Stock copper washers & the RPM brake line kit

[aigram]

I recently installed the front, rear, and clutch line kit from RPM. I was wondering what washers people typically use when making the banjo bolt connections. When I used the included aluminum washers, I noticed that they are significantly thicker than the stock copper washers. This added thickness is perhaps why when I went to bleed my rear brakes, brake fluid pushed past the banjo bolt/washers. Closer inspection shows that when using the aluminum washers and the stock Yamaha banjo bolts, that the groove all the way around the inside the brake line fitting may not line up very well with the orifice in the banjo bolt when using the thicker aluminum washers. Thus the fluid had no where to go.

I switched to copper washers only on the rear master side of the brake line, and left the aluminum washers in place at the caliper side of the brake line. I was then able to bleed the rear brake successfully. I don't understand why I did not see fluid spit out past the fitting on the caliper side of the brake line. I ensured that my connections were tightened.

My question is: When using the stock Yamaha banjo bolts and installing the RPM brake / clutch line kit, do you use stock copper washers, or the included in the kit aluminum washers?

[racerrad8]

Alex, we always use the new aluminum washers supplied with brake line kits.

If you would, please send us some pictures of what you are seeing so if there is an issue I can take it up with Spiegler.

Keep me posted so I can see what issues you are seeing so I can see what needs to be addressed.

Randy - RPM

[aigram]

Hi Randy,
To reproduce the issue exactly I would need to flush my rear brakes and start over. Or are you just asking to see the difference in thickness between the Spiegler aluminum and stock Yamaha copper washers?

[Pat Conlon]

IIRC the Spiegler installation instructions clearly specify to use only aluminum crush washers.

[racerrad8]

Sorry Alex, after reading the post again, I better understand the question now.

I thought you were saying the thicker washer was blocking the hole on the banjo bolt and not allowing the flow of fluid. But in fact you are concerned with the "center groove" of the banjo fitting aligning with the hole in the banjo bolt.

I have attached a couple of photos that hopefully will help understand the banjo bolt system. The changing of the washers you did didn't have any affect on the flow of fluid within the lines.

The Yamaha copper washer is .040" thick. The Spiegler aluminum washer is .055". This is a difference of .015" (or the thickness of about 5 pieces of paper)

The "banjo" bolt works on the principle that fluid can travel 360* around the bolt and withing the fitting to flow in to the hose. There is not need to have to line up the holes to make them work. The key to the system is actually the bolt, not the fitting. In fact I have seen several times that some banjo hose ends to not have an internal groove within.

But back to your question, I have taken several photos.

The first photo is with the Stock Yamaha banjo bolt and the position of the hole in the bolt to the center of the fitting. You can see the fluid hole is slightly to the right of center of the fitting.


This photo is the Yamaha bolt with the copper washer. This has now move the hole of the bolt slightly to the left of center on the fitting.


Now the Yamaha bolt with the aluminum fitting and the bolt is .015" further off center to the left.


And finally the Spiegler bolt with the aluminum washer. It is offset approximatley the same distance as the Yamaha bolt and the aluminum washer.


Now, the key to all of this as I mentioned before is the banjo bolt itself. The bolt has a reduced diameter to allow flow of the fluid around the bolt from the outlet fitting of the center of the bolt to the hose port. This reduced diameter is the crucial part of the fluid flow and not the groove in the fitting itself.

The should of the bolt is .390" and the reduced shank is .360" which is what the fluid travels in.


The use of either washer is fine, but if the old copper washers are "crushed" as they are designed to be which is how they seal, they are going to be more prone to leakage down the road. The new aluminum washers function properly and have no effect on the fluid flow within the line.

There are some purist that believe the copper is a better sealing material than aluminum and that is why I stock both.
Brake Line Aluminum Crush Washer
Brake Line Copper Crush Washer

Regardless of what washer type you prefer to use, they should always be new.

Randy - RPM

[aigram]

Hi Randy,
Thanks for the very detailed explanation!
"But in fact you are concerned with the "center groove" of the banjo fitting aligning with the hole in the banjo bolt."
>That is exactly what I am concerned with.

If I am reading your responses correctly, are you saying that using the aluminum washer with the stock Yamaha banjo bolt, and Spiegler lines, should be acceptable because the offset difference is only 0.015" , and that should not be enough to affect the flow of fluid around the fitting and into the banjo bolt fluid orifice?

To be clear, after I set up the lines in exactly that way (Spiegler lines, aluminum washer, stock Yamaha banjo bolt) I observed fluid squeeze past the aluminum washer and Spiegler fitting.

I'm happy to try again this weekend since I will have an abundance of free time on my hands.

[aigram]

IIRC the Spiegler installation instructions clearly specify to use only aluminum crush washers.

Sadly the packaging did not include any instructions from Spiegler. Only a product brochure.

[racerrad8]

To be clear, after I set up the lines in exactly that way (Spiegler lines, aluminum washer, stock Yamaha banjo bolt) I observed fluid squeeze past the aluminum washer and Spiegler fitting.

I'm happy to try again this weekend since I will have an abundance of free time on my hands.

If you have fluid leaking externally you have not tightened the banjo bolt sufficiently to "crush" the washer and allow it to seal.

Yes, the stock bolt with the Spielger  washers and hoses work as designed.

IIRC the Spiegler installation instructions clearly specify to use only aluminum crush washers.

Sadly the packaging did not include any instructions from Spiegler. Only a product brochure.

As far as the instructions are concerned, they are the back of the "product brochure" your received in the box. Also, Pat is correct, #4 says; "Note use only the Spiegler aluminum crush washers..." I have attached a couple of photos of the card that comes with all kits. I have attached a couple of photos so you can download and enlarge if needed.

They also explain the process of clocking the hose ends.

Randy - RPM