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Old Mar 21, 2018 | 05:28 PM
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joeybbad's Avatar
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Default transmission troubles

2002 chevy trailblazer
I mashed down on thew throttle, and at about 30-40 mph, there was a loud bang. At that point, i rolled to a stop with no forward movement. I tried 2wd, 4wd, still nothing in D. I shifted to 2, and was able to move forward. I have to put it into 2 to take off from stop. once above 30 mph. i can manually shift into D, and it holds, unless i drop below 30 mph, then i have to manually shift down to second to get it to catch, and go again.
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Old Mar 21, 2018 | 05:34 PM
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Sounds like the forward sprag let loose
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Old Mar 21, 2018 | 06:15 PM
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^^^ yep,blown forward sprag. Starting in 3rd or 4th,the sprag does the work. Starting with shifter in 1st or 2nd,the overriding clutches take over and the sprag plays no role. I drove my Z for 4 years that way,it took that 4 years to blow the 4th gear clutch,then replaced the tranny with a used one.
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Old Mar 21, 2018 | 07:33 PM
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Originally Posted by FirstYrLS1Z
^^^ yep,blown forward sprag. Starting in 3rd or 4th,the sprag does the work. Starting with shifter in 1st or 2nd,the overriding clutches take over and the sprag plays no role. I drove my Z for 4 years that way,it took that 4 years to blow the 4th gear clutch,then replaced the tranny with a used one.
The forward sprag is engaged in 1st, 2nd and 3rd even when manually selected.

The sprag is not engaged in 4th.
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