You have only one option... make your own... I made urethane mounts.. it isn't that bad really. You'll need to:
- air chisel off the hold down tabs on the tops of the stock mounts
- dump the interiors and sandblast clean
- locate correct size bolts that match existing mount thread (or at least rough size so they can bolt back to the top bracket) make sure that the bolts have the overall length so that they have similar height to the stock top bolts when suspended about 1/2" - 3/4" above the bottom of the bottom cup.
- locate washers larger enough to NOT slip through the top retainer plate (which came off after unbending the tabs)
- weld two washers to each bolt, one at the bottom, and one at the same height as the bottoms of the rounded slots in the bottom cup when the bottom of the bolt is 1/2" -3/4" from the bottom of the bottom cup. (it helps to build a jig, because you need to suspend this bolt/washer assembly dead center, and at the correct height inside the cup for filling)
- place the washer/bolt assembly inside the cup, place the retainer plateonto the cup, and tack weld at approx the same level it was before removal
- grind off excess tab and weld material (optional)
- masking tape closed all holes on outside of cup
- mix up shore hardness 90A room temp vulcanizing urethane (you can get from many plastic companies, I got it from a place in chicago pretty cheap)
- while holding cup level, and assembly dead center in cup and at the correct height (1/2" -3/4" off bottom of cup) inject the cup from the top with the urethane
- allow to set up a day or two.
you really need to inject the urethane, it is too thick otherwise and the working time isn't very long. I built one out of 3" PVC pipe and screw on end caps. One end had a hose barb, to which I attached a vinyl injector hose(the bottom of the injector) and at the top I attached an air fitting. I used a gas station style tire pressure filler to maintain a constant 60-90 PSI in the chamber and push the urethane through the hose into the cups. just keep up up and down down and this method works great and the injector is then reusable as well.
also make sure that you don't run out of urethane.
my urethane mounts KICK BUTT over the stock ones. I was trying to locate more stock cores to make more, but nobody keeps old ones around so I can't find any.
good luck, I have some pics of the jig I made and some sketches, as well as the mounts themselves, but no place to host them so the list can see.
Great post Jim...you know your stuff. You should talk to Rich from mn12performance.com...maybe you two should make some for the 5L and 4.6L!
He can just use some 5L mounts from a 91-93 bird as the cores (or maybe you can make him some?). I think a torque strap would be a good thing to use given the chassis was not designed for greater than 300ft-lbs.
Yeah a torque strap might be nice if you are pushing some serious ponies... the other option would be to strengthen the mount points on the crossmember. The crossmember itself is incredibly beefy (I know this after having swapped mine after smaking a steel construction plate that was sticking up too high) the mounts are the weak point... the mn12 chassis are also surprisingly robust even without braces... if you could strenthen the mount points on the crossmember I would seriously doubt that you would even need the torque strap... the full urethane mounts are really really great.
I actually bought mounts from Rich when he thought he had some for 91-93 5.0's (which turned out not to be the case) and that is what prompted me to realize that I had to make my own. Like I said, if I can find cores, I'd definately make more.
They're not bad...but my ride is noisy and rough anyway, so it's hard for me to say.
Daily driver, I probably wouldn't go solid. I've only got about 300 miles on them...I'm happy with mine, between the cam and solids it gives female passengers a special tingly feeling
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