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 03-15-2017, 01:21 PM   #1
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
69 c20 lowering questions

1st off I'm sorry, I know this is beat to death, and I did search but most everything is referring to a c10. But my question is pretty straight forward. How low can I go with out a c notch? I won't be hauling anything at all with the truck. I plan on Staying 8 lug and keeping the rear (eaton I believe?) I have. It's also coils all around. Will the larger rear limit me any?

The plan is drop spindles (disc conversion), Springs and new shocks all around, and a block in the rear if need be. I'm assuming I'll need an adjustable Panhard bar and rear shock relocations as well. I can switch to smaller bumpstops if needed. I'll be running steel wheels off of a 90s suburban, and am flexible on tire size (open to suggestions).

So what's the lowest I can go? Am I missing anything in my parts list? Thanks guys
Adam4pt6 is offline   Reply With Quote
Old 03-15-2017, 04:32 PM   #2
demian5
Registered User
 
demian5's Avatar
 
Join Date: Aug 2016
Location: Lake Forest, CA
Posts: 2,177
Re: 69 c20 lowering questions

Measure the distance between the top of the axle and the frame rail. Then subtract at least 2 inches for suspension travel and that would be a safe way to estimate.
__________________
"Work hard, use your vacation days."
1970 C15 GMC Long Bed
1986 C20 Scottsdale
1983 K2500 Sierra Classic Suburban 6.2
Instagram: C10sofOC
demian5 is offline   Reply With Quote
Old 03-15-2017, 05:15 PM   #3
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

That's a good point, and obviously easy to do. I won't be around the truck unail later so I'm just curious what every one else has gotten away with
Adam4pt6 is offline   Reply With Quote
Old 03-15-2017, 05:15 PM   #4
JustToxic
Registered User
 
JustToxic's Avatar
 
Join Date: Jul 2016
Location: Elkhart, Indiana
Posts: 292
Re: 69 c20 lowering questions

GMC Pauls makes drop springs for our C20 trucks and POL make disc brake drop spindles for our trucks as well. So with that, you can drop as much as your heart desires. I personally wouldn't drop it lower then 4" in the rear without a c-notch. For the front if you drop it 3" or more with springs then you'll need a camber adjustment upper control arm cross shaft. Without doing more modifications to the C20 best bet would be doing a 2/4 drop with springs, or a 2 1/2" front drop with spindles and a 4" drop rear with springs.
__________________
1967 Chevy C20 to K20 Conversion "Simply Toxic"
http://67-72chevytrucks.com/vboard/s...d.php?t=749409

1971 Chevy C20 Custom Camper LS Swap http://67-72chevytrucks.com/vboard/s...d.php?t=763775
JustToxic is offline   Reply With Quote
Old 03-15-2017, 06:14 PM   #5
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Also, on the measurement idea...how accurate is that really? Think about it... 50 year old springs...there's probably some sag going on there. It may already sit a little lower then factory...making the measurement for new lowering Springs possibly off... right?
Adam4pt6 is offline   Reply With Quote
Old 03-15-2017, 06:23 PM   #6
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Quote:
Originally Posted by JustToxic View Post
GMC Pauls makes drop springs for our C20 trucks and POL make disc brake drop spindles for our trucks as well. So with that, you can drop as much as your heart desires. I personally wouldn't drop it lower then 4" in the rear without a c-notch. For the front if you drop it 3" or more with springs then you'll need a camber adjustment upper control arm cross shaft. Without doing more modifications to the C20 best bet would be doing a 2/4 drop with springs, or a 2 1/2" front drop with spindles and a 4" drop rear with springs.


Just checked them out. What's the difference between c10 and c20 Springs? I was under the impression I could just run Springs marketed for the c10, is that incorrect?
Adam4pt6 is offline   Reply With Quote
Old 03-15-2017, 07:11 PM   #7
northerngmc
Registered User
 
northerngmc's Avatar
 
Join Date: Jan 2004
Location: Whitehorse YK Canada
Posts: 2,651
Re: 69 c20 lowering questions

Quote:
Originally Posted by Adam4pt6 View Post
Just checked them out. What's the difference between c10 and c20 Springs? I was under the impression I could just run Springs marketed for the c10, is that incorrect?
I used C10 springs in my C20 when I lowered it. Worked well. 2" front, 4" rear. Left it with stock drum brakes.

Biggest problem I had was most threads said to simply pop the lower ball joint open and swing the brakes out of the way to swap the front springs. Popping the ball joint took some work and then the brake backing plate would not clear the suspension and come out. So I ended up unbolting the lower control arm from the frame.

Pics for reference on 2" front and 4" rear C10 Springs.

Before.....



After....



I did take measurements on the top of the fender lip to the garage floor before and after and it was close to 2"/4" on the tape.
__________________
Blaine
59 GMC 9314 a.k.a. Whoopee
68 C20 50th Anniversary a.k.a. The Rat

http://www.flickr.com/photos/northerngmc/
http://www.members.tripod.com/P-wee/index_032.htm

1.61803 is one H of a lot better than 3.14159, no really it is!
northerngmc is offline   Reply With Quote
Old 03-15-2017, 07:13 PM   #8
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Thanks man those pictures are helpful
Adam4pt6 is offline   Reply With Quote
Old 03-15-2017, 11:53 PM   #9
Jose's 69
Registered User
 
Join Date: Oct 2015
Location: Norwalk, CA
Posts: 114
Re: 69 c20 lowering questions

I used c10 4" lowering springs and a 1.5" block in the back. 2.5" drop spindles and 1 inch drop springs in front. Converted to front disc brakes in the process. I would like to go another inch lower in the back but not sure if I can without the rear end hitting the bed.
Attached Images
 
Jose's 69 is offline   Reply With Quote
Old 03-16-2017, 08:39 AM   #10
JustToxic
Registered User
 
JustToxic's Avatar
 
Join Date: Jul 2016
Location: Elkhart, Indiana
Posts: 292
Re: 69 c20 lowering questions

Quote:
Originally Posted by Adam4pt6 View Post
Just checked them out. What's the difference between c10 and c20 Springs? I was under the impression I could just run Springs marketed for the c10, is that incorrect?
If you still want to use the C20 as a C20 then you'd want the slightly heavier duty springs. But if your like most of us with C20's then you can use C10 springs. The C10 spring will give you a smoother ride compared to a C20 spring.
__________________
1967 Chevy C20 to K20 Conversion "Simply Toxic"
http://67-72chevytrucks.com/vboard/s...d.php?t=749409

1971 Chevy C20 Custom Camper LS Swap http://67-72chevytrucks.com/vboard/s...d.php?t=763775
JustToxic is offline   Reply With Quote
Old 03-16-2017, 09:15 AM   #11
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Quote:
Originally Posted by Jose's 69 View Post
I used c10 4" lowering springs and a 1.5" block in the back. 2.5" drop spindles and 1 inch drop springs in front. Converted to front disc brakes in the process. I would like to go another inch lower in the back but not sure if I can without the rear end hitting the bed.
Any chance you can snap a few pictures of your truck for me? I like the stance of yours, but do you have a picture of a straight on side view? And would you be able to take a picture showing axle to frame clearance?
Adam4pt6 is offline   Reply With Quote
Old 03-16-2017, 09:16 AM   #12
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Quote:
Originally Posted by JustToxic View Post
If you still want to use the C20 as a C20 then you'd want the slightly heavier duty springs. But if your like most of us with C20's then you can use C10 springs. The C10 spring will give you a smoother ride compared to a C20 spring.

So basically a c20 lowering spring will be stiffer and have less travel then a c10 spring?
Adam4pt6 is offline   Reply With Quote
Old 03-16-2017, 09:18 AM   #13
JustToxic
Registered User
 
JustToxic's Avatar
 
Join Date: Jul 2016
Location: Elkhart, Indiana
Posts: 292
Re: 69 c20 lowering questions

Suspension travel will be close to the same it'll just be a stiffer ride.
__________________
1967 Chevy C20 to K20 Conversion "Simply Toxic"
http://67-72chevytrucks.com/vboard/s...d.php?t=749409

1971 Chevy C20 Custom Camper LS Swap http://67-72chevytrucks.com/vboard/s...d.php?t=763775
JustToxic is offline   Reply With Quote
Old 03-16-2017, 09:20 AM   #14
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

What I'm getting at is, with the c20 spring there will be less of a chance bottoming out on smaller bumpstops and such as there would be with the softer c10 spring...correct?
Adam4pt6 is offline   Reply With Quote
Old 03-16-2017, 09:24 AM   #15
JustToxic
Registered User
 
JustToxic's Avatar
 
Join Date: Jul 2016
Location: Elkhart, Indiana
Posts: 292
Re: 69 c20 lowering questions

Since your not wanting to do a c-notch, yes the C20 springs would be less chance of bottoming out.
__________________
1967 Chevy C20 to K20 Conversion "Simply Toxic"
http://67-72chevytrucks.com/vboard/s...d.php?t=749409

1971 Chevy C20 Custom Camper LS Swap http://67-72chevytrucks.com/vboard/s...d.php?t=763775
JustToxic is offline   Reply With Quote
Old 03-16-2017, 10:19 AM   #16
Jose's 69
Registered User
 
Join Date: Oct 2015
Location: Norwalk, CA
Posts: 114
Re: 69 c20 lowering questions

Quote:
Originally Posted by Adam4pt6 View Post
Any chance you can snap a few pictures of your truck for me? I like the stance of yours, but do you have a picture of a straight on side view? And would you be able to take a picture showing axle to frame clearance?
Sure no problem. I'll try to get some pics uploaded later.
Jose's 69 is offline   Reply With Quote
Old 03-16-2017, 12:37 PM   #17
Adam4pt6
Registered User
 
Join Date: Feb 2017
Location: Tennessee
Posts: 31
Re: 69 c20 lowering questions

Quote:
Originally Posted by Jose's 69 View Post
Sure no problem. I'll try to get some pics uploaded later.
Thanks man I appreciate it
Adam4pt6 is offline   Reply With Quote
Old 03-16-2017, 01:01 PM   #18
Jose's 69
Registered User
 
Join Date: Oct 2015
Location: Norwalk, CA
Posts: 114
Re: 69 c20 lowering questions

Ok. Here's a couple of shots. Hope they help. I have about 3 inches before the axle hits frame in the rear bit I think the pumpkin is closer to hitting the bed.
Attached Images
     
Jose's 69 is offline   Reply With Quote
Old 03-16-2017, 01:04 PM   #19
JustToxic
Registered User
 
JustToxic's Avatar
 
Join Date: Jul 2016
Location: Elkhart, Indiana
Posts: 292
Re: 69 c20 lowering questions

Quote:
Originally Posted by Jose's 69 View Post
Ok. Here's a couple of shots. Hope they help. I have about 3 inches before the axle hits frame in the rear bit I think the pumpkin is closer to hitting the bed.
That's a good looking C20.
__________________
1967 Chevy C20 to K20 Conversion "Simply Toxic"
http://67-72chevytrucks.com/vboard/s...d.php?t=749409

1971 Chevy C20 Custom Camper LS Swap http://67-72chevytrucks.com/vboard/s...d.php?t=763775
JustToxic is offline   Reply With Quote
Old 03-16-2017, 01:19 PM   #20
Jose's 69
Registered User
 
Join Date: Oct 2015
Location: Norwalk, CA
Posts: 114
Re: 69 c20 lowering questions

Quote:
Originally Posted by JustToxic View Post
That's a good looking C20.
Thank you. I'm swapping in a newer 350 with vortec heads off a 92 2500 this weekend hopefully. After that, replace the wood bed and I should be done... for now. Ha.
Jose's 69 is offline   Reply With Quote
Old 03-16-2017, 02:35 PM   #21
azle
Registered User
 
Join Date: Feb 2017
Location: Fort Worth Texas
Posts: 69
Re: 69 c20 lowering questions

This low.... Sorry just saw C20 this is a 10 obviously...
Attached Images
 
azle is offline   Reply With Quote
Old 03-16-2017, 04:38 PM   #22
Spullar
Registered User
 
Join Date: Dec 2016
Location: Ronkonkoma
Posts: 76
Re: 69 c20 lowering questions

Quote:
Originally Posted by azle View Post
This low.... Sorry just saw C20 this is a 10 obviously...
So exactly how low is that?
Spullar is offline   Reply With Quote
Old 03-16-2017, 07:50 PM   #23
Boog
laying low
 
Boog's Avatar
 
Join Date: Mar 2001
Location: Searcy, Ark. USA
Posts: 12,888
Re: 69 c20 lowering questions

Here ya go Joe. It's easier on the neck.
Attached Images
 
__________________
Boog
69 Chevy stepside, 358/T350, 4.11 posi, 4.5/4 drop, rallys, poboy driver
primer is finer
91 Chevy sportside, Tahoe, Yukon & GMC Crewcab All GM..'nuff said.

I stand for the flag and kneel at the cross
Boog is offline   Reply With Quote
Old 03-16-2017, 09:24 PM   #24
Jose's 69
Registered User
 
Join Date: Oct 2015
Location: Norwalk, CA
Posts: 114
Re: 69 c20 lowering questions

Quote:
Originally Posted by Boog View Post
Here ya go Joe. It's easier on the neck.
Hahaha. Thanks. I had no idea how that happened.
Jose's 69 is offline   Reply With Quote
Old 03-20-2017, 10:30 AM   #25
azle
Registered User
 
Join Date: Feb 2017
Location: Fort Worth Texas
Posts: 69
Re: 69 c20 lowering questions

That is rear differential sitting on frame on 1 inch rubber blocks and front A arms sitting on modified rubber bushing, also about 1 inch. That is fully slammed not driving stance. Kind of new to the BAG world but I run 60psi on both front and back to drive, it is still low. Hope that helps.

Azle
azle 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 05:10 AM.


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