Modify Upper control arms? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

4oldcars · 07-10-2013, 04:15 PM

I need help. Understand from the start that your talkin to a dummy. I have this 71 2wd that I bought with air bag suspension. I took the front bags out and put in 2" drop springs with dropped spindles. Had some play in the steering so I replaced the steering box, tie rods, lower control arms (PO had been dragging the ground with them), pittman arm, & idler arm. Hey, everything was 40+ years old. I take it to the local shop for an alignment. They say the left front has about an inch of shims and needs another inch of shims. Too many shims. They suggest I get a modified (longer) upper control arm. They say if I drive it I'll tear up the left front tire. Does this make sense? And where would I get such a thing as a modified upper control arm?

tinydb84 · 07-10-2013, 06:32 PM

The bags are shorter than the original springs. It increase camber and you need the tire to be more upright. You can do this two ways:

Longer upper control arms
Shorter lower control arms

I am sectioning both but I am taking 1'' out of the bottom and .25'' of the the top. With longer upper control arms you will end up with clearance issues with the fender.

ulakovic22 · 07-10-2013, 10:38 PM

Really need pictures to see everything. 2" of shims is a lot of shims, so I'm hoping something is glaringly wrong and can be fixed.
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SCOTI · 07-12-2013, 12:38 AM

Two things here..... The first is what alignment spec is the guy using? If he's trying to obtain the OE numbers, he's going to utilize more shims to get the +.5 spec vs. -.5 which would yield the same amount of tire wear but have better handling. Second, its not uncommon to have to utilize slightly longer studs when aligning with dropped springs.
Posted via Mobile Device

4oldcars · 07-12-2013, 10:15 AM

Thank you scoti. Sounds reasonable. I took it to a different shop.

07-10-2013, 04:15 PM	#1
4oldcars Registered User Join Date: Jun 2004 Location: On The Beach, S C Posts: 613	Modify Upper control arms? I need help. Understand from the start that your talkin to a dummy. I have this 71 2wd that I bought with air bag suspension. I took the front bags out and put in 2" drop springs with dropped spindles. Had some play in the steering so I replaced the steering box, tie rods, lower control arms (PO had been dragging the ground with them), pittman arm, & idler arm. Hey, everything was 40+ years old. I take it to the local shop for an alignment. They say the left front has about an inch of shims and needs another inch of shims. Too many shims. They suggest I get a modified (longer) upper control arm. They say if I drive it I'll tear up the left front tire. Does this make sense? And where would I get such a thing as a modified upper control arm? __________________ 4oldcars Driving: 1971 Jimmy w/68 Chev front clip, 1953 Bel Air 2 dr hdtp, 1996 Roadmaster wagon, 2000 Eldorado The ones I let go: 1931 2 dr sedan, 1935 pick up, 1938 2 dr sedan, 1962 SS 454, 1963 409 wagon, 1970 short bed, 1972 short bed, 1972 sub, 1976 short bed, 1986 long bed, 03 short bed

07-10-2013, 06:32 PM	#2
tinydb84 Registered User Join Date: Jul 2009 Location: San Jose Ca Posts: 2,871	Re: Modify Upper control arms? The bags are shorter than the original springs. It increase camber and you need the tire to be more upright. You can do this two ways: Longer upper control arms Shorter lower control arms I am sectioning both but I am taking 1'' out of the bottom and .25'' of the the top. With longer upper control arms you will end up with clearance issues with the fender. __________________ David Used parts build: http://67-72chevytrucks.com/vboard/s...d.php?t=638991 My brother's Nova: http://www.67-72chevytrucks.com/vboa...d.php?t=727985 Rear suspension rework: http://www.67-72chevytrucks.com/vboa...d.php?t=750557 Instagram: myfabguy

07-10-2013, 10:38 PM	#3
ulakovic22 Registered User Join Date: Aug 2008 Location: Lantana, TX Posts: 419	Re: Modify Upper control arms? Really need pictures to see everything. 2" of shims is a lot of shims, so I'm hoping something is glaringly wrong and can be fixed. Posted via Mobile Device

07-12-2013, 12:38 AM	#4
SCOTI Registered User Join Date: Apr 2001 Location: DALLAS,TX Posts: 22,066	Re: Modify Upper control arms? Two things here..... The first is what alignment spec is the guy using? If he's trying to obtain the OE numbers, he's going to utilize more shims to get the +.5 spec vs. -.5 which would yield the same amount of tire wear but have better handling. Second, its not uncommon to have to utilize slightly longer studs when aligning with dropped springs. Posted via Mobile Device __________________ 67SWB-B.B.RetroRod 64SWB-Recycle 89CCDually-Driver/Tow Truck 99CCSWB Driver All Fleetsides @rattlecankustoms in IG Building a small, high rpm engine with the perfect bore, stroke and rod ratio is very impressive. It's like a highly skilled Morrocan sword fighter with a Damascus Steel Scimitar..... *Cubic inches is like Indiana Jones with a cheap pistol.*

07-12-2013, 10:15 AM	#5
4oldcars Registered User Join Date: Jun 2004 Location: On The Beach, S C Posts: 613	Re: Modify Upper control arms? Thank you scoti. Sounds reasonable. I took it to a different shop. __________________ 4oldcars Driving: 1971 Jimmy w/68 Chev front clip, 1953 Bel Air 2 dr hdtp, 1996 Roadmaster wagon, 2000 Eldorado The ones I let go: 1931 2 dr sedan, 1935 pick up, 1938 2 dr sedan, 1962 SS 454, 1963 409 wagon, 1970 short bed, 1972 short bed, 1972 sub, 1976 short bed, 1986 long bed, 03 short bed

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