Front Brake Line Splitter Bolts

Not sure if anyone has come across this before but I'm restoring the top triple tree and bottom yoke on the steering and am at the point of attaching the brake line splitter on the bottom of the lower yoke.

In my infinite wisdom I did away with the old bolts (x 2) that held the splitter in place.

Now I find that a standard M5 (5mm) metric bolt is a tad too small and a standard M6 (6mm) bolt too big!?

Was this some sort of ancient M5 metric bolt with a different thread pitch? My research says that current M5 thread pitch is 0.8 but that Japanese bikes used an 0.9 thread pitch on some bolts in the 70's and 80's.

Just curious.

I think the solution might have to be drill and tap to M6...but that means I'll have to also drill out the mounting holes on the splitter.

Always something...!

;-)

 

you don't say which bike!!
my 600 deff, has bog standard m6 x 1.0 bolts



just been out and checked em.
stu

 

Or use 2 hoses and skip the splitter

 

Try this...
http://www.xjbikes.com/forums/index.php?threads/xj-parts-catalog-section-j-brakes.44636/
Very Bottom of the Page, Section J, If I remember correctly. Proper mounting bolts for your distribution block.

If you decide to try something like Polock mentioned, be sure that you are using DOT cert. Stainless Braided lines... Using 2 longer OEM-Style Rubber Brake Line hoses and bypassing the distribution block results in a much longer amount of hose and possibly a 'squishy' brake feel because of additional pressure swell in the longer lengths of hose.

 

Hi,

Thanks for the feedback. Any information is appreciated.

Firstly, my bike is a 1985 XJ900F. Apologies for leaving this out earlier. Also, I changed over to stainless brake lines some time ago and we be reinstalling them on this build.

Unlike the pics above which appear to show the splitter being attached at the front of the yoke, on the 900 the splitter is bolted from underneath. Attached is a pic of the bottom of the yoke and the splitter. The yoke has been powder coated black but there has not been any overspray into the threads. The splitter has been painted red with caliber paint. Also visible is the stainless M5 bolt located in one of the mounting holes. The M5 slides into the hole with some interference from the threads. An M6 just won't get past the opening.

I think I'm going to try a normal socket head M5 bolt from the local hardware store. I suspect that there might be half a millimetre at stake here with the M5 bolt, and perhaps the stainless bolt, which was part of a larger order of stainless bolts which I'm using to replace the old ones, might just be that half millimetre out. Unlikely...but it is the path of least resistance and least work. Just as an experiment, I took a 5mm drill bit and sized it up in the bolt hole. The bit barely made it inside before being stopped by the threads. Which leads me to suspect the 5mm M5 stainless bolt isn't exactly what it's meant to be dimension wise.

Hope the pic is clear enough.

 

Any possibility someone in the past put SAE bolts in there?

 

Possibly. It's crossed my mind on more than one occasion. Just seems strange that every other bolt on the front end and indeed the whole bike fits as it should without this sort of problem.

I'm contemplating whether to see if a non metric bolt will fit.

 

bolt size - thread pitch = hole size ........so a hole for a 5mm X .8 pitch would be 4.2mm
then a hole for a 6mm X 1 pitch bolt would need a 5mm hole
a unf 10/32 will be way small and a unc 1/4-20 will be way big

 

A 12/28 will fit the specs.
Not a common one but still possible.

 

Thanks for the tech information. I'll add that to the armoury in dealing with this issue.

Cheers.

 

OK. Have investigated this further and as always the solution is always the simplest and most obvious (isn't that the principle behind Occam's Razor...?!).

The bolt hole was actually oversprayed internally during the powedercoating process for the bottom yoke, although not anywhere near apparent when I first looked. This made starting off an M6 bolt in the hole almost impossible and it felt like I was going to something bad if I persevered. So...decided to try an M6 tap into the hole and although there was some resistance it tapped deep into the hole without damage at all.

Which means I'm back to the initial helpful post by bensalf who suggested they were M6 bolts...and they are on my XJ900.

Even the smallest things can teach you a lesson. Don't overthink or over complicate what could be otherwise a simple and straightforward matter.

Thanks to all who contributed.

 

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The bolt hole was actually oversprayed internally during the powedercoating process for the bottom yoke
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right! , so , why wouldn't the bolt go through the splitter, or was that also coated .
stu

 

The powder coating I have learned these past few days was so well done that it had considerable thickness compared to paint.

Yes...the bolt holes on the splitter were well powder coated. What was a close fit before became even closer...

Happy 2015 New Year to all!

 

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Happy 2015 New Year to all!
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no prob! , and same to you, and all.
and ,by the way , the powder coating looks awesome,
stu.