The M20 in my car has some issues. When I first got the car together, it shifted nice under normal and somewhat aggressive driving. Once I got everything broke in and made some WOT blasts, I began to notice that under very heavy throttle, I sometimes couldnt upshift into 2nd gear. It kinda felt like the gear wasnt there. No grinding. It just wouldnt go in. After some fiddling I could get it in. 4 th gear would do the same at times. Under lighter throttle it shifted ok. I had the car out yesterday, and now, its grinding into 3rd and 4th gear even under light throttle. The clutch is adjusted good. About an inch of freeplay in the pedal. I took the shift stops out to try that. I put good GL-4 oil in it when I put it together. I have no idea how many miles are on this tranny, and im sure im putting some decent power to it. So im pretty sure it needs to come out for a rebuild, which sucks, But im curious if anyone has any ideas that I havent though of yet before I look for a rebuilder.
Clutch is still engaged. Could be: Bellhousing out of alignment Clutch disc bent Broken spring on the pressure plate Does it happen all the time or only when the car is warm?
Yes, try a little less free play. Are you using a diaphragm clutch? This happens under load, if I read this correctly, or does it happen more at high RPMs?
Ok, ill take some free play out. I wanted to mention that it goes into gear easy with the engine running. Doesnt fight me to go into 1st at a stop light. Clutch is a new Centerforce dual friction. It does it all the time regardless of temp. It started fighting me going into 2nd and 4th under heavy throttle. Now it grinds into 3rd and 4th. May do it slightly into 2nd also. Doesnt feel bad downshifting though. But I also double clutch when I downshift. It will shift pretty good if I double clutch upshift, which led me to thinking synchros.
Don't rule out the shifter as the culprit. Although 2-3 gear shifts usually are more indicative of a shifter. Also, if you have slightly above basic mechanical skills and access to a press, you can rebuild a manual trans easier than you think.
What type of fluid are you running? My new Autogear supercase was giving me all sorts of trouble, I switched to the recommended GL-4 only spec fluid in it and it was a whole new tranny. I had GL-5 and GL-4 compliant stuff, I bought the recommended stuff from napa and it fixed all my problems..
might want to recheck that the 4 transmission bolts are tight. if coming loose it might be allowing a bind on the pilot bushing under high load.
The clutch adjustment sounds about right and since it goes into 1st easily I think your clutch is probably OK(any chatter or engagement near the floor on take off?).If these seem normal,it may be a case of the wrong gear lube.They originaly ran an 80-90-140 multi vis.Now a 90-140 is about all you can get.Try a lube change and check for metal traces or shavings in the old fluid.you may find some chunks or just metallic color.if it's gold you may have syncro problems.One other distant possibility I have seen,the 1st gear may have semi-welded itself to the mainshaft,if the box had been run with low gear lube levels.This condition will cause a "in box" friction that won't allow the syncros to slow the clutch speed down for engagement.What usually occurs when they do gaul,the main shaft and 1st locks up solid and grenades the box.This would explain why it goes into first easily but not the other gears.another test of this would be to put it in 2nd or 3rd before first and feel the drag going into those gears at rest.You may have a close weld up.just a thought.Bill
Ok I took some free play out. Didnt help any. I run Brad Penn 80-90 classic GL-4 lube, which is supposed to be great for these. Tranny bolts are good and tight. It goes in 1st and 2nd real easy when stopped and running. A very slight grind going into 3rd and 4th when stopped and running. If you hesitate a moment it will go in without grinding. You can feel the tranny stop when you push the clutch in. Clutch starts to grab about 3-4 inches off the floor. No clutch chatter. It seems like it has to be the tranny. From what I can tell the clutch is working as it should.
Brandon,Based on what you've checked,I'd get it into the hands of a experienced tranny guy.They know all the little nuances of 4 gears.I went to the offered link and it looks like this guy has his ducks in a row.He's in your neck of the woods and he looks like a good choice.Check your pilot bearing if you pull the tranny.It's possible that could be part of the problem.If you have it out check everything,that way you only need to do it once.good luck,Bill
Thanks for everyone's responses and insight. I pulled the tranny today, and my suspicions were confirmed. Very gold glittery oil, and some nice metal chunks on the bottom. I did some calling around, and found a guy 2 hours from me, who has a redone M20 for sale. Talked to him for quite some time, and he sounds very knowledgeable. Should have a rebuilt one in my hands later this week.
Got the new M20 installed, and installed a new Hurst Super shifter. Had to cut out about half the floor to make it work, but it does shift nice and feels much tighter than the old Competition plus. Everything feels pretty good. Time will tell.
