Replacement lower A-Arm shaft holes are different - The 1947 - Present Chevrolet & GMC Truck Message Board Network

gmebey · 10-09-2014, 11:43 AM

I'm in the process of rebuilding the front end of 1969 C20 pickup, and as far as I can tell all the current parts are original.

When comparing the new lower A-arm shaft to the old one I noticed that the indexing/alignment holes are different.

On the old one the holes are closer the end.

Is this an intentional change to increase caster?

**LEEVON** · 10-09-2014, 11:54 AM

Not sure, but I can tell you that I ordered about 8 lower shafts to get 2 that were correct (fit, finish, not missing parts, size, etc.) and I own a shop with about a dozen suppliers making deliveries all day. Frustrating, but I think that most of the "regular" parts store inventory has dried up for these trucks and the best bet is specialty suppliers like our forum vendors.

However, if you're not afraid to give it a try, that amount of caster should be adjustable depending on your suspension set-up. I have 4 degrees both sides with a 4.5" front drop (springs and spindles). Somewhere there is a thread about relocating the holes to add caster, and they are moved quite a bit. Find that thread and you might have a better idea whether or not you want to use those.

**70shortfleet** · 10-09-2014, 12:04 PM

Take off the end caps and measure the total lenght of the part. I think I ran into that when doing mine and it all worked out when I mounted them to the frame.

Lattimer · 10-09-2014, 12:21 PM

Even if it wasn't intentional, more castor will certainly help the way the truck drives.

gmebey · 10-10-2014, 12:20 AM

I compared the old shaft to the new and found that the total length is the same.

So I'm moving forward with the project.

BTW, I purchased a complete front end kit from http://stores.a-resto-parts.com/, and I have to say I have been impressed with both the quality of the kit and customer service.

kamikazekyle05 · 10-18-2014, 08:29 PM

How did it end up working out for you?

gmebey · 10-19-2014, 11:29 AM

I decided to use the new shafts. Which was justified by the amount of shims used in the rear of the upper control arm shaft. There was double the amount in the rear as the front. This indicates to me that old lower shafts were indexed wrong or for manual steering.

But I won't know for sure if I made the right choice until I get an alignment done.

10-09-2014, 11:43 AM	#1
gmebey Registered User Join Date: May 2011 Location: Fort Collins, Colorado Posts: 95	Replacement lower A-Arm shaft holes are different I'm in the process of rebuilding the front end of 1969 C20 pickup, and as far as I can tell all the current parts are original. When comparing the new lower A-arm shaft to the old one I noticed that the indexing/alignment holes are different. On the old one the holes are closer the end. Is this an intentional change to increase caster? Attached Images

10-09-2014, 11:54 AM	#2
LEEVON Registered User Join Date: Jul 2006 Location: Ozark, MO Posts: 4,887	Re: Replacement lower A-Arm shaft holes are different Not sure, but I can tell you that I ordered about 8 lower shafts to get 2 that were correct (fit, finish, not missing parts, size, etc.) and I own a shop with about a dozen suppliers making deliveries all day. Frustrating, but I think that most of the "regular" parts store inventory has dried up for these trucks and the best bet is specialty suppliers like our forum vendors. However, if you're not afraid to give it a try, that amount of caster should be adjustable depending on your suspension set-up. I have 4 degrees both sides with a 4.5" front drop (springs and spindles). Somewhere there is a thread about relocating the holes to add caster, and they are moved quite a bit. Find that thread and you might have a better idea whether or not you want to use those. __________________ '20 Silverado Trail Boss ~ '17 Tahoe ~ '79 K15 Sierra Grande ~ '76 Blazer 2wd ~ '71 Cheyenne swb ~ '55 Pontiac Safari ~'50 3100 bagged ~ '80 Wife ~ Late model kids

10-09-2014, 12:04 PM	#3
70shortfleet Senior Member Join Date: Apr 2010 Location: St.Peters, MO Posts: 2,226	Re: Replacement lower A-Arm shaft holes are different Take off the end caps and measure the total lenght of the part. I think I ran into that when doing mine and it all worked out when I mounted them to the frame.

10-09-2014, 12:21 PM	#4
Lattimer Registered User Join Date: Jan 2013 Location: Mickleton, NJ Posts: 1,776	Re: Replacement lower A-Arm shaft holes are different Even if it wasn't intentional, more castor will certainly help the way the truck drives. __________________ Shawn 1970 Chevy C-10 SWB, 350, TKO 600 5 speed My build http://67-72chevytrucks.com/vboard/s...d.php?t=559881

10-10-2014, 12:20 AM	#5
gmebey Registered User Join Date: May 2011 Location: Fort Collins, Colorado Posts: 95	Re: Replacement lower A-Arm shaft holes are different I compared the old shaft to the new and found that the total length is the same. So I'm moving forward with the project. BTW, I purchased a complete front end kit from http://stores.a-resto-parts.com/, and I have to say I have been impressed with both the quality of the kit and customer service.

10-18-2014, 08:29 PM	#6
kamikazekyle05 Registered User Join Date: Nov 2007 Location: Vernon, Texas Posts: 331	Re: Replacement lower A-Arm shaft holes are different How did it end up working out for you?

10-19-2014, 11:29 AM	#7
gmebey Registered User Join Date: May 2011 Location: Fort Collins, Colorado Posts: 95	Re: Replacement lower A-Arm shaft holes are different I decided to use the new shafts. Which was justified by the amount of shims used in the rear of the upper control arm shaft. There was double the amount in the rear as the front. This indicates to me that old lower shafts were indexed wrong or for manual steering. But I won't know for sure if I made the right choice until I get an alignment done.



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