Slipping out of 3 rd on compression

[SSsssteamer]

Has any one experienced this? I bought the complete transmission rebuild package for my '29 Tudor from Mac's. The shifting tower was rebuilt last year and it was working fine then and it still is. The transmission works fine all of the way around, but on compression in third gear after about 500 yards of compression, if the gear shifter is not held in, third pops into neutral. I can hold it in third but it tries for neutral all of the time while under compression. Under power in third, it holds very tightly in gear on its own. What did they do wrong? Did they cut the 2 & 3 gear slider wrong? I could give the third gear engagement teeth a little help with a Dremel grinder. Any other thoughts to a fix on this except for buying more new gears from Mac's?

[rally 1]

Two things,
1. Was the pilot bearing replaced?
2. Are the shift forks bent?

KK

[pat in Santa Cruz]

was the main drive gear replaced? That pilot shaft that fits into the flywheel pilot bearing must not be worn more than .002 or it can slip out on compression. It should be .668 diameter.

[tbirdtbird]

nose of input shaft (main drive gear) and pilot bearing as stated

[Tom Wesenberg]

Originally Posted by tbirdtbird

nose of input shaft (main drive gear) and pilot bearing as stated

I agree with tbird, and that's where I'd look first. Also be sure the flywheel housing is dialed in, so the tranny input shaft is in line with the crankshaft.

Also, how is the bearing and shaft between the input shaft and output shaft?

Is the 2-3 gear a good slip fit on the shaft?

[SSsssteamer]

Sponsored Links (Register now to hide all advertisements)

The 1929 Tudor's transmission worked well before the rebuild but the transmission was well worn out and making lots of noise at the time. It wasn't jumping out of third gear on compression then. Everything in the gear box is now brand new. The only thing that was used again was the transmission housing. The shifting forks worked well before the rebuild and they should work well now. I have good detent engagement for the shifting tower gear positions. On compression, the shift lever continues to slowly climb out of gear until you are eventually in neutral. I can hold it in third but it will eventually require about a 10 pound pull on the shift lever to keep in in third while coasting on compression. I did not replace the throw out bearing and that is a very good suggestion. The new input shaft was part of the new transmission package. When I assembled the transmission, everything went back together properly and I thought that it all fit very well. When I get this sorted out, I will share with you the fix. I was just hoping that someone else had experienced the same problem as I am. When I pull the transmission out, I will check the pilot bearing fit. If it is loose, than I will only replace the throw out bearing. The bell housing was dialed in perfectly when I rebuilt the engine about four years ago.

[Mitch//pa]

another thing to look at is the end play of the main shaft and cluster gear, check that after you remove the shifter tower but before you dissasemble...

[J Franklin]

I had rebuilt a transmission with new gears that did the same. I had to find another mainshaft that fit better with the sliding gears. This is covered in the mechanics bulletins Dec. 1928 Pg. 303.

[larrys40]

It can be a number if things from the shift tower and forks to the main drive gear ( front input shaft) to a 2nd high slider gear and main input shaft issue . If it were mine this is what I would do first . Drain trans, pull the shift tower and examine for any issues/ bent forks/ sliding detention issues, etc

If none found I would check the fit and slide of the 2nd and high slider to the main input shaft for fit . It should slide in freely. If not you have an issue .
You can remove the main shaft and sliders with the trans in the car by pulling the rear retainer and the rear bearing, then shaft and sliders up and out . Inspect for fit and any issues you. Can also check for cluster issues but I don't think that's where the problem is

If you have another good 2nd and high you may want to replace . Also check the pocket bearing at the front forth main shaft to input shaft . Replace shaft and bearing if warranted
You have the option to pull the trans if need be from there

Please make sure your flywheel housing shims are in as well
People don't know and realize the shims are required there
If you disassemble in this method don't forget to put it back correctly and with gasket and lock wire on thrh rear bearing retainer

Larry Shepard

[tbirdtbird]

let us know how you make out

[Larry Seemann]

Most of the times that I have encountered this problem it has been caused by a warped flywheel housing AND most of flywheel housings ARE warped. (so are some of the drivers)

[tbirdtbird]

except that he didn't have this problem before

[SSsssteamer]

"What does the pilot bearing have to do with the throwout bearing? A bad throwout bearing will not cause it to jump out of hi ..." ...........Oops. I had a brain fade. Sorry. I meant to say that I would only replace the pilot bearing if I found that it was bad. I will dial in the bell housing again. I have other main shafts that can be swapped out with this one and I will try it. I purchased replacement every thing from Mac's. I think the gears all came from Poland. I believe that is what the cardboard boxes said. The only used part used again was the transmission case. I had rebuilt the shifting tower a couple of years ago, and it was working good. When i took the trans apart for the rebuild, all of the bearings were badly worn out and the gear teeth were cupped from wear. since the new input shaft was new, I didn't mic the nose of the input shaft. This next time I will try the new pilot bearing for fit on the input shaft before I do installation. The pilot bearing was a new one about four years ago when I rebuilt the motor. The bearing between the input and output shaft as well as also both shafts are all new. Here is a thought, the old bearings were all worn so badly that they were somewhat self aligning. The new bearings are all running true to their shafts and they probably won't allow for any error on misalignment? Another thing that I noticed, while I am running down a hill in 3rd gear on compression, if I push the clutch in, the transmission relaxes the effort to push it out of 3rd and into neutral. Let the clutch back out and it resumes to build pressure to push it out of third gear again. So far I have about 150 miles on this new transmission. With the new transmission, the first time I drove it, it was pushing it out of 3rd on compression. Nothing has changed since then, to the good or to the bad.

[Bruskie]

your biggest mistake was buying from macs.

[tbirdtbird]

i was reluctant to say that

[Tom Wesenberg]

I would remove the shift tower and feel the fit of the 2-3 gear to the shaft. Try to rock it on the shaft. If you can feel any twisting movement, I'd call it too loose.

[Tom Endy]

Check if there are .010 horse shoe shaped shims installed in the ears between the engine block and the flywheel housing. These shims are commonly left out. Their purpose is to align the flywheel housing with the bell housing and transmission. The shims are to compensate for the gasket thickness on the lower part of the clutch housing. The shims can be added if they are missing by removing the accelerator assembly bolts and prying the ears back to slip the shims in. Most suppliers carry the shims.

Tom Endy

[Mac VP]

Pull the trans. Mic the snap rings on the front and rear ball bearings. Let us know how thick. Were these replaced with the new ball bearings?

[SSsssteamer]

Originally Posted by J Franklin

I had rebuilt a transmission with new gears that did the same. I had to find another mainshaft that fit better with the sliding gears. This is covered in the mechanics bulletins Dec. 1928 Pg. 303.

That was my fix too, another main shaft and gears. In my case the input shaft and main shaft did not have enough end play and they were binding end wise front to rear. The needle bearing cage that was provided in the transmission rebuild kit was too long for the input main shaft and it pressed the input shaft forward a bit which didn't help with the engagement of third gear. That plus the 3rd gear shifting fork lacked 1/8" of being in full engagement going with the third gear detent position. The pilot bearing was still fine, but I will buy a new one tomorrow just to be on the safe side. I found an almost new transmission on my shelf that had a broken case. I used the main shaft, the 2nd and third gear slider, and the needle bearings for the main shaft out of the found transmission. To be safe, I should have probably swapped all the innards out into my transmission case. An interesting observation was that Ford's 2nd and 3rd gear slider will not fit onto Mac's main shaft but Mac's 2nd and 3rd gear slider will easily fit Ford's main shaft. Reminds me of the Chinese parts that we buy that don't fit properly. Thank you all for your help.

[SSsssteamer]

Here is our 1929 Tudor that had the transmission problems. My wife of fifty years is cleaning the wheels for me. We drive this car year round.