Even since I've had my roadster on the road its had a habit of jumping out of 3rd when the throttle was released or when coasting downhill. It wasn't constant but it done it enough that it was differently a problem. Why 3rd? 2nd is the one that always gives trouble and 2nd on this is perfect. The 'box was meant to have been a fresh rebuild and there's nothing to suggest otherwise. While the car was together I tried an uprated top shifter spring and ball from "Plainjane" on Ebay and while it made a more positive gear change it didn't help the problem. I also used proper 600W oil and again no improvement. With the engine out of the car it gave me a chance to strip the 'box. Well now I'm even more confused. This thing is completely mint inside. No repro parts that I can see, gears are all good, syncros are perfect, no end play in the cluster etc etc. Same story with the shifter. The only possible problem I can find is the mainshaft bearing. There is a noticeable amount of 'play' in the bearing itself and to a lesser extent in the bearing at the other end as well. The 'play' is differently in the bearing as I can see it rocking on the balls in the bearing when I wiggle the mainshaft. Is this right? Bearings look new. Cheap bearings? Possible cause? Another thing I noticed was when the 'box was together that I could push and pull the mainshaft in and out a good 1/16". Is that right? I've been over the "shifts Happen" thread again and again and am still at a blank. http://www.jalopyjournal.com/forum/showthread.php?t=201308 Help!!
suhr, wouldn't second still be a problem if the syncro balls/springs were the issue?? looking at the condition of the gears and syncros (MINT!) only a few other things can be a problem. like suhr said, the balls and springs in the syncro housing the shafts/bushings in the shifter the bearings on the shaft. I would check all of the above and replace anything that looks remotely questionable. if 39 boxes aren't set just so, they can do some strange things.
The bearing with your finger on it looks as though it's been spinning in the case.Check the bearing in the case for fit and make sure it's push fit and not loose. if the bearing feels worn,replace it. A little movement there will let the gears move enough to let it jump out. All the rollers in the cluster? ,cluster shaft OK ,no scores or other marks?
when I did the trans in the roadster the bearing was loose. when we put it back together we used a ***** punch around the id of the case to tighten it up.
Just checked the hub. All springs and balls are there and the hub doesn't show any uneven or excessive wear. Yeh, both bearings show signs of spinning in the case. Good idea. Its getting to that stage!
There is something wrong with the shifter or shifting forks. The gears are not totally meshing and are popping out when a certain force is applied. either a full load or coasting. I had a tractor doing this and it had a cracked fork also another had the shifting lever worn down so much it was not fully engaging and was popping out and also sticking in reverse. look for something worn bad or bent and that will solve it.
I know a muncie 4 sp isn't the same as the old Ford trans, but I put an extra shim between the front bearing and the input shaft to make the gear run deeper in the shifting drum. From your picture you have a little more clearance on 3rd sycro than you do on 2nd. Just a thought.
When you said the shaft will move in the case about 1/16 inch, that tells me a thrust washer is missing. Look behind where the synchro is connected to the rear main shaft, and add a spacer to take up almost all the movement. That will move the synchro foreward the amount you add.
Went back for another look yet again with all the suggestions and the found the following.... One of the rolloer bearings in the cluster has three broken rollers! The ball on the end of the shifter is worn on both sides. The syncro hub on the 2nd and 3rd fork has alot of play left to right and front to back compared to the 1st and reverse fork. Looks like someone has been there before with the grinder on the fork pads but haven't put any metal back.
This is one of the symptoms that can have a number of faults...either individually or working together to cause the problem. Could you remove the input shaft (Main Drive Gear) and take a pic of it for us? Get a good shot of the tapered end that goes against the synchro please. The ball bearings (front and rear) are not a press fit in the case. They are normally just tapped in with a soft hammer (as part of the shafts they are pressed onto). If you can literally drop the bearing into the case opening, either the case is worn there or the bearing is not the correct OD. The shifter ball end can have flats on the side. When the wear is almost the size of the ball end, I would either replace the shifter lever or build up the end with weld and grind it to the correct contour. The wear occurs on the sides, which does not affect the front-to-rear movement of the shifter forks. Double check that front fork (2nd/high). On the top of the U part of the fork, you should see the Ford part number 91A-7230. If you see any other number (or no number) you do not have the correct fork. Some folks have tried to grind the tips to allow the older style fork to fit the newer synchro, but the basic offset of the fork is different, and can cause the problem you described. Obviously, replace the caged roller bearing. If the gears are allowed to move up/down or front/rear more than normal, they can cause popping out. This can happen with worn gears, worn, bearings, and worn thrust washers. For a simple test on the countershaft and gear, place it back in the case with the front and rear thrust washers in place. Try to fit a feeler gage between the rear thrust washer and the case. You want to have .005 to .017". Ford specified replacing stuff when the clearance reached .025". Sometimes, replacing the two thrust washers isn't enough to bring it back to spec because the case itself is worn badly at the rear thrust surface. We have developed a process to renew that surface but you spend a few bucks to do so. There can be a variety of things that in small ways add up to clearance problems. Check the stuff I mentioned and post a pic of the main drive gear. I wanted to make sure you have the correct one. Also, count the teeth on that gear (15 or 16?) and the front end of the cluster gear (28 or 29?). Let us know. I wrote a book on these transmissions last year. We are in the 4th printing now. Lots of pics and more detail than you can imagine. Some HAMBers have bought it and can vouch for the book. If you want to get a copy click on the link: http://www.vanpeltsales.com/FH_web/flathead_trans-book.htm
These are pics I think you wanted. The bearing slids freely through the case. No use of a soft hammer needed! The fork has the correct 91A-7230 part no. Would it be wise to build the pads up with weld and grind back for a tighter fit? Mainshaft has 16 teeth and the cluster has 28. Thanks
Another thing to check is the condition of the pilot bearing in the end of the crank. If it is worn and you have play in the main shaft bearing the gears can have enough movement to cause the jumping out of gear problem.
OK...that eliminates a couple questions. Your MDG is correct and tooth count matches. I'll get a measurement of the tip width for you to compare your's. Maybe later on today when I stop in at the shop. The original fork tips were babbit coated but don't worry about that. I ***ume your front and rear ball bearings have the snap rings on their OD??? Normally that fit is such that I can wiggle and push the gear/bearing ***y into place in the case. Sometimes, tapping with the hammer helps move them into place. I wonder if a previous bearing had become stuck and turned in the case. You could have it rebushed at a machine shop if you felt it needed it. What make are those bearings? I can't quite tell from the pics you posted, but is there a thick thrust washer in back of second gear? (on the mainshaft). There should be a washer here that is .184-185" thick. Also, there should be a thin br*** thrust washer in front of second gear that is .063-070" thick. Your mainshaft should have a small steel pin sticking out of it slightly, located just in front of the spiral spline. I am basing these questions on the picture of the 01A-7124 synchro I see in the picture.
Are you saying not to worry about the play between the drum and the fork?? Can't find any makers name on the bearings. Sounds promising! Washers you mention are all present.
Fortyfordguy it's been a while since i've gone through the rebuild process on one of these trannies. after using your site for reference a couple times I'm definately buying your book before helping my brother rebuild his ******!
Generally, the fork (and the shaft it rides on) have the ability to move the synchro sleeve more than the distance required to engage 2nd or high gears fully. A high degree of wear on the tips of the fork might affect that motion but it would take a lot of slop in my opinion. I would be looking at the fork for its proper orientation.....in other words, that the tips aren't bent to a weird angle for some reason. I am wondering about the 1/16" play you mentioned. It sounds like something is missing or something is badly worn. With all parts in place, and the snap rings on both ball bearings, and the bearing retainers bolted up (front & rear) there should not be any detectable front-to-rear play like that. Thinking out loud here, I wonder if the bearing snap ring grooves are not where they should be. On both bearings, the groove should be to the outside edge of the bearing. From your pics, the front bearing on the main drive gear is correct. I don't see a pic that shows the rear bearing. Also, is this a closed drive or open drive trans?
Another thing with endplay at front bearing and rear beaing--this means there can be play at center where main drive and output come together. Synchro engagement is a very small distance...could be disengaging due to synchro engagement being less than the movement of the parts.
I've got a blueprinting source calling out synchro engagement as .1", so that much movement at that centerpoint from endplay and high gear is potentially unplugged...
Check your shifting froks i dont think the stick is in there right,some thing dont right to me is the bottom end bent a little.are those sweg pins hanging up on something .
Put top two shafts and their bearings back together, see how much axial play there is and what it does in the middle where the twp shafts come together. Remember there are 2 pilot bearings in the mix, too--clutch area one and the one inside main drive for nose of output. Slop in either is potential movement at synch, center area
Thanks for the all the suggestions. I've got a new set of bearings coming and the syncro spring and balls. These are easily and cheaply replaced. Thees no arguing the fact that there was a broken roller bearing in the cluster. I'll mock it all up and see if theres anything out of place or not right and go from there. I don't think the shifter has any cause for concern. I've never had any problem shifting or it jumping from any other gear. I'll keep this thread updated.
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