Motor Mount bolts

Upon removing my engine and trans from my 79 Caprice.  I started to remove the old motor mounts on the frame.

"OH, guess what"?  New problem.  The bolts and nuts turn.  They won't let me replace the inner rubber mounts.  

My thoughts were to cut the bolts and replace.  Access is next to nothing.  Houdini would cuss this one.

I could cut a hole in the front of the frame.  Install the bolts and weld it back.  Not my better thoughts.

Or cut the bolts.  Weld the plate to the frame w/bolts sticking out.  I may have to put a spacer in between the plate and frame to get a solid contact.

I am at a guess.  Someone else said, "I would just weld the plate in"!  You still need the bolts to mount.

Anyone have this issue on their car?

I'm open to suggestions.   No goofy comments please.

Thanks

When I yanked my engine I had the same issue nuts on the back spin
Used a long handle box wrench 9/16 and slipped it between the lower control and frame
Took patience a magnet and flat head
Either that or remove control arm
Good luck

Isn't there a chance of the bolts falling back down inside the front end?

That's where the magnet comes in
I laid down basically hugging the crossmember held with left hand and loosened with my impact driverwith my right put the gun down while still hold the wrench against the frame and get the magnet and secure with magnet had a 2.5lb snap on one size of a quarter
Then loosely fasten the nut to bolt you'll have enough slack to remove one corner of the old mount swing it out the way and put the new mount one corner at a time the screwdriver just help you get the bolt better

Sounds like a contortionist is needed.

I will think on this. I will wait to see if I get some others.

Thanks

Lmfao
Not that hard maybe I make it sound complicated
Loosen the nut till it free spins
From under hold the bolt head and from top remove the nut
Use magnet to hold bolt up
Loosely attach nut to keep bolt from falling
Since the is 3 bolts you can one by one getting enough slack to put the nut under the mount
Pivot the mount from the 3rd bolt (one that doesn't have a bolt next to it)
Now you can attach the top nuts and bolts to the new mount but only 2-3 turns so you have wiggle room
Just need to be slow and steady so you don't drop any and should be good
Took me like 30 mins

The engine is out.  And I have the Polyurethane replacements.  Their already to go.

I will be replacing the old bolts.  I had to cut them w/grinder wheel.

15mm. nut on top. And about 25mm. long. Its a 10mm. bolt w/10.9 hardness from what I can read.

Always fun finding replacements.  3/8" grade 8 is a little smaller but easier to find.

Any other suggestions?

PS:  I do have an idea of using 1/2 inch self tapping bolts.  Although someone suggested not doing that.

I could put 4 for each mount.  Just have to drill out the one not through.  

If all else additionally weld the holes close that are there for the rivet to the frame.

My '77 used 3/8 grade 8 bolts from the factory, so using a 3/8 should be fine. If you can make it work, having a fourth bolt isn't a bad idea.

The problem with a self tapping bolt is it relies on the material it's threaded into, and there isn't all that much material on the engine crossmember. Maybe 1/8" at best. A good shock load from a hard shift or standing on the throttle too many times runs the risk of pulling the bolts back out of the holes.

When i replaced my motor mounts, I had to snake a wrench all the way up inside the frame to get to the back side, which was a bit easier since I didn't have the springs in, so I could kinda move the control arm out of the way.

Quick note: Pay attention to which way the motor mount sits on the crossmember. those little metal tabs on either side of the bolt sleeve are directional. (They should sit roughly parallel to the ground when the motor mount is on the crossmember.) I put mine on the wrong way the first time and had to flip them.

My '77 used 3/8 grade 8 bolts from the factory, so using a 3/8 should be fine. If you can make it work, having a fourth bolt isn't a bad idea.

The problem with a self tapping bolt is it relies on the material it's threaded into, and there isn't all that much material on the engine crossmember. Maybe 1/8" at best. A good shock load from a hard shift or standing on the throttle too many times runs the risk of pulling the bolts back out of the holes.

When i replaced my motor mounts, I had to snake a wrench all the way up inside the frame to get to the back side, which was a bit easier since I didn't have the springs in, so I could kinda move the control arm out of the way.

Quick note: Pay attention to which way the motor mount sits on the crossmember. those little metal tabs on either side of the bolt sleeve are directional. (They should sit roughly parallel to the ground when the motor mount is on the crossmember.) I put mine on the wrong way the first time and had to flip them.

I just had a discussion with a longtime mechanic.  His suggestion was make a big enough hole on the backside of the front cross-member to reach in.

I will go on the backside and open a 1.25 hole X 1.5 2/each (in line with both mounts) and slotted some vertically.  Then using a 15mm. socket welded on some flat stock, reach in w/bolts and put through the mount.

Also drill open the forth hole and fill it.   Upon completion of tightening the bolts and mounts, weld a plate over each hole.  Good to go.

If an engineer figured how to make it difficult, I can figure how to make it easier.  

We will see how that goes.  When in process, we'll take some pictures.

Seems like a lot of work if the bolt were rusted it be ok
I just used a wrench I talked into reach around a corner
Maybe you can magnetize it and snake the new bolts up
Good luck though

That looks like my special wrench except it is a socket welded on a 1/2' wide piece of flat stock.  With a socket (11/16).  The bolt head was large.

The 11/16" socket was just a little loose.  But worked well.  Never broke off.

I did find the bottom of the lower control arm at the rear was a window to the bolt heads.

I actually welded very lightly a piece of 14ga. soft wire to the head.  Then proceeded to snake them through from the front.

The same hole the fuel line goes through is on the left as well.   So lightly tack the wire on the bolt.  slip through and up in the hole.

Set the mount on then screw the nut as tight as you can get.  Using my impact wrench hit the nut, it breaks the wire off.  On to the next.

Then when all are in, down we go and tighten the bolt/nut w/special wrench.  About 2 hours with a half hour break.  85 degrees and humidity the equal.

A little tough on a 70 year old.  But enjoyed the finish trip.  Its mine!


PS:  Cutting the bolts off was a lot easier than trying to save some rusty bolts.  I replaced them anyway.

What was nice was the flat stock was easy to bend it for additional clearance when snaking the socket up in.

A good feeling to have them in.

Now with the engine out, clean it up.

Spray some gloss black paint around to clean up the area.

Install gauges pre-installing the engine and transmission.

Measure the driveshaft length to get my driveshaft cut and balanced.

Lots to do.