We know the large driver side diff mount tends to fail. Question is why? My theory is that because of the engine rotation (clockwise from the back) all the drive line stress goes to the passenger side small mount and the driver side mount.

Another hypothesis is that if either small or big mount goes it shortens the life of the other one. So if you have a bad small diff mount it accelerates wear of the big one.

I could be wrong, in my experience the passenger side small mount usually fails along with the driver side big mount.

 

this is how my mounts failed.

your theory sounds fine.

 

Install hard rubber bushings(no fluid inside) from Spoon/similar brands or M&M Honda Racing differential damper kit to extend the life of your OEM mounts. I have both of these products in-stock too.

 

Put something like this on and they will limit the movement of the stock diff mounts.
https://www.ebay.com/i/233195431372?...QaAjiUEALw_wcB

If you mostly track your S then go with solid mounts but if your mostly on the street these work very well.

Rod

 

Any pics as to which mount goes bad and what it looks like?

The CV joints tend to wear more on the DS as well so the DS seems to be "flexing" more. My guess is it has to do with the asymmetrical setup of the rear diff.

The rear diff is slightly offset to the DS and the DS axle is shorter. For any movement in the suspension the angles at the diff are larger on the DS than the PS. This translates to a larger vertical force component, and thus torque, on the DS mount as compared to the PS mount. Momentum on the DS would also generally be higher than on the PS as well. The horizontal forces should more or less cancel each other out so any torque from horizontal movement should be minimal when compared to the vertical.

That's my theory for now. Anybody want to do the FBD and math?

 

The tires also tend to slightly wear more on the driver side than passenger side, perhaps the diff has a bias on that side?

 

What is the easiest way to tell if the small diff mounts fail? I had to replace the fluid filled driver's side mount last summer and inspected the others at that time. But based on my experience sometimes looking at a mount does not really tell the whole story.

 

Look closely worn mount will have split the rubber somewhere. Easier to see where they fail when looking from behind the car.

When they are really bad they will transmit resonance from the drive train into the cabin.

They're cheap and easy to change.

 

thoughts on stiffer diff mounts causing more wear on oem engine mounts?

 

I would recommend doing a Spoon engine/transmission mount upgrade(I have these in-stock).

I have Spoon Engine/Transmission/Differential mounts, ASM transmission brace, NRG ETD/Puddy mod mount and M&M Honda Racing differential damper. This is a pending test setup.