Popping out of 4th Gear

[troutstreamnm]

My A-833 is popping out of 4th gear while driving, mainly when the car is cold.  Doesn't do it after everything warms up.  Just slips out of gear while driving down the road.  I'm running Redline synthetic manual transmission oil.  What's causing this?  Thanks.

[Cooter]

Don't want to shoot straight for this right off the bat, but I'm thinking a Synchro. Blocker ring/and or the Input shaft "Dogs" that actually hold the slider onto the gear are worn out...

[troutstreamnm]

Thanks for the response Cooter.  Humm....worn out?  That's interesting because I did an auto to 4-spd conversion and supposedly purchased a fully rebuilt A-833.  I've got 1700 easy miles on this transmission and it's been popping out of 4th periodically since early on.  Did I get burned?

[ntstlgl1970]

Sorry if this is long winded-
I agree with Cooter on the synchro possibility, especially if it pops out when you let off the gas in 4th. If it was me, I'd drain the gear oil, save it, put ATF in it (it's approved per the service manual) and see if the problem goes away. If the problem goes away and you aren't comfortable with ATF in there, try a lighter gear oil weight (especially you put in the redline 75/140 stuff) in the trans. If it isn't something that is repeatable consistently, it might be worthwhile to make sure the shift rods are adjusted correctly and the interlock detents are all in place in the side cover. Another, though rare, possibility could be if the endplay is not tight enough on the input to output shaft clearance since 4th locks the input to the output shaft. The input shaft and input bearing have a selective thickness snap ring if i remember right to adjust the clearance. If the problem is still there with the ATF, it's probably 1) the synchro or the input shaft/synchro hub/detent spring is worn/damaged/missing (common) 2) shift linkage is out of adjustment (common) 3)end clearances are too high (not as common) 4) damaged/missing shift detent/worn shift fork/or interlock issue in the side cover (uncommon but possible)
hope you get it figured out

[troutstreamnm]

I don't doubt the syncros are worn, it just bothers me that could be the problem.  I probably need to check the linkage adjustment first.  What is the procedure to get the linkage properly adjusted?  Thanks for the help 

[vinb]

  This may sound stupid, but I just checked my friends out,  it was popping out of 2nd gear, then adjusted it, 2nd gear is fine now . A week or so later he calls me up because it started popping out of 3th ,  so I had him bring it over and re-adjusted 3th/4th rod. It was 75% better but still popped out of 3th.

  So, by luck checking the shifter boot (yep the shifter boot) it was hard as a rock (almost) I took off the bezel and took the screws out of the boot and bingo no more popping out of any gear. I guess the boot was to hard and just pushing the shifter out of gear. Weird..

  Hey it's fixed thats all I care about. Now he'll find something else for me to do...

[Cooter]

See the problem with a "Rebuilt" 4-speed is while the synchro and the blocker rings are replaced NORMALLY, the GEAR isn't and the Dog's are on the GEAR itself....Putting a new synchro in it may/may not solve a worn GEAR Dogs...Alot of people make this mistake when they rebuild their transmission...They ASSUME that the synchros are the only thing that gets "Ground" on when a shift is missed..IT's the GEARS that get the worst end of things....The FIRST thing I look at are the dogs on the GEAR itself...


However, I too have seen the shifter/shifter boot give alot of problems when popping out of gear...Check all the things mentioned here first, then if they don't work, you might be in for a tear down...

[ntstlgl1970]

The synchro teeth on the gear should look like a little pointed roof house i.e. ^ = good
If the point is flat or rounded that is not good. Same with the sleeve that slides over the blocker ring and gear, should have a good point on the roof of the house...

[troutstreamnm]

Who would have thought the boot could be the problem.  That's another thing I need to check.  thanks a bunch 

[Aussie Challenger]

Another problem can be the spigot bearing in the back of the crank, if it is missing or badly worn the input shaft can wobble around. I have struck several problems with gear sticks being held by shifter boots or pieces of insulation under the carpets.   

[black71]

Hopefully its just the boot, I had the same problem in my mustang, the cold weather here made the boot rigid and woukd keep pulling the stick out of gear once I let off the gas, but once things warmed up inside the car and from underneath the problem woukd quite. A simple little thing, hopefully that's all you have to contend with

[Chryco Psycho]

Change back to 80-90 non synthetic gear oil , this has fixed 3-4 I have done this on , if it doesn`t change see if the input our output shaft will pull in & out if the brgs are worn

[brads70]

Did you indicate the bell housing to the crank? Common problem in circle track cars when it keeps popping out of gear. Especially road race cars.

[troutstreamnm]

So my high $$$ Redline synthetic could be causing this?  That would be disappointing to say the least.  From the responses here, it sounds like it could be related to a number of things.    Seems like the key here is that it only does it when the transmission is cold.

[Cooter]

At best on a Forum, you are dealing with guesses...You want to know for sure?? Pull it out and down...