|12-10-2019 10:03 AM|
|12-10-2019 09:55 AM|
The system had a proportioning valve in it with the rear drums. I could not get the rear disks bled out with it in the system. I removed the PV from the system, and the rears bled right out. I was afraid that this might cause the rear to come on too hard, but after some hard stops in gravel the proportioning seems to be just about right without a PV.
As far as the PV goes, I have a '27 roadster also with non-power 4 wheel disks. Same GM type calipers on both hot rods. I had to completely remove the PV in it also in order to get enough rear brake.
I know this goes against all conventional brake plumbing practices, but it works for me.
|11-27-2019 01:00 AM|
|techinspector1||Nicest tall T coupe I have ever seen.|
|11-26-2019 08:08 PM|
Oh one more thing what are you using for a proportioning Valve?
Again, Nice Coupe
|11-26-2019 07:17 PM|
|11-04-2019 05:59 PM|
Have you made the change to the 1 1/8" bore yet? How did you like it?
It would definitely reduce the pedal travel, but at cost of too much foot pressure has been my experience. With a manual 4 wheel disc setup, decreasing the bore to 15/16" or leaving it at 1" is probably the best solution. Due to the fact that discs don't 'self-energize' like drum brakes calls for increasing line pressure in the system and going larger on the master cylinder bore and reducing line pressure (all else being equal) usually doesn't work out.
Regardless of master cylinder bore size, make sure you have enough pedal travel in the car to bottom out the master cylinder should you happen to lose pressure on half the system. This can happen when a hose or caliper seal fails on either the front or rear brakes. If that happens, you will need all the travel available to stop the car.
|09-23-2019 06:22 PM|
|jaw22w||My pedal hits right at the ball of my foot right where I like it because I built it that way. The 3" movement is within ankle range, it just feels kinda' long because it is longer than before. The car has 21K on it now. I just got used to it. I'm thinking it is probably worth giving the 1-1/8" MC a try. Thanks guys.|
|09-23-2019 03:42 PM|
That is correct.
Pedal will move less so less pressure at the caliper for the same foot effort.
I don't think it's gonna matter much to ya though. You also have the option to try a different pad compound and see if you like that. A pad with more grip will negate the extra pedal effort.
Decreasing pedal travel reduces feel by giving you less distance from initial pad engagement to wheel lock up. Having less "graduations" per say is what reduces the feel. Picture only 1" of travel to lock up vrs 7" inches and you might imagine this. However, having too many, mean you have to use your whole ankle/foot, perhaps the knee and leg to lock up. The leg and knee are not as good at fine motor controls as just the ankle so in performance theory, adjusting things so that the brakes lock up at the end of the drivers ankle travel is what you want. You also have to adjust the pedal height not only from the all the down, but also from the floor to the ball of the driver foot to be comfortable. Although I suppose its all subjective because while I like my foot resting on the pedal just below the ball of my foot, leg and ankle at 90', and 6 or 7" of travel, but I have had other professional drivers that prefer it differently such as the toes or arch on the pedal. I also tend to use the brakes more than most so that could be part of it. That's probably more info than you were really asking for but it gives you something to think about. I'd guess that a 1 1/8 bore MC is gonna get you were you want be.
|09-23-2019 03:05 PM|
Correct me if I'm wrong. All else being the same with only a change from 1" bore to 1-1/8" bore, wouldn't pedal pressure increase to achieve the same clamping pressure at the caliper?
|09-23-2019 01:26 PM|
|09-23-2019 12:56 PM|
The bigger MC will move more fluid but reduce the "feel" somewhat.
You can try, if it's possible, to change the ratio but I don't think you'll like it.
|09-23-2019 12:05 PM|
I'm like techinspector1. There is a force in play here, just as techinspector1 said. I'm sure I have read something about the effect of position somewhere, but I have had them all over the place on different cars and never could tell the difference. Anyway, the installation of the rear disks is complete. I have mounted the calipers at about 4 o'clock. Getting them bled out was a pain. I had never messed with Ebrake calipers before. I finally discovered that the Ebrake arm was installed 1 flat off on the shaft. Wouldn't keep the puck tight enough to have pedal on the first shot. Fixed that and they bled right out. The kit worked, but I had to drill, cut, grind, and weld before it was over. I had to make rotor sized spacers for the calipers for bleeding them off the mount, but it worked fine. I also had to completely remove the proportioning valve from the rear system to get enough fluid back there.
Now the results. I have the best brakes I have ever had in my 1926 T coupe. Even the proportioning seems good after some hard gravel stops, which I thought might be a problem after removing the PV.
The problem is the pedal now takes more stroke. Actually seems kind of excessive. But they work good once you get the pedal down far enough. I am attributing this to the fact that the calipers need more fluid movement than the old wheel cylinder did. This is a corvette type MC (didn't change MC, supposed to be good for either) with a 1" bore. I'm thinking to go to a 1-1/8" bore MC to move that extra fluid. Pedal ratio is 6:1. The pedal moves 3" with hard pedal pressure, where the brakes would be locking up. There is no pump up, so all air is out.
Am I thinking right in going to the 1-1/8" bore MC? I think that should shorten the stroke. What should that do for the "feel"?
Like I said, the brakes are working good, I'm just fine tuning.
Oh yeah, these are manual, no power brakes.
Thanks for any input.
|09-19-2019 01:15 AM|
You can mount them anywhere they dont interfer with suspension or linkage.
I ran them at 7 o clock before. Cantilever air ride with coil over shocks that ended up almost inside the rim. I wanted to maximize my side to side damping so I put the shocks behind the axle.
Just used a old rotor to bleed them then slid the caliper and pads from the old rotor to the new.
Generally I like 10 because that allows for linkage and bags in the future.
|09-18-2019 08:10 PM|
I prefer mounting rear calipers, more to the front 9, 10 11 o'clock
The Clocking usually depends on the E-brake arm on the caliper and the direction of the cable
|09-18-2019 06:56 PM|
Iíve run the both ways and never ever felt a difference.
We put the fronts at 10pm for the added shock clearance. We put them at 2pm on the back for the added weight distribution.
I have put the brakes on a bracket (floated) that has a rod that goes forward to the chassis to use the brakes to load the chassis and keep the rear up in the air on corner entry in our dirt cars.
The brakes will aid in the downward pinion movement if the bushing allow but itís not enough any driver can feel.
|This thread has more than 15 replies. Click here to review the whole thread.|