[plain OM]

Just back from a long (winter) trip and was changing the oil and inspecting underneath when I noticed the space between the transmission mount lower bushing and the support. Is this normal? I seem to recall there was a thread here some time back with similar photos, but I don't recall if the gap was found to be normal. Funny I never noticed this before (having been under there many times for oil and ATF changes) but can't say it wasn't like this all the time.

The shaft is clearly not threaded higher up, and I doubt the bolt has backed off, so either the upper support bushing has compressed downward, or the shaft has backed out (down), but that gap seems a long way.

 

[cardoc]

Yes, its normal. That center bolt is a safety bolt. Should the mount break, that bolt and bushing keeps the transmission from hopping around. The two flush bolts go into the lower portion of the mount, while that center one goes through to the upper portion.

 

[plain OM]

Ah, yes, that makes sense.

I was looking at this diagram

but just didn't take into account the "should the mount break" scenario. Now that you mention it, it's actually quite clear. The gaps between that lower bushing and the bottom of the crossmember and between the shaft and the opening in the crossmember allow the tranny to move slightly in all directions to the limit of the rubber filling between the mount upper and lower steel plates. But if the rubber were to tear, the shaft going to the upper steel plate would still limit overall movement. I would imagine that if the rubber were torn through, the shaft and/or bushing could make a noticeable clunk or clang as they hit the crossmember, signalling that the mount is broken. Interesting . . .

Thanks.

 

[plain OM]

Update note: There's a more recent discussion about the gap. See https://www.subaruoutback.org/forums/110-gen-2-2000-2004/508787-transmission-mount-h6-2003-a.html). When a new transmission mount is installed, there should be virtually no gap. The gap in the photo above was after 7 years of service, and some lowering over time is possible due to compression of the rubber blocks in the transmission mount.