I have heard this from a few people now that they put a big bolt through their motor mount to keep it from breaking. Anybody done this?? Do you tighten the bolt all the way up to keep it from moving at all or do you leave a bit of a gap so it can still flex the one way a bit??
I have done this, I learned of the idea from an article Mustangs Plus did. I tightened the bolt snug, using a vinyle lock nut. I have broke 3 motor mounts on my car before I did this, but no problems since.
jasonn said:
I have heard this from a few people now that they put a big bolt through their motor mount to keep it from breaking. Anybody done this?? Do you tighten the bolt all the way up to keep it from moving at all or do you leave a bit of a gap so it can still flex the one way a bit??
Don't leave any slop, this would put more stress on the bolt-head during hard accleration. You will most likely have to grind a considerable portion of that head down to get it to fit to the frame as well. Grinding the head is better than the nut though.
I'd suggest tightening the bolt just enough to take out any looseness, then maybe another 1/4 turn or so. You wont hurt anything by torquing the crap out of it but if you do you may want to look into some solids since you'll have almost no "give".
actually for the street you do want a little play, something like 1/16" as i recall. that way you have a little flex to allow the mount to absorb vibration. when you go to the track, then tighten the bolt down so you get maximum throttle response.
actually you want it so that the nut is just touching the mount don't tighten enough to compress the mount though, you just want it to hold the mount together in the event that it breaks, but the chances of it breaking with bolt through it are greatly reduced since it will not allow the mount to give under tension, but it still allows the mount to do it's job properly and still isolate vibrations
That's an old school trick. Some cheap tricks can't be improved on... bnickel's comments were right on the money. Be sure to use ARP or at least grade 8 bolts for this.