ENGINE MOUNT: Removing Rubber from OEM Mount W/O a Torch

[Rich Norman]

How can I remove the rubber insulator in the OEM-type engine mount without resorting to burning with a torch ?
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Showing another method.

This should work also on the front transaxle mount.

[aithanmier]

ok so anyone figured out a part number for a poly bushing to fit in the gutted mount?

[Rich Norman]

ok so anyone figured out a part number for a poly bushing to fit in the gutted mount?

Normally I would just use a castable polyurethane ( compression mold or open cast ) to impart greater control of the properties of the cured product.

But you also can turn polyurethane rod on a lathe.

Off-the-shelf, closest thing might be found from semi-truck parts catalogs ( some vendors supply large O.D. poly bushings for cab mounts, etc ). Good luck finding the right size. You probably would still need to turn it down, which makes fabricating one from scratch just as attractive.

[aithanmier]

thats what i figured. any ideas on securing it in the mount after you turn the bushing? i would say an oversize metal washer style plate on either side of it, but youy would have to bolt that together to keep it in place i'm guessing...

[Rich Norman]

thats what i figured. any ideas on securing it in the mount after you turn the bushing? i would say an oversize metal washer style plate on either side of it, but youy would have to bolt that together to keep it in place i'm guessing...

Lathe-cut bushing : Choose a low-lubricity PU compound for starters to reduce unwanted movement ( and possible performance issues with adhesives ).

Try to get the finished diameter of the bushing to provide an interference fit ( measuring at 75% of the expected service temp of the mount should get you close to ballpark ). The less slop, the better. If there is difficulty in maintaining dimensions ( creep ), then go for a slightly higher durometer ( at least 90-95 A ) than you normally would for injection molded or castable methods.

Washer stacks or spacer added to the sides ( center hole ID sized to OD of bolt sleeve ) will prevent axial movement of the PU bushing. It will also transmit more vibration to the body. It does not stop axial movement of the mount's metal ring, unless a " lip " is added to the outer diameter of the bushing that matches the OD of the metal ring.

The lip contains the movement of the ring. But unless you use a split bushing, this will be in one direction only ( since you cannot insert the bushing through the ring with a raised edge on both sides ). Ideally, the edge should have a gradual sloping transition towards the center for strength.

Alternately, you can use a compatible primer /adhesion promoter / adhesive system to bond the PU to the metal ring. Makes the lip unnecessary.

With the bond to the ring fixed, the only other source of axial movement will be on the bolt sleeve. If you don't use washers, then try bonding to or knurling the OD of the sleeve.

Castable/Injection Molded :

Washers and lips are unnecessary, since a compatible primer on the ring and a knurled sleeve should suffice to keep the bushing in place. But if you think that isn't enough, you can always space out some tack weld beads at the edge on both sides of the ring before the part is cast or molded. These will limit the bushing from shifting sideways once the PU cures.

The nice thing about casting / injection is that you can mold in strengthening ribs. The downside is shrinkage ( hard to predict due to many variables ).