WRX hates Reverse

[Mark Santa Ana]

Yup. There is no sychro in reverse (its why the car has to be fully stopped
before you put in reverse, or the thing will grind like hell). They also
put a protection mechanism in it, so you can't accidently grab reverse when
you are downshifting. The Kartboy bushings might exacerbate the problem,
but it is already there anyway, and you are doing what you need too; find
another gear and pump the clutch a bit and you'll be good to go.

This isn't true of the USDM tranny. I'm looking at the diagram in the
service manual right now, in the exploded view there is clearly a
reverse synchro. Page MT-9, part number 28; "Synchro cone (Rev)"
Obviously not a good synchro, but one none the less.

 

[Mark Santa Ana]

It has something to do with reverse being a non-synchromeshed gear. If you
try to engage reverse when the gear teeth aren't alight to mesh together,
the outer edges of the teeth will hit each other and prevent reverse from
engaging. When you select a synchromeshed gear (like all the forward
gears), the synchromesh mechanism will rotate the transmission's lay shaft
just enough to permit the gears to mesh rather than bounce off one another.
Bumping the clutch serves exactly the same purpose: It rotates the lay
shaft, though using this method is more random than selecting a forward
gear -- the lay shaft might still wind up misaligned and prevent engagement
of reverse.

It's perfectly normal -- and it sounds like my own tranny is far more
difficult than either of yours, since mine often refuses to engage reverse
even after first selecting a forward gear. I often find myself in the
driveway going "reverse? Nope. First -- reverse? Nope. Fourth --
reverse? Nope. Bump clutch -- reverse? Nope. Hell with it! Bump clutch
while pulling back into reverse -- <grind> There it is!!

Just to reiterate: In the exploded view of the tranny in the factory
service manual there is clearly a reverse synchro. Page MT-9, part
number 28; "Synchro cone (Rev)" Obviously not a good synchro, but one
none the less.

Even with synthetic, i find myself having to row through the gears to
line up the dog teeth. This is no different than any other MT car I've
owned though foreign or domestic.