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Discussion Starter · #1 ·
I'm replacing the automatic transmission behind a 2001 4.0 with a manual. When comparing the timing slots on the original flex plate with the timing slots on the new flywheel (which replaces the flexplate), I noticed that they are shifted by around 1 degree (which equates to around 3/16" at the outer surface of the flywheel). So for my question: I have to drill a hole in the bellhousing for the crank position sensor. Should I duplicate the CPS sensor location relative to its original position in the transmission housing - which is optimized for a flexplate installation? Or, should I shift it 1 degree (~3/16")? I'm inclined to guess that the slots are shifted on the flywheel to account for the higher magnetic permeance of the flywheel. Does anyone has any insightsuggestions? Or better yet, does anyone have a factory manual transmission lying around - where you they could measure from center of CPS to center of transmission bolts (left and right of CPS)? Many thanks!
 

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You should put it exactly where the factor put it on the manual bell

Assuming you ain’t using that POS German 6 speed


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Discussion Starter · #4 ·
You should put it exactly where the factor put it on the manual bell

Assuming you ain’t using that POS German 6 speed


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Given that I started off with an automatic transmission, there is no factory bellhousing (in my possession). The bellhousing that I will be using does not have a pre-drilled hole for a CPS - I need to drill one (and I'm only gonna get one shot at it).

So, I know where the factory put it on the automatic transmission, but I don't know (for sure) where the factory would put it on the bellhousing of a manual transmission (ie. same location, or shifted by 1 degree)???
 

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Seems like the logical action would be to get your hands on a factory bellhousing and take precise measurements
 

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Better yet just get the proper bell that has the hole already

Fortunately both the TJ 4.0 5 speeds have removable interchangeable bells

I did drill a hole for a sensor on a rebuilt pathfinder auto tranny that lacked it but fortunately the raised flat part where hole belonged was cast into the housing already




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Discussion Starter · #7 ·
UPDATE: I did a little test this evening by hooking-up an LED+1k resistor to the CPS signal lead (with a +5v DC source) and manually slid the CPS along the slots of the flywheel and flexplate – to see if they trigger the LED at different relative positions. They behaved identically, both, on the rising pulse and falling pulse. This leads me to conclude that the physical differences between the flexplate and bellhousing have no effect on the CPS switching behavior. Hence, the 1-degree offset is probably due to a manufacturing flaw of the aftermarket flywheel that I purchased. As such, I plan to offset the CPS to match the flywheel. When it’s all done, I’ll post an update with the results.
 
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