71 C10 rear shock bolts breaking - The 1947 - Present Chevrolet & GMC Truck Message Board Network

71C10Guy · 01-19-2020, 11:13 PM

I've had a constant problem with my truck, both rear shocks will eventually wear through the bolts and fall off. I'm not sure why at this point, but I do have 3/4 ton coil springs in her. I thought it might be a missing tracking arm but I realised I do have mine.
Additionally when I first got the truck both lower shock mounts on the rear were completely worn through. I got new mounts from lmctruck and they seem pretty solid, but again both shocks will fall off after either shearing the bolts or just wearing them down.
The truck is stock height as far as I know and I haven't done anything else to the truck suspension. When bolting the shocks on I put a washer on the bolt, the bolt through the shock and mount, then a washer and bolt on the end.
Is this something that just happens with these trucks or is something wrong? Afaik the truck hasn't been in any serious accidents, though there is a big patch of Bondo on the passenger side right above the rear wheel. Could the trailing arm be slightly bent and shearing the shocks?
This happens about every month or two, it's pretty frequent and starting to get expensive replacing 4 grade 8 bolts and nuts as well as 8 washers every month or two.

Andy4639 · 01-19-2020, 11:36 PM

This is something you need looked at. This is no way a common thing. Grade 8 bolts getting sheared off is big time trouble some where. Are the trailing arms in good shape? I'd have some one looking at it real closely.

Post some pictures of it so we can have a look.

71C10Guy · 01-20-2020, 12:13 AM

Quote:

Originally Posted by Andy4639

.

Post some pictures of it so we can have a look.

Here's an album of some different angles
C10 shock problems https://imgur.com/a/EBykzCl

**Sheepdip** · 01-20-2020, 12:53 AM

Quote:

Originally Posted by 71C10Guy

Here's an album of some different angles
C10 shock problems https://imgur.com/a/EBykzCl

No pics on the link provided.

Andy4639 · 01-20-2020, 12:54 AM

Can't see nothing out of the ordinary in the pictures but if you breaking grade 8's you need something fixed.
I've owned my 71 now for 35 years and have never broken a rear shock bolt are front.

**Ironangel** · 01-20-2020, 01:37 AM

I think the shock length may be suspect. Other than that everything looks normal to me. Have you noticed any hammering when you go over bumps or hauling loads? The only time I've seen shock bolts or even the welded eye the bolt goes through break is when the shock bottoms out.

Mike C · 01-20-2020, 08:18 AM

Quote:

Originally Posted by Ironangel

I think the shock length may be suspect. Other than that everything looks normal to me. Have you noticed any hammering when you go over bumps or hauling loads? The only time I've seen shock bolts or even the welded eye the bolt goes through break is when the shock bottoms out.

This would be my guess as well. Shocks are too long would be my guess as well. I just replaced a set on an ‘83 2500 crew cab and all the bolts were perfect and the shocks looked to be the original ones. My Jimmy has the original shock mount bolts and over 350,000 miles on them, so something clearly is out of whack on your truck and shock length seems most likely.

Andy4639 · 01-20-2020, 10:27 AM

I would have thought the same thing as ya'll but he made no mention of anything in his first comment's.

So what about it 71C10Guy, any bottoming out, may have some worn out springs also.

**AussieinNC** · 01-20-2020, 05:54 PM

Your shocks are too long and are bottoming out, bending the bolts and eventually breaking them....

Grab a new set of the correct length shocks next time you chew thru the bolts...

LMC part number 38-1695....KYB Gas...need two...$59.95 per shock...

30-0363 are the bolts need 2
30-0820 are the nuts need 2
30-0680 are the lock washer need 2

Hope this helps...

olcarguy · 01-20-2020, 06:10 PM

C10guy

Are you using the proper shock shoulder stile bolts, just a thought.

**Ol Blue K20** · 01-21-2020, 08:26 AM

Is there a rubber snubbed to keep from bottoming out? I didn't see any.

**AussieinNC** · 01-21-2020, 05:17 PM

As Dale mentioned, there should be a rubber snubber mounted to the chassis above the differential housing to prevent the housing bottoming out on the shocks....

LMC has them under 30-1875....around $10 each...

Question...Is it the upper mount bolt that breaks or the lower one? The lower one is in single shear and prone to move around if it is not tightened to specs....

**HO455** · 01-22-2020, 03:45 PM

Grade 8 bolts were mentioned at one point but grade 8 bolts should never be used in situations where shear forces are anticipated. For the same reason that you would never use a file as a pry bar.
From the photos it may be possible that all of the oil has leaked out of those shocks and they may be seizing up when hot.

01-19-2020, 11:13 PM	#1
71C10Guy Registered User Join Date: Jul 2017 Location: Dripping Springs Posts: 40	71 C10 rear shock bolts breaking I've had a constant problem with my truck, both rear shocks will eventually wear through the bolts and fall off. I'm not sure why at this point, but I do have 3/4 ton coil springs in her. I thought it might be a missing tracking arm but I realised I do have mine. Additionally when I first got the truck both lower shock mounts on the rear were completely worn through. I got new mounts from lmctruck and they seem pretty solid, but again both shocks will fall off after either shearing the bolts or just wearing them down. The truck is stock height as far as I know and I haven't done anything else to the truck suspension. When bolting the shocks on I put a washer on the bolt, the bolt through the shock and mount, then a washer and bolt on the end. Is this something that just happens with these trucks or is something wrong? Afaik the truck hasn't been in any serious accidents, though there is a big patch of Bondo on the passenger side right above the rear wheel. Could the trailing arm be slightly bent and shearing the shocks? This happens about every month or two, it's pretty frequent and starting to get expensive replacing 4 grade 8 bolts and nuts as well as 8 washers every month or two.

01-19-2020, 11:36 PM	#2
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 71 C10 rear shock bolts breaking This is something you need looked at. This is no way a common thing. Grade 8 bolts getting sheared off is big time trouble some where. Are the trailing arms in good shape? I'd have some one looking at it real closely. Post some pictures of it so we can have a look. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

01-20-2020, 12:54 AM	#5
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 71 C10 rear shock bolts breaking Can't see nothing out of the ordinary in the pictures but if you breaking grade 8's you need something fixed. I've owned my 71 now for 35 years and have never broken a rear shock bolt are front. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

01-20-2020, 01:37 AM	#6
Ironangel Senior Member Join Date: Feb 2010 Location: Falls City, Nebraska "100 Miles From Nowhere" Posts: 2,219	Re: 71 C10 rear shock bolts breaking I think the shock length may be suspect. Other than that everything looks normal to me. Have you noticed any hammering when you go over bumps or hauling loads? The only time I've seen shock bolts or even the welded eye the bolt goes through break is when the shock bottoms out. __________________ Michael of the clan Hill, "Two Seventy Two's" 71 1-ton Dually 350 4-Speed 71 C/50 Grain Truck, 350 Split-Axle 4-Speed 02 3/4 ton Express 14 Indian Chief Vintage 1952 Ford 8N, "Only Ford Allowed On The Property" "Be American, Buy American"

01-20-2020, 10:27 AM	#8
Andy4639 Old member Join Date: Jan 2002 Location: Liberty, & Garden City S.C. , U.S. Posts: 19,945	Re: 71 C10 rear shock bolts breaking I would have thought the same thing as ya'll but he made no mention of anything in his first comment's. So what about it 71C10Guy, any bottoming out, may have some worn out springs also. __________________ 1971 LWB Custom, 6.0LS & 4L80E, Speedhut.com GPS speedometer & gauges with A/C. 20" Boss 338's Grey wheels 4 wheel disc brakes. My Driver Seeing the USA in a 71 Upstate SC GM Truck Club 2013,14 and 2016 Hot Rod Pour Tour http://upstategmtrucks.com/ Get out and drive the truck this summer and have some fun! It sucks not being able to hear! LWB trucks rule, if you don't think so measure your SWB! After talking to tech support at Air Lift I have found out that the kit I need is 60811. Per the measurements I gave them. Ride height of truck inside spring and inside diameter of springs.

01-20-2020, 05:54 PM	#9
AussieinNC Moderator Join Date: Jun 2017 Location: Cherryville, NC Posts: 2,204	Re: 71 C10 rear shock bolts breaking Your shocks are too long and are bottoming out, bending the bolts and eventually breaking them.... Grab a new set of the correct length shocks next time you chew thru the bolts... LMC part number 38-1695....KYB Gas...need two...$59.95 per shock... 30-0363 are the bolts need 2 30-0820 are the nuts need 2 30-0680 are the lock washer need 2 Hope this helps... __________________ Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox

01-20-2020, 06:10 PM	#10
olcarguy Registered User Join Date: Sep 2019 Location: Maynooth, Ontario, Canada Posts: 174	Re: 71 C10 rear shock bolts breaking C10guy Are you using the proper shock shoulder stile bolts, just a thought. __________________ http://67-72chevytrucks.com/vboard/s...82#post8619382

01-21-2020, 08:26 AM	#11
Ol Blue K20 Proprietor of Dale's Corner Join Date: Nov 2012 Location: Vacaville , CA Posts: 16,242	Re: 71 C10 rear shock bolts breaking Is there a rubber snubbed to keep from bottoming out? I didn't see any. __________________ "Some Days Chickens And Some Days Feathers" Dale XNGH ECV Sam Brannan 1004 R.I.P. 67ChevyRedneck R.I.P. Grumpy Old Man R.I.P. FleetsidePaul

01-21-2020, 05:17 PM	#12
AussieinNC Moderator Join Date: Jun 2017 Location: Cherryville, NC Posts: 2,204	Re: 71 C10 rear shock bolts breaking As Dale mentioned, there should be a rubber snubber mounted to the chassis above the differential housing to prevent the housing bottoming out on the shocks.... LMC has them under 30-1875....around $10 each... Question...Is it the upper mount bolt that breaks or the lower one? The lower one is in single shear and prone to move around if it is not tightened to specs.... __________________ Family and country before all others... 2006 Chevy Silverado (Daily Driver) 2012 Chevy Equinox

01-22-2020, 03:45 PM	#13
HO455 Post Whore Join Date: Feb 2016 Location: Portland Oregon Posts: 11,279	Re: 71 C10 rear shock bolts breaking Grade 8 bolts were mentioned at one point but grade 8 bolts should never be used in situations where shear forces are anticipated. For the same reason that you would never use a file as a pry bar. From the photos it may be possible that all of the oil has leaked out of those shocks and they may be seizing up when hot. __________________ Thanks to Bob and Jeanie and everyone else at Superior Performance for all their great help. RIP Bob Parks. 1967 Burban (the WMB),1988 S10 Blazer (the Stink10 II),1969 GTO (the Goat), 1970 Javelin, 1952 F2 Ford OHC six 4X4, 29 Model A, 72 Firebird (the DBP Bird). 85 Alfa Romeo If it breaks I didn't want it in the first place The WMB repair thread http://67-72chevytrucks.com/vboard/s...d.php?t=698377



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