Need help with Brakes,master cylinder

[1550vt]

Now...the very least thing that I want to do here is make matters worse and get you more confused. I am not "condemning" the use of 5. If you have that many cans of 5, you could flush the system with the 5 and use 5. You just have to get it flushed with one thing and use one thing all the time. The only reason I was recommending 4 is because it is much cheaper and more plentiful.
If you have that many cans of 5 on-hand, you can use a couple of them to flush with. 5 or 4 will work...BUT NOT BOTH!

To answer your question, there are a gazillion brake systems running around out there with DOT3 and DOT4 in them. DOT2 is practically obsolete. Based on what I have read, the 3 and 4 are actually better on the seals as the glycol fluids have more lubricity than the DOT5. In other words....no...the DOT4 will not harm a thing and your seals will simply love it. Just...for gods sake....don't mix the 3 or 4 with the 5. Use one or the other and let's just not mention 5.1 again to prevent that number from even coming up and adding to the confusion.

[Gorilla]

Why they did not name 5.1 4.1 and save the confusion is beyond me.

[1550vt]

Excellent observation. I am just guessing they based it on the boiling-point rather than the fluid base. 5.1 has a higher boiling-point like 5 does and it affords the people that would rather run the glycol based fluids with a superior product that would equal DOT5 in boiling-point performance.

There are even other special application fluids out there with higher DOT numbers that most people don't even know or hear about. It does make sense to me that they should have called it 4.1....but who knows the logic that went into the designation.

I suppose the very safest thing a person should do is only put in what's on the MC cover and we would have fewer problems. I like to convert to 4 because 5 is not that easy to find out there in no mans land. I have cut a brake line before and you can't just walk into a Wal-Mart and find DOT5, but you can find plenty of DOT3 and DOT4 anywhere.

[BIBS]

Points well taken Guys!!
ULTRA....do you know if P.M.calipers are constructed the same way as is the calipers that come with the DNA rear I have?...............I may replace them,are most of these 4 piston calipers interchangeable?

[1550vt]

BIBS...Ultraboy is probably doing something important right now. Unlike me.....I think he has a job (LOL). He can correct me or add to this, but yes...calipers are interchangeable as long as you get the correct ones with the same mounting system that sits over your rotors in proper orientation and have the same volume as the ones you want to replace. Most companies like Wilwood, Brembo and others post specifications on their calipers in terms of fitment. Such as piston diameter, mounting hole spacing, required rotor thickness/diameter, set-back, etc.

The replacement does not have to be a 4-piston caliper and could be a dual-piston...or even a 6-piston. It's the mounting system, compatibility with your rotor and volume that determines interchangeability and not piston numbers.

Dave may chime-in with a particular set that he knows will work with your set-up.

[1550vt]

Let me mention one thing that I happened to see when I took a close look at the Santiago site. We know they now use, or have used different brands of brake calipers, which may-or-may not be causing a problem, but I noticed one "no-no" that should be avoided. When they use the same caliper with the bleed-nipple on the end, you invariably wind up with one bleed-nipple on the bottom of the caliper, if they are mounted at an angle. The bleed-nipple should be on the TOP of the caliper, or you will never get the system bled with the calipers mounted on the brackets in that orientation. Air will be trapped in the top of the caliper cavity and the only way you can bleed those are to remove the caliper, stick something the same thickness as the rotor in between the pads, turn the caliper upside-down and bleed it with the nipple up.

If you notice the particular page where they offer the Wilwood calipers....they are mounted in the vertical plane...90-degrees and the bleeders are on top no matter which side you mount either caliper on.

BIBS...I know you are worn-out from this, but if you have one air-bubble in that system anywhere...you will never get a hard pedal. The Wilwood's with the 90-degree orientation will likely fix your problem. HOW WERE THE DNA CALIPERS MOUNTED? Straight-up or at an angle?

[BIBS]

Let me mention one thing that I happened to see when I took a close look at the Santiago site. We know they now use, or have used different brands of brake calipers, which may-or-may not be causing a problem, but I noticed one "no-no" that should be avoided. When they use the same caliper with the bleed-nipple on the end, you invariably wind up with one bleed-nipple on the bottom of the caliper, if they are mounted at an angle. The bleed-nipple should be on the TOP of the caliper, or you will never get the system bled with the calipers mounted on the brackets in that orientation. Air will be trapped in the top of the caliper cavity and the only way you can bleed those are to remove the caliper, stick something the same thickness as the rotor in between the pads, turn the caliper upside-down and bleed it with the nipple up.

If you notice the particular page where they offer the Wilwood calipers....they are mounted in the vertical plane...90-degrees and the bleeders are on top no matter which side you mount either caliper on.

BIBS...I know you are worn-out from this, but if you have one air-bubble in that system anywhere...you will never get a hard pedal. The Wilwood's with the 90-degree orientation will likely fix your problem. HOW WERE THE DNA CALIPERS MOUNTED? Straight-up or at an angle?

They were about 30 degrees to top pointing slightly towards the rear.The way the mounting brackets were made...there is a 5 hole pattern that positions the caliper in 72 degree increments around the diameter.There by making it impossible to get a true 90Degrees.
Hope I'm making sense here.
When I get the new calipers,I'm going to modify the(hopefully it wont be nessessary)Mounting plates so that they mount the same as the picture shows in step #9 on the santiago tutorial IN MY OTHER THREAD....wilwood calipers for trike use.

[1550vt]

If you go to the products drop-down menu and select "brake set ups", the very last item on the page shows the Wilwood's mounted straight up-n-down with the bleed-nipples on top. That's what you need to try and duplicate. Try and get the bleed-nipples as close to 90-degrees as possible. In that tutorial...they are not 90-degrees and you can see the right side is mounted with the hose connection and the bleed-nipple on the bottom. Air can get trapped in the top of that caliper at that angle.

[KZQ]

Bibs, just give the above trick a try before you go spending money.

I'm new to this forum. I'll introduce myself elsewhere but I've got to thank Ultraboy for his suggestion about extending the pistons to grip a 1/16" shim. It worked! Actually the pads wouldn't quite grip the shim as the springs kept moving the pads back between pedal strokes. However, once the pistons were extended I was able to push them back in with a prybar between the pads and once the calipers were back on the disks my 5/8" master cylinder no longer bottomed out before getting a firm grip on the disks.
At first, I was thinking that I wasn't getting all the air out while bleeding the system. Once I was sure that the system was properly bled I decided that I needed a larger capacity master cylinder.
One question still remains: if the pistons wouldn't initially advance to grip the disks will they advance to make up for pad wear?
Thank You UltraBoy!
Bill

[Servi]

Hoping that someone can/will tell me where I can get kits to rebuild the DNA trike kit standard rear brake calipers. Like a bonehead, I used dot 3 brake fluid when I first started bleeding the rear brakes on my '98 Harley trike conversion, using the DNA trike kit. Suffice it to say that I almost immediately noticed that the brake fluid in the master cylinder turned black. Then, I finally noticed that the cap said, plain as day, to only use Dot 5. Dumping the fluid and refilling with Dot 5 still had the fluid black. Finally rebuilt the Harley master cylinder, filled with Dot 5, bled the brakes, all good. Trike sat for a month and no rear brakes. All I can figure is that the DNA calipers were destroyed the same way the the master cylinder was.

All my own fault. Where can I get rebuild kits?

[Horsehammerr]

Bibs, here's the trick with those calipers on the DNA axels. Remove the calipers (leave the brake lines & banjos connected) get a strip of 1/16" thick steel, and place between the brake pads. Push your brake pedal down a few times, forcing the pistons to come out farther. Let off the pedal, and gently spread the pads just far enough to get the calipers back over the disks, bolt them down, and you should be good to go. The seals in these DNA calipers tend to roll the pistons back when you let off the pedal. Clamping down on a "thin" disk, if you will, will take care of this tendency. Most of the DNA rear ends I have installed also have light springs on the pad pins, which will slightly retract the pads, and make your residual pressure valve unnessary. A 5/8 bore master is really all that is neces

UB

Will this work on WILWOOD BRAKES ?