Drilling out Lower Control Arm U-bolt holes for 9/16" U-Bolts - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**RoyL** · 02-27-2022, 08:42 PM

Passing on in case others are going to upgrade your smaller 63-66 U-bolts to 9/16" when swapping to '73-87 C10 control arms for disc brakes or whatever reason.

Get a sharp bit...
Drill from the bottom and put a tight fitting bolt in the opposite hole to keep the saddle bracket from moving.

One of mine shifted a tad when the drill bit caught the bracket as it was almost thru. Before I realized it, I drilled out more of the bracket than needed, which caused the control arm not to want to seat in the alignment pin. So I had to line up the saddle and ream it out some more so the pin would line up.

I ended up using a 5/8" bit to get the 9/16 u-bolts through.

02-27-2022, 08:42 PM	#1
RoyL Senior Member Join Date: Aug 2010 Location: HSV, AL Posts: 281	Drilling out Lower Control Arm U-bolt holes for 9/16" U-Bolts Passing on in case others are going to upgrade your smaller 63-66 U-bolts to 9/16" when swapping to '73-87 C10 control arms for disc brakes or whatever reason. Get a sharp bit... Drill from the bottom and put a tight fitting bolt in the opposite hole to keep the saddle bracket from moving. One of mine shifted a tad when the drill bit caught the bracket as it was almost thru. Before I realized it, I drilled out more of the bracket than needed, which caused the control arm not to want to seat in the alignment pin. So I had to line up the saddle and ream it out some more so the pin would line up. I ended up using a 5/8" bit to get the 9/16 u-bolts through. __________________ 1965 Suburban Waiting on Time and Money Last edited by RoyL; 03-04-2022 at 12:12 AM.



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