Bottom bracket 72 Paramount, Dura Ace?
I'm building up a 72 P-15 Paramount frame. I was planing on using a 1st generation Dura Ace crankset (double) that I acquired. The dimensions for the bottom bracket I believe should be 68 mm by 112 mm for the spindle length and english threads. I've seen Dura Ace 7400 BB for sale with these dimensions, will they work with the first generation Dura Ace? How does the Dura ace # sysytem work (year) ? Did the first ones have a #? I tried some cups from old japanese BB and they threaded on fine but the cup with the two flat sides did not completely thread on at the very end where the threads ended on the cup but continue on the frame (at least that looked like the case). Any thoughts?
BB can be a real mystery, especially when experimenting with vintage components. I always find the entire process a bit of a challenge. There are so many factors; frame geometry, crankset, chainring size, etc., that knowing how to advise is nearly impossible.
If money is of no concern, Phil Wood BB system probably makes the most sense. You will need the English threads, and the 68mm width is correct. A Phil BB will set you back about $130-150 for the basic stainless steel spindle and cups. So which taper and what length do you need?
Here's a link to the Phil Wood BB Spec page. As you can see there are lots of possibilities. My guess is you will need JIS 108mm to 113mm spindle width. But this is only my guess. Best of luck.
Check Sutherland's Manual. I don't think it will work properly if I understand what you want to do. You want to use an older DA crank with a 7400 BB, right?
What model # crank?
All I know about the crank is that is supposed to be from the 1st dura ace group. Looking at pictures this appears to be true. I'll look at it again but I didn't see a lot of info other than a 3 near the bb portion of the crank with chainrings. I was planing on using a bottom bracket from the 7400 group with simillar dimensions as they seem to be readily available.
If they are both the same length, and are the same as far as symmetrical/asymmetrical, they should work.
The 7400 BB's I've seen are about $60+ shipped for a new one.
Could you explain symetrical/asymetrical as it relates to the bb (spindal)? Iv'e seen this before but not an explination. The crank hole are square with a slight grade (angle).
Karl, if the spindle is asymetrical, it simply means it extends beyond the BB shell further on one side than the other side.
Originally Posted by KarlWilker
You could also get a sealed Shimano cartridge bottom bracket for under $20-30 (UN54 for instance). They come in many spindle widths (107, 110, 113, 115, 118, 122, and 127) so I am sure you would be able to find one that works. They are a set and forget part and in the way distant future if it does go bad you just replace it.