Quote:
Originally Posted by sethkestenbaum
Rebuilt Engine + Rebuilt Bellhousing + Rebuilt Transmission + My Reinstall of these parts = a car that kicks out of second gear when driven up a steep hill.
Background:
110 miles on a rebuilt engine, bellhousing, and transmission. While driving up steep hills, the car "kicks" itself out of 2nd gear. By "kick" I mean that the shifter slams itself out of gear with speed and force. It doesn't seem to do this on flat roads under normal driving, but will do it when I have to hit the gas and am working my way up a decent hill.
What I know and have checked so far:
1) The tower appears in good shape. It was rebuilt with new parts. The forks aren't bent and appear seated into the slots.
2) The car seems to be shifting correctly when I am driving around town.
3) The transmission has all new gears, barrings, etc from Brattons.
4) The two brass horse shoe shims at the accelerator pedal mechanism bolts were installed when the engine was put in the car (although they took considerable effort/prying to put in place).
5) I am using Bratton's 600W oil.
6) The car doesn't seem to kick out of 1st gear and or 3rd gear. Then again, with less than 500 miles on the new engine, I don't think I have driven the car over 45 MPH yet.
7) Before the rebuilds and reinstalls, the car didn't kick out of gear.
Before I pull the engine/transmission (which I would hate to do), I was hoping to get some suggestions on things to try and possible causes. I have Tom Endy's article It Jumps Out of Gear and shared a copy with the local model a mechanic. We still can't figure out the cause.
Thoughts? Insights? Suggestions?
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Hello Seth, that is very bad luck to hear you have more problems.
I have a couple of thoughts which ay help narrow the problem.
Firstly, there are two types of coming-out-of-gear I have experienced. The first if "falling out", where the gear can be held in by minimum contact with the gear lever. On the way up a hill in second, one sees the lever gradually moving down from the dash board, and by relieving engine power it can easily moved back into mesh –sometimes, even without backing off the power it can be moved back into full mesh. I think this tends to be caused by the forks not holding the gear in mesh due to something like weak detent springs, worn detent plungers, slack in the shift fork mechanism somewhere (maybe loose fork retainer pins) or, particularly, a combination of all of these. It is mainly vibration and the downwards weight of the gear lever that is not resisted strongly enough by the detents etc that allows this.
Then we come to your case, in which there is a strong force generated to slam the lever out of gear. This force needs "camming" or ramping" action to be generated somewhere in the gear train- one cannot produce significant acceleration of the shift forks and gear lever without a significant end-thrust along the direction of movement of the forks i.e. in line with the gearbox shafts. And one cannot generate this force without misalignment of the gears, causing them to "cam" apart along their axes of rotation. This can be caused by the first-motion shaft being out of line due to a warped flywheel housing, by the flywheel sitting out of line with the centre line of the gearbox, by a worn or loose pilot bearing or bearing shaft, or by gears loose enough to cant on the mainshaft or layshaft. Or, unlikely in your case, by two gears badly machined so their meshing surfaces do not meet at right angles. Maybe also by the lay cluster being out of line with the mainshaft for some reason.
This is a long-winded way of saying that I doubt whether your problem is due to anything in the shift tower, which is not capable of producing enough end thrust on the gears to make them forcibly fly out of mesh – except for the little flourish produced at the end of the falling out motion as the bevels on the two gears meet, just as they disengage.
And of course, as so often happens, you may have a combination of a little of all of these effects adding up to your problem.
I am not sure if this will help at all, but it is food for a bit more thought.
My roadster “fell” out of gear in second pulling strongly up hills. I had to back off power to push it back into gear every 30 seconds or so. In the end I lost a tooth off the cluster gear up a very long hill shortly after changing down at about 40 mph in overdrive (Mitchell). I stopped almost immediately and drained the oil, removed the tooth replaced the oil and continued to a repair station where we put in another box. Someone else on the same rally did not stop when a tooth broke and blew the whole bottom clean out of the gearbox! Maybe I was plain lucky, too – there is very little room above the drain plug for a loose tooth to sit out of harms way.
SAJ in NZ
I apologise for viglink causing the word "flywheel " to redirect the screen. This is a new one on me!