Early vs. late control arms - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gringoloco · 09-04-2007, 07:08 PM

All thing being equal i.e.: spindles, springs, brakes, etc.- if I swap my early(71-72) control arms out for late(73-87) arms, will my alignment be affected?

I know the upper balljoints are a different diameter, but will still bolt in place. The shaft pivot points will obviously be the same, but are the balljoint distances from the shaft equal? Also, is the bottom of the spring pocket on the same plane; given the same spring will there be more/less drop with one or the other?

The obvious answer is: "Just go get it aligned". Just want to know if I can bypass this.

Thanks -Chris

gringoloco · 09-04-2007, 07:55 PM

Here's a diagram expalining what I mean:

PBFAB.COM · 09-05-2007, 12:18 AM

I snapped a few pics for ya on a comparison. Looks like the spring cups are a little different, but as far as my tape measure says the distances are the same (that's what I though, but I wanted to verify first). Be careful though... that tape measure has been known to be off by an inch every now and again!

gringoloco · 09-05-2007, 06:37 AM

Thanks Nate, that's exactly what I was looking for. The difference in pockets is actualy why I'm swapping. The 73-up is much shallower/wider, allowing a shorter cup which means more drop and a few more PSI for the front at ride height.

I also seem to remember something about the cross-shaft locating stud being diferent between the early/late crossmembers. Anyone run into this?

jlaird · 09-05-2007, 08:36 AM

one difference that I notice is the angle of the shock mount. The later style would come in handy for me right now because I wanted to fab up an upper shock mount, but the shock would hit the upper control arm. So I might have to adjust the positioning of that lower shock mount to something like what I see in the picture of the later control arm. sorry, just rambling...

Spray-Bomb · 09-05-2007, 11:40 AM

On mine I have 85 A-arms & never got to see the 67 ones, cuz the PO had already changed them out for some later year

From what I have heard, the earlier A-arms are narrower than the later ones & it makes sense to me

The locating pins on mine do not line up !!! & if the A-arms were narrower I would have less clearance issues

Hope this helps mang

BACKYARD88 · 09-06-2007, 12:01 PM

My 85 arms lined up fine with my 71 crossmember locating studs. As long as you don't ahve a sectioned crossmember you should be fine.

09-04-2007, 07:08 PM	#1
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,921	Early vs. late control arms All thing being equal i.e.: spindles, springs, brakes, etc.- if I swap my early(71-72) control arms out for late(73-87) arms, will my alignment be affected? I know the upper balljoints are a different diameter, but will still bolt in place. The shaft pivot points will obviously be the same, but are the balljoint distances from the shaft equal? Also, is the bottom of the spring pocket on the same plane; given the same spring will there be more/less drop with one or the other? The obvious answer is: "Just go get it aligned". Just want to know if I can bypass this. Thanks -Chris __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy Last edited by gringoloco; 09-04-2007 at 07:13 PM.

09-04-2007, 07:55 PM	#2
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,921	Re: Early vs. late control arms Here's a diagram expalining what I mean: Attached Images __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy

09-05-2007, 12:18 AM	#3
PBFAB.COM Senior Member Join Date: Dec 2003 Location: Mesa,Az Posts: 3,981	Re: Early vs. late control arms I snapped a few pics for ya on a comparison. Looks like the spring cups are a little different, but as far as my tape measure says the distances are the same (that's what I though, but I wanted to verify first). Be careful though... that tape measure has been known to be off by an inch every now and again! Attached Images __________________ www.PorterbuiltFabrication.com Phone: 480-297-2621 E-mail: sales@pbfab.com Find us on FaceBook under Porterbuilt Fabrication Specializing in Chassis and Suspension Components for your Classic Chevrolet Truck. We offer components from the following manufacturers: Porterbuilt Accuair Ridetech (Air Ride Technologies) Air Lift Wilwood Intro Unisteer ECE Gotta Show Air Lift Borgeson CPP Supporting this forum since 2003!

09-05-2007, 06:37 AM	#4
gringoloco A guy with a truck Join Date: Sep 2005 Location: Germany, for now Posts: 5,921	Re: Early vs. late control arms Thanks Nate, that's exactly what I was looking for. The difference in pockets is actualy why I'm swapping. The 73-up is much shallower/wider, allowing a shorter cup which means more drop and a few more PSI for the front at ride height. I also seem to remember something about the cross-shaft locating stud being diferent between the early/late crossmembers. Anyone run into this? __________________ -Chris Instagram _elgringoloco_ '70 Short-Wide How to: Ruin a perfectly good C10 ‘70 Blazer ConversionHow To: Ruin a Perfectly Good 4wd '72 Highlander How To: Ruin a Perfectly Good K/5 (SOLD) '72 Blazer 2WD How to: Ruin a perfectly good Blazer (SOLD) '05 Yukon Daily Driven (not so stock) Yukon (SOLD) ‘07 Yukon Denali (daily) Members met list: SCOTI, darkhorse970, 67cheby, 67cheby'sGirl, klmore, porterbuilt, n2billet, Fastrucken, classicchev, Col Clank, GSFMECH, HuggerCST, Spray-Bomb, BACKYARD88, 5150, fine69, fatbass, smbrouss70, 65StreetCruiser, GAc10boy

09-05-2007, 08:36 AM	#5
jlaird Senior Member Join Date: May 2004 Location: johnstown, NY Posts: 2,393	Re: Early vs. late control arms one difference that I notice is the angle of the shock mount. The later style would come in handy for me right now because I wanted to fab up an upper shock mount, but the shock would hit the upper control arm. So I might have to adjust the positioning of that lower shock mount to something like what I see in the picture of the later control arm. sorry, just rambling...

09-05-2007, 11:40 AM	#6
Spray-Bomb Texas Big Wig Join Date: Jan 2007 Location: Mineola, Texas Posts: 5,620	Re: Early vs. late control arms On mine I have 85 A-arms & never got to see the 67 ones, cuz the PO had already changed them out for some later year From what I have heard, the earlier A-arms are narrower than the later ones & it makes sense to me The locating pins on mine do not line up !!! & if the A-arms were narrower I would have less clearance issues Hope this helps mang __________________ Just not low enough... ----------------------------- Sinister Killer

09-06-2007, 12:01 PM	#7
BACKYARD88 On the fast track to nowhere.. Join Date: May 2006 Location: Splendora, Texas Posts: 5,316	Re: Early vs. late control arms My 85 arms lined up fine with my 71 crossmember locating studs. As long as you don't ahve a sectioned crossmember you should be fine. __________________ -Mike Owen- Support the board here! 71 Chevy short fleet build thread Double D Norwood, Houston, Cecilia, Jackson, Monroe and counting



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