TR2/3/3A Help needed. TR3A transmission popping out of 1st gear

First let me start by saying I aside from knowing how to shift gears I know nothing else about transmissions. After 40 years of not operating I finally got the car running. I have drained, cleaned out, and replaced all the fluids. The transmission gear oil was replaced with 80/90w oil. I don't ever recall the transmission popping out of gear but now the transmission pops out of first gear, all other gears function okay. What are some of the things I can check/expect with fixing this issue?

As always, thanks for any and all help.

Just curious, do you have a 1st gear synchro or not?

There are spring loaded balls in the tranny cover/shifter assembly that lock into detents in the shift levers. If the car sat for a long time, the ball may be stuck so it is not engaging the detent. This is not a hard fix...but you must remove the tunnel to access the top of the tranny.





This is a view of installing the ball and spring...they go into the underside of the cover. There is one for each lever, and they are held in by the screws you see at the bottom of the picture.

Thank you so much Yoda. I've already learned so much.

Don't grease the balls however, grease will slow the action . Use oil on the balls.

Not sure what you mean and how I determine if I have "1st gear synchro or not"? As I understand, the counter shaft is a common failure point on these. If failed would 1st gear work at all? (while on jack stands) I engaged the emergency brake to apply pressure to the rear wheels so they wouldn't turn freely. I engaged the trans and it immediately jumps out, I apply pressure to hold it in first and it pops out but also makes a grinding noise when I begin to release the clutch. The similar situation is occurring in 3rd gear with but not as servery and I am able to hold the shiftier in 3rd so that it does not pop out.

Your countershaft has not failed. If it did you would be shopping for a complete tranny. The countershaft bearings fail first, making a hissing noise in neutral with the engine running. If you let the failed bearings go too long, then the countershaft breaks, destroying the tranny.

Do you really not know what a synchronizer is? I would then assume you have one on first gear, or you’d be complaining about 1st grinding all the time?!?

I know what the synchronizer gear looks like but and know what the word means but haven't a clue how it functions. Pics before I cleaned them up.

You have the correct TR3 box with the non-synchronized 1st gear. That means it will grind if you push the clutch and rapidly shift straight to 1st. If you quickly shift to another gear before selecting 1st, then you will not get the grind.

The 2nd pic shows what looks like a good bit of surface rust on the gears themselves. If that is what it is, vs. just old greasy looking oil, then I agree with Randall. It would be best to rebuild the countershaft with new bearings. The bearings will become sticky from the old grungy oil, and then they will slide rather than roll...resulting in a countershaft failure.

Edit...Doe...scratch that. Your box has a broken dog tooth on the second gear, visible in pic 2. You will need a non-optional rebuild, as you have no idea what that dog tooth did as it circulated through the box.

Here’s a rebuild thread I did years ago. It supplements the other online articles with more pictures and common problems:

https://www.britishcarforum.com/bcf/showthread.php?100241-TR2-3-Gearbox-Rebuild

As I am sitting here studying your pictures...Your 1st gear is also shot. The edge that mates with the 1st/rev idler gear is worn way back at a steep angle...indicating that the gears are not meshing well at all, and have not for some time to get that wear pattern. Sorry to bear the bad news, but that box has seen better days. It very well may be more cost effective to find a donor box to swap the internals, assuming you want to keep the original case. If not a complete new box may be a better starting point.

"Your 1st gear is also shot. The edge that mates with the 1st/rev idler gear is worn way back at a steep angle...indicating that the gears are not meshing well at all"
And I was thinking that was normal by design. I guess that happens when you don't know what to look for.

UGH! John, what might one estimate my issue to cost me to repair? 1) if I can manage to do the work myself? 2) if I am able to find someone that has the skills?

Edit: also is it safe to assume that the 1st gear on the counter shaft will need replacement?

You can find very decent rebuild candidates in the $100-150. A typical rebuild will run about $400-500 in parts to do it right. Add about $400-500 in labor to have it done at a shop. Of course these are just rough estimates. Rebuilding a tranny is not hard at all, but you will need access to a press...even if it’s a cheap $99 Chinese press.

You could pickle this tranny for later, and then look for a fully synchroed Tr4 box...as an improvement that would probably increase the value of your car. Eventually even the die-hard guys want a 1st gear synchro!

As far as your question about gear condition, yes, I would expect several gear issues to show up as you rebuild . Second gear, 1st gear, the synchro rings, 1st/reverse slider gear, the countershaft, and all bearings will need to go as a minimum. When you have a box with mechanical damage like yours, it is usually much cheaper to start with a donor box where all the gears are decent. Then all you need to worry about are seals and bearings.

This is what a fresh 1st gear looks like. Note the rather sharp edges and shallow angle.

Again thank you for sharing your advice and knowledge. You have my gratitude and respect.