I know its prob a syncro, but downshifting into second sucks, you have to wait till you could damn near downshift into 1st before it will go into second. upshifting isn't near that bad and shifts almost clean yet i wont rip it in to second for fear of grinding someting. has this ever been a prob for anyone or does anyone have anysuggestions for fluids that might help ease my prob. great for daily driving, not so much for autocrossing.

 

Worn 2nd gear synchro is a very common problem. Learning how to double clutch will help. So will changing to a premium gear oil, or as some have suggested. 1/2 gear oil, 1/2 ATF.

 

I didn't think we had synchros.

 

What did you think we had, hamsters?

 

you got a gerbil in your tailpipe

 

lmao!

Yeah, you can try a mix of ATF/Gear Oil. Works wonders for certain issues, and worth a shot before you replace or rebuild your tranny....

 

I would suggest 1/4 ATF 3/4 oil. If you have worn bearings you want to make sure they are coated well.

 

does lucas make a additive for gear oil? cause i know i've heard great things about their ATF additive.

 

The ATF provides plenty of lubrication, but adds **** loads of detergents which will clean all the gunk out of your synchros. This information comes from the book How to hodtrod and race your Datsun, and was used by one of the two main teams (may have been Bre, not sure). They recommended it, I tried it in many vehicles, satisfied with the results.

If the car is new to me, and has substantial miles on it, I'll usually do this and then drain it after 1k miles or so. Stuff looks pretty nasty coming out. Then I refill with the same mixture and forget about it. Faster shifting and no grinding. Can't beat that.

Which is not to say that it will fix your problem. But if your problem is sticky synchros (good chance of that) then it would be worth a shot before looking for a replacement. A few members have gotten back with me to let me know that it worked for them as well. Hope this helps...

 

Yeah, my GSL has a worn syncro too. I just double-clutch whenever I downshift and its fine.

I'll hopefully be changing the fluid in it soon, I'll be sure to try a bit of ATF in it.

Any suggestion as to what kind of ATF to use?

 

If I remember right, the book was from the early 80s. And the Datsun race teams were most likely 70s to early 80s. I would assume you'd be looking for whatever you would put in a 1980 Impala (to pick a car at random), rather than anything designed for the new cars.

I use the one that says dextron 1 or 2 or something like that. I never remember what it is until I see it sitting on the shelf. Might be a jug of it out in the garage if I had an hour or two to search for it, but it's like 2 degrees out and I'm feeling a bit lazy.

 

Try changing to fully synthetic gear oil, 75w 90, e. g. Valvoline Synpower.
That should improve gearchanges no end, but if it fails to improve things then, as said above, double declutching will put off the day when the box has to be rebuilt.