This M 21 is rebuilt by a reputable local builder but he is out of town for 2 weeks! When I shift from 2ND to 3RD the trannie will not go into gear (just grinding noise like a synk is bad ????) The tranny shifts into reverse just fine, First and Second seems to be fine and Fourth gear is fine. Any suggestions would be appreciated. Thanks Team Camaro.....

Assuming you have the linkage adjusted properly then it has to be internal.. The 3- 4 gear are on the same slider so if the shifter dogs are broke or springs not installed properly u most likely would get 2 gears that have a problem.


Can u get it in gear with it just sitting NOT RUNNINg the car? My guess is probably not but If yes put it in gear and start the car Do u have grinding? Can u move the car?

Since this is a fresh overhaul my thoughts are u have a stuck blocker ring. Typically they come loose but there have been cases where they had to be unstuck with a screw driver or were stuck so bad they broke the ring.

ZL14ME

If your shifter body has the overshift stop bolts, loosen the rear stop bolt one revolution. A too tight shifter stop bolt may also cause this condition.

I am not stating this is your problem but, something to check before you remove the trans. I cannot tell you how many times we have seen this.

If your shifter body has the overshift stop bolts, loosen the rear stop bolt one revolution. A too tight shifter stop bolt may also cause this condition.

I am not stating this is your problem but, something to check before you remove the trans. I cannot tell you how many times we have seen this.

Exactly. I've had to do this to my uncle's 65 Nova. I had problems with it going in 1st and 3rd. I loosed that stop bolt about one turn, and problem solved. Another thing you can do is get the car on a lift, put it in neutral with the park brake on. Get under the car, disconnect the 3-4 shift linkage from the shifter, but leave it hooked up to the trans. Engage 3rd gear from the underside of the car, by give giving the linkage a good tug. I am pretty sure you pull it back for 3rd, and push it forward for forth, maybe Jody can chime in here. Once you are certain it is fully engaged in that gear, have someone get in the car, and put it in the third gear position. Readjust and hook up your linkage as necessary. When I did my 4 speed swap, I had this exact problem your having. Mine would grind like everything when I tried to put it in third. After I adjusted the linkage as stated above, I have been trouble free since then.

Jody made an excellent point on the stops on the shifter, Personally I back them out and leave them just to fill the hole. I've seen more problems caused by these being adjusted wrong when used with a Muncie trans.The internal shifter sizzors do not allow it to be overshifted or cause damage so I believe they are NOT needed period but then maybe that's just me.:(