I recently replaced my transmission with a used one i bought at a scrap yard and everything seemed fine at first. Now when I put the truck into reverse, it shifts pretty hard. Every other gear shifts fine its just reverse. When I took my old tranny off, the entire pan was full of metal shavings and i did not think about flushing the cooler system. Could shavings have gotten into the cooling system or could I have gotten a bad tranny or installed something wrong?

I am going to replace my tranny fluid tonight but if anyone has any suggestions it would be very much appreciated

 

Metal particles from the old trans have probably contaminated the "new" trans.

You shouldn't flush the coolers after replacing a failed trans. You need to replace the coolers, there is no effective way to clean them. Metal particles from the coolers is one of the leading reasons for multiple transmission replacements.

 

is it a bad idea to buy a used cooler or should i just get a new one?

 

If a used one is probably no better than the one you took off.

 

alright well i will be looking into getting a cooler soon! I just changed my fluid and when i pulled the pan off, the filter was on the bottom of the pan and next to it was a large nut, maby 1/2". any ideas where this came from? did i mess up going with a used tranny?