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I am preparing to do my first transmission (manual) rebuild job. I was just curious if it is possible to test whether the job has been done right while the tranny is off vehicle while simulation torque transfer and clutch hydraulics ? E.g. can you manually or some other way be cranking the transfer shaft while using a hand-held (or pedal driven) clutch simulation so that I know I did everything right before putting the tranny back on?

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    You can test the transmission by putting it through the gears while turning the input shaft and examining the output shaft for proper rotation. You cannot test the clutch while off the car. I has to be mounted to the flywheel, and the flywheel needs to be mounted to the engine. You can bench test the hydraulics to ensure they work. Other than that, you have rely on doing a good job and putting it back together correctly. – Pᴀᴜʟsᴛᴇʀ2 Jun 8 '15 at 23:23
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You can test the transmission by putting it through the gears while turning the input shaft and examining the output shaft for proper rotation. What I mean by this is, put the transmission in first gear and check the output shaft rotation speed as you turn the input shaft. Next, put it in second gear and again check the output transmission speed. Does the speed seem slower than when you have it in first? Check the rest of the gears, sequentially to ensure the transmission is shifting into the correct gears and the transmission is performing as expected. Put it in reverse to see if the output shaft counterspins.

You cannot test the clutch while off the car. It has to be mounted to the flywheel, and the flywheel needs to be mounted to the engine.

You can bench test the hydraulics to ensure they work. Other than that, you have rely on doing a good job and putting it back together correctly.

  • does the tranny need to have oil in it while "dry" testing it off vehicle ? – amphibient Jun 9 '15 at 20:27
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    It wouldn't hurt anything not to. You aren't putting any really torque on anything nor causing any mesh issues which would cause any wear. You are just running it through the gears to see that everything works. – Pᴀᴜʟsᴛᴇʀ2 Jun 9 '15 at 20:49
  • BTW, do you have any idea on the weight range for the tranny on a Tacoma ? I'm trying to figure what size jack i should get – amphibient Jun 9 '15 at 20:51
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    @amphibient - If you have to buy one, get a transmission jack. They are a lot safer and easier to use. Anyway you look at it, you'd need to buy jack stands to get it out from under the vehicle (unless it's a 4x4 and you have it up on mudders ... but then you have the transfer to worry about as well). You may be able to get the tranny lowered down, but I doubt you'll get it out from under the body without having it jacked up (refer back to mudders though). Tranny jacks are fairly universal in size and capacity. You can get a decent one from Harbor Freight here in the States relatively cheap. – Pᴀᴜʟsᴛᴇʀ2 Jun 9 '15 at 22:45
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    @amphibient - Get the largest tranny jack you think you can afford. If you ever want to use it again for a different vehicle, you'll have the capacity if needed. Yes, I'd get all four corners up. It makes it a lot easier to stab the transmission back into the vehicle if you have the vehicle and engine level (may require you to have a jack under the pan of the engine to get it that way). – Pᴀᴜʟsᴛᴇʀ2 Jun 9 '15 at 22:56
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you can test the clutches, just apply some air to the holes at the enf of the shaft, get something to seal it so the air doesn't leak. weberauto on youtube shows him applying shop air to test clutches, sounds like a clack sound, loud

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