| Texas40 | -- 03-11-2013 @ 8:40 AM |
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Following Mac Van Pelts book, we rebuilt a friends 46 transmission with all new parts and followed the clearance specs etc. It up shifts great with a snappy click into gear and no clashing whatsoever. Shift from first to second is great and second to third is also smooth, quiet, no clash whatsoever and "feels normal". The problem is in the down shift from third to second which no matter what driving technique you use it clashes rather violenly trying to go back into second. Any ideas as to the cause of this?
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| alanwoodieman | -- 03-11-2013 @ 9:43 AM |
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try slowing down the shift and remember these trans are not made to provide de-acceleration, thrust washers are not too good for this
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| Texas40 | -- 03-11-2013 @ 11:10 AM |
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I have been driving these flatheads for over 40 years, I know you can't shift quickly, this problem is that it will not engage on the downshift without clash no matter how carefully you try but shifts upward 2nd to 3rd very smoothly. As a side, it will go from third to second more smoothly into gear if less than 10 miles an hour but it still feels "in conflict"
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| carcrazy | -- 03-11-2013 @ 11:30 AM |
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Are you sure the synchro rings are installed correctly?
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| rotorwrench | -- 03-11-2013 @ 12:55 PM |
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I've heard that some of the brass blocker rings that are available out there are not the correct dimension in the tapered area. This can cause problems with movement of the blocker during the shift. Mac VanPelt mentioned something about this on the Ford Barn one time.
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| Old Henry | -- 03-11-2013 @ 3:24 PM |
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I've not been able to downshift from 3rd to 2nd without double clutching from the day I rebuilt my transmission. I didn't see any mention of you doing that. If not, may be the only way to downshift without grinding. Old Henry (The older I get, the better old looks.)
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| supereal | -- 03-11-2013 @ 8:01 PM |
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Like OH, most of us learned "double clutching" back in the days before synchronized transmissions, particularly in trucks. Down shifting smoothly depends on matching engine speed with the drive line, requiring raising or lowering engine rpm to come close to that required in the next gear. Forcing a shift in either direction will eventually damage the teeth on the sync rings. Smooth shifting an old vehicle requires practice until it comes as a "second nature". Using 140 weight oil in the transmission does help a bit, but not much.
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| Texas40 | -- 03-12-2013 @ 6:31 AM |
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Guys, thanks for your input. Double clutching is the first thing I tried-making a turn I would double clutch the downshift but it still clashes and maybe even more so with the double clutch. I suspect rotorwrench is on to the problem as we had to use repop internal parts. I suspect a rebuild with genuine Ford parts will do the trick. Again, thanks for the responses.
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| supereal | -- 03-12-2013 @ 9:13 AM |
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Be patient and give it some time. Tranmissions often loosen up after some running. If it doesn't improve, look up Charlie Schwendler (NY) in your roster. He is an old pro with transmissions and probably has some advice. Check your clutch pedal free play. If more than an inch it may not be releasing completely. Down shifting smoothly is usually difficult, as the differential between the input and output of the transmission is greater.
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| deuce_roadster | -- 03-12-2013 @ 9:31 AM |
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Before removing the trans and swapping out the brass synchro ring that is not working correctly you might drain out the oil, take off the side plate and check to see that the brass ring isn't stuck on the tapered cone it engages. That could have happened during assembly when there wasn't as much oil available. With the trans in neutral you should be able to make them move enough to determine that they are not stuck. If it is stuck you might be able to carefully pry it loose with a couple of small flat blade screw drivers. I also do recall several years ago hearing about a bad batch of brass rings and have used OEM ones since.
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| Texas40 | -- 03-13-2013 @ 4:31 PM |
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Thanks again for that suggestion. I think a side plate inspection might bear fruit if we can free up a stuck syncro. Its worth a try. Another question while I have you guys with experience online. When properly assembled how much in and out free play should I have on the mainshaft (output shaft) with the rear bearing retainer (mount) installed before I install the ujoint? If I have several thousands of in and out play is that okay or should it be just a slight in and out?
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