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Old 06-14-2009, 09:58 PM
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2door 2door is offline
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Location: Littleton, Colorado
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Default Re: engine mount bolts

Originally Posted by Nashville Kat View Post
That's a good suggeston- but do they loosen with vibration?

with long studs you can double up the nuts for a secure lockdown.

I do not use LocTite anymore, red, blue or any other color and I've never had a bolt loosen, fall out, break or fail. I know that as far as vibration problems I've probably been fortunate in that vibes have never been a real issue with any of my engines. I tighten the bolts against a lock washer just enough to flatten it then give it a slight bit more torque. (very slight) If you are shearing studs then there is a good possibility that you are over tightening them and/or tightening them too often. Poor fitting engine mounts will allow movement even with minimal vibration and this can lead to metal fatigue which is often blamed on poor quality Chinese fasteners. If the engine mounts fit the frame and have good contact throughout the circumference of the mount and if the fasteners are torqued properly and not overtightened, then the probability of fastener failure is greatly reduced. This goes for studs with nuts or bolts. Improper installation is still the biggest culprit with these kits and this opinion is shared by several others here who have years of mechanical experience to back up their claims, me included. I like the Allen head cap screws in place of the kit studs for reasons other than strength. They look cleaner, are easy to install and remove and there is far less chance of overtightening them than with a ratchet and socket; use an Allen wrench and your ability to overtighten is reduced due to less leverage And, they're easier to keep track of than a handfull of nuts for eyes as old as mine. Another plus is that there is only one set of threads to worry about. With studs you have to be concerned with those in the engine and those in the nuts. A bolt reduces the thread involment in the fastening. That being said you might ask why I do not use bolts instead of studs for the cylinder and head. The Chinese have done something here very odd. Look and you'll find that bolts long enough to hold the head and cylinder to the block are difficult/ next to impossible to find. That's because bolts of that diameter and length are only available in a 1.25 thread pitch and the studs the factory uses are a 1.00 pitch. I do replace the acorn nuts with hex nuts because I've found a couple of them that had bottomed out on the stud and would not allow a proper head bolt torque. Hope this answers some questions but it will probably ruffle some feathers and stir up dust too. So be it.
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