I have a 2005 Chevy Astro van with about 185,000 MI the past week having a hard shift between first and second gear never had the problem before.
Saw one of Scotty's videos .. removed one quart transmission fluid replace with Lucas Transmission.. sometimes it shifts smooth sometimes it doesn't I've got about a hundred miles on it since I put the Lucas treatment in.
I've read online it could also be a transmission solenoid causing the problem also with throttle positioning sensor.
Sometimes it's shifts very smoothly and then sometimes thuds between first and second at around 15 to 20 miles an hour.
I am not the original owner probably a couple previous owners I don't believe the transmission was ever serviced don't want to change the fluid only for the simple reason it could do more damage than good.
I'm at a total loss right now just don't have the money to have a transmission rebuilt hoping this could be a minor repair like I said the Lucas treatment seems to have made the transmission shift a little smoother but still having that thud between 1st and 2nd.... wondering could it be a rear-end problem or perhaps broken motor mount or transmission mount as well I'm at a loss I'm going to try to get by with the Lucas but I just feel totally lost here any advice would be great thank you.
At that age and mileage the transmission is probably wearing out especially if it has not been serviced regularly over its life. You can't really expect an additive like Lucas to do much beyond a certain point. However it is worth examining motor mounts and u-joints for wear and slop, which would be typical wear items for a vehicle that old. Beyond that you'd need to have the transmission analyzed by an expert using a professional-grade scan tool.
the transmission has had it. You're lucky it made it this far without service.
