bolt sizes and thread pitch
01-28-06, 11:08 PM
#1
Rotary Freak
Thread Starter
bolt sizes and thread pitch
Does anybody know where to find info on this??? I havent gotten under my car in a while but I have a feeling i might find a surprise or 2.
I am getting some bucking which is most likely caused by the semi stripped motor mount bolt. However the last time i was under the car I noticed that the bolts on the diff brace were a bit loose. I tighten them but i'm wondering if they might have loosened up again.
Would getting new bolts help? What about just drilling and tapping for a thicker bolt? and as long as were on the subject, anybody know how long a bolt has to be in order to go through(aftermarket motor mounts)the rubber and the metal mount/subframe????
TIA
I am getting some bucking which is most likely caused by the semi stripped motor mount bolt. However the last time i was under the car I noticed that the bolts on the diff brace were a bit loose. I tighten them but i'm wondering if they might have loosened up again.
Would getting new bolts help? What about just drilling and tapping for a thicker bolt? and as long as were on the subject, anybody know how long a bolt has to be in order to go through(aftermarket motor mounts)the rubber and the metal mount/subframe????
TIA
01-29-06, 08:48 AM
#2
I'm not too familiar with these bolts since I've never disassembled them. But here is my general knowledge of loosening bolts and stuff. The size of the bolts is not usually the problem - the condition of the threads and overtorquing is usually the issue.
Overtorquing is often the problem when fasteners are coming loose - get new bolts (Mazda replacements should be fine), and use solvent to clean the threads of the surfaces that aren't new. Motor mounts are often covered with a layer of engine oil - this contributes to the overtorquing problem. So replace, clean, and tighten to spec with a proper torque wrench. I thought that aftermarket motor mounts simply re-use the stock bracket and fasteners, so I dunno about what sizes fit them.
If you have stripped threads you might consider installing a heli-coil. This is a better solution IMO than a different size of fastener.
If you want to be sure it doesn't move, I usually use an adhesive like Loc-Tite (Blue or Red), since a shot of heat from a propane torch nicely breaks the bond if I need to disassemble it later. But the heat of the engine might do that at the mounts, so a single split lockwasher might work better.
Dave
Overtorquing is often the problem when fasteners are coming loose - get new bolts (Mazda replacements should be fine), and use solvent to clean the threads of the surfaces that aren't new. Motor mounts are often covered with a layer of engine oil - this contributes to the overtorquing problem. So replace, clean, and tighten to spec with a proper torque wrench. I thought that aftermarket motor mounts simply re-use the stock bracket and fasteners, so I dunno about what sizes fit them.
If you have stripped threads you might consider installing a heli-coil. This is a better solution IMO than a different size of fastener.
If you want to be sure it doesn't move, I usually use an adhesive like Loc-Tite (Blue or Red), since a shot of heat from a propane torch nicely breaks the bond if I need to disassemble it later. But the heat of the engine might do that at the mounts, so a single split lockwasher might work better.
Dave
01-29-06, 12:02 PM
#3
Rotary Freak
Thread Starter
Originally Posted by dgeesaman
I'm not too familiar with these bolts since I've never disassembled them. But here is my general knowledge of loosening bolts and stuff. The size of the bolts is not usually the problem - the condition of the threads and overtorquing is usually the issue.
Overtorquing is often the problem when fasteners are coming loose - get new bolts (Mazda replacements should be fine), and use solvent to clean the threads of the surfaces that aren't new. Motor mounts are often covered with a layer of engine oil - this contributes to the overtorquing problem. So replace, clean, and tighten to spec with a proper torque wrench. I thought that aftermarket motor mounts simply re-use the stock bracket and fasteners, so I dunno about what sizes fit them.
If you have stripped threads you might consider installing a heli-coil. This is a better solution IMO than a different size of fastener.
If you want to be sure it doesn't move, I usually use an adhesive like Loc-Tite (Blue or Red), since a shot of heat from a propane torch nicely breaks the bond if I need to disassemble it later. But the heat of the engine might do that at the mounts, so a single split lockwasher might work better.
Dave
Overtorquing is often the problem when fasteners are coming loose - get new bolts (Mazda replacements should be fine), and use solvent to clean the threads of the surfaces that aren't new. Motor mounts are often covered with a layer of engine oil - this contributes to the overtorquing problem. So replace, clean, and tighten to spec with a proper torque wrench. I thought that aftermarket motor mounts simply re-use the stock bracket and fasteners, so I dunno about what sizes fit them.
If you have stripped threads you might consider installing a heli-coil. This is a better solution IMO than a different size of fastener.
If you want to be sure it doesn't move, I usually use an adhesive like Loc-Tite (Blue or Red), since a shot of heat from a propane torch nicely breaks the bond if I need to disassemble it later. But the heat of the engine might do that at the mounts, so a single split lockwasher might work better.
Dave
I did want to stay away from the thread lock but guess i'm gonna have to at least consider it.
As for the motor mounts, these are different from stock in that they use a single bolt through the polyurethane/metal bracket/subframe as opposed to the built in studs on the stockers.
I will try to chase the threads on my diff brace and get all new bolts.
thanx
01-29-06, 04:56 PM
#4
Originally Posted by 2FAST7S
Yup, thanx Dave. Pretty much the direction i was heading...I do have a question on the heli-coil, what keeps it from coming out?? the bolt itself spreads and makes the coil expand thus keeping it in place???
Dave
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