MR2 Swap Question

We swapped in a 1 mz-fe in our MR2 using the stock S54 trans, the one we blew up the engine on at the challenge. We are replacing the engine and thought while it is coming out we could address a couple of issues. We have a vibration at low speeds coming from the passenger sides rear that I think is the axle. The axle has a bit of play in and out when not under load . There is a rubber donut that looks like a damper of some sort but it does not have a mount or housing of any kind. 

The car came as a parts car so this was not something we took apart so I do not know what it is supposed to look like stock. I was told there is not any mount for it but that does not make much sense. Anyone else with this issue or have any ideas? I know the e153 has a bearing in about the same location but we are not up to switching transmissions at this time.

Yes the oil pan is off, there was about 1/2 cup of ground up aluminum in the pan, my guess is parts of a piston that got broken up by a valve hitting it. We will know more when the motor come out in a couple of weeks.

That's correct, for the S54 transmission there is no carrier bearing on the longer passenger side axle.  When using a 1MZ with an E153 in an MR2, you SHOULD have some machining done and add a ~10mm spacer to make it fit correctly. 

All that to say, there are some minor geometry changes introduced with the 1MZ swap and you're pumping a lot more torque through the unsupported passenger axle when using a 1MZ and an S54.  

I'd take the axle out and take a hard look at that wheel bearing, or at least retorque the axle nut and see if it moves.  Start with the simple stuff, then work up from there.  

Is the vibration only under acceleration at low speeds?

CV axles tend to put slight wear in their outer cages. If you change the 'plunge depth' of the inner CV joint a smallish amount, the angle of the dangle (I actually don't know what to call it, the tripod thing with the rollers) will cause the rollers to go in and out of this low spot, and under torque will create a lateral push/pull force as they go across that 'ramp' that you feel as a weird side-to-side vibration only under acceleration and really only at low speeds (only in low gear will most cars have enough torque on the axle to make the side to side force noticeably intense and low enough frequency that its direction is discernible). If the axle isn't overextended, just replacing the axle with one that has no worn areas inside it would fix the problem. 

Thanks, I'll check all of these when we take the motor out a week from Sunday. We are compiling a list of things to go through when the engine comes out. 

The rubber donut is just what it appears to be. It is a kind of harmonic damper, and not very important. Vigo and Tyler have probably correctly isolated the source of the vibration.