Crankshaft Alignment/Transmission Problem

G

goodcar

Senior Member
I'm reposting my reply/question to an earlier post concerning Turlock Engines. Guess maybe the discussion was too old to have my questions answered. Anyway would appreciate any suggestions or advice related to my earlier post. Thanks.


This is interesting. I have a rebuilt engine (babbit), the cam/crank spacing was tight and the transmission jumps out of 3rd when slowing down. In order to get the flywheel housing correct, had to have .001 shim on the left ear and .010 on the right but still jumps out of gear. Have also suspected the rebuilt transmission (by one of the big three) may be the problem. I'm not a machinist. Is there any way I can determine exactly how far out the crank alignment is. Even if the crank is misaligned. shouldn't have gotten the flywheel housing alignment correct fixed the jumping out of gear problem??
 
You can have the the flywheel housing parallel with the crank flange but if the crank
is not centered in the block it won't be concentric with the flywheel housing.


Bob
 
I'm a little dense, but can you further explain...

"the cam/crank spacing was tight"

I'm also having a hard time picturing why flywheel/flywheel housing alignment and/or crank centering alignment can contribute to it jumping out of third gear. Can you explain that further?

Thanks
 
Bob C said:
You can have the the flywheel housing parallel with the crank flange but if the crank
is not centered in the block it won't be concentric with the flywheel housing.


Bob
Click to expand...
Bob: Won't you know immediately when the transmission pilot shaft won't enter the center of the flywheel.

Goodcar: If it went together I dare say that while it may be off a tad - but probably not enough to make a difference. Also, you don't get a lot of "off" on that rear main before it becomes apparent in the line boring. "Tight" at the timing gear IS the desired condition. Most start their life that way.

It sounds like you (or someone) have indicated the crank and shimmed it properly. A lot of shims in one location is possible as the flywheel housings are (ahem) flexible not only in original design, but who knows what time will do as cast iron "seasons."

I dare say your transmission issues are probably from another origin. As 3rd gear is the "direct drive" you may have a bad pilot bearing, a bad pilot bearing seat (these tend to wear down), or simply wear & tear between the male input gear and the female output gear.

I confess I'm not acquainted with "The Big Three" in transmission re-builders, how meticulous they are, whether they use all new gears (tend to solve any issues but new tends to be "loud" at least until everything "wears in.") Generally a "mix & match" of new gears and old can lead to problems. I tend to go one way (all new) or the other (best possible looking old gears) and each of these transmissions are good service.

Perhaps if you could clue us in on what exactly they did to your transmission it might help?

Joe K
 
Dick Steinkamp said:
I'm a little dense, but can you further explain...

"the cam/crank spacing was tight"

I'm also having a hard time picturing why flywheel/flywheel housing alignment and/or crank centering alignment can contribute to it jumping out of third gear. Can you explain that further?

Thanks
Click to expand...
From Turlock Machine Post, Mike K's reply: I remember a certain "Miracle engine" guy, (Flanagan?) that used to butcher, er, I mean 'improve' blocks like this. You get the best of all worlds:

1) The cam/crank gear spacing gets pinched too tight.
2) The pistons, already higher after decking, will now be alarmingly high.
3) Your transmission will now work automatically. With the lost alignment of the crank center to the ******, the thing will pop out of gear all by itself!
 
Joe K said:
Bob: Won't you know immediately when the transmission pilot shaft won't enter the center of the flywheel.

Goodcar: If it went together I dare say that while it may be off a tad - but probably not enough to make a difference. Also, you don't get a lot of "off" on that rear main before it becomes apparent in the line boring. "Tight" at the timing gear IS the desired condition. Most start their life that way.

It sounds like you (or someone) have indicated the crank and shimmed it properly. A lot of shims in one location is possible as the flywheel housings are (ahem) flexible not only in original design, but who knows what time will do as cast iron "seasons."

I dare say your transmission issues are probably from another origin. As 3rd gear is the "direct drive" you may have a bad pilot bearing, a bad pilot bearing seat (these tend to wear down), or simply wear & tear between the male input gear and the female output gear.

I confess I'm not acquainted with "The Big Three" in transmission re-builders, how meticulous they are, whether they use all new gears (tend to solve any issues but new tends to be "loud" at least until everything "wears in.") Generally a "mix & match" of new gears and old can lead to problems. I tend to go one way (all new) or the other (best possible looking old gears) and each of these transmissions are good service.

Perhaps if you could clue us in on what exactly they did to your transmission it might help?

Joe K
Click to expand...


Transmission was exchanged for a rebuilt, all new gears and sealed bearings, also new pilot shaft bearings. Engine was rebuilt with new Burlington counter balanced crank, lightened flywheel, v8 pressure plate, unit was balanced, new aluminum timing gear. Flywheel housing dialed in to within .001 at 12,3,6 & 9 o'clock.
 
So you bought all new or rebuilt parts.Perhaps now you have to disassemble it and find out if what you paid for has actually been done...Id start with the transmission,popping out of gear the issue is 95% of the time located in the transmission,input shaft alignment is critical,but Ill bet its not the root cause.
 
Railcarmover said:
So you bought all new or rebuilt parts.Perhaps now you have to disassemble it and find out if what you paid for has actually been done...Id start with the transmission,popping out of gear the issue is 95% of the time located in the transmission,input shaft alignment is critical,but Ill bet its not the root cause.
Click to expand...

This has been my gut feeling as well. Plan to try a different transmission. When I first installed the transmission it shifted hard. Also noticed that the baffle was left off of the input shaft bearing and had some sort of a washer installed instead, apparently to maintain clearance.
 
The input shaft of the Model A Transmission is held by a single bearing externally - by the needle bearing internally where it over-runs the output shaft.

The input external bearing bears against the teeth of the countershaft driver gear on the rear side, and there is a dust shield first, then the bearing, THEN a collar which IIRC, is "split" and is normally held in place "a la spring-ring" style by a groove on the input shaft.

These collars being sprung for removal/replacement CAN get less springy. As in not properly engaging the groove. Some use a sleeve and a proper C-ring to replace more positively the Ford ring. If this collar is sprung and the ring loose then the input shaft is free to sneak "backwards"

If the dust shield is missing then the input shaft is free to sneak "forwards" - possibly disengaging from the 2nd/3rd sliding gear which is sort of held in position by the shifter fingers.

The input shaft external bearing is located by the throwout bearing retainer in the forward direction and by a spring-ring to the rear. Spring-rings can walk out or be mis-seated and come loose, or be absent altogether.

The transmission cross section is shown at http://www.motormayhem.net/wp-uploads/2008/04/transmission1.jpg - which can be blown up for better examination.

This lack of dust shield you mention would describe EXACTLY the issue you're having in 3rd gear.

Joe K
 
Thanks Joe and everyone else who responded. These are all great suggestions and I will respond with what I discover. Will be awhile yet. Maybe these suggestions will be of help to others as well. I know this is a common problem. This has been frustrating for me especially since I tried to follow all the correct procedures in trying to get it right the first time.
 
Before you go ripping the transmission out, was the shift tower part of the rebuilt transmission? Take it off and check for excessive wear in the forks and on the ball.
 
ryanheacox said:
Before you go ripping the transmission out, was the shift tower part of the rebuilt transmission? Take it off and check for excessive wear in the forks and on the ball.
Click to expand...
Agree with Ryan. Check those forks and particularly how they are attached to their "rails." My check would be to place the top in 3rd gear - then remove the top WITHOUT Jiggling, and by pulling directly "up" - then see where the 2nd Intermediate/3rd gear sits with respect to the input shaft - which you can see right there on top.

There are those detent balls and springs and rail grooves which you can check the action. There should be decided "positions" as you stroke the gearshift lever.

You want to continue disassembly and check that the original assembler hasn't done something like use two of the incorrect slider rails together. Per Don Snyder's most excellent description:
The shafts in the tower of the transmission that the shifting forks mount to. A-7240 (R & 1st) has the 3 detents equally spaced, A-7241 (2nd & High) has 2 very close together and 1 near the end of the shaft. USA.
Click to expand...
Joe K
 
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Tried lifting the tower off while shifter in 3rd was tried awhile back. Unable to lift, too tight, had to go back to neutral. Also tried known good tower, same result.
 
goodcar said:
Tried lifting the tower off while shifter in 3rd was tried awhile back. Unable to lift, too tight, had to go back to neutral. Also tried known good tower, same result.
Click to expand...


Well, given you have another tower - try that one in place of the one you've been using - this would prove out any shifters/stroking/detent issues and perhaps lead you deeper into the transmission?


Joe K
 
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