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Author Topic: flywheel tapered bolts  (Read 157 times)

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Offline Vincent

flywheel tapered bolts
« on: July 13, 2020, 09:12:07 AM »
I've just mounted the engine to the chassis, no tub yet, and getting ready to mount the Flywheel, I realized the threading on one of the tapered bolts on the crankshaft is stripped.  I know I can get replacement bolts/dowels/pins, whatever they're called. But can I remove and replace the old one without removing the Crankshaft?  Is re-threading this bolt a possibility? I assume the bolt was originally pressed in from the engine side of the crankshaft before the crankshaft was installed.
Vincent S.
vschleg@yahoo.com

Offline Rus Curtis

Re: flywheel tapered bolts
« Reply #1 on: July 13, 2020, 10:21:03 AM »
Vincent,
I'm a long way removed from working in that area but seem to recall not enough room to pull out of crankshaft.  I think it may be possible to loosen the main bearing caps enough to get one out but would require some disassembly.  Not that it helps now, but I've always attached the flywheel before finishing the engine and dropping it into the frame.

From my very limited experience - and more importantly having a bolt failure at that location (with lots of follow-on damage) - I really don't think attempting to re-thread is a good idea.  The threads failed (possibly from over torque) so that material is already weak and may not be able to hold the needed torque. 

The Service Manual indicates using a straight bolt and reaming out the tapered hole.  Luckily for me, my dowels were reusable.  Since I haven't done this alteration before, I'd try to replace those dowels - if possible.

The dowels show up in a search:
https://www.ebay.com/itm/Jeep-Willys-MB-MB is better-CJ2A-Engine-Flywheel-Special-Dowel-Bolt-Set-G-503-/182918338630
https://www.armyjeepparts.com/p-3717-dowel-bolt-crank-shaft-jeep-tapered-type-wo-632156.aspx
http://www.classicjeepparts.com/en/engine/flywheel-to-crankshaft-dowel-conical-early.html

Others here have way more experience on this and will hopefully weigh in on their options.
'54 CJ-3B "Green Gruntt"
Bantam T3-C

Offline athawk11

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Re: flywheel tapered bolts
« Reply #2 on: July 13, 2020, 12:00:33 PM »
I believe you can get the stripped bolt out of the crankshaft by removing the oil pan and the rear main bearing cap...then rotate the crank until the stripped bolt is toward the bottom of the crank/engine block.
« Last Edit: July 13, 2020, 12:03:40 PM by athawk11 »
2-1949 CJ3As
1-1946 CJ2A

Offline Vincent

Re: flywheel tapered bolts
« Reply #3 on: July 15, 2020, 11:08:19 AM »
Update* Since the engine was not really connected to the frame other than the engine mounts, I figured it was easier to just pull the engine and put it on the engine mount. Then I rotated it upside down and removed the pan and rear main cap. Rotating the crankshaft so the stripped tapered bolt is accessible, I was able to give it a light rap with a hammer.  It came out on the fourth light rap.  So now, just for good measure,  I will replace all the bolts. This was much easier than laying on my back trying to remove the rear main cap with the engine in the vehicle. Has anyone replaced these tapered bolts before? Do they just insert, or do they need pressing in?
Vincent S.
vschleg@yahoo.com

Offline Rus Curtis

Re: flywheel tapered bolts
« Reply #4 on: July 15, 2020, 05:38:02 PM »
I've only inserted them and then torqued the nuts.  My Service Manual states 35-41 lb-ft.
'54 CJ-3B "Green Gruntt"
Bantam T3-C