Rear suspension bolts? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

benscool1 · 03-28-2005, 08:51 PM

I'm switching the rear suspension on my truck to a different chassis, leafs, differential, hangers and all. Well I have all the rivets off but the hole is a weird size, its bigger than 3/8 and smaller 7/16. I think I might have to use a metric. I'd prefer not to have to drill EVERY ONE of the holes out to 7/16. What did you guys do? Can you get metric grade 8 bolts anywhere? I'd need a cobalt bit to drill them out, and that would cost me an arm and a leg. What have you guys done? Like I said, if I can get a metric to fit that would be awesome, but I don't wanna have to drill out all the damn holes unless I have to.

BTW, to save myself the trouble of starting another thread, will a bezel out of an 84(but the guy says it has the wiper controls in the dash, not on the turn signal) fit a 73?

RockHQ · 03-29-2005, 04:18 PM

Metric bolts are not measured by "grade", instead they have a number indicating the quality standard. 8.8 class is equivalent to grade 5. 10.9 is equivalent to grade 8. The number should be stamped on each bolt&nut. 10mm is slightly bigger than 3/8 but smaller than 7/16.

*1FaastC10* · 03-29-2005, 08:59 PM

the rivets are 3/8". my entire chassis is held together by 3/8" bolts, no problems whatsoever getting things to line up.

us111 · 03-31-2005, 01:26 PM

i also used 3/8 grade 8 bolts to replace the rivet's..when i done mine i took a grinder to the rivet head's then beat them out with hammer and punch..some were easy other's were pretty tough.

piecesparts · 03-31-2005, 02:58 PM

Drill the hole out to use grade 8 7/16 bolts. It is stupid to go undersized and take a chance on the bolts moving around and causing a distrtion in your metal. I did it with the bed on my truck once and it can be done.

us111 · 03-31-2005, 05:52 PM

sorry,boy i said that wrong,(been a while since i done mine)..i DID drill the holes out and went to the larger bolt so it was a good fit...wasn't that hard to do,just used a good drill bit...sorry for the miss information...

*1FaastC10* · 03-31-2005, 07:17 PM

Quote:

Originally Posted by piecesparts

It is stupid to go undersized and take a chance on the bolts moving around and causing a distrtion in your metal.

it is also stupid to do more work than necessary, especially when the cause for doing more work isnt really that big of an issue. the outer diameter of the bolts are .37", and the diameter of the hole is .385". use a good quality lock nut, and you'll never notice the .015" difference. any tigher, and you would have issues with getting all of the bolts into the parts easily. threading them through the holes isnt good for them, as it wears the threads right off the bat, causing their clamping force to be less.

piecesparts · 03-31-2005, 07:47 PM

OK; Whatever you want to use on yours, I chose the other method of going to a 7/16 bolt. I felt that drilling out the rivet hole to that size was not a real hard issue and with that approach I had the comfort of putting a bigger and well-fitting set of bolts into my truck's substructure. To me the extra work was worth it. I am somewhat of a BIGGER is better kinda guy.. By the way ever hear of a Charpy V-notch test ? It has to do with shear factors of metal and distortion when put under certain conditions. That is why I went to the extra effort.

benscool1 · 03-31-2005, 11:12 PM

Yeah, thanks for all the info guys. I picked up a few good bits and used some drilling oil and already have all the holes drilled to 7/16 on the hangers but I still need to do it on the frame rails. I was surprised how much easier it was w/cutting oil and a good bit.

03-28-2005, 08:51 PM	#1
benscool1 Registered User Join Date: Mar 2003 Location: Williamsfield, IL Posts: 781	Rear suspension bolts? I'm switching the rear suspension on my truck to a different chassis, leafs, differential, hangers and all. Well I have all the rivets off but the hole is a weird size, its bigger than 3/8 and smaller 7/16. I think I might have to use a metric. I'd prefer not to have to drill EVERY ONE of the holes out to 7/16. What did you guys do? Can you get metric grade 8 bolts anywhere? I'd need a cobalt bit to drill them out, and that would cost me an arm and a leg. What have you guys done? Like I said, if I can get a metric to fit that would be awesome, but I don't wanna have to drill out all the damn holes unless I have to. BTW, to save myself the trouble of starting another thread, will a bezel out of an 84(but the guy says it has the wiper controls in the dash, not on the turn signal) fit a 73? __________________ Ben 84 C10 Silverado 14 Silverado Z71

03-29-2005, 04:18 PM	#2
RockHQ ROCKET POWER! Join Date: Feb 2003 Location: Finland, Europe Posts: 509	Metric bolts are not measured by "grade", instead they have a number indicating the quality standard. 8.8 class is equivalent to grade 5. 10.9 is equivalent to grade 8. The number should be stamped on each bolt&nut. 10mm is slightly bigger than 3/8 but smaller than 7/16. __________________ What did i do last nite? I had a wonderful time, That's what they tell me What did i do last nite? 1979 C-10 shortfleet: Olds 350, Th400, 12 bolt Current project: 1969 Olds 455 W-30, needing a rebuild

03-31-2005, 01:26 PM	#4
us111 Registered User Join Date: Jul 2004 Location: ashland oh Posts: 660	holes i also used 3/8 grade 8 bolts to replace the rivet's..when i done mine i took a grinder to the rivet head's then beat them out with hammer and punch..some were easy other's were pretty tough. Attached Images

03-31-2005, 05:52 PM	#6
us111 Registered User Join Date: Jul 2004 Location: ashland oh Posts: 660	bolts sorry,boy i said that wrong,(been a while since i done mine)..i DID drill the holes out and went to the larger bolt so it was a good fit...wasn't that hard to do,just used a good drill bit...sorry for the miss information...

03-31-2005, 11:12 PM	#9
benscool1 Registered User Join Date: Mar 2003 Location: Williamsfield, IL Posts: 781	Yeah, thanks for all the info guys. I picked up a few good bits and used some drilling oil and already have all the holes drilled to 7/16 on the hangers but I still need to do it on the frame rails. I was surprised how much easier it was w/cutting oil and a good bit. __________________ Ben 84 C10 Silverado 14 Silverado Z71

03-29-2005, 08:59 PM	#3
1FaastC10 Account Suspended Join Date: Oct 2002 Location: Elkhart, IN Posts: 6,399	the rivets are 3/8". my entire chassis is held together by 3/8" bolts, no problems whatsoever getting things to line up.

03-31-2005, 02:58 PM	#5
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	Drill the hole out to use grade 8 7/16 bolts. It is stupid to go undersized and take a chance on the bolts moving around and causing a distrtion in your metal. I did it with the bed on my truck once and it can be done.

03-31-2005, 07:47 PM	#8
piecesparts Parts and more parts Join Date: Nov 2003 Location: Lebo, Kansas (middle of nowhere Posts: 6,821	OK; Whatever you want to use on yours, I chose the other method of going to a 7/16 bolt. I felt that drilling out the rivet hole to that size was not a real hard issue and with that approach I had the comfort of putting a bigger and well-fitting set of bolts into my truck's substructure. To me the extra work was worth it. I am somewhat of a BIGGER is better kinda guy.. By the way ever hear of a Charpy V-notch test ? It has to do with shear factors of metal and distortion when put under certain conditions. That is why I went to the extra effort.



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