Hard Shifting into Reverse

[sdyck]

I have a new issue;  4 speed MT, It has become difficult to shift into reverse, feels really stiff.

 

I did a search but didn't find anything that was consistent with my problem.

 

The problem doesn't get bettter as the car warms up.  It does't grind just really stiff, no problem with any other gear.

 

I recently changed the transmission fluid to Redline MT90 as there seemed to be many recommendations for this oil for the early Datsun 4 speed tranny. I don't know what the PO had been using, could this switch be causing the issue?

 

Thanks,

 

Steve

[Kurbycar32]

I had this problem when replacing the clutch recently.  My issue was that the clutch wasn't fully engaging with a pedal push and the problem was resolved by bleeding the hydraulic system and adjusting the pedal.  I also drove a diesel truck with wasted synchros that would do this, pushing the clutch in and out twice made it shift normally.

[Pop's Z]

Steve, I had this same problem when I first got my Zed. The solution was to readjust the clutch pedal height to factory specs. When I did that the problem went away and hasn't come back in 5 years. Now if the bearing that the pivot pin goes through is wallowed out that won't work, and will require a more complex solution. This subject has been covered on this site before. Search is your friend.

 

Cheers, Mike

[sdyck]

isnt it weird that clutch pedal height would only impact the reverse gear? I'll do a search and give it a try.

Thanks

[EuroDat]

I would check the clutch pedal adjustments and the series I slave cylinder adjustment (If you have the Series I version) first and then bleed the clutch. 

New oil can cause this, but its mostly an accumulation of things and the new oil is a new factor. Your synchos are probably in good condition, mostly 2nd and reverse are the first ones to show these problems.

 

Is the lever hard to move or does it seem to hit a stop and not go into reverse? If its the later, then its probably hitting the reverse gear and the gear is sitting dead still. A new reverse gear is pointed to allow easy selection, but with old transmissions these pointed sections wear down and exaggerate the problem. You can test this by someone rocking the car back and forth while you select reverse or engaging and disengaging the clucth and then select reverse. The new oil is thicker than the old oil and the gears are stopping quicker.

 

You should read this thread. The GM oil might be an option for your problem. I have never used it, its not available over here so Im only going by the experiences of other members.

http://www.classiczcars.com/topic/51698-how-should-a-71-240-4-speed-feel/

[bartsscooterservice]

And if you press the clutch pedal a few times, does it go easier in reverse then ? Could be your not depressing the clutch enough. Or else the synchro..

[sdyck]

Thanks for the responses.

It's just difficult, but I can push the shifter into reverse. After that I can shift through all the gears and it's easy to get into the reverse position.

I'm. Away from home on business but will try the suggestions and see the results.

Steve

[rossiz]

not sure why, but it seems that getting into reverse is affected most by clutch drag - happened to me after a rebuild and new clutch. just a few turns of the adjuster nut at the pedal and problem solved. as others stated, however, if the problem has appeared over time you may have issues elsewhere in the hydraulics (master, slave or air in the lines) which aren't giving you full range of motion at the fork.  a good flush/bleed and rod adjustment first (low $$) then if it persists, master and slave (also pretty cheap) and check the lines - especially the rubber one from the frame to the slave down at the bottom of the tranny - they get old and cracked.

[Captain Obvious]

Forgive me, but I'm not sure I can see how this could be a clutch issue. Because reverse is non-synchronized, clutch drag would manifest itself as a grind when trying to put the car into reverse (because the gear teeth would collide until the collisions were severe enough to stop the clutch disk from spinning).

 

But since there's no grind, why is the clutch adjustment theory so prevalent?

 

I'd be more suspicious of a linkage issue with one of the shift rods or maybe something to do with the interlock detent balls?

[rossiz]

perhaps i didn't read the op carefully enough - i thought he was talking about difficulty with a grind, which is exactly what mine did.

[Zed Head]

The one "trick" that always works but can be embarrassing if not done just right, is to put pressure on the lever while slowly letting the clutch pedal up,  The gear will eventually move just enough to let the gears mesh.  But, if the clutch grabs too quickly, you get a grind or a ka-chunk.

 

It's odd that the problem came up with the oil change but maybe the Redline lets the non-synchro reverse gears gears snag each other, rather than sliding past to mesh.  Maybe an unintended consequence of better synchro perfromance.  Reverse is just jamming two gears together.

[beermanpete]

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.