Hi everyone. I have a EFI 1991 samurai. Here is my problem:

At the start of this winter I had a really hard time shifting into 2nd gear. It was really bad at first. Some mornings I could hardly even get it to shift. After encountering this i decided to replace all of the driveline oil. That seems to have helped it but it isn't completely fixed. Still on cold mornings sometimes it grinds, most other times it just feels like a rough shift. I replaced the oil everywhere except the transmission because of stripped plugs, so I got my mechanic to do that. Afterwards he test drove it and told me that my clutch was on its last legs. Could it be that it is damaged so that it doesnt completely disengage and therefore grinds? Could it be a synchro in the transmission? Im pretty confused because it DEFINITELY shifts better the warmer it is outside.

*as a side note, double clutching seems to lower my odds of having it grind, but does not eliminate the problem.

Thanks for your help

If the clutch oil was real dirty before it could have damaged the synchro in 2nd. That is usuallt the one that goes first. My soft top has no synchro in 2nd. I just skip second most of the time and go straight to 3rd.

If the clutch oil was real dirty before it could have damaged the synchro in 2nd. That is usuallt the one that goes first. My soft top has no synchro in 2nd. I just skip second most of the time and go straight to 3rd.

  Clutch oil What vehicle are we discussing here?

Dirty oil, in and of itself (or for that matter in the clutch or elsewhere), will not damage the transmission synchros, although worn synchros can result in the oil becoming contaminated - as a side note - a clutch, contaminated with oil, will sometimes burn the oil off (heat generated when it slips), leaving a sticky residue that causes the clutch to drag, and that drag can cause grinding and increased wear on the synchros.

It is possible that the grinding is caused by not disengaging completely, it is also possible that it is caused by worn synchros, but, to the best of my knowledge, double clutching done correctly can eliminate the grinding that results from worn synchros, 100% of the time - that it does not always work for you could point to two things - one, the synchros are not the problem, the clutch is, or, two, you need more practice, you're not getting it right.

perhaps you are running too heavy wt. oil.
i have experienced this in the past.
i think 70W-90 is for most temps, but in real cold, perhaps something lighter.
could be worth another oil change before tearing it all out......?

i had the factory recommended 80-90 in my kick and it was a dog in the cold (2 grand cold idle and let the clutch out in nutural and it stalls) had it replaced with 75-85 sythetic GL4!!! fluid and it never had a problem since.

Hi everyone. I have a EFI 1991 samurai. Here is my problem:

At the start of this winter I had a really hard time shifting into 2nd gear. It was really bad at first. Some mornings I could hardly even get it to shift. After encountering this i decided to replace all of the driveline oil. That seems to have helped it but it isn't completely fixed. Still on cold mornings sometimes it grinds, most other times it just feels like a rough shift. I replaced the oil everywhere except the transmission because of stripped plugs, so I got my mechanic to do that. Afterwards he test drove it and told me that my clutch was on its last legs. Could it be that it is damaged so that it doesnt completely disengage and therefore grinds? Could it be a synchro in the transmission? Im pretty confused because it DEFINITELY shifts better the warmer it is outside.

*as a side note, double clutching seems to lower my odds of having it grind, but does not eliminate the problem.

Thanks for your help

Probably the synchro. 
I have a trackick tranny that acts the same way.....hard to shift and usually grinds when shifting into 2nd when cold outside.  But once the tranny oil get warm, it shifts fine.  I put some synthetic oil in the tranny and that made a little easier to shift when cold and it doesn't grind as "hard" as it used to....but it still grinds.  I'll probably rebuild the tranny with new bearings and synchros eventually....but I am living with it for now.
If it was the clutch, it wouldn't matter if it was cold outside or not....my .02.

Skyhiranger, you have just described exactly how it is. The thing that baffles me is how can 10 degrees cause that much distortion in the transmission to affect it that much. I know for a fact how metal changes as it is cooled and heated (I am a machinist), but with that little temperature and that much change......

Oh and also, when I had the transmission oil changed it was switched to Synthetic 75w-90 GL5. If the problem was the clutch, I am thinking that maybe the clutch cable has stretched over time. I might need to adjust it so it pulls a little harder to completely disengage. Or maybe I just have to replace both clutch and transmission and I should just start rebuilding a tranny now...

I think it has to do with the oil and the viscosity of it and how well it lubricates when cold vs. hot/warm, more so than the metal being affected.
You can check the clutch, to make sure it is fully disengaging.  But if it was a clutch adjustment problem, then it would be there all the time, not just when it is cold out.

If it is warm and shifting well, I should say that is at about 30-40km/h or 20-25m/h. If im at 60km/h then put the clutch in and shift (double clutch) it will grind everytime. So the conditions that work best are: warmer weather (10C/50F), double clutching (Shift into neutral, rev then shift into gear...right?), and doing the shift at about 35km/h or 20m/h. I really thought it had something to do with the oil too, thats why I changed it.

It really sounds like your syncro's are going out, as Skyhiranger said.  Changing the oil just helps to disguise the issue.

So what do you guys think I should do?

Your choices are....
live with it.
find a different tranny, or rebuild that one.

A good quality rebuild kit will cost you a little under $150ish off of ebay.  You can rebuild it yourself, if you are good at paying attention to how stuff comes apart and reassembling it correctly.  You can also find an FSM (factory service manual) online that shows exploded views of the tranny, to help you put it back together correctly.  A puller is needed to remove a couple of things off the shafts, so you can do it yourself, if you have a puller that will work, or you can take it to a shop a they should be able to pull them off pretty quickly.  Then just use a length of pipe to tap them back down on the shaft.
Replacement tranny prices vary....anywhere from $50-$200...but the problem with those are you don't know how long it will be until you will need to replace/rebuild that one.

Unfortunately rebuilding my tranny is out of the question. Im sure it would take me a couple of weekends and seeing as it is my DD, I would need it to get around. I could find one and rebuild it myself....or would it really be that much more expensive to just go out and buy a rebuilt? Also what is the best place to find a rebuilt or old tranny to rebuild myself?

PS thank you everyone for helping me with this annoying problem!

I would guess a newly rebuilt tranny would run $500ish at the minimum, to around $1000 max.