seperating engine from transmission after break

scottangove · 03-19-2010, 07:27 AM

The throttle linkage stuck and I over-revved and broke something in the engine. The flywheel spins, but the valves and fan pulley don't.
I've since removed the engine and transmission, but after removing the pair, I cannot separate them more than 1/2 inch. I can see in the 1/2" crack and through the hole where I removed the starter, that the flywheel is moving with the transmission. I can see that the flywheel is pulling out of the oil seal, indicating that the gland nut must be broken apart, or threaded out. Somehow the transmission input shaft (and splines) must be stuck in the flywheel.
I don't want to pry hard, and don't want to hammer hard, what can I do to take things apart? Do I have to take off the heads, cylinders, and split the case?
The engine is a 1968 912. I replaced cylinders and pistons with a big-bore kit just 600 miles (and 6 years) ago.

Jaems · 03-19-2010, 09:19 AM

Try turning the crank at the rear of the engine with the a 36mm wrench. If it is locked up. Then you have broken the crank. The weakest part of the engine is the crank on a 912.

Though folks do it. You should never, just, replace the P and C. The crank takes a lot of pressure, in a 912 engine, and should be checked for cracks. Also the cam can have excessive wear with these new oils. Some have know to wear flat during break-in. They have taken the Zinc additives out of the oil.

I hope it is not too serious. However, it doesn't sound like it.

scottangove · 03-19-2010, 09:32 AM

The crank does turn some. I'll play with it some more and see if I hear any broken crank parts grinding against each other.
The engine was split just 1000 miles ago by the previous owner; the crank was inspected and the cam was replaced with a new "performance" cam. I did the big-bore replacement as the previous owner had used old/worn pistons and incorrect spacer shims, leading to poor compression.
Back to my issue. How do I get the engine and transmission apart?

pete3799 · pete3799's Garage

Not sure on a 68 but check that the clutch release arm is disengaging from the throw out bearing. On some years the throw out bearing must be turned to a certain position before
the release arm will disengage .

djdsc · 03-19-2010, 01:16 PM

Quote:

The flywheel spins, but the valves and fan pulley don't.

This sounds like broken crank. The flywheel can still turn when the crank is rotated by the rear pulley depending on the break. They can even still run and be driven if conditions of the break are right.

Quote:

I can see that the flywheel is pulling out of the oil seal, indicating that the gland nut must be broken apart, or threaded out.

You don't mention how much the flywheel moves. There is some end play, enough to see and feel, possibly more, again depending on the break.

Quote:

indicating that the gland nut must be broken apart, or threaded out.

True there could be a gland nut problem but it doesn't take much to bind the transmission spline shaft in the clutch attached to the flywheel. Make sure when trying to separate the trans and the motor that there is no binding of the shaft. Brace the parts up with blocks of wood to insure they are aligned as if installed.

scottangove · 03-20-2010, 03:37 PM

I've got some more information.
Per Pete, I've tried pulling things apart with the clutch lever pulled, and not pulled. Either way, the engine does not pull away from the transmission more than that 1/2". The flywheel is apparently stuck on the transmission shaft. I can see easily 3/8" of the "flywheel boss" being pulled out of the oil seal (much more than end-play).
Per Jaems & DJD, I am able to rotate the crank around and around from the pully and I can hear the pistons sucking air in the intakes (I've got the carbs removed). I worked as best I could to get an even gap all the way around the two mating castings to make sure things were aligned. I can even spin the entire transmission and flywheel around and around the axis, leaving the engine setting there (tranny fluid leaks out the breather when it's upside down)
I've now got ratchet straps around the engine cylinders and the transmission mounts pulling opposite directions across the garage. I can wiggle and wiggle, and spin the flywheel and tranny by holding one of the tranny output flanges (that were attached to the half shafts) and turning the other. I can pry and pry (gently) at the castings, but nothing moves.
What's left to do?? Does anyone know any magic for seperation?
It is easier to take apart the transmission to get at things, or shoud I take off the heads & cylinders and split the case?

C. Clark · C. Clark's Garage

This is a bit outside the box, but I would try making wooden wedges and placing them strategically around this half inch space you have (if I'm visualizing this correctly).
Then taping them in symmetrically, wedging or pushing the two pieces apart. The up side is the wood should break or squish before the case and transmission materials do...that's the theory anyway. A soft wood like pine or redwood, maybe Doug fir, oak might be to hard. Sounds to me the input shaft is stuck in the pilot bearing, or the spline is jammed someway in the clutch disk. Interesting problem....wish I was there....
Chas.
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WFBowen · WFBowen's Garage

Of all the logical suggestions mentioned above, I'd still stick with djdsc's , as it seems that the input shaft is binding, so IMO stay with pulling while any weight is off of the case. Be very careful not to damage (bend) the input shaft. Maybe it's time to tear the motor apart since that's going to have to happen anyway and you can lessen the risk of damage to the trans (which I assume is still good.)

djdsc · 03-21-2010, 05:00 PM

You didn’t mention if you knew when that last time the engine and trans had been separated?

Visualize what is going on; the clutch plate is bolted to the flywheel, the input shaft runs freely through the clutch plate and through the splines of the clutch disk and into the pilot bearing inside the gland nut. Unless the throughout bearing/fork is hanging on the plate there is nothing to hold it in place. The input shaft can get rusty on the disk splines, perhaps spray some PB blaster or the like all around the splines and let it do its work (through the clutch fork hole). Prying is dubious but,,,,,, can you get something around the bell housing and the flywheel teeth like the two screwdriver method for removing bearings and pulleys?

Can’t wait to hear the answer for this hang-up.

scottangove · 03-22-2010, 06:34 PM

Another three hours of struggle with no answers, just questions.
Per suggestions above, I sprayed a good bit of penetrant into the holes where I can see the clutch fingers, fork and throw-out bearing.
Following the "two screwdriver" and wooden wedge suggestions; I made 10 little closepin-looking metal spreaders with 3/8-24 bolts & nuts and some scrap metal bar stock. I placed these evenly around the space where the cases are pulled away from each other, where I can look in and see the flywheel. I tightend the screws gradually until each piece of barstock bent. Each one of the 10 are exerting a near-casting-breaking force trying to seperate the cases. Fortunately, the cases did not break in any of the 10 locations. Unfortunately, nothing seperated.
What next?
Through the hole where the starter came out I can see the bolts that hold the clutch to the flywheel. As I stated above, I can turn the flywheel freely without moving the crank. Do I dare remove the bolts that hold the clutch to the flywheel, and pull them one at a time out through the starter hole? If I loosen then gradually, a little bit at a time, can I get them all out? What will happen then?
I mentioned splitting the engine case at this point, will that even help, or will I just be left with a transmission with a crank sticking out of it?
DJD, you ask about the last time the tranny was away from the engine, I know the previous owner swapped cams (he gave the the original and the box from the one that's in it). That must have been the last time. That was 1000 miles and 12 years ago.

C. Clark · C. Clark's Garage

[QUOTE Through the hole where the starter came out I can see the bolts that hold the clutch to the flywheel. As I stated above, I can turn the flywheel freely without moving the crank. Do I dare remove the bolts that hold the clutch to the flywheel, and pull them one at a time out through the starter hole? If I loosen then gradually, a little bit at a time, can I get them all out? What will happen then?
I mentioned splitting the engine case at this point, will that even help, or will I just be left with a transmission with a crank sticking out of it?
DJD, you ask about the last time the tranny was away from the engine, I know the previous owner swapped cams (he gave the the original and the box from the one that's in it). That must have been the last time. That was 1000 miles and 12 years ago.[/QUOTE]

If the flywheel moves and the crankshaft does not, one of two things have happened. Either the crank is broken, or the dowels that position the flywheel on the crankshaft have sheered...neither is good.
As far as removing the bolts from the clutch... at this point you have little to lose from what you say, if the spline is stuck in the clutch disk that would separate the trans from the engine. I would re-soak the spline going into the clutch disk with penetrating oil and let it soak for a day or so, re-soaking from time to time during this process. Then try the wedging or whatever method you like again. Very interesting situation....
Best of luck and keep us posted.
Chas.
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djdsc · 03-22-2010, 08:58 PM

Quote:

or the dowels that position the flywheel on the crankshaft have sheered

That is where I just flashed on as I was reading scottangove's last post.

If you do loosen the clutch attachment bolts, do it like you were installing it and work your around loosening each bolt a bit at a time so as to minimize any dangerous spring loading on the plate.

scottangove · 03-24-2010, 05:07 PM

The clutch bolts loosened easily. As suggested, gradually a bit at a time, around and around until they were all out. I could then pry the flywheel away from the clutch, and suddenly they were free! I could then remove the gland nut to take the flywheel completely off of the engine, and found each of the 8 little pins were sheared. Thanks to all of you so far! I feel less lonely in the garage knowing there's a team of guys across the country rooting for me.
The clutch is still stuck on the transmission input shaft spline. I put some penetrant on that, and will reapply for the next few days. What can I pry on without hurting the clutch? It looks brand new, and supposedly has only 1000 miles on it.

Back to the big problem. the crank-to-flywheel pins look like they broke cleanly, with little or no damage to either the flywheel, or the crank. This must be common. What's the next step? I assume I am to take the engine apart to get the crank out, but what then?

Scott Douglas · Scott Douglas's Garage

Hate to be the barer of bad news but 6 of those 'little pins' are bolts.

C. Clark · C. Clark's Garage

Quote:

Originally Posted by Scott Douglas

Hate to be the barer of bad news but 6 of those 'little pins' are bolts.

Don't you just love it when someone jumps in to be the "bearer" of bad news......without any help.

Back to the issue, seems like you had a catastrophic event. Now that the two are separated does the front end of the crankshaft move the rear end of the crankshaft? If it does the crank is not broken, if one end moves and the other does not it is. Regardless the engine is going to have to be torn down, the crank may be repairable. If the bolts are broken and the dowels are sheared the crank may not be a total lose. I suppose I would tear the engine down and take the crank to the best machine shop I could find...see what they say, and how much it will cost. A major rebuild is probably in you future. The clutch disk can probably be driven off the transmission spine without damage if you soak it and are careful, best of luck.
Keep us posted,
Chas.
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pete3799 · pete3799's Garage

I wouldn't be too quick about splitting the case. A good welder can get the bolts and pins out as is. Might get by with just a top end rebuild. Might get real lucky and just bolt a new flywheel on and go but i doubt it.

djdsc · 03-25-2010, 05:10 PM

Quote:

Hate to be the barer of bad news but 6 of those 'little pins' are bolts.

Damn Scott I am always amazed at what you see in photos. Are there really bolts where the dowel pins should be?

If that is the situation then this is not that crank's first rodeo.

Quote:

I wouldn't be too quick about splitting the case. A good welder can get the bolts and pins out as is. Might get by with just a top end rebuild. Might get real lucky and just bolt a new flywheel on and go but i doubt it.

Depending on what is actually going on; bolts and dowels, they might be able to be removed and you luck out. Not likely if bolts but it wouldn't be the first time over sized dowels were fitted into the crank and flywheel.

C. Clark · C. Clark's Garage

It would be good to get a better photo of that crankshaft end....what was the event that caused this? did you drop the clutch with it floored?
If there was sheering... either the dowels, bolts or whatever were sub par / weak....or the torque was massive, maybe this was a shade tree fix or something......
Interesting problem though, keep us posted.
Chas.
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scottangove · 03-28-2010, 04:12 AM

All 8 are pins, just like original. The only mention of bolts was scott douglas' post of 3/24. he's wrong, all of the pins are pins. The ends that were into the flywheel fell out when I removed the gland nut and took the flywheel off.
Clark asked about the crank being intact. It does appear to be, as a wrench on the pulley end turns the entire crank, and seems to move all the pistons correctly without any grinding noises, and I can see the flywheel end rotating.
My plan is to put the engine on end (pulley-down) and put it under the drill press. slowly spinning a drill into the center of each pin. The bit may bite in allowing me to extract the pin, or I may have to use an easy-out. Has anyone had luck with this method? I hate to introduce any heat, possibly warping the crank. Are replacement pins available? What else have others done in this case?
Clark asks about what caused it. In my first post I mentioned the sticking throttle linkage. In my panic, I reached for the key and the clutch at the same time. Damn key was on the left, but I did find the clutch, sparing the entire car and driver from a crash, but did over-rev the engine terribly. It all happened so fast.

C. Clark · C. Clark's Garage

Pins... that Porsche place in Willoughby, OH... which our host does not allow in text here, it starts with a st and ends with ds...very weird, sells the pins.

I would at the least consult a machinist about removing the pins, although someone may chime in. The pins are hardened steel and could be a problem drilling, removing, etc.
I still believe the proper method at this point is to remove the crank and contact a machinist. I believe the pins are pressed in ...and out with a press, drilling could damage the seat.
Best of luck,
Chas.
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