early 944 brakes, stock MC....dosent feel right

[H2OSB]

Originally Posted by Wally

Ah! Now I see why you said used n/a rotor
But euh...no, sorry. Due to me trying to minimize parts hoarding a bit, I brought all old rusty rotors to the dump.. sorry.

It's all good. Can you please measure the bolt circle of the rotor attachment bolts? The 944 has a 126mm bolt circle.

I actually kinda got on the guy at CB who designed those hubs/rotors. I asked "why would you re-invent the wheel, so to speak, when Porsche rotors are readily available?" He had no answer.

[Wally]

Originally Posted by H2OSB

I asked "why would you re-invent the wheel, so to speak, when Porsche rotors are readily available?" He had no answer.

Interesting!
I think all porsche rotors (except the 914 rears) are vented and they wanted something for the type 1 market?

I'll try to measure the bolt spacing ;-)

[H2OSB]

Originally Posted by Wally

Interesting!
I think all porsche rotors (except the 914 rears) are vented and they wanted something for the type 1 market?

I'll try to measure the bolt spacing ;-)

Their source for un-drilled rotors has dried up so they needed something to offer a 5x130 pcd for the front. A lot of potential...which I don't think they realized (well, perhaps not until I started bugging them about it)

[Wally]

Originally Posted by H2OSB

Their source for un-drilled rotors has dried up so they needed something to offer a 5x130 pcd for the front. A lot of potential...which I don't think they realized (well, perhaps not until I started bugging them about it)

Interesting indeed.
I just measured it, but was difficult to do. I needed to sort-of eye-ball it a bit, but I think its about 112-113mm bolt spacing. What is the 944 n/a ?

They are big bolts however, like M10, not the M6 of the original 944 n/a front hubs.. (on which 911 3,2 rotors in 24mm thickness also fit BTW, but you may already know that).

[H2OSB]

Originally Posted by Wally

Interesting indeed.
I just measured it, but was difficult to do. I needed to sort-of eye-ball it a bit, but I think its about 112-113mm bolt spacing. What is the 944 n/a ?

They are big bolts however, like M10, not the M6 of the original 944 n/a front hubs.. (on which 911 3,2 rotors in 24mm thickness also fit BTW, but you may already know that).

I suspected it wasn't the same They didn't even consider the Porsche rotor when they created those. The n/a 944 bolt circle is 126mm. I did know the later rotors would fit. Flat told me that some time back (in the event I could use those 44mm 964 C2 rear calipers on the front). I wonder if n/a 944 rotors could be re-drilled in the off spaces to fit the CB hubs? 944 rotors are dirt cheap (I bought my set for $13 per side). I MAY try experimenting to see if it would work.

Edit: NVM, I just went out and looked at my 944 rotors. There's not enough meat to the inside of the 126mm bolt circle to drill M10 holes, much less on a tighter bolt circle. If the CB hubs don't have enough meat outside their bolt circle for a M6 holes, it's a non-starter

[Wally]

Is it that difficult to find 944 n/a hubs then? I thought they just needed two (or even just one?) adapter sleeves for the bearings to fit the beetle spindles? 944 is alu too and the CB hubs can't be bought separate iirc?

[H2OSB]

Originally Posted by Wally

Is it that difficult to find 944 n/a hubs then? I thought they just needed two (or even just one?) adapter sleeves for the bearings to fit the beetle spindles? 944 is alu too and the CB hubs can't be bought separate iirc?

Nah, that's doable. They are getting a bit more difficult to find, but I think I have 3 sets. The difficult part is finding someone to do the machine work. Flat does that work, but he's only at it part time and has a huge que of people who want his work. Most of my local machine shops try to send me elsewhere. They don't like one-off projects and cannot comprehend why I'd put custom brakes on a Beetle.

[H2OSB]

Originally Posted by Wally

Is it that difficult to find 944 n/a hubs then? I thought they just needed two (or even just one?) adapter sleeves for the bearings to fit the beetle spindles? 944 is alu too and the CB hubs can't be bought separate iirc?

CB hubs cannot be bought separate, but the hub/rotor is not expensive compared to, say, custom made hubs. You can buy the rotors separate. They're about $50 per side, versus the hub/rotor together for about $159 per side. Buy the set, remove the rotor and resell for $45. Cheap hubs, made for the VW spindle and in a 5x130 pcd.

[Wally]

Originally Posted by H2OSB

I If the CB hubs don't have enough meat outside their bolt circle for a M6 holes, it's a non-starter

Hmm, there is plenty 'meat' to drill a wider pattern I think. Seems pretty solid, but the disk is still on it. I'll look sometime coming days to get you more info

[eskamobob1]

Anyone mind going over the math for why a stepped MC does not effect the preasure output by each cylinder?

A dual MC is set up with a floating piston between the two separate cylinders.



if we assume we are at steady state (piston no longer moving, just generating more or less force), that the brake line ports are plugged, and that this piston is not connected by a bar and the spring force is minimal when breaking, the pressure in the primary circuit (P1) is going to be the input force (Fin) divided by the plunger area (A1). Without any solid connection or added force between the two channels, Fin must be equal to the force the fluid in the first circuit applies to the floating piston (F1) must be equal to Fin. Secondly, the force the floating piston applies to the second circuit (F2) must be equal to the force applied by the fluid in the primary circuit. This force (F2) is equal to the pressure (P2) in the piston multiplied by the area applying the pressure (A2). Therefor, if the area of the two circuits are not identical, the pressure within them will be different as well