Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

**wesmigletz** · 02-16-2020, 04:18 PM

While searching other threads, I saw Dorman 13503 recommended. These are a lot bigger than the ones they're replacing.

Did you just drill out the saddle/crossmember with a 9/16" bit?

Thank you

**Getter-Done** · 02-16-2020, 05:00 PM

I would suggest drilling it 14mm (0.5512)
And then reaming it with 9/16 (0.5625) reamer.
14mm drill
(link):https://www.homedepot.com/p/Drill-Am...-0MM/306365125

(9/16 reamer that could be used with 1/2 inch drill)
Link:https://www.homedepot.com/p/Drill-Am...9-16/307840594

Or 9/16 reamer that would require a chuck that would accept 9/16 shank.
link:https://www.homedepot.com/p/Drill-Am...3A%7B1%7D%3Anf

Yeah you could probably drill it with a 9/16 drill
Just be careful about breaking the edges off the twist drill.

Link:https://www.homedepot.com/p/DEWALT-9...20-G/202579650

.

**wesmigletz** · 02-16-2020, 05:11 PM

Getter-Done. I appreciate your advice. I will get the 14 mm drill bit and reamer. I'll be doing both our 67 C10 and 70 2wd Blazer.

68 P.O.S. · 02-16-2020, 08:50 PM

Yeah, when I replaced mine I drilled em out with the 9/16" bit. It's a good safety upgrade.

wpavlis · 02-16-2020, 11:05 PM

Could you use a step bit?

**wesmigletz** · 02-22-2020, 09:45 PM

I installed them today. I just used a 9/16th drill bit, because I couldn't get a 14 mm bit locally and didn't want to wait for a mail order one. Went pretty quick, and the new u bolts look a lot beefier.

Thanks for the advice.

Barnfind46 · 02-22-2020, 10:17 PM

I did this upgrade after I took a wild ride with a camper in tow.u-bolt broke and almost lost the whole rig.

02-16-2020, 04:18 PM	#1
wesmigletz Senior Member Join Date: Feb 2009 Location: Parker, Texas Posts: 685	Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? While searching other threads, I saw Dorman 13503 recommended. These are a lot bigger than the ones they're replacing. Did you just drill out the saddle/crossmember with a 9/16" bit? Thank you __________________ 1970 2WD K5 1968 Camaro Conv 1967 Chevy SWB 1964 Malibu SS 1957 Corvette Pics www.picturetrail.com/wesmigletz

02-16-2020, 05:00 PM	#2
Getter-Done Senior Member Join Date: Dec 2009 Location: TN. Posts: 7,699	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? I would suggest drilling it 14mm (0.5512) And then reaming it with 9/16 (0.5625) reamer. 14mm drill (link):https://www.homedepot.com/p/Drill-Am...-0MM/306365125 (9/16 reamer that could be used with 1/2 inch drill) Link:https://www.homedepot.com/p/Drill-Am...9-16/307840594 Or 9/16 reamer that would require a chuck that would accept 9/16 shank. link:https://www.homedepot.com/p/Drill-Am...3A%7B1%7D%3Anf Yeah you could probably drill it with a 9/16 drill Just be careful about breaking the edges off the twist drill. Link:https://www.homedepot.com/p/DEWALT-9...20-G/202579650 . __________________ ________________________________________________________________________________________ ____________________________________________ 84 Chevy K-20 63 Impala (my high school car) http://67-72chevytrucks.com/vboard/s...Crew Cab Build

02-16-2020, 05:11 PM	#3
wesmigletz Senior Member Join Date: Feb 2009 Location: Parker, Texas Posts: 685	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? Getter-Done. I appreciate your advice. I will get the 14 mm drill bit and reamer. I'll be doing both our 67 C10 and 70 2wd Blazer. __________________ 1970 2WD K5 1968 Camaro Conv 1967 Chevy SWB 1964 Malibu SS 1957 Corvette Pics www.picturetrail.com/wesmigletz

02-16-2020, 08:50 PM	#4
68 P.O.S. Registered User Join Date: Jan 2007 Location: Puyallup, WA Posts: 1,661	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? Yeah, when I replaced mine I drilled em out with the 9/16" bit. It's a good safety upgrade. __________________ 72 C10 lwb fleetside -stock 350/350 combo

02-16-2020, 11:05 PM	#5
wpavlis Registered User Join Date: Oct 2015 Location: San Tan Valley, Arizona Posts: 313	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? Could you use a step bit?

02-22-2020, 09:45 PM	#6
wesmigletz Senior Member Join Date: Feb 2009 Location: Parker, Texas Posts: 685	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? I installed them today. I just used a 9/16th drill bit, because I couldn't get a 14 mm bit locally and didn't want to wait for a mail order one. Went pretty quick, and the new u bolts look a lot beefier. Thanks for the advice. __________________ 1970 2WD K5 1968 Camaro Conv 1967 Chevy SWB 1964 Malibu SS 1957 Corvette Pics www.picturetrail.com/wesmigletz

02-22-2020, 10:17 PM	#7
Barnfind46 Registered User Join Date: Aug 2014 Location: Mena,Arkansas Posts: 485	Re: Dorman 13503 Lower Control Arm U Bolts - just drill out with a 9/16" Bit? I did this upgrade after I took a wild ride with a camper in tow.u-bolt broke and almost lost the whole rig. __________________ 68' with no bells or whistles unless I add'em.



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