Hard Shifting into Reverse

[Captain Obvious]

I've thankfully never needed to open up a Z transmission but I have been inside a couple other manual transmissions in the past and I assume the basic concepts are identical. Point is, I'm no expert and other than pointing out that it sounds more like a linkage or interlock problem than a clutch problem, I'm not the guy who can pinpoint the exact location of the issue.

 

I did in the past work on a transmission where it was hard to get it into a non-synchronized (first) gear and it turned out that the two gears that meshed were both badly damage and the teeth had actually smeared to the point where getting them to mesh was difficult. On that one, there was a also a loud whine when in first gear. I don't think that's what is going on here.

[sdyck]

I'm with the Captain on this, it sounds like a shift mechanism problem, not a clutch problem. How does the shift lever move when the engine is off? As a test, how ever you can, select reverse and then turn off the engine. Without letting the car roll, move the gear selector from reverse to neutral and back. If takes the same forced as when the engine is running then the clutch is not the problem.

 

As for possible causes, there is a reverse lock-out detent that may be partially seized. While it is technically lubricated by the gear oil it is very high up and not force oiled. It may need to be removed for servicing. Anoth thought, a bent shift rod. Since this is a 4-speed reverse does not share its linkage with 5th. It can get damged without affecting the forward gears. Less likely, the reverse idler shaft may be damaged causing high friction and making it difficult to move.

Tested as you suggested and I still have the problem car running or not.  I'm betting its the "reverse lock-out" detent; when I shift it into reverse running or not, with the clutch depressed I can then easily run through all the gears and back into reverse. The resistence has been removed. Wait a minute and its back.  I'm going to have to do some research into how that lock-out works.

 

As I said above the problem started after I changed my gear oil to MT90.  Its been leaking a little, not enough that I belive my tranny oil is low, but I will change it to something different just to be certain.

[sdyck]

This may be a dumb question, but I'll ask it anyway.  Could my issue be the result of overfilling the transmission.  When I refilled it I'm pretty sure it took almost 2 litres/ quarts.  But I was just looking at the FSM and it shows 1.5 litres, or .4 US gallons. 

 

Potential issue?

[beermanpete]

Not to likely overfilling would cause your problem. Two quarts is about right. The service manual amount is an approximation anyhow. Fill it until the oil starts running out from the filler hole. Make sure the car is level while filling or checking the oil.

Edited August 29, 2015 by beermanpete