I had this problem as well; after doing a search it turns out it's not that uncommon.

I fixed it by roughing up the parts of the seat rails that contact the clamp.

I used a medium file and just did a mild criss-crossing; nothing too deep since you don't want to create a stress riser that could cause a rail to break.

FWIW, I don't think a "Y" tool provides enough leverage to properly tighten a seatpost clamp.


To answer your questions:

1. Cheapo seat posts usually have clamps that can go either way. Pictures of yours would help.

2. Odds are good that the seatpost was sourced from China so replacement parts might be hard to come by. 31.8 mm is not uncommon; replacements are available for well under $40.

3. While there are some variations in saddle rail width yours is most likely standard so yes, you could swap them over. Occasionally you have to coerce the rails to go into the clamp grooves but since the rails of most saddles are mounted in a flexible shell this is not an issue. Again, photos might help.