Bottom Bracket Conversion, Need Help
 

I'm working on a late 1990s donor bike for our church's Bicycle Ministry. It's a vintage, rigid for, mountain bike. The original bottom bracket, a cartridge type, is toast. The objective is to repair these bikes with a minimum of cash outlay. So my plan is to replace the cartridge with a spindle type of which I have about a dozen in my spare parts bin. I should point out, this has an E type front derailer that mounts to the frame via the right side of the BB. The original BB is 113mm to fit a 68mm shell. So I found the smallest spindle I had, a 116mm and figure a little overhang on each side, no problem right? I was wrong. Two problems. First, the cup I chose went in so far that the lock ring had no threads to screw on to. So I replaced that cup with another that extended outward. Now I can get a purchase for the lock ring (barely) but when I torqued down the left crank arm, it hits the cup and won't turn. It appears the E type derailer that mounts on the right side of the BB is messing up my calculations. Before I go crazy trying different spindles and cups, is there something I'm missing here? Should I just throw in the towel and buy a cartridge type replacement?
I've successfully done this before, but never with an E type derailer. Any thoughts or suggestions appreciated.

Cannot give you exact help but to say I've had the similar problems, with the left crank once bolted up rubs on the near side NDE, also the same with the NDE side retainer ring screwing in all the way. There was a similar posting on here recently, & I dug out 6 NDE BB retainers cups they all had the same OD thread but were all different length, & different I.D. as well I posted the photos but since deleted them from my photo files.

As you know doubt know going from 113 to 116 will only give you 1.5 mm each side, I recently built up a BB assembly having took out a 113.mm axle, & using a different crank had to install a 126.mm axle so that the small chain ring did not hit the chain stay ??

I think you have a severs case of trial & error, sorry cannot be much more help, go for longer axle.

Use a spindle made for a 70 or 73mm BB.

The problem is that the FD mount effectively widens the shell, and you have to choose parts with the new effective BB width in mind.

Also, keep in mind that cups with thicker outer walls use up more of the outer segment of the spindlemail, which is why your crank was bottoming against the cup face.

Shimano UN26 is only $8.
Cup and cone bottom brackets have no seals. So, a cartridge-type bottom bracket is much superior.
Shimano UN26 Square Taper Bottom Bracket | Chain Reaction Cycles

New brake pads for old brakes are also cheap. I wouldn't skimp on these either.

When exact-fit replacement cartridge bottom brackets can be sourced for around ten bucks, that's probably not a bad idea.

do you not have a clamp-on front derailer lying around in the junk parts bin? just lose the E-type

Lots of really good input here, including some factors I didn't think of. So thanks to everyone. I agree, this is going to be trial and error. However, based on the posts here, I'm going to try one more spindle, but a longer spindle. If that fails, I found a slightly longer cartridge type BB going through my spare parts. If neither of those work, I'm just going to donate the $$ and buy a direct replacement BB for it.
Thanks again for the great responses.

OUTCOME
I gave up on trying to use a spindle. Just won't work with the E type derailer. I used the slightly longer cartridge and it worked first try. Just had to adjust the front derailer. Thanks again for the input.

+1 this. You're likely to spend as much or more converting it to a cup-and-cone bottom bracket.

Not necessarily. Several manufacturers, including Tange, Shimano, and Campagnolo, made cups with neoprene seals that fit tightly around the spindle. When used with an appropriate sleeve inside the shell, they're quite effective at sealing out contamination.

http://www.os2.dhs.org/~john/sealed-cups.jpg