what size bolts for spring hangers to replace rivets? and part #for shorter shock? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

dragn91 · 01-30-2015, 06:20 PM

I'm going to be lowering my truck next weekend so I'm trying to have everything I can lined up for me to do so. I'm going to be raising my stock spring shackle and hanger brackets 3-4 inches and drilling new holes on the frame I need to know what size the rivet hole is so I can have the bolts ready on hand as I do all my crap outside by myself so I'd like to have it ready to go. Also does anyone have a part number for a 3 or 4 inch shorter shock? My truck is a 1980 c20 thanks in advance.

J Knight · 01-30-2015, 06:49 PM

3\8 x 1in coarse thread grade 8.

EDIT: Thats the bolt size I used on my c10.

**396ci** · 01-30-2015, 11:21 PM

some have used the 7/16" also.

mrolds88 · 01-31-2015, 04:42 PM

3/8" will work, but they are usually a bit smaller than the rivet holes. I would go with the 7/16" grade 8's and drill the holes.

greg64 · 01-31-2015, 05:11 PM

The rivets are probably the equal of grade 8, and they don't have threads cut in them. (Compare bolt minor diameter) When I had to remove an reattach the hangers on my 77, I used 1/2". Figured what the hell, and there was plenty of metal in the hanger to accommodate the larger hole. Well, it's been like that for 15 years now.

Bowed · 02-01-2015, 12:27 AM

It is my understanding that the rivets used in the chassis are grade 5 . They have to be a softer grade in order to crush properly .

324matt · 02-01-2015, 11:17 AM

I just finished replacing all of the rivets in the rear of my frame after sandblasting last week. I used 1" long 7/16 grade 8 flange bolts, torqued them to 77ft/lbs with lots of red locktight. rivets are grade 5, but I used grade 8 because I am not looking for flex, Im looking for rigidity and stiffness.
flangebolts.com was where I bought them.

greg64 · 02-01-2015, 02:42 PM

I was interested in finding out more, and discovered the following article:
http://www.tech-cor.com/AutoResBulle...0-6/2000-6.htm
Now, this is for a ford f-150, but it gives factory recommendations on rivet replacement. Near the bottom if you don't want to read the whole thing.

Keith Seymore · 02-01-2015, 04:14 PM

3/8" grade 8 bolts were the assembly line repair for missing or miss hit rivets for our trucks.

Mine is going on 29 years and 200,000 miles with bolted on spring hangers.

K

greg64 · 02-01-2015, 04:47 PM

Thanks Keith. I guess I'm not surprised, since a 3/8 grade 8 can take nearly 10,000 lbs in shear. https://nucor-fastener.com/Files/PDF...r_Strength.pdf

01-30-2015, 06:20 PM	#1
dragn91 Registered User Join Date: Aug 2007 Location: charlestown maryland Posts: 272	what size bolts for spring hangers to replace rivets? and part #for shorter shock? I'm going to be lowering my truck next weekend so I'm trying to have everything I can lined up for me to do so. I'm going to be raising my stock spring shackle and hanger brackets 3-4 inches and drilling new holes on the frame I need to know what size the rivet hole is so I can have the bolts ready on hand as I do all my crap outside by myself so I'd like to have it ready to go. Also does anyone have a part number for a 3 or 4 inch shorter shock? My truck is a 1980 c20 thanks in advance.

01-30-2015, 06:49 PM	#2
J Knight Registered User Join Date: Jun 2011 Location: Baytown TX Posts: 2,219	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock 3\8 x 1in coarse thread grade 8. EDIT: Thats the bolt size I used on my c10. __________________ John 82 Chevy Silverado 350ci/TH350

01-30-2015, 11:21 PM	#3
396ci Senior Member Join Date: Jun 2005 Location: Modesto, CA Posts: 810	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock some have used the 7/16" also. __________________ Brian XNGH ECV Chapter 58 1972 Jimmy / Blazer Project 2wd 1974 Chevy Crew Cab Shorty

01-31-2015, 04:42 PM	#4
mrolds88 Registered User Join Date: Jul 2011 Location: WV Posts: 946	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock 3/8" will work, but they are usually a bit smaller than the rivet holes. I would go with the 7/16" grade 8's and drill the holes. __________________ 72 GMC C2500 402/Th400 first truck (still have) 77 GMC C3500 CC dually Sold 70 C50 dump truck "Rusty" 87 K10 Suburban Sold 93 K2500 xcab 6.5TD 96 GMC K2500 Suburban 6.5 TD

01-31-2015, 05:11 PM	#5
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock The rivets are probably the equal of grade 8, and they don't have threads cut in them. (Compare bolt minor diameter) When I had to remove an reattach the hangers on my 77, I used 1/2". Figured what the hell, and there was plenty of metal in the hanger to accommodate the larger hole. Well, it's been like that for 15 years now. __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt

02-01-2015, 12:27 AM	#6
Bowed Registered User Join Date: Oct 2002 Location: where it's hot Posts: 1,059	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock It is my understanding that the rivets used in the chassis are grade 5 . They have to be a softer grade in order to crush properly .

02-01-2015, 11:17 AM	#7
324matt Registered User Join Date: Oct 2011 Location: Prarietown IL Posts: 118	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock I just finished replacing all of the rivets in the rear of my frame after sandblasting last week. I used 1" long 7/16 grade 8 flange bolts, torqued them to 77ft/lbs with lots of red locktight. rivets are grade 5, but I used grade 8 because I am not looking for flex, Im looking for rigidity and stiffness. flangebolts.com was where I bought them. __________________ 1985 GMC K2500. 350/TH400/208. 4:10's. stock. 1987 Chevy V30. 454/TH400/205 4:10's. Stock SOLD.

02-01-2015, 02:42 PM	#8
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock I was interested in finding out more, and discovered the following article: http://www.tech-cor.com/AutoResBulle...0-6/2000-6.htm Now, this is for a ford f-150, but it gives factory recommendations on rivet replacement. Near the bottom if you don't want to read the whole thing. __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt

02-01-2015, 04:14 PM	#9
Keith Seymore Registered User Join Date: May 2009 Location: Motor City Posts: 9,230	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock 3/8" grade 8 bolts were the assembly line repair for missing or miss hit rivets for our trucks. Mine is going on 29 years and 200,000 miles with bolted on spring hangers. K __________________ Chevrolet Flint Assembly 1979-1986 GM Full Size Truck Engineering 1986 - 2019 Intro from an Old Assembly Guy: http://67-72chevytrucks.com/vboard/s...d.php?t=342926 My Pontiac story: http://forums.maxperformanceinc.com/...d.php?t=560524 Chevelle intro: http://www.superchevy.com/features/s...hevy-chevelle/

02-01-2015, 04:47 PM	#10
greg64 Registered User Join Date: Dec 2007 Location: Kimberley, BC, Canada Posts: 799	Re: what size bolts for spring hangers to replace rivets? and part #for shorter shock Thanks Keith. I guess I'm not surprised, since a 3/8 grade 8 can take nearly 10,000 lbs in shear. https://nucor-fastener.com/Files/PDF...r_Strength.pdf __________________ Greg 64 GMC Suburban - 283, NV3500, 14 bolt 77 C10 swb - 292, SM465, 12 bolt



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