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Motor mounts from stock shackles

When I bought Anchor mounts off rockauto they were horrible quality, made in either india or korea, and the rubber was such low grade that they were leaving marks on the box and felt greasy before they ever went in... they didn't. I ended up using them on a random project that didn't need any real strength, just a bushing with a convenient mount.

I would never run those... and I run some pretty hack shit :laugh2: good welding practice and fab practice, just consider it a lesson learned before your engine falls out because of them. If you put a gusset or two on them and maybe boxed in the ends of that open area they might survive, but they'll break, and quickly, the way you have them now.

I would get a set of broken aftermarket control arms (preferably a crushed/kinked tube set) from someone local and cut the ends off, then weld those to plate and use that if you want to fab your own. Bonus, they will take regular bushings for whatever control arm brand you based them off of. Might have to stack washers (ghetto! I'm gonna get slammed for suggesting this! :eyes:) to make the bushing sleeves fit the brackets on the motor, but it should work.
 
Heres a pic of my stock mount, I got my money out of this one!

100_1579.jpg


I went with brown dogs -

and always remember...

f206196d.jpg
 
kastein said:
I would never run those... and I run some pretty hack shit :laugh2: good welding practice and fab practice, just consider it a lesson learned before your engine falls out because of them. If you put a gusset or two on them and maybe boxed in the ends of that open area they might survive, but they'll break, and quickly, the way you have them now.
Click to expand...


Yeah, I know it's bootyfab. But where exactly do you think it'll break, and why?

Geometry?
Not enough weld length?
Metal too thin and weak after welding? - sounds like this is the difference between old MORE mounts and Brown Dog.

This has to be stronger than stock, right? 1/4" vs. 1/8 or whatever stock is.
 
Geometry, mostly. If there is much sideways force on them (cornering and hitting a pothole, wheeling) the vertical pieces of metal will bend. Since you have both tipped the same way, even the weight of the engine combined with a rough road will flex the vertical pieces, even if it isn't enough to bend them, repeated flexing will fatigue the metal until they break loose.

I'm not sure if it's stronger or weaker than stock, but stock has a big block of rubber there instead of angled sheets of metal, the difference being that the rubber will compress and bounce back instead of flexing the metal back and forth till it breaks off.
 
kastein said:
Geometry, mostly. If there is much sideways force on them (cornering and hitting a pothole, wheeling) the vertical pieces of metal will bend. Since you have both tipped the same way, even the weight of the engine combined with a rough road will flex the vertical pieces, even if it isn't enough to bend them, repeated flexing will fatigue the metal until they break loose.

I'm not sure if it's stronger or weaker than stock, but stock has a big block of rubber there instead of angled sheets of metal, the difference being that the rubber will compress and bounce back instead of flexing the metal back and forth till it breaks off.
Click to expand...


Exactly what I needed to know, thank you :cheers:.
I will reinforce them or start over from scratch. May run these for a little bit while I make new ones.
 
I would put some triangular gussets on the sides welded to the metal et the edges of the bushing tube as well as along the base. That should make them last well for you. I modified some stock mounts for one of our socal folks and the bracket ripped out of the block without the mount failing.
 
I'm going to be putting in some brown dogs when they arrive, but since where on the topic of weak mounts...

Does anyone happen to know why engine block mounts/bolts/brackets fail? Is this common on all years of the 4.0 or just the pre-96 body style? (mainly what I have heard was this was common on the old body style not the new)
 
3 bolts isn't really that much to hold the mount on, and they're in a stupid pattern. That's my opinion on it anyways...

For what it's worth, I've wheeled multiple jeeps with only two bolts in the passenger side, and the only time I've broken the mount off the block is when I got super bad deathwobble in my stock MJ doing about 50. By the time I got it to stop wobbling the mirrors weren't pointing the right direction, the steering wheel was no longer centered, the tires had scrub marks on them, and the passenger side motor mount bracket had torn off the block. Scared the hell out of me.
 
kastein said:
3 bolts isn't really that much to hold the mount on, and they're in a stupid pattern. That's my opinion on it anyways...

For what it's worth, I've wheeled multiple jeeps with only two bolts in the passenger side, and the only time I've broken the mount off the block is when I got super bad deathwobble in my stock MJ doing about 50. By the time I got it to stop wobbling the mirrors weren't pointing the right direction, the steering wheel was no longer centered, the tires had scrub marks on them, and the passenger side motor mount bracket had torn off the block. Scared the hell out of me.
Click to expand...
man, i've had bad ball joints, bad track bar, loose track bar bracket, poor alignment, etc, and i still have yet to experience death wobble. i feel so left out!
 
Vanimal said:
man, i've had bad ball joints, bad track bar, loose track bar bracket, poor alignment, etc, and i still have yet to experience death wobble. i feel so left out!
Click to expand...

Toe in a bit. Disconnect steering dampener and sway bars. Hit a bump at 45 mph, that should do it.


I tried to test my motor mounts. 4low on the street, anchored to a tree. Nothing broke, should be OK for a little while.
http://www.youtube.com/watch?v=erHg0RvNAXE&feature=youtu.be


I did order bushings from polyperformance to make good mounts with.
 
srimes said:
Toe in a bit. Disconnect steering dampener and sway bars. Hit a bump at 45 mph, that should do it.


I tried to test my motor mounts. 4low on the street, anchored to a tree. Nothing broke, should be OK for a little while.
http://www.youtube.com/watch?v=erHg0RvNAXE&feature=youtu.be


I did order bushings from polyperformance to make good mounts with.
Click to expand...
havent had sway bars for a while. im sure my alignment is wayyy off, my steering wheel is at 3 o'clock, and i just swapped the front axle and put on 33's
 
jeeperjohn said:
I would put some triangular gussets on the sides welded to the metal et the edges of the bushing tube as well as along the base. That should make them last well for you. I modified some stock mounts for one of our socal folks and the bracket ripped out of the block without the mount failing.
Click to expand...

that would be me, and these are the mounts John built for me :D the block side mount didn't rip off it shattered from repeatedly jumping the XJ without good suspension up front.


CIMG4143.jpg
 
the issue is not the up and down support of the square tube, it's the side loading that is only going to be supported by the welds. as the motor twists it's going to attempt to push the round section sideways off the top of that piece of square tube. an angled brace would help to keep that from happening.

There is a reason nobody else's motor mounts are built the way you built that one. much better than your first attempt but it really should have an angled brace on it as stated above.
 
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