68 Cutlass Tranny Swap - Flywheel Question

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Old Jan 1, 2012 | 09:39 PM
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cbold68's Avatar
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68 Cutlass Tranny Swap - Flywheel Question

Hello,
I have a 68 Cutlass with a 2-barrel/350 engine and the jetaway transmission. I am swapping out to a TH350 and the bolt holes on the torque converter match up with the flywheel but there is a gap between them when I try to bolt them together and it looks like it needs some washers to fill in the space between the two at each of the bolts because I can't get two to bolt together flush. I believe the TH350 is out of a 72 Cutlass. Could it be that I need to get a different flywheel?

Thanks, Chris
Old Jan 2, 2012 | 03:45 AM
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Run to Rund's Avatar
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All 68-up flywheels are the same. No washers. Your torque converter isn't plugged into the end of the crankshaft all the way--but it needs to be.
Old Jan 2, 2012 | 06:00 AM
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Unless your looking for a reason to tear into the engine don't shim the converter to flexplate gap! The flexplate is designed to "flex" if you shim all the free play the converter will push the crank forward and wipe out the thrust bearing. You need about a 1/4 inch of clearance.
Old Jan 2, 2012 | 08:42 AM
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Originally Posted by matt69olds
Unless your looking for a reason to tear into the engine don't shim the converter to flexplate gap! The flexplate is designed to "flex" if you shim all the free play the converter will push the crank forward and wipe out the thrust bearing. You need about a 1/4 inch of clearance.
I have no idea what this means, but the converter MUST be seated against the flexplate. Likely there is some rust in the end of the crank where the converter sits. Try spraying a little penetrating oil on the pilot on the converter before pushing it against the crank. The bolts should pull the converter the rest of the way, but don't pull all the way with one bolt. Rotate the engine and progressively tighten them to avoid bending the flexplate.
Old Jan 3, 2012 | 04:56 AM
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Thanks for the help.
Figured I must be doing something wrong.


i appreciate the info!
Old Jan 3, 2012 | 05:13 AM
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Originally Posted by joe_padavano
I have no idea what this means, but the converter MUST be seated against the flexplate. Likely there is some rust in the end of the crank where the converter sits. Try spraying a little penetrating oil on the pilot on the converter before pushing it against the crank. The bolts should pull the converter the rest of the way, but don't pull all the way with one bolt. Rotate the engine and progressively tighten them to avoid bending the flexplate.

I meant don't shim the converter into the trans. I have seen people use a stack of washers, thinking the gap between the flywheel and converter is excessive. Then the converter isn't line up with the crank centerline (due to the converter pilot not sitting in the crank hub) and the converter is bottomed out in the transmission pump. When the flywheel flexes and has no room to move it will wipe out the thrust bearing and the trans pump. Something has to give.
Old Jan 3, 2012 | 09:20 AM
  #7  
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Originally Posted by matt69olds
I have seen people use a stack of washers

wow
Old Jan 13, 2012 | 01:21 PM
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It should be a direct bolt in. Pulled the jetaway out of my 68 and replaced with a 350 trans and heavy duty converter from a 72 pontiac. The lines, driveshaft, and trans mount are all the same size / mounting locations. The only change is that you need either the correct gas pedal with the extra slot to hook the downshift cable through the firewall or a bracket to hook a downshift cable to the carb. If your jetaway has low miles on it you can use the converter right from that. Mine had a 130k on it so I went with the converter from the 350.
Note the torque converter bolts from the jetway were not the same size as the ones from the 350. they fit but were very sloppy.
Old Jan 15, 2012 | 06:22 PM
  #9  
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You may want to check your torque converter alignment to the transmission pump...If it is not aligned,,this could possibly be causing your offset issue....

Last edited by panther80; Jan 15, 2012 at 06:23 PM. Reason: spell check
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