1992 engine mount rubber bushing, off centered.

[Pat Conlon]

Hey folks, I hope this post finds everyone healthy...

My buddy Carson City Paul is working on a rebuild on his 1992 FJ. When he took the engine out he noticed what appears to be collapsed rubber bushings on the engine mounts.
As we know the 1991-1995 Gen 4 FJ's have a special (and effective) rubber engine mounting design.
Here is a picture of the front mount. If you enlarge the picture, notice the off centered steel sleeve bushing in the middle?
It appears one side of the rubber mount is compressed.
Both right and left front bushings show the same off centered middle bushing.



Do we need to address this offset? Do new rubber bushings correctly center the middle sleeve, or do new bushings have the same offset as what the picture shows?

Paul is a machinist so if we can identify the durometer of the rubber Yamaha used in these mounts, Paul can fabricate new rubber mounts.
Question is, do we really need to?


Thanks folks, stay safe and healthy......wear your masks, yada, yada, yada....

Cheers. Pat

[FJmonkey]

Pat, my experience with working on vehicle suspension parts tells me that the rubber has taken a set in the direction of the greater force. A polyurethane would be a better material and is the common (modern) material in these kind of applications for the same reason. The isolator is still doing its job as long as it is not degrading or rotting out. As far as replacing it goes, the durometer can be guessed or approximated.



Or for a few $ get one of these

[Pat Conlon]

Thanks Mark. Yes, I am thinking along the same lines on the bushing compression.
Having a Miata I know about the advantages and disadvantages of polyurethane bushings. We use them on our sway bar mounts and upper and lower A arm mounts.
Advantage: They are harder than rubber and don't deflect.
Disadvantage: They are harder than rubber thus bad for NVH on street cars.
That said, I'm not sure polyu would be my first choice for the FJ engine mounts.
Although....perhaps a polyu mount drilled with 6 or 8 holes around the perimeter would work.

Easier to just get a block of the right rubber and mill it into shape.

Cheers

[edit] NVH = Noise, Vibration and Harshness