Just put an M20 back in my SS396 clone. The previous owner took out the 4-speed and went automatic!! I have a Hurst comp plus shifter that feels great and aligns with no problems. My trouble is that I am popping out of 4th gear. Any thoughts? I have backed off the Hurst stop bolts to be sure my throw is complete! I am thinking the trouble is in the side cover. I can hold it in 4th or it will hold itself until I get it (the gas):confused:

Shifter linkage adjustment is crucial. Also make sure the bolts that stop over shift is not locked to close to the shifter arm. Back the bolts out make sure of your linkage rod ajustment and then ajust the overthrow bolts. Doug

To add to what Doug advised, you also should align the levers in neutral then place a drill bit (1/16 ) into the alignment hole. It will go right through if its all lined up in neutral. After taking the levers off the ears on the trans, put the ears on the trans in neutral then adjust the rods to the position of which the levers align to the ears on the trans. Be sure that the shift arm is not hitting the floor or console which is preventing the shifter full travel. Doug mentioned the stops adjustment.

Kev

I'll go back and check again! Isn't the drill bit supposed to be 1/4 inch?

I'll go back and check again! Isn't the drill bit supposed to be 1/4 inch?
Yes it is.

hmmmm.... sometimes I hate "rebuilt" transmissions. I had one once that poped out of first! It sounds like you have the bases covered... shifter adjusted properly, stop bolts loosened for testing... Another check sure wouldn't hurt, but if that doesn't do it...

If your motor will pull fourth from a stop, take the darned linkage off. Put her in fourth (front lever forward??) and slide her away and see if it still jumps out. Fourth is unusual, but it sounds like a worn out slider, or maybe bad bearings where the input shaft fits into the mainshaft.

I don't think it can be anything in the side cover, unless the 3-4 fork is worn or bent enough so when the lever is in the detent the trans isn;t all the way in gear.