No Reverse

[Yellow Rose]

95 NSX with 5 spd - what is the most logical reason for the transmission to not shift into reverse? Additionally, although all of the forward gears can be shifted into, it takes a little more effort to push on the stick. Yes, the clutch is in all the way. This started with no pre-existing symptoms.

 

[nsx4fun]

I haven't disassembled a NSX tranny, so i don't know enough to give any hardcore definitive answers. Most newer trannies have a reverse lockout so you can't accidently shift from 5th to reverse when down shifting. They typically require that either the car be stopped or that you go from 1st gear to reverse. If something breaks in the release for the lockout, this will cause reverse to be locked out. Maybe this broken piece has now wedged itself somewhere in the linkage making all shifting more stiff. This is all speculation on my part, but I think it is a pretty good guess. Can anyone with a more intimate knowledge of our trannies confrim or deny my explanation?

Fritz

 

[sjs]

Assuming you mean with the engine running, then most likely the clutch is not fully disengaged. It's either the clutch, the master, or the slave. Shift cables/linkage is a possibility but far less likely. I'd bet (hope) against the tranny itself.

 

[Lud]

I agree w/ sjs the first place to start troubleshooting is the clutch. Let us know what you end up finding!

 

[Yellow Rose]

As it turns out, the culprit is a piece of metal from the disc assembly that let go and jammed itself into the pressure plate, negating the ability to fully release. The unit is an aftermarket refurbished clutch, so there is no telling how many "original" miles there are on the unit in the first place. In my car, I got 34k supercharged miles (with many track events) out of the unit before its retirement.

Observation #1 - approximately half of the lining was gone, so one can surmise that *about* about another 34k miles remained on the lining.

Observation #2 - there were absolutely *zero* blue spots on the pressure plate, middle disc, flywheel. There were no grooves, no scores, no waves on these surfaces.

Observation #3 - the OEM discs have 360° of lining. These aftermarket discs have "segmented" lining. Therefore, even if the friction factor is higher, the net-net clamping force appears to be on the same order of magnitude as OEM discs.