Here's the story, '41 Pontiac original 6 cyl, 3 on the tree. Needed some work-fixed radiator leak, replaced rear main rope seal that was dumping oil, rebuilt clutch and went over all internal parts in transmission. Tranny has been popping out of 1st gear when starting off and won't go into 3rd gear.(for 2 months) Tore down all internal parts on trans looked good. Got right amount of free play in clutch pedal . No leaks, everything looks as it should. I can't get the damn trans to stop popping out of 1st gear and it still won't go into 3rd. What the hell????? Any and all recommendations would be appreciated.
I'm surely stating the obvious; check your linkage for adjustments and start playing with that to see if it helps any. Especially since you have already been into the trans itself; on that, did the levers and forks work while you had it on the bench. Maybe one of those bent/broke/wore the hell out?? Just a few guesses...
Times two on the linkage. If that doesn't do it the sideplate maybe worn out and not keeping tension on the forks. Will it stay in gear with light pressure on the shifter? plan 2; look for a newer;'50's, pontiac trans to do an upgrade. Some poor bastard probably parked it because oh this back when. A 350/350 isn't the answer.
when my son in law drives it, he can get it to stay in 3rd by holding down with pressure, the gear shift . when i do the same thing with him in the car, can't get it into gear. a 50's trans won't bolt up to the selector type trans. tried to get a 37-38 Pontiac floor shift trans which will, but no salvage yards around here within 100 miles has any. will look at linkage. it did this last year and after fiddling with the free play in the clutch pedal, it worked ok for about 400 miles and then started up again(that's with the old clutch). Thanx for the suggestions, keep them coming.
Have you checked the motor/tranny mounts? A worn out mount cause cause binding in the clutch. I have a friend with a 51 pontiac, having similiar problems until he replaced the motor mount(s). Good luck, hope you get it figured out.
what Pitts64 said...start with the basics and eliminate possibilities one by one. Don't forget Occam's Razor dj
Could be the engine/tranny moving within the fram. Could be the frame moving (rotted?). Could be too much play in the side plate on the tranny/ in the linkage pivots, etc..
Disconnect the linkage at the trans, put it in High, then adjust the linkage to fit. Do the same with Low. If that doesn't fix it, the problem is inside the trans, worn forks, stuck detent balls, something like that.
Start with the linkage adjustment first. If that doesn't do it, it's possible that the forks inside the box are bent not allowing the gears to go all the way into gear. Part way in the pressure can cause the gears to pop out. I had it happen on a floor shift Ford. The gears and syncros looked great. Changed the top including the forks and it works great. The problem was not in the gears.
I spent a number of years behind a parts counter and can't tell you the times I saw parts that looked great (like they were made that way) untill laid beside a new one. I am betting bent fork but all good suggestions.
ok, going back at it. this is Rocky's old '41 coupe from years ago. frame is solid, no rot. motor mounts are solid. I was going to replace the engine and trans with an SBC and automatic, but the wife put the kabosh on it. she wanted to keep it old school and frankly, so do I.
Check that the shift forks are tight to the shift shafts inside the trans. If the pins that retain the forks are partly/fully sheared, the fork may rotate on shifting and never engage 1st and 3rd completely. Dan
Went back and fiddle-farted with the linkage and so far(about 35 miles of driving), it's actually "clicking" into 3rd, i can feel it it engaging, which i didn't before. Like I said before, after putting back in the fixed radiator and putting the tranny back together, no leaks. The radiator still isn't leaking, but I've got the leak back from the tranny bearing which I replaced. I'm also getting some seaping of oil out through the dipstick(not overfilled). When I tore down the tranny originally, instead of the quart or two of gearlube it should of had, there was maybe a few ounces of lube in it from coming out the bearing. Don't know what's causing it to happen or why oil is coming out the dipstick. HELL, MAYBE I'M A DIPSTICK!!
I'd look for slop in the linkage. Jack it up, get it to click into gear all the way, then have someone move the shifter, but not enough to pop it out of gear. Look at each moving piece while doing that. Fix or shim every loose joint. The bad thing about letting it jump gears, is that it will start to wear the gear teeth at an angle. When it does, it will never stay in gear. If it jumps a lot in 3rd gear, it will angle-wear the internal teeth inside the back of the input shaft, as well as the mating teeth on the 3rd syncro. 1st and reverse don't have those small internal teeth. Those gears rely on "face contact" Yes, they can wear at an angle, but I'd suspect the linkage is worn, and you are not getting full throw.
When you say everything looks good does that mean you have experience looking at wear on transmission gears and sliders. To an experienced trans mechanic he may see wear you don't. Popping out of gear with no linkage issues usually is the dogs.
possible blockage causing it to become pressurized perhaps? would explain away leaking bearing seals too. time to take 'er out the car and make buddies with your local gearbox mechanic me thinks..
Sounds like you're slowly sneaking up on the problem with linkage adjustments. I put thousands of miles on the ol' girl with no problems like that which leads me to believe a motormount may be slowly degrading. Yeah, I know you said the motormounts are solid but I've dealt with those damn Pontiac motormounts may times...same design up through '58 and I've litterally had dozens of those cars...in fact, it seems like I modified the left rear mount on that car to be solid..welded the two halfs together to eleminate the rubber between the two halves...if I did, look super hard at the right mount. Try this. Open the hood, block behind the rear wheels and fire the engine. Put the tranny in reverse and let out the clutch at about 2500-2000 rpm and have somebody watch to see how much the engine lifts on the passenger side. Do the same test in 1st gear with the blocks in front of the back tires and watch for the engine llifting. That should show any problems in the motormounts...good luck. BTW, I've grown to HATE these weak trannys after blowing up about 6 of 'em. Never wore one out...always broke them but never with a little 239 flathead 6 banger.. Hey, you might wanna go over to the "Year one" pontiac board and register...click on the 54 and earlier forum to get some answers from old-timey pontiac owners..a great forum. Rocky...
THANX to all and I'll check it out Rocky. Still can't figure the seapage from the dipstick and why the NEW trans bearing is still leaking lube. When I originally went into the trans, there wasn't much gear lube left in it-still leaking from bearing???
Check/clean the road draft tube and oil filler cap. One or both are probably clogged up causing pressure to build in the crankcase then pushing oilly vapor out the dipstick. Front bearing in the trans leaking? The oil return threads in the front bearing retainer are probably worn ,no easy fix there other than a new retainer.
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