The 1947 - Present Chevrolet & GMC Truck Message Board Network







Register or Log In To remove these advertisements.

Go Back   The 1947 - Present Chevrolet & GMC Truck Message Board Network > 47 - Current classic GM Trucks > The 1967 - 1972 Chevrolet & GMC Pickups Message Board

Web 67-72chevytrucks.com


Reply
 
Thread Tools Display Modes
Old 04-19-2018, 11:44 AM   #1
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
70 C-10 Disk Brake Conversion Question

I have a 70 Chevy C-10. I was looking at doing the front suspension swap from a mid 80's C-10. I was also thinking of getting a modern rear axle (from something in the 2000's) that has rear disk brakes & 3.42 gearing - I will be using a 93 5.7 ltr engine (it will eventually push 400+/- HP) and a 700r4 tranny. I wanted to keep the 6 lug bolt pattern, as I want to use some 18" wheels and tires from a 2013 Silverado. I have found rotors that swaps the front to 6 lug (CPP Rotors Link). My biggest concern is the wheel mount to wheel mount measurements from the front end to the newer rear end. I have looked and looked - I can't find a definitive answer to this. At worst case I could use adapters to get the correct spacing - if the rear end won't be too wide!

Any help with this would be great also!
matthamby is offline   Reply With Quote
Old 04-19-2018, 11:53 AM   #2
lolife99
67-72 parts collector,…
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 22,673
Re: 70 C-10 Disk Brake Conversion Question

Don't get hung up on using 6-lug late model wheels and 6-lug rotors.
The '99-up truck wheels have a smaller center hole even though they are the same bolt pattern.
This will make you to run wheel spacers, or bore out the centers of your late model wheels.
Switching to a late model rearend will solve that issue for the rear,... but the aftermarket front 6-lug rotors are just new 5-lug blanks that have been drilled with the 6-lug pattern.
__________________
Keith

Convert to disc brakes.
http://67-72chevytrucks.com/vboard/s...d.php?t=444823
lolife99 is offline   Reply With Quote
Old 04-19-2018, 11:53 AM   #3
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
Re: 70 C-10 Disk Brake Conversion Question

One thing that I have found and just want to make sure I'm understanding correctly - a 91 suburban front cradle should work also & it comes with the sway bar. The CPP rotors should still work, etc...?
matthamby is offline   Reply With Quote
Old 04-19-2018, 11:55 AM   #4
lolife99
67-72 parts collector,…
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 22,673
Re: 70 C-10 Disk Brake Conversion Question

Quote:
Originally Posted by matthamby View Post
One thing that I have found and just want to make sure I'm understanding correctly - a 91 suburban front cradle should work also & it comes with the sway bar. The CPP rotors should still work, etc...?
There were some 81-87 trucks that had a light duty 1" rotor.
You need to verify it has the HD 1.25" rotors,... since that's what all the aftermarket 6-lug rotors are.
__________________
Keith

Convert to disc brakes.
http://67-72chevytrucks.com/vboard/s...d.php?t=444823
lolife99 is offline   Reply With Quote
Old 04-19-2018, 12:07 PM   #5
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
Re: 70 C-10 Disk Brake Conversion Question

Thanks, I'm aware of the 1" & 1.5" spindle problem. The next question I have for the front CPP rotors - are they not the smaller diameter centers that would allow for use of the modern wheels? This is what I'm trying to work out so that I get the correct items to start with. I may end up using wheel spacers anyway, depending on the wheel mount dimensions to get them to run the same track.
matthamby is offline   Reply With Quote
Old 04-19-2018, 12:15 PM   #6
lolife99
67-72 parts collector,…
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 22,673
Re: 70 C-10 Disk Brake Conversion Question

I doubt the CPP rotors are any smaller than the 5-lug rotors that they are copied from.
But they are definitely a different rotor than what comes on the 99-up trucks. That’s something you will need to verify since you have the 2013 wheels.
__________________
Keith

Convert to disc brakes.
http://67-72chevytrucks.com/vboard/s...d.php?t=444823
lolife99 is offline   Reply With Quote
Old 04-19-2018, 12:38 PM   #7
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
Re: 70 C-10 Disk Brake Conversion Question

I know that the wheels fit 87 4wd trucks, I've personally seen them and talked with the owner. I can stop by the auto parts place and check out the stock rotor dimensions and verify that easy enough. Thanks for the thoughts!
matthamby is offline   Reply With Quote
Old 04-19-2018, 12:58 PM   #8
notsolo
Registered User
 
notsolo's Avatar
 
Join Date: Apr 2008
Location: Md
Posts: 2,446
Re: 70 C-10 Disk Brake Conversion Question

I thought the front cross member disk brake swap was 71-87. I could be wrong. Double check frame width etc.
notsolo is offline   Reply With Quote
Old 04-19-2018, 01:26 PM   #9
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
Re: 70 C-10 Disk Brake Conversion Question

OK, so I took a quick trip to O'Reilly Auto Parts, I had them pull the rotor for a 73 C-10 (5006RGS Link) I also had them check the part number for a 91 2WD Suburban to which they are the same. The outer dimension (center of wheel opening) where the wheel will mount is 3". I had them pull a hub for a 2WD 2013 Silverado (Precision Hub Assembly Link), the outer dimension (center of wheel opening) was 3". That solves that problem. Now my only concern is the wheel mount to wheel mount dimensions matching up.

notsolo - I have found that (supposedly) the 88-91 Suburbans use the same cradle as the 73-87 trucks. I will get this verified before buying.

Last edited by matthamby; 04-19-2018 at 01:32 PM.
matthamby is offline   Reply With Quote
Old 04-19-2018, 01:38 PM   #10
LH Lead-Foot
Registered User
 
Join Date: Jan 2018
Location: Omaha, NE.
Posts: 214
Re: 70 C-10 Disk Brake Conversion Question

I rebuilt the 1967 OEM 6 lug rear end to a 3.08 and disc type posi, new bearings & seals... I have done dozens over the years, but I also have a housing spreader to make it easy. Using bone yard spindles from 91-98 HD C1500 (Ext Cab) / 2001 Express-Savana, to get 1 1/4" rotors with 6 lug pattern for about $75. With a 51 year old truck, I choose to rebuild the front end to get disc brakes and new bushings to last another 50 years. Using new G20 lower control arms, shaft & bushings, calipers, GM tie rod ends & ball joints, ACDelco hoses and bearings from Rock Auto. Calipers came power coat red for $40 each which are GM calipers with 2 15/16" pistons. All for $300 new except for booster, bracket, master and proportioning valve that you'll have to get.
The problem with 03 wheel from a GMT800 is the major positive off-set from center to cover the hub/bearing assembly as with most new vehicles. I believe you will be hitting the control arms or frame depending on what disc brake conversion kit you buy.
My wheel purchase was pacer 16 x 8 that have a +10mm off-set from center to keep the tire at zero scrub. Yes, hub rings are required to center & support the wheel.
I did not have the $2,000 - $3000 to spend on front disc brake kits, just went with all off-the-shelf GM parts as the lower control arms and rotors are used on 3/4 ton and those labeled heavy half. I use stock height spindles that are found clear into 2001 on the Express / Savana. They use the same 1 1/4" rotors, they just come with an ABS tone ring on them.
LH Lead-Foot is offline   Reply With Quote
Old 04-19-2018, 02:53 PM   #11
lolife99
67-72 parts collector,…
 
lolife99's Avatar
 
Join Date: Nov 2002
Location: Mid-MO
Posts: 22,673
Re: 70 C-10 Disk Brake Conversion Question

Quote:
Originally Posted by LH Lead-Foot View Post
I rebuilt the 1967 OEM 6 lug rear end to a 3.08 and disc type posi, new bearings & seals... I have done dozens over the years, but I also have a housing spreader to make it easy. Using bone yard spindles from 91-98 HD C1500 (Ext Cab) / 2001 Express-Savana, to get 1 1/4" rotors with 6 lug pattern for about $75. With a 51 year old truck, I choose to rebuild the front end to get disc brakes and new bushings to last another 50 years. Using new G20 lower control arms, shaft & bushings, calipers, GM tie rod ends & ball joints, ACDelco hoses and bearings from Rock Auto. Calipers came power coat red for $40 each which are GM calipers with 2 15/16" pistons. All for $300 new except for booster, bracket, master and proportioning valve that you'll have to get.
The problem with 03 wheel from a GMT800 is the major positive off-set from center to cover the hub/bearing assembly as with most new vehicles. I believe you will be hitting the control arms or frame depending on what disc brake conversion kit you buy.
My wheel purchase was pacer 16 x 8 that have a +10mm off-set from center to keep the tire at zero scrub. Yes, hub rings are required to center & support the wheel.
I did not have the $2,000 - $3000 to spend on front disc brake kits, just went with all off-the-shelf GM parts as the lower control arms and rotors are used on 3/4 ton and those labeled heavy half. I use stock height spindles that are found clear into 2001 on the Express / Savana. They use the same 1 1/4" rotors, they just come with an ABS tone ring on them.
Did you have any alignment issues using the 88-98 light duty 6-lug parts?
There have been a couple people on here that proved that there is too much positive camber when using the 88-98 spindle, rotor, caliper, balljoints, combined with a 3/4-ton 67-72 lower a-arm. (or 73-87 lower a-arm)
__________________
Keith

Convert to disc brakes.
http://67-72chevytrucks.com/vboard/s...d.php?t=444823
lolife99 is offline   Reply With Quote
Old 04-19-2018, 03:27 PM   #12
matthamby
Registered User
 
Join Date: May 2015
Location: Walnut Cove, NC
Posts: 109
Re: 70 C-10 Disk Brake Conversion Question

I think I'm on the right path, I may have to use spacers on the front to get the tracking to match the rear. Would really like to get those measurements if anyone has them!
matthamby is offline   Reply With Quote
Old 04-20-2018, 12:21 PM   #13
LH Lead-Foot
Registered User
 
Join Date: Jan 2018
Location: Omaha, NE.
Posts: 214
Re: 70 C-10 Disk Brake Conversion Question

My results did not create too much positive camber. The relationship of the ball joint on the lower control arm from a G20 to the shaft, measured the same as the OEM lower used on the 1967 C10. They did change the lower "U" bolt from 5/16" to 3/8", but everything else is the same. Since I am reusing the upper control arm, with the same shims, resulted in no increase in camber meaning the top of the wheel/tire is further out. I did not find any difference in the later spindles, but I did use power steering specs to align.
Over the years from repair shops to dealerships, I have had to use the alignment machines. I hated it because your only as good as the machine you are using. This take the control away from me. With that being said, the technology has changed from strings, to lights and now laser's. We all know how expensive these alignment equipment are and every few years, they show up with a new type, so it becomes something you're into or not. I quit alignments as I was more than busy in diagnostics and repair.
For manual steering, the camber remains the same but caster is reduced to help the driver turn the wheel while not having the weight of the vehicle to lift as this action occurs due to more positive caster. Increasing positive caster help the steering return to center, so generally, vehicle equipped with power steering have more positive caster with the right side / passengers side with slightly more caster to help with control as that side of the road is rougher. This helps the wheel take the compression and extension produce less force on the linkage.
I did not have any problems with achieving correct caster, while I did increase caster due to adding P/S. Toe in remained the same and the tires wear fine and driving down flat interstates with a light grip on the wheel goes dead-on straight. The relation between the upper ball joint and lower, on the suspension system used on these trucks and many others (SLA) short arm, long arm, are very reliable, but understanding that the imaginary line drawn from upper to lower ball joint, under load, strike the ground & tire tread in dead center results in "Zero" Scrub". Careful consideration of the wheel"s center off-set, either positive or negative has to be considered in changing wheels. I have had many customers vehicle with wheel adaptors, holding wheels with the wrong off-set and it will yank the steering wheel out of your hands, while just pulling onto a service lift rack. Even with power steering, rack & pinion or recirculating ball control box. The latter is not so bad, but driving very far is uncomfortable at the least.
I am not a suspension engineer, but while acknowledging what the engineers are trying to accomplish, was easy to understand during dealer class explanations. Zero scrub is common from the early 90's to date. "Steering Axis Inclination" cannot be changed, it is check third after inspection of components, suspension book height, them rotate left & right to make sure it is the same. This indicates that no parts are bent.
This is one of those subjects that when you ask 100 guys, you get 100 different answer's. I would talk to an alignment tech to ask questions. But the G20 lower control arm measured the same with the only difference being bracing welded on the bottom to reduce flexing under higher loads. Other than that, my side by side observations found no difference. As for the late model spindles, I had the same exact caster, just a heavier casting.
LH Lead-Foot is offline   Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 07:40 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright 1997-2022 67-72chevytrucks.com