I have a mild 318 in front of a 904 trans I got used. It runs pretty well but sometimes it sort of finds neutral and revs way up between the 1-2 shift if I get aggressive on the gas. When it happens I release the gas pedal and let it shift into D and it holds fine after that.
The throttle pressure arm is correctly adjusted. It holds the gears longer when the gas is hit harder. It doesn't seem to slip in gear, just on the 1-2 change. 2-3 will shift fine on the gas. 1-2 will shift fine if cruising normally.

Any ideas?

check the kickdown band adjustment

Sorry, Im a transmission virgin. I have pulled them out and put them back in lots but the deepest I ever got was changing the filter. What am I looking for and what do I have to do?
Thanks

the low/rev band is in the pan area

the kick down band for 2nd gear is above the gear selector levers

you need a 5/16 wrench or 8 point 5/16 socket

back off 3/4 lock nut adjust stud to 72 inch pounds,back off 2 turns,hold while you lock the 3/4 lock nut back down

I have had it slip on 1-2 and go as far as to "seem" to not have 2nd

adjust band and it came back and did not slip after that

best to drop pan and do both adjustments IMHO

you dont have to use an inch pound torque wrench,you can snug it by hand with a wrench or 1/4 drive ratchet (snug it by hand till its stops and feels snuged up good)

i find removing the shift linkage and throttle pressure linkage,it gives more room to get at the adjuster

i use a painted line on the side of the socket to count the turns,using a spot for referance when eyeballing it and counting turns

you can just do the one and not drop the pan though...

I have swaped many also and never been to far past a VB R&R,but have learned to adjust them up before install any more on a used unit

also when looking at a used one in a JY,I look to see how much adjuster threds are showing

thats a tell tell sign of how much of the band is left

I have seen them with just 2 threds for the lock nut to just grab on to,very used up

so look at your adjuster first to see how much you have left for adjustment

if its allready run down..you may need to look for a spare soon...I have a couple i keep on hand for that reason alone

the smaller 904/a999 that are stock and "used" and not "built" up are ez to kill with some

I have had a few slip/no 2nd and adjust it back up tight up to 3x before needing another one

but if the clutches are slipping and not the band

good luck

thanks Scratch I didn't elaborate on adjustment procedure
I usually run my band just a little tighter 1.5 turns after I tighten the strut to 72 inch pounds
just my preference

As said snug the outside band down then back it off 2 turns and hold it in position as you tighten the locknut and note (for reference) how many turns total you changed it from where it was

Thanks tons fellas.

How long has this been going-on ? .. if awhile .. you have probably TOASTED the band. I would pull-the-pan and report on what is in the pan and the spec of the KD lever.

Only happened two or three times so far. It's just a fun beater/cruiser, I don't hammer on it much. Plus the '67 318 has high compression but tiny valves and ports, so no big hp, even with a 268 cam.
Anyway, wish me luck and Ill let youse know what happens.

Is your KD linkage hooked up. It could need adjusting if it is.