Datsun Roadster Forum-311s.org

Help I put new bearings and synchros in a 1969 5 speed and on the bench it shifts fine all gears. In the car it shift into all but 4 th gear. It grinds like crazy and pops out of gear. Took it to a shop and it works fine on the bench and they can't find anything wrong. Any ideas?

I seem to remember that there is a problem selecting some gears if the gear lever bushings are missing or badly worn: the little cup type one that slips onto the end of the gear lever needs to be present.

For avoidance of doubt, aluminum (and Delrin) shifter bushings perform far more precisely and superior to OEM rubber.

Nissanman wrote: ↑Wed Apr 10, 2024 12:39 am I seem to remember that there is a problem selecting some gears if the gear lever bushings are missing or badly worn: the little cup type one that slips onto the end of the gear lever needs to be present.

The little cup on the end of the shifter is on the other Datsun 5-speeds, not the roadsters

It grinds down shifting? Up shifting?
Mild throttle ? hard accel ? Worse in 1st &2nd ? Doesn't kick out of gears?
Usually the speed gear taper gets
Polished/ glazed which is the problem like glazed brake rotors that get wet ( new speed gear taper looks like the surface of a new brake rotor ) what gear oil are you using ? Gm syncromesh used to help its very thin
The syncro blocker can't grab the gear taper to bring it to the speed of the synchro hub
If it shifts normal on the bench turning the imput shaft ,then this is very likely your issue , a way to check is going down the road apply clutch fully ( brain fart , no clutch just try gently down a gear but only to hear the lower gear come up to speed ,then put back in same gear ),if it's like new , in other words you just move the shifter in the gate to say 2nd but never all the way listening for the speed noise ,loud exhaust makes it hard to do

Mike by your comments you have a 69 5 speed box, is it a Warner or servo box? The 69 box can be either, so it is an important piece of information. Also it sounds like something did not go back together the correct way if it shifted properly before the rebuild. Take pictures of the shift forks and the point where the input shaft meets the output shaft.
Dave

Thanks for the help. I will be giving it another try soon.