I recently had a manual transmission repaired because it was slipping out of 4th gear while driving down the road. I took out the engine/transmission and gave the transmission to a local garage to overhaul. After getting the transmission back, I put everything back together and now the car is acting strangely. I put the car in 1st gear and start going and get a lot of clanking noises and can not shift to 2nd.
Prior to doing this job, the car was shifting nicely. Now with the engine stopped and in neutral the car will roll easily. If I depress the clutch it will also roll easily. However if I put it into 1st gear with the clutch still depressed, it will stop rolling. I'm not sure if it is the clutch or transmission. I took out the clutch again but could not find the problem. But after putting the clutch back and taking it for a test, it was working properly. But then after 2 kilometres, I got the clanking back and grinding the gears trying to put it in 2nd.
I would be grateful for any help. The car is an Austin Allegro 1981.