From: Kenyon Wills <imperialist1960@xxxxxxxxx> Reply-To: mailing-list@xxxxxxxxxxxxxxxx To: mailing-list@xxxxxxxxxxxxxxxx Subject: IML: Dual MC Conversion Logic Puzzle Date: Thu, 7 Apr 2005 09:19:42 -0700 (PDT)
I did a conversion on my currently unfinished/untested 1960.
I have been talking to Mark Lamp about his brake lockup problem on the phone and his problems now have me questioning my setup.
In general, I really abhor putting non-stock parts onto my cars. The 67-69 supra disc conversion is the only one that seems to make sense. I do this because I generally think that I'm not in the same position to make intelligent design decisions as Chrysler Engineering was when the car was designed, and I really want the car to work durably and correctly for the long term.
On the other hand, the single master cylinder setup on the older cars is admittedly not as safe in the event of a failure, and I plan to drive the car quite a bit, so decided to deviate from stock on this one item.
So I violated my own rule of going stock and am now second-guessing myself, and here's why: ================================================= I put a 1967-69 full-size Chrysler (Newport, etc.) Bendix Master Cylinder on and fabricated new brake lines and installed 100% new everything brake-wise.
http://imperialclub.com/Yr/1960/Kenyon/Page09.htm Photo E = front brake Photo F = rear brake
I roll the car out of the garage and down the driveway and they work great for that, seem to be operating on all 4, but they are untested in a driving situation (engine not done/installed yet).
The 1967-69 cars had Bendix brakes. These have one two-piston wheel cylinder per wheel.
===================================================== http://imperialclub.com/Yr/1964/FSM/html/05-002.htm http://imperialclub.com/Yr/1964/FSM/html/05-003.htm =====================================================
The 1960 that the 67-69 MC is on has the older Center Plane brakes that have TWO! single piston wheel cylinders on the front and one dual on the rear.
====================================================== http://imperialclub.com/Repair/Lit/Master/138/page07.htm ======================================================
The question that I have is: If there are two on the front and one on the rear, is there a difference from having one on each? (I don't think so?)
Since the single piston ones on the front are functionally similar to having a dual, as there are still 2 pistons per corner that are similar (I think) in size, shouldn't things be the same?
This all comes down to measuring the diameter of the 1960 wheel cylinders and comparing them to the diameter of the 1967/69 cylinders, I suppose.
The 1960 single MC Applies pressure to all 6 wheel cylinders equally. The 1967/69 applies pressure in either equal or unequal rates depending on whether those wheel cylinders are the same size. Since they are Bendix, and the Bendix on my 1964 are the same, I am leaping to the assumptive conclusion that the 67-69 bendix are also the same inner diameter, front and rear.
If all four 67-69 wheel cylinders are the same inside diameter, and all 1960 wheel cylinders are the same inside diameter, and all have a total of 2 pistons per wheel, they should operate the same, riiight?
Lastly, the 1960 Wheel cylinders appear to have a larger diameter, so the same amount of pressure in the line might move them fractionally less? Pedal travel seems very acceptable, and I'm not bothered about it so far.
Did I mention that I absolutely hate math and consider myself a marginal engineer? Now that I'm thinking about this, I'm fretting about it, despite having a car that's set up, done, and seems to work superficially.
Will the 3 club members that are still awake after reading this offer a technical opinion? I'll probably leave the stuff on there till I get to drive the car, but would like to be mentally settled, so that's why I'm asking.
Kenyon Wills
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