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Gelcoat Driving Maniac!
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4,373 Posts
Discussion Starter #1
I've seen a bunch of question posts, but I haven't seen a reference. Does anyone have bookmarked a good Loc-Tite thread for when to use it? Are you all just using it on every bolt that doesn't use a nyloc? That seems like overkill, though probably a good idea.

If not, let's start one. Submit your loc-tited bolt and I'll update the thread. If we list every bolt and whether it needs it or not, it could make for a good reference.

My questionables are:


Rear Suspension:

1. IRS Upper Shock Mount - Nyloc - Loc-Tite Not Needed?
2. IRS Lower Shock Mount - Nyloc - Loc-Tite Not Needed?
3. IRS Knuckle Mounting Bolts - Using Lock Washers - Loc-Tite needed?
4. IRS Upper Control Arm Heim Bolt - Loc-Tite Needed?
5. IRS Lower Control Arm Heim Bolts - Loc-Tite Needed?


Front Suspension:

1. SAI Mod Upper Control Arm Bracket - Loc-Tite Needed?
2. SAI Mod Ball Joint Bracket - One Bolt is not a pass through hole - Loc-Tite needed?
3. IFS Lower Control Arm - Loc-Tite needed?


Steering:

1. Outer Tie Rod/Bump Steer kit - Loc-Tite needed?
2. Steering Rack Mounting Bolts - Loc-Tite needed?
 

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Senior Member
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715 Posts
I've never had any issues using Nyloc nuts, so long as the bolt extends through the nylon at the top of nut. That said, I never use Nyloc nuts for high heat areas like exhaust since the heat may melt the nylon. For those areas I like to use some type of all metal interference locking nut. I use loctite when I don't have a nyloc nut if it's necessary. Use the blue stuff for the suspension & steering parts.

$0.02
 

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Premium Member
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8,065 Posts
In a perfect world you never need loc-tite. In my less than perfect world, I use loc-tite everywhere I can.

If I can easily reach the area with a heat gun (suspension), I use red. If I can't get to the area with a heat gun (engine) I use blue.
 

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Senior Charter Member
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2,424 Posts
I would be carefull to not go overboard with the loctite. We all know why it is used, but when bolts call out a torque specification, we need to be carefull. When we torque a bolt, we are actually trying to stretch the bolt a predetermined amount, within its elastic limit.
A more accurate method is to measure the actual stretch on the bolt, instead of the torque. If this method is used, it would not matter if it was lubed or dry.

The question we should ask when given a torque value is; lubed or dry, and if lubed, what lube? If a given torque value is intended as dry and we use loctite on it, we have in a very real sense, lubricated the threads with loctite. This could easily take the fastener past the elastic limit and into a yeild condition because it will stretch the fastener much more with the same torque indication on your wrench.

If we torque a fastener properly, it should have stretched appropriately within its elastic limits and as such, it will provide a "clamping" force on the assembly. Loctite or lock washers are not generally needed in this case. I have always reserved its use for when it is called for in the procedure. Otherwise, the correct torque, applied under the correct conditions (good thread condition, no burrs, etc., proper lube) should be sufficient.

Personnally, I have found over the years, that it is more important to use Neverseize on threads, than loctite. I use it on wheel studs, suspension bolts, etc., and when it comes time to remove the parts, they come apart easier without breaking bolts and studs.

Jerry
 

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Premium Member
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8,065 Posts
Bolt stretch is only an effective method when bolts are loaded in tension (such as rod and main caps). The torque on a bolt loaded in shear is often much lower than what is required to stretch it.

Loc-Tite is a fairly effective anti-sieze as well. I wouldn't use it in an are prone to galling, but it will help.

In the real world nuts and bolts come loose. If nothing else, loc-tite helps keep them from falling all the way off.
 

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Senior Charter Member
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2,424 Posts
Mikeinatlanta,

You said:The torque on a bolt loaded in shear is often much lower than what is required to stretch it.

I have never seen a chart that differentiated shear from tension but I understand what you are saying. I'd be interested to know what your source is.
 

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Premium Member
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8,065 Posts
Originally posted by Bitten2:
Mikeinatlanta,

You said:The torque on a bolt loaded in shear is often much lower than what is required to stretch it.

I have never seen a chart that differentiated shear from tension but I understand what you are saying. I'd be interested to know what your source is.
There is no chart that fits all applications. I have 25 plus years in avation torquing bolts loaded in shear. An example would be similar to suspension bolts, something like aileron or spoiler hinge bolts. They are very large diameter with low nut torque, sometimes barely over finger tight. Steel shear pins (hy-locs) used in sheet metal repairs normally have low torque aluminum nuts (collars) that break away to automaitcally keep torque low.

An example of tension would be the fan hub tie bolts on a JT8 engine. They are toqued with stretch.
 

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FFCobra Craftsman
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23,307 Posts
I'm w/ Jerry. I use nylocks on everything i can and very little loctite.I always think about connecting rod bolts/nuts.No washer even,no loctite,just properly torqued.The few times I loctite something it's usually something small that I really wonder about how tight, and is subjected to a lot of vibration. But that's just me!
 

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4 Posts
Machinery's Handbook has an excellent section on fastener torque, as Does Marks-standard handbook for mechanical engineers. Both are valuable reference documents.

Chris
 
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