Downshifting to 2nd

[SER240Z]

I've checked the search but could not find anything on my problem. The car seems to shift fine going up, but when I try to shift into 2nd, it won't go in without grinding. Any suggestions on what's wrong and how to fix it?

Thanks
Scott

[DatsunBucky]

I assume the problem is when downshifting from third to second gear? All upshifts are OK?

So, based on that assumption, it sounds like the 2nd gear sync ring. Are you double clutching? Heel and toeing? Or just shifting normally? For any uninitiated out there, the first two are methods of matching the engine revs to what they would be if you were already in that gear.

When you shift up, the revs naturally fall unless you keep your foot on the gas, but when downshifting, the engine needs to speed up to match. When I was autocrossing regularly, I was replacing that synchronizer ring about once a year or so. I didn't particularly like the "crunch", but didn't want to take time for a leisurely shift, either.

I never had a problem with having to replace the 2nd gear itself, so the crunch was more annoying than anything else. The only other thing I ever replaced in the transmission was the split pin that holds the 1st/2nd gear shift fingers on the shaft. I knew what it was, but the dealers quoted me from $150-$400 to fix it. Over the parts counter, the pin cost me 12 cents, and took part of a Saturday to replace.

I did all my transmission work myself, and I didn't have access to any sophisticated tools, either. I just laid the parts out on newspaper as they came out, and used that and a service manual to help me put everything back together. Same idea with the carbs the first time. If you're even moderately mechanically inclined, you can do it. Just take your time, and pictures, if you can.

Hope this helps, if even a little.

[SLOroadster]

My advice, check the fluid level, and then get really good at double clutching the shift. Tranny parts are getting very pricy and hard to find. I have a very tired 5 spd that I D.C. up and down (because it grinds from 1 to 2, and from 3 to 2). I would rather replace a clutch disk every 2 years than

Just my $.02

Will

[oilleak]

Agreed, learn to double clutch downshifts. The synchros will live longer which is a good thing especially on a servo box. My car has a Borg Warner in it now and the only time I've gotten grinding in second was due to a failing clutch master cylinder. But that was on up shifts. You've probably got a worn out synchro ring.

[SER240Z]

Thanks for the responses. I've tried double clutching when I down-shift, but it ditn't seem to help. I'll try again and see, maybe I just messed up.

Oh, it's when I down shift normal. Although I've tried to match rev's and that didn't seem to help either. Unless I messed that one up too.

Upshifting seems to be ok though. At least I got one.

Thanks
Scott

[SLOroadster]

Roadster gear boxs can be a pain to double clutch. I still can't heal and toe the shift, but I have the double down shift pretty clean. Sometimes I have to rev the engine pretty high to get it to go willingly. Usually a rev to about 4500 will do the trick. Sometimes I just don't get it reved high enough, but usually it only happens when it is cold. I think it is a syncro issue.

Will