2nd gear shifter wobble/shake

[Jmoyet]

So as the title says is pretty much my problem. 

Now getting into more detail explaining the problem. Under acceleration it shift perfectly normal and accelerates fine but, under acceleration in 2nd gear the shifter itself wobbles up and down under acceleration, all other gears do it very minimal more so vibrates for the rest of the gears but 2nd gear you see it move up and down. 

Is this normal? Is this a sign of problems to come? 

[psdenno]

Is it normal?  No.  Sign of problems to come?  Don't know.  Have you checked the bushings at the base of the shifter lever?  Worn bushings cause a,rattle and a loose feeling shifter.

Dennis

[siteunseen]

You may want to look at the rubber in the transmission mount.  I found one of mine had no rubber left but it wasn't just the shifter wobbling, the transmission was bumping up and down against the crossmember.

But your's probably is what Dennis says.  Here's something to read, http://atlanticz.ca/zclub/techtips/shifterbushing/index.html

Not mine but close. 

A new one,

[EuroDat]

There are lots of things that can cause a chattering gear stick. This is a typical frequency related rattle and can be caused by several things. Frequency and momentum. If you have worked on gas turbines you wil, have heard of critical speed or critical frequency. Google "critical speed", "rotordynamics" or "Rayleigh and Ritz theory" and read all about it.

Certain speeds in second are ceating a critical speed for the transmission and selector components. Worn selector bushings are a common cause of noise in such a situation. Check if someone changed the gear selector knob for a heavier version. That can change the dynamics of it all and generate noise. Try removing the gear knob and take it for a test drive. Siteunseens transmission mount is another good one. A sagging transmission mount may look good, but because it has saged so much the metal pieces in the mount contact at certain frequencies.

Check the selector for excessive movement and the transmission mount. Check wwwatlanticz.ca in the replacing diff mount tech tips for an examlle of a bad mount. Its a diff mount, but gives you an idea of the problem.

 

[Jmoyet]

First thing I did when I bought the car was replace the diff and trans mount. Did it before and after installing new mounts. No noises no "ill" effects from it that I've noticed. Just unusual to see a shifter moving up and down while still in gear during acceleration. New mounts iv checked the shifter mounts its the series 1 style before it got changed. I also forgot to mention it is a 1/71 Series 1. My trans mount bracket does not have that leaf spring looking piece on it nor looks anything like that but the mount itself looks the same. Funny cuz the one every auto parts shows has 4 bolts coming out of it had to buy mine from zcardepot.

 

*Edit* I also bought those hinge bushings awhile back, took the center console all apart only to find that the shifter mount is completely different.

Edited May 5, 2016 by Jmoyet
adding on.

[Jmoyet]

Mine looks like the one closest to the camera. 

[psdenno]

When the car isn't running, how loose does the shift lever feel when you wiggle it around without changing gears?  The Nissan plastic shift lever bushings are still available and inexpensive.  There are three to change - the two on the pivot point and one at the base of the shift lever.

Dennis

 

 

Dennis

[Zed Head]

He has the "monkey motion" shifter.  Seems like the assumption is that the tail of the transmission is moving up and down.  Would be good to confirm that that's the case.  On old 240Z's I'd guess that the crossmember mounting points get rusted out sometimes.  You might have good parts bolted to a flexy body.

Might check the motor mounts also.  The trans mount is only meant to handle so much.

[Jmoyet]

Engine mounts are good. I've inspected them in the past. This 240z barely has any surface rust. I've bolted everything down good when I installed new mounts and last week tried moving the transmission up and down where the driveshaft connects and no movement. So mounts are definitely good. I'm thinking it might be something internal. Only does it at 2nd and no other gear at any RPM.

Mine does not have that plastic bushing at the base like other shifters it has an open end somewhat like a bracket at the base where a pin goes and has a metal pin going through it with a C clip connecting it to the rod that goes into the transmission. Iv tried finding a pic of it but this is the only one i could find. And at the middle pin there is 0 play at all. And besides that middle one wouldn't be the case since it moves up and down not side to side or at random directions.

[Jmoyet]

Here we go. This is what the part looks like without the shifter knob rod bolted to it. 

number 328-66 is where pin 328-64 goes through at the open end at the bottom connecting it to the rod that's in the transmission. Like I said very early design on the 240z's

[Jmoyet]

the shifter is pretty solid. almost 0 play up and down just side to side a little due to the early design of the bottom end of the shifter

[Zed Head]

Maybe monkey motion refers to what happens to the shifter in second gear.  Never did understand why they called it that.