Damn Banjo Bolts...

[JoKing]

Hi guys,

while i am reconditioning my brakes & clutch, i waas going to exchange all banjo bolts.
So i ordered the bolts 78140011a, for brake & clutch. See Picture.

06222847.jpg (8.94 KiB) Viewed 6757 times

The bolts i received have a lower diameter of the holes for the fluid to circulate. There is only one hole below the head as well, wile the original bolt has 2 holes.
Are these bolts sufficient?

Next issue:
The Banjo bolt i removed from the clutch cylinder at the engine is 25mm in length, while all others are 21mm. Is the long one correct? The parts catalogue says 78140011a (21mm) for this one as well, but i found many mistakes in the catalogue until now....

@Higgy: I hope this question is sophisticated enough

/edit: Pictures will follow this evening, i hope.

[higgy]

@Higgy: I hope this question is sophisticated enough

I have never had any issue with you at all
Matter of fact when I get out to the garage to day I will measure up what I have
assuming someone does not beat me to it


guess I should have kept my big trap shut

[JoKing]

Higgy, everything is fine. I am just JoKing, you know....

Thanks for looking & measuring...

[JoKing]

In the pictures you can see the different length & the "see through" hole of the original one & the "not-see-through" of the provided bolts..

/edit:
left to right: new part, old part for brakes, oldpart from clutch.

[higgy]

I just ran across that longer clutch Banjo myself not too long ago when upgrading lines for the 906.
They are still sitting in my tool box. Now I have the incentive to look into it further

Just dropped off my last good M59( the 2004 in good shape one) to get changed so tomorrow when I pick it up I guess I will at last do something about these lines.
The longer banjo If I remember is due to the larger and angled block fitting on the end of the standard
clutch line. I remember discussing the issue with the guy from Venhill when he made up the new clutch line but don't recall what we decided. I do have some notes around here somewhere,just have to find them.

As far as the lower hole in your replacement banjo I don't think that it being lower is an issue as long as it fits the line within the trough for the line fitting.
The fact that it has one hole instead of two,could possible cause an issue with the flow of fluid which could concievably make the brakes act slower in terms of rate at which the pressure builds and releases and the fact that the hole is smaller could make it that much worse. I would also expect it to have more of an effect on the release side of the equation. Don't know for sure if it would be detrimental on a clutch, at least on the street.

I think in the end I'd have to give it a careful test to see. If in fact it is an issue it would be a simple matter to make the one hole larger and try it again. I don't see much difference between one hole and two as long as the one is sized to take into consideration the cross sectional area. In other words as long as the one hole has the same area as two they should work the same.
And if that don't fix it you can always drill another hole. I don't think I would try to drill it by hand,you need a drill press and a vise to hold it properly to do a good job.

Now wether two holes is better than making the one bigger to accomodate the cross sectional area of the two hole option, I don't see the difference as it is a pv/t thingie

So you will have to decide for yourself wether to make the one hole bigger or drill the second hole first,either way the hole need to be a similar size to the old in my opinion,FWIW

[Mc tool]

1 hole 2 holes ,I dont believe it would make a shit of difference in the real world, otherwise we would have people marketing ported and polished ,hydrodynamically "correct" bango bolts for anyone stupid enough to pay .I made my own banjos out of 8mm cap screws for the Guzzi's rocker cover breather hose bango's but I certainly would NOT recomend anyone rolling their own banjo's for brakes and probly not the clutch either.Iguess that the more holes and/or the larger the diameter of said holes , the lower the tensile strenght of the banjo , but you wouldn't want them to small either , as Higgy sez to much restriction would affect performance

[higgy]

otherwise we would have people marketing ported and polished ,hydrodynamically "correct" bango bolts for anyone stupid enough to pay

Hey Mctool Want to be my distributor down under

[paso750]

as the brake lines are mounted fix could it be the clutch line uses a longer bolt as the line is constantly in movement when steering which may loosen the bolt if it was too short ?

Johannes, is the inner hole of the new banjo bolt also smaller than the original ?

G.

[samandkimberly]

The brakes have a high pressure/low flow hydraulic system. The clutch operates under much lower pressures and much higher flow, which means the system is more sensitive to things like flow restrictions. It is quite possible you'll notice the smaller holes as slowed clutch action if you use them there.

Bolt length is usually a function of banjo thickness and, as Higgy pointed out, the clutch banjo fitting is bigger than the brake ones. Id try to stick to the stock clutch banjo if I were you, or find a longer bolt with a bigger through hole.

Sam

[higgy]

One other issue I ran across doing some reading
Smaller holes are bad when using silicone fluids.
Apparently silicone fluids(dot 5) absorb air faster than glycol based fluids(Dot 3 or 4) and the smaller holes can agitate the fluid more leading to brake failure similar to high water content in glycol based fluid

So it would seem even if you use silicone based fluids you need to change it frequently especially if you are doing a lot of track days. Unless of course you like high pucker factors


Also I think the larger bolt for the clutch lines is due to the bolt threading into the less dense metal of an engine case as opposed to the higher density brake block

[JoKing]

@ G.:
Brake Banjo:
Removed - 2 x 2mm, longitudinal hole 3mm
Delivered following OEM partnumber - 1 x 2mm, longitudinal hole 3mm

Clutch Banjo:
Removed - 2 x 3mm, longitudinal hole 4mm
Delivered following OEM partnumber - 1 x 2mm, longitudinal hole 3mm (same as brake banjo. Both have the same #!)

What Dimensions have your banjos?

[higgy]

Have not forgotten you

Have everything together now to install the braided lines
I'll have a report very soon and will include the dimensions you need as I go along
Some of the banjos will be new some will be reused

[JoKing]

Great!

I started to drill an additional hole in all the banjos for the brake lines. I managed to drill 3 holes until the drill broke...

The one for the clutch cylinder is still not known...

[higgy]

Next issue:
The Banjo bolt i removed from the clutch cylinder at the engine is 25mm in length, while all others are 21mm. Is the long one correct? The parts catalogue says 78140011a (21mm) for this one as well, but i found many mistakes in the catalogue until now....

The one I have is 30mm long at the clutch cover and 24mm at the master and all calipers for the brakes

13x5mm head
17mm of thread at the clutch
12mm of thread at the master and at all the brake calipers

The banjos at both ends of the old clutch line and all the brake lines ,I assume to be original are 10mm

So I would have to say you need to measure the thread depth on your cover to determine the correct length banjo bolt for your euro version.

[JoKing]

Hi Higgy,

thanks for measuring.
Are the length-values including the head or only the "bolt part" of the banjo?

Cheers,
Johannes