Bicycle Mechanics - Oddball BB threads on DB Crestline?

I'm in the process of trying to rehab a Diamondback Crestline touring frame. I assume it's from the early '90s. I'm having difficulty getting a cartridge BB into the shell. The BB shell is threaded in the right directions for a standard, English-threaded BB (left-threaded on drive side), and it seems to be the correct diameter, but it feels like the threads aren't quite matching on either side. The cups will thread in about half a turn, then come to a halt. It's possible that I just gunked up the threads during the re-paint, but before I start applying cutting oil and brute force, :) I thought I should check here to see if anyone here might have some knowledge of peculiar threading on these frames. Anyone?

DO NOT APPLY BRUTE FORCE!!! It should be possible to install a clean, greased BB *by hand*, using the wrench only to tighten it once it's fully in. I've seen too many threads ruined from brute force (most recently a newbie friend of mine destroyed his pedal threads after I encouraged him to install pedals himself and tried to brute-force them in).

I'd be very surprised if that frame wasn't threaded for a standard English BB, definitely. Have you tried cleaning the threads with degreaser and a toothbrush, then inspecting them for any slight damage or cross threading?

Sorry, I can't give any more specific info on the frame, but good luck.

Thanks for the calming guidance. As it turns out, I found a complete older, non-cassette BB in a ziploc at the bottom of my toolbox. I cleaned and greased it, and it just glided smoothly into the Crestline shell. Glad I still had the tools for it.

Now I'm trying to figure what the deal is with the BB I tried first. Are there 68mm cassette BB's that are left-hand threaded on the drive side, but don't have English threads? This one came from a 1997-ish Wheeler road bike, and everything else on that bike as been as standard as they come.

Thanks for the calming guidance. As it turns out, I found a complete older, non-cassette BB in a ziploc at the bottom of my toolbox. I cleaned and greased it, and it just glided smoothly into the Crestline shell. Glad I still had the tools for it.

Now I'm trying to figure what the deal is with the BB I tried first. Are there 68mm cassette BB's that are left-hand threaded on the drive side, but don't have English threads? This one came from a 1997-ish Wheeler road bike, and everything else on that bike as been as standard as they come.
Glad you found something that works!

The other cartridge BB sounds like a mystery. Is it possible that you have the left and right sides of the cartridge BB mixed up? Usually the left-side mounting ring ("cup") is free, while the right-side mounting ring is permanently pressed onto the cartridge body. Sorry if that seems too obvious, but I've been known to make that kind of mistake a lot :)

Are there any marking on the cartridge BB? Sometimes they say "1.37 x 110mm" or something like that. The 1.37 inch part is the diameter of the threads on an English BB, which would confirm that it's English-threaded.