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Old 09-25-2022, 06:00 PM
Argess Argess is offline
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Just got power back after Hurricane Fiona raged through, so I'm a bit late reponding to your posts, but T-Y. I appreciate the replies.

So what's going on? I did some measurements today and I get what I once did before for pedal ratio; 4.5:1. I measured with the pedal arm in the car and got 9" from pedal face pivot to the arm pivot and 2" from the arm pivot to the balance bar shaft. So it's not 6 as far as I can tell. The 5:1 was from a thread on this site where it appears the poster measured more accurately most likely due to having the arm on the workbench.

Here's my calculations for front caliper pressure:

Say 150 lbs pedal force, which I might have achieved when I tried extra super hard, times the ratio of 4.5:1 = 675 lbs.

Next divide by 2 as the force is split between the front and rear cylinders by the centered balance bar and we get 337.5 lbs. As the pedal arm currently is off 14 degrees from vertical, we multiple by the Cos (14) and that reduces the force to 327.5 lbs for the front master cylinder.

So the pressure at the caliper is that force divided by the cylinder area which is Pi * (r^^2), or 0.6 sq.in for a 7/8" cylinder, and we get 544.9 psi which is exactly what I measured within a pound or two.

OK, so we all agree the pressure is too low, but it matches the system theory.

Now, as mentioned above, the offset angle is only 14 degrees, so not much to gain from adjusting it.

The balance bar is not like what's shown in the current manual as mine is an older ERA. It uses tubes for spacers vs. washers, so new tubes of different lengths would have to be made. For all intents and purposes, the exisitng tubes are the same length (one does appear to be 1/32" longer).

So, I appear to be getting the maximum out of the design but it seems low compared to quoted recommendations, so trying a smaller dia. cylinder seems worthwhile. Removing glaze seems to be a good idea, but I agree, it won't change the pressure.

So, I'm a little stuck on all this..... more experimenting I guess.

ps: On the brake temp indicators, I have no idea hot brakes should get... no baseline, so that's out.
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