Shifter doesn't center

[Destructo]

My shifter will not center left to right unless I give it a little help. I figured it was weak centering springs, so I pulled the shifter to have a look. Turns out I have a B&M shifter that I didn't know about.
I called B&M support to see if I could get stronger springs and they have no interest in helping me. The shifter centers itself when out of the car, and the centering springs don't seem weak.
How difficult should it be to rotate the shift rod by hand? With the transmission in neutral, I cannot move it with just my fingers. Is this normal?

 

[Destructo]

Forgot to mention it is a 2000 GTS. No mods (that I know of).

 

[AZTVR]

I didn't have the problem you are having; but, I wanted my B&M shifter to have more centering force left-to-right than it had out of the box. I removed the spring that controlled this movement, and went to Ace Hardware and found a similar diameter spring that appeared like it might be stiffer. I cut it a little longer than the spring that I removed and installed it. The result was like I wanted it to be. (I am not sure that cutting the spring longer helped at all. Spring length should have no effect on spring rate I think; but, I was experimenting.)

 

[Bobpantax]

Check your transmission and engine mounts to make sure that the real problem isn't your tranny being slightly off center. The mounts can go bad over time and there are past threads on this in the context of Gen IIs.

 

[Dom426h]

How difficult should it be to rotate the shift rod by hand? With the transmission in neutral, I cannot move it with just my fingers. Is this normal?

On my 97 (which has a slightly different T56) I am able to rotate and pull the shaft in/out by hand.
Click to the left(1/2 gate),
Click right to the center(3/4) gate,
click right to the 5/6 gate.
Not real easy, but considering you can only get two fingers on it that could make it hard for some people to apply enough twisting torque.

I don't see how the motor/trans mounts would effect the self centering action like Bob suggested. The shifter is bolted to the trans, is bolted to the motor. Everything that moves is fixed... Unless everything is shifted far enough either way for the upper boot(mounted independently to the tunnel) to be restricting the movement.
Speaking of which... Did you drill out your rivets to get to the shifter or drop from below? and in what condition is the thick rubber upper boot?
Mine was cracked so I replaced it, then a year or two later she cracked again, so I now just annoyingly deal with it letting heat come through to the leather boot and my hand.

 

[Destructo]

I ended up replacing the springs with a set from the hardware store. I had to use two sets of springs (one inside the other) to provide enough centering force, and it's just barely enough. My transmission is very notchy and I could not rotate the shift rail with just my fingers. The original springs measured at 1/2" diameter by 3/4" long and 0.075" wire. I used dual springs with 0.080" wire and cut to length.

The original installer drilled out the rivets, so I went in from the top. There is just barely enough room to get it in and out. Getting it back in was much harder than getting it out. You can't see if the ball is in the socket, so it often feels like it's in the right place but it won't drop down.

My rubber boot has a crack about an inch long in a valley behind the shifter. I covered the crack with black RTV on both sides to get it back together tonight so we'll see how long that lasts. The bottom side of the boot is looking a bit heat checked.

I now have a B&M shifter with an IPSCO 2" lowering adapter, a stock knob and it self-centers. It is just about perfect for me. I could do with moving the knob about 2" forward as shifting to 2nd, 4th, & 6th feel like my arm is too far back.