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Stripped Speed Sensor Threads. Need tap


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I stripped my speed sensor thread on the tranny of my 96 outback manual. I'm putting a new one in but the first 2 rows of threads are knarled up on the tranny. Does anyone know what thread size that is so I can get a tap? Or at the very least a bolt that fits in there that I can fake it with. Any help would be greatly appreciated. Thanks

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Doubt you'll be able to find a tap.

How bad are the treads on the old sensor chewed up? Usually those can be cleaned up with a wire brush or something. Or use a dremel to grind off the first couple rows of chewed up thread, then cut some notches in the remaining threads and use that as your tap to clean up the threads in the case.

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take the speed sensor to a hardware store and see if a nut threads onto the speed sensor threads?  if it does - then that nut has the thread size.

 

speed sensors are odd - but Subaru typically uses the larger sizes of M12x1.25 and M10x1.25.   so look for metrics and 1.25 pitch.

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I nearly had to do similarly on my 97 Impreza. I managed to get it in and attached using the wire brush.

 

If all else fails, just grind the threads down on the sensor and used some JB weld on the sides and pop it in. Let it set and drive. You likely would have to break and drill out the sensor to ever replace it again, but they are not an extremely common failure.

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Most anything will work for cleaning threads just so you can get a new bolt or part to thread in. You're not cutting new threads in a freshly drilled hole, you're just getting the rough edges and crud/shavings out of the current threads. If the sensor were plastic, then it may not work too well to clean threads in an aluminum case.

 

Speed sensors don't fail all that often, why is this one being replaced a second time?

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Ive used a dental pick top clean the threads but its still pretty jacked up. Best I can tell is that it's either a 22 x1.50 or a 25 x 1.50 so I don't think a spark plug is anywhere near that size. I replaced it the first time cause my speedometer stopped working after flying down a rather bumpy road. The little blade that turns on the speed sensor had broken loose inside the sensor. The new one did the same thing after 2 weeks or so. I'm wondering if I just didn't get it screwed in far enough because the threads were screwed up, if thats the case then maybe it wasn't fully seated and that broke the blade.  I check so see if part that turns the sensor was loose or something but its all tight so I'm not sure what else it could be.

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woah - that's a very strange failure.  if it happened twice then i'd think something is causing it...you're thinking threads?

 

take the sensor to a hardware store and match up the threads.  alternately if you want to guess - measure the diameter with a caliper or keep inserting something until it's a tight fit - meausre it and extrapolate the size of the bolt.

go to the hardware store for a bolt that fits. 

 

you can lay another 1.25 or 1.50 thread pitch bolt against any other 1.25 or 1.50 matching bolt and they'll mesh perfectly - even if the diameters are way off - the pitch is the same and they meld togehter like butter.  so you can easily confirm the thread pitch that way - lay a 1.25 and 1.50 thread pitch bolt again the threads and see which ones line up.

 

i've gone in and bought multiple bolts - guess and then buy your guess and one or two sizes larger and smaller depending how accurate you think you are.  at 0.03 cents each it's a no brainer.

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