance Online, and several other vendors. This is an aftermarket part that is a direct swap for the 5 lug. If your 66 has rear coil springs you can get a kit which contains weld-on brackets for the trailing arms and panhard bar. If you want 6 lug shafts for the 76 rear, you can use stock shafts for a 71-87 4WD. Your 66 shafts are too short for the 76 rear.

Ray

HEY!!! I just saw your post and was wondering if you knew where to get the kit you mentioned for the trailing arms?
Im working with an extream drop GMC C10 and the pinion angle is going to be way wrong. I knew i was going to have to vut the mounting perches off the rear end and re weld them back to where the pinion angle is at a more useable height, buit if they make the brackets still, i wont have to worry so much about saving the origional ones!
Thanks for the input!

Heres a photo pf the project for fun

[Captainfab]

Welcome to the forum and hello neighbor

raycow pretty much covered it.

Let me know if you need a power steering box adapter or any of my other parts I make. No shipping since you can just come pick them up.

Originally Posted by TheTurtleMan

Ok, sorry I am sure this has been talked about somewhere in here but I couldn’t find it. Anyway I have a 66 short fleet, and I bought a 76 short step side to part out for my truck. I am really unsure what I want to do. Kinda wanna keep it 6 lug because I like my wheels and used 6 lug wheel are much easier to find. So what could I do to the 76 ft end to make it 6 lug? But if I go 5 lug anything weird with putting the 76 rear end in my truck. Sorry for the dumb questions. LOL

[TheTurtleMan]

LOL.... Thats funny. I was actually checking out your stuff but didnt look that you were in CDA. Ill post up a deal bout my truck. I got too many ideas and dont know what to do. LOL BTW, thanks for the help guys. If that 76 rear end is wider maybe Ill just keep mine, and keep it 6 lug.

[old_1966_GMC]

what also a good 5 lug rear end axle that would bolt in with my shaft im not quit sure if it has spring i think it has leaf spring for sure though

[fryer1979]

I've got a slightly different question for you guys that have done this swap already. After the swap is done, how is the ride height for a full '73-'87 crossmember and control arms in comparrison to the original '63-'66 front end? Does the truck sit any higher or lower? Mostly I am just curious in a stock for stock contrast. Thanks

[aggie91]

Originally Posted by fryer1979

I've got a slightly different question for you guys that have done this swap already. After the swap is done, how is the ride height for a full '73-'87 crossmember and control arms in comparrison to the original '63-'66 front end? Does the truck sit any higher or lower? Mostly I am just curious in a stock for stock contrast. Thanks

Back when I did mine, it did not change the height so that I noticed. I did not measure it to know for sure. I did not do the complete crossmember swap, i only did the spindle/rotor/caliper swap.

If the coil springs are the same, I mean the original ones were for a V8 and the swapped in ones were from a V8 truck (or 6 cyl/6cyl) the heights should be close not counting any amount of settling in the spring...

[old_1966_GMC]

1963-1966/5 lug
post#1

Parts Swap:
From '73-'87 you can unbolt the upper and lower control arms with the spindles attached and bolt these pieces onto your existing cross member. (clarification needed on 5-6 lug)

well i finally got the front suspension from a 76 chevy c10 during the weekend everything getting rebuild rigth now i had a few question the suspension wasnt removed by me when i got it they had a quy uninstall it for free there were these little y looking spacer on there how are those spacer supposed to go. every truck ive look today at pick n pull were all diffrent and last can i just bolt in the suspension on to my existing crossmember sence my 305e v6 is in and still running.

[Captainfab]

Those little 'Y' spacers sound like the shims for the upper control arms. Those are used between the upper control arm shaft and the part of the crossmember against the side of the frame. The shims are added or removed during the front end alignment process to adjust the caster and camber of the front wheels. There's really no way of knowing how many and what thickness to put where without doing a front end alignment. Yes you can bolt the '76 C10 control arms to your '66 GMC front suspension crossmember. As long as it isn't a 3/4 ton. I would recommend upgrading to the larger '76 U-bolts used on the lower control arm shaft. You will need to drill out the holes in the crossmember to do so.

Originally Posted by old_1966_GMC

well i finally got the front suspension from a 76 chevy c10 during the weekend everything getting rebuild rigth now i had a few question the suspension wasnt removed by me when i got it they had a quy uninstall it for free there were these little y looking spacer on there how are those spacer supposed to go. every truck ive look today at pick n pull were all diffrent and last can i just bolt in the suspension on to my existing crossmember sence my 305e v6 is in and still running.

[old_1966_GMC]

what should i do with the shims i mean can i just put them on how ever for now till its time to get a front end alignment

[Captainfab]

I would just keep track of the shims that are on your GMC right now. When you put the '76 control arms on, use the same shims that were on your truck to start with and in the same places. That will get you close enough to get your truck to an alignment shop.

Originally Posted by old_1966_GMC

what should i do with the shims i mean can i just put them on how ever for now till its time to get a front end alignment

[chopttop]

Have a '70 C30, am picking up a complete running '81 C30 donor truck. Had planned on doing complete crossmember swap but it has been suggested that I just swap parts onto existing cross member, donor has low milage, late '80's 454 that will be part of the swap, plan to install drop spindles on at same time. I would imagine that most of what has been referenced concerning C10's would relate across the board to the C30. Just wondering if I should remove the complete donor crossmember, rebuild it as needed w/dropped spindles and swap out crossmembers or start w/existing crossmember in '70 and swap parts from '81 ? Thanks in advance.

[Captainfab]

I don't remember for sure on a '70 C30 if the lower control arm shafts are round or flat like the '63-'66's. If they are round there is no reason you can't swap everything from the '81 including the control arms. I would suggest going with the lower control arm shaft U-bolts from the '81. I believe they are a little bigger than the '70 pieces.

If the LCA shafts on the '70 are flat, you'll have to either keep the '70 LCA's or swap the entire crossmember

[chopttop]

Thanks, will check that out.

[LostMy65]

oops,
I figured it'd be better to just start a new thread:
http://67-72chevytrucks.com/vboard/s...92#post4308992

[blackmopar]

Hey Guys - hope its cool to post in this FAQ still - Sorry if these questions were answered - I missed if they were.


will 80-87 3/4 ton or 1 ton trucks work for the conversions? What about 73-87 c20's also? As long as theyre 2wd? im assuming they would have the 1-1/4 rotors instead of light duty, right?

Im looking to swap to my 64 c10 6 lug - and keep 6 lug - i see the parts store call out for them (thanks) in one of the thread posts

a side question - ive got drop coils in my stock arms now - could I resue them? or are the 73-87 coils different for some reason? Can you run drop coils AND spindles?

Sean

[Captainfab]

The C20's and C30's prior to '88 are going to have the 8 x 6.5" wheel bolt pattern. Those parts will certainly work if you wanted the 8 x 6.5" bolt pattern.

There are 2 ways to have 6 x 5.5 front disc brakes. one is to use the factory light duty '88-'98 C2500 parts as listed earlier in this thread. Or you can use the typical '71-'87 C10 front suspension parts and then purchase the aftermarket 6 x 5.5" rotors for those spindles.

As for the springs, I believe the '73-'87 springs are a little different, but I think the early ones will work. And yes you can run both drop spindles and drop springs at the same time......many guys do to get their desired amont of drop.

Originally Posted by blackmopar

Hey Guys - hope its cool to post in this FAQ still - Sorry if these questions were answered - I missed if they were.


will 80-87 3/4 ton or 1 ton trucks work for the conversions? What about 73-87 c20's also? As long as theyre 2wd? im assuming they would have the 1-1/4 rotors instead of light duty, right?

Im looking to swap to my 64 c10 6 lug - and keep 6 lug - i see the parts store call out for them (thanks) in one of the thread posts

a side question - ive got drop coils in my stock arms now - could I resue them? or are the 73-87 coils different for some reason? Can you run drop coils AND spindles?

Sean

[panelrodder81]

My dad just did this swap on a 64 c20 w 75 c20 parts. He wanted to keep the 8lug because he had nice wheels on the truck. He had to swap the whole xmember becaused the control arms didn't match up. Also, we found that using the 75 motor mounts pushed the engine about 2 inches forward of where it was originally. Other than that it was the easiest and most problem free part of the build.

Panelrodder

Originally Posted by blackmopar

Hey Guys - hope its cool to post in this FAQ still - Sorry if these questions were answered - I missed if they were.


will 80-87 3/4 ton or 1 ton trucks work for the conversions? What about 73-87 c20's also? As long as theyre 2wd? im assuming they would have the 1-1/4 rotors instead of light duty, right?

Im looking to swap to my 64 c10 6 lug - and keep 6 lug - i see the parts store call out for them (thanks) in one of the thread posts

a side question - ive got drop coils in my stock arms now - could I resue them? or are the 73-87 coils different for some reason? Can you run drop coils AND spindles?

Sean

Posted via Mobile Device

[blackmopar]

thanks cap'n - could I use the c20/c30 a-arms, steering components, sway bar and brake parts with aftermarket drop spindles and rotors (5 or 6)?

theres quite a few 3/4 and 1 tons as parts trucks right now in the area here for cheap

id be sourcing drop spindles anyway even if i went with a 73-87 c10 - any diff in a-arms between c10,20,and 30s in the 73-87 yrs?

i have 6 lug wheels now, but i also have 5 lug rotors and calipers from another project so Im not sure really if i want to do 5 or 6

[Captainfab]

The C20 and C30 control arms use the steel bushings just like the '63-'72 C10's did. The main issue with using the C20 or C30 control arms, is the lower ball joints are bigger than the C10's. There's really nothing to gain by swapping your '64's control arms for the C20 or C30 arms unless you want to use the '88-'98 LD C2500 parts. This would give you 6 lug front discs

If you're having trouble locating the '73-'87 C10 control arms, I would just keep your original arms. Then just buy your drop spindles, and which ever rotors you decide on.

The steering boxes are the same whether from a C10,C20 or C30. However I don't know if the steering linkage will be the same. It is doubtful. The C20 or C30 sway bars will work on your truck. Often times you will find the larger 1- 3/16" bar.

[blackmopar]

thats what i was looking for - ill keep looking for 73-87 c10! thanks again as always capt!