View Full Version : 10mm or 12mm banjo
18th March 2005, 17:38
What exactly is being measured at 10 or 12 mm?
18th March 2005, 18:12
Any metric bolt you buy is measured at the threads ... A bolt that is sold as a 10mm may have a 14mm head that requires a 14mm wrench to tighten.
18th March 2005, 18:28
OK Ron, does that just apply to metric bolts? what about SAE?
now let's go back to metric bolts, since that's what we're talking about before - is the measurement taken at the edge of the threads, or on the inside? If you measure with a dial caliper the outside of the threads on the bolt, then the inside of the nut, there would be a difference of twice the thread depth, right? That might be outside of the tolerances - which measurement is the right one (or neither).
The reason is: I've got an FXDX braided brake line that I'm going to put on my 1200R - which has a wierd banjo bolt at the master cylinder (I think it's 1/2"/ 12.7mm) If I ream out the banjo fitting to the size of the threads on the bolt, will that be too large?
18th March 2005, 18:41
I have not read the info in this link, but I believe it will explain everything you want to know about fastener sizes: http://www.boltdepot.com/fastener-information/Default.aspx#general
Here is something that costs no more than 5 bucks that is readily available. Seems like you could put it to good use:
18th March 2005, 18:56
This may be the best internet site I've ever found (except for www.xlforum.net)!
18th March 2005, 19:06
Thanks for the input. I think I need to clarify further. I am in the process of looking for all new banjo bolts for the entire brake system. The basket case i picked up did not come with these items. Better yet, the brake system is a combination of parts produced over the past twenty years. So unfortunately, I can't go to good old JP's and order a standard replacement set for an 86 xl.
So, the real reason I asked the question. The front brake line is an OEM off a ~97-99 dyna. The master cylinder end clearly requires a 7/16" banjo bolt with 24 threading. The caliper end requires a 3/8" with 24 threading. So, at which point in the equation is the 10mm or 12mm taken into consideration?
The only thing I can figure, is that the thickness of the Banjo fitting is 10 or 12 mm. I say that because when I hold the two ends side by side the caliper end is thicker than the master cylinder side. :yikes
18th March 2005, 19:24
Nurple .... I wish I could be of some help, but I'm not sharp enough with the problems your faced with ...
Maybe someone one else here could lead you down the right path.
18th March 2005, 21:16
Nurple... The 10mm or 12mm refers to the size of the Banjo fitting opening. The bolts themselves can be metric or SAE. Metric size banjo bolts have 2 thread pitches 1.00 and 1.25 mm. the SAE is usually 3/8" x 24 threads. New HD's use Metric thread Banjo bolts but I'm not sure what thread pitch. Hope this helps
21st March 2005, 05:56
The 10mm or 12mm refers to the size of the Banjo fitting opening.
FWIW, a 10mm banjo and a 3/8" banjo are one in the same. Some of the aftermarket performance plumbing company's (Earl's, for instance) will have two part numbers but the banjo is the same. The difference will be in the banjo bolt.
21st March 2005, 10:15
just to add to this..... HD uses 2 bajo bolt sizes...
a 10 and a 12... one is for twin disc master cyls and the other for singles....and I can't remember which is which off the top of my head...
the 10mm and 12mm refers to the major or outside diameter....
a 10mm or 12mm banjo bolt or washer refers to the inside diameter or hole of the banjo bolt or washer
21st March 2005, 15:02
Only thing is, Stevo. The 2004+ 1200R's (and I'd guess the 883R's too now) use a 12.27mm bolt aka 1/2". If you look in the catalogue, the braided brake lines for the 1200R doesn't come in the extended lengths like the others. Probably some newbie engineer who had a last minute fix on his hands and wasn't worried about backwards compatibility. Makes life more difficult for us trying to do a little customization on our bikes!
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