Anyone just using a standard grade 8 bolt on the lower control arms? Don't realy want to spend $6 a bolt. Doesn't need to look factory, but also don't want the cotntrol arm to fall off as well, so prob need a locking nut as well.
Lower Control Arm Bolts
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Works well for me...I use a grade 8 locking nut or a nyloc with the GR 8 bolt and a drop of Locktite.
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Grade 8 is fine but please use Nylock nuts.
Grade 8 are fine for the rear arms (stock are grade 5). Poly lock/ nylock nuts are okay but all metal lock nuts such as Stovers are even better and they`re reusable. Be careful what you use in the front the factory LCA arm bolts have a special shoulder on one end. You can run hardware store bolts but one side (the head side) will be loose in the holes and eventually egg shape the holes in the frame. Watch using poly lock or nylock nuts in the LCAs too because they can get really close to the header tubes and they only work to about 350* then they loose their locking ability forever. The Stovers work through elastic deformation of the nut itself (one side of the hole will look oval or slightly triangular) so they`re good for MUCH higher temps. Mark SC&C
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THANK YOU!!!! I have been preaching the importance of these style lock nuts forever! I have personally seen nylocks melt on motor mount bolts and front suspension bolts! I now use rocker arm nuts because most auto parts stores will have them in stock and they are the same locking style.
Ok, I pulled the whole front suspension out... had the controls blasted and powder coated... and now I am ready to reassemble. I've thought about cleaning up the factory bolts/nuts and reusing..... but they're 41 years old. I took the bolts to the local True Value and they have the same bolt.... only in a course thread. And the factory's are fine thread. Will that matter? I just want something safe and nicer looking that the rusted ones I removed. I'm not doing a factory restoration, so I'm not too concerned with the "right bolt." But... again, just safe and better looking. Any suggestions?
are you working on a Chevelle? The only fine thread bolts I've seen in the front suspension are the one in the ends of the upper A-arm crosshafts. Where is the bolt you're talking about?
Here's a pic of what I ended up with.... and you're right. The bolts are a course thread. The new bolts are Grade 8.... but.... are not identical in length. I think they're going to be ok. The new LCA bolts are just a touch longer... but no too much they won't fit. I'm also going with loc washers instead of the nyloc or similar nut. What are your thoughts there?
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These are the UCA bolts I got.... they're a little shorter than what I pulled out. Again, I couldn't find the exact length. But.... I think they'll be ok too. The originals that I pulled out had quite a bit of length and nearly touched the headers. So I think the new shorter length will be perfect. Or... I hope anyway. Again here I am goin with Loc Washers instead of a nyloc style nut. There was a lot of mention as to the header heat effecting the nyloc type material. So.... I opted for the loc washers. Think I'll be ok?
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lock washer not a good thing here. be guided by what the factory used.
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I share Tom's opinion about lock washers. Lock washers don't do much locking until the fastener is loose anyway.
The lower a-arm bolts are in double shear and can be remarkably low in tensile strength as shear strength is easier to come by (a good example is a 5/8" dia pin through a trailer hitch pulling a gigantic camper -not much bigger than a lower a-arm bolt). The trick is making sure the nut doesn't come loose in the first place by proper torquing. Regardless of grade, the nut needs to apply enough pressure to stretch the bolt and clamp the system. The mechanical interference locking nut ensures the fastener stays on place even if the nut comes loose.
The uppers are the opposite situation in that the bolt actually has to have decent tensile strength.
As mentioned, Grade 8 or more importantly a good quality fastener such as it appears you have, should work well. Torque values increase as you have to overcome the locking resistance to get the proper torque.
The lower a-arm bolts are in double shear and can be remarkably low in tensile strength as shear strength is easier to come by (a good example is a 5/8" dia pin through a trailer hitch pulling a gigantic camper -not much bigger than a lower a-arm bolt). The trick is making sure the nut doesn't come loose in the first place by proper torquing. Regardless of grade, the nut needs to apply enough pressure to stretch the bolt and clamp the system. The mechanical interference locking nut ensures the fastener stays on place even if the nut comes loose.
The uppers are the opposite situation in that the bolt actually has to have decent tensile strength.
As mentioned, Grade 8 or more importantly a good quality fastener such as it appears you have, should work well. Torque values increase as you have to overcome the locking resistance to get the proper torque.
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Once you buy new hardware store grade 8 bolts and nuts, the CORRECT suspension bolts with the proper shoulder at the head end aren't really that much more expensive and as Mark said above, that shoulder is there for a reason. And you only need four bolts to do the entire front suspension (lower control arms).
If the originals are in decent shape, a few minutes cleaning them up with a wire wheel can do wonders and will work just fine and save you even more money. Unless the bolts are heavily rusted, there's no reason they can't be reused, it's not like they are exactly a wear item. Once properly torqued, the bushings deflect when the suspension moves, the bolts shouldn't move a bit.
Bottom line: If regular everyday bolts were acceptable as suspension bolts, GM would have used everyday bolts instead of the unique shouldered ones they did use. Those unique bolts are there for a reason, as are the unique pinch nuts used as a locking device.
If the originals are in decent shape, a few minutes cleaning them up with a wire wheel can do wonders and will work just fine and save you even more money. Unless the bolts are heavily rusted, there's no reason they can't be reused, it's not like they are exactly a wear item. Once properly torqued, the bushings deflect when the suspension moves, the bolts shouldn't move a bit.
Bottom line: If regular everyday bolts were acceptable as suspension bolts, GM would have used everyday bolts instead of the unique shouldered ones they did use. Those unique bolts are there for a reason, as are the unique pinch nuts used as a locking device.
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1,507 Posts
If using a standard fastener instead of a GM shouldered bolt and locking nut, I'd use a flat washer under the bolt head, another under the nut, and an all metal lock nut (Stover, etc.).
Mark's original point above concerning the shoulder is a good one as GM used that as a way to stabilize the fastener and prevent the bolt from moving in a wide tolerance hole. When moving from GM style to standard hardware, we can minimize the impact by selecting quality hardware and torquing properly.
Ramey Womer
Product Development Engineer
UMI Performance, Inc.
(814)343-6315
Mark's original point above concerning the shoulder is a good one as GM used that as a way to stabilize the fastener and prevent the bolt from moving in a wide tolerance hole. When moving from GM style to standard hardware, we can minimize the impact by selecting quality hardware and torquing properly.
Ramey Womer
Product Development Engineer
UMI Performance, Inc.
(814)343-6315
Ramsey, Rich, Mark, thank you all for your replies and help. It's very appreciated. I definitely do not consider myself a nuts & bolts professional..... so I'm ok with say I can't seem to see/find/understand the "Shouldered" bolt that we're referring to? The heads of the bolt appear to be the same to me..... I've noted the area I "think" we're talking about in red.... is this the part we're referring to as "shouldered?"
I just want the thing safe.
I just want the thing safe.
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10 stover lock nuts for $100.00 plus?
http://www.fastenermart.com/html/NT112-8572.html
Goooood GAWD man....is that normal for this hardware or am I missing something? Holy crap, can you melt them down and make jewelry?
http://www.fastenermart.com/html/NT112-8572.html
Goooood GAWD man....is that normal for this hardware or am I missing something? Holy crap, can you melt them down and make jewelry?
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1,507 Posts
I'd try something like this from McMaster-Carr.
Part Number: 90636A060
Zinc-Yellow Plated Grade 8 STL Center Locknut Hex, 1/2"-13 Thread Sz, 3/4" Width, 7/16" Height
www.mcmaster.com
McMaster is a very customer friendly company. I use them for fasteners quite often. If you inquire you can find out source/made in USA/certs, etc.
ramey
Part Number: 90636A060
Zinc-Yellow Plated Grade 8 STL Center Locknut Hex, 1/2"-13 Thread Sz, 3/4" Width, 7/16" Height
www.mcmaster.com
McMaster is a very customer friendly company. I use them for fasteners quite often. If you inquire you can find out source/made in USA/certs, etc.
ramey
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