Hi
Im in the process of a lot of changes on my 26T one thing I'm moveing the brake assy to a frame mount (it was on the firewall) I bought a kit from speedway that says bolt or weld on. My frame is 1 1/2 X3 and I hate to drill two 7/16 holes through it so I'm thinking about welding it on, the only thing is that the bolt that goes through the bracket that holds the pedal on would be in the way so I thought about cutting the head off of it and welding it to the bracket and then weld the bracket to the frame. Any suggestions? Also ,do the frame mounts use a return spring on the pedal?
Thanks
Weld it. Although it's not absolutely necessary, use a return spring. There is a company that makes a spring and cup shaped MC adapter that puts the return spring on the pushrod, but I can't remember who it is.
That looks good ,I see you have an in-line brakelight switch. Any problems with it? I raed somewhere that u can't use certain kinds of brake fluid with them?? I forget the reason or what kind (maybe synthetic)
Gary
I have used this type switch 48 years and have never had a failure. Don't get me wrong, I could not say for sure the one I have on my 36 coupe is the one I put on in 1964 when converting to hydraulic brakes, but it could be.
I have changed the stoplight switch once after 6 months because it didn't come on every time. I understand that the 1-1/8" M/C I use, has less pressure then the 1" bore does, but more fluid volume is needed for discs. I have 4 wheel disc brakes.
I have been using Dot 5 only in my bucket. Mostly because it would not attack the paint. See my last journal post. I researched the fluid, and found Dot 3, and 4 were petroleum based. Dot 5 is synthetic silicone, and it will not mix with the others. Unless the manufactures for brake parts haven't caught up yet, I don't see a problem. Have never seen silicone attack any rubber before. I have used silicone in R/C cars, and boats with out any problems. BMW said " There problem was with the solvent they used to flush the system, not the silicone". If I have anymore problems I might think of changing back to Dot 4.
I have changed the stoplight switch once after 6 months because it didn't come on every time. I understand that the 1-1/8" M/C I use, has less pressure then the 1" bore does, but more flow needed for discs. I have 4 wheel disc brakes.
I have been using Dot 5 only in my bucket. Mostly because it would not attack the paint. See my last journal post. I researched the fluid, and found Dot 3, and 4 were petroleum based. Dot 5 is synthetic silicone, and it will not mix with the others. Unless the manufactures for brake parts haven't caught up yet, I don't see a problem. Have never seen silicone attack any rubber before. I have used silicone in R/C cars, and boats with out any problems. BMW said " There problem was with the solvent they used to flush the system, not the silicone". If I have anymore problems I might think of changing back to Dot 4.
The reason DOT 5 brake fluid is not recommended is because it can not absorb moisture. Here is a quote from the brake article I have linked to.
"Silicone brake fluid has a higher boiling point (around 700 degrees F.) than the ethylene glycol base fluids, but the major disadvantages is not "hygroscopic". Hygroscopic? "Altered by the absorption of moisture" What this means is since it is not a glycol based, when moisture enters the system it is not absorbed by the fluid. This results in beads of moisture moving through the brake line, collecting in the calipers. Since it is not uncommon to have temperatures in excess of 212 degrees F. (the boiling point of water), this collection of moisture will boil causing steam and vapor lock, this in turn will cause system failure. Silicone (DOT 5) is also highly compressible due to aeration and foaming under normal braking conditions."
This will result in poor braking performance. See this Brake Fluid Article You should also read the section pertaining to master cylinder sizing and the use of an adjustable proportioning valve.
As to the 1 1/8" master cylinder yielding less pressure than the 1" bore; this is correct. However, you have a vacuum assist which increases the pressure. I also have 4 wheel disc brakes with a 1 1/8" bore master (more volume which is needed when going to 4 wheel disc brake calipers) and a dual diaphragm power booster. I also have a hydraulic brake light switch installed in line. No problems with it.
What I do see in your photos in your project journal (see below) is that you have the adjustable proportioning valve installed in the brake lines that feed the front calipers. This is incorrect and will cause less pressure to the front calipers even if the valve is wide open as it will have some resistance even then. The adjustable proportioning valve should be installed in the rear brake lines and is used to "balance" the braking front to rear so that the rear brakes can not lock up before the fronts. The next potential area for consideration is the mounting of the front calipers at the bottom (closer to the pavement). This is OK and should work well. The problem would be when attempting to bleed the system. The only sure way to bleed the front calipers would be to have them removed from the mounting brackets to enable you to have the bleeder valve at the highest point of the caliper to expel all air from the lines. Then re-install the calipers to the mounting brackets.
Your problem concerning the chrome master cylinder not being able to be bench bled may be a result of the chroming process. Your overall braking problem may be the result of what I have posted above.
To yragat: Bolt or weld the bracket to the frame. Either will work fine. If you bolt it to the frame use grade 8 bolts. You may also wish to weld a tube in the frame (if the frame is rectangular tubing) where the bolts are to be installed. This will assure that the frame will not be "crushed" when tightening the bolts.
That's a great article , Frisco :thumbup:
On a quick read, it explains alot of the physics of a brake system that other similar articles leave out.
My experience with pressure activated switches is that with some light cars with efficient brakes, you don't always build enough pressure at light braking application to activate the switch...Has nothing to do with the fluid type.There are low pressure brake switches available . I know they make a difference in some cars.
I will say that I've been running mechanical switches in most of the stuff I've been putting together, just because the switch is easier to deal with at replacement time and I know it will work with any movement of the pedal, not just when the system has pressure..
If you do switch back from DOT5 to DOT 4 or lower, make sure you flush out your brake system with denatured alcohol..several times.
I remember a couple of folks who bought police cars, at an auction and put dot 4 back in the system without a complete wash..(some cop cars got dot5 put in as a performance upgrade)
Each and every rubber part in the system swelled to the point of being unuseable, and unsaveable.
WOW,I didn't realize there was that much difference in brake fluids!!! If you use a pressure switch in the line,should it be in the front or rear line? Is there a particular brand of switch that is more reliable than others? NOW this is off of the subject,but on a SBC is there anywhere you can screw the water temp sending unit in that would be more toward the rear of the engine than the normal place?
Thanks
Gary
The research I've done shows that Dot 3&4 mix with water, while Dot 5 separates water, causing a straight shot of water, rather than mixed. I have seen nothing to suggest that Dot 5 which is silicone based (synthetic) will mix with water.
On my particular car the manufacturer requires that the proportioning valve be installed on the front brakes, in deference to the normal practice. This is because the rear axle of a T-Bucket has superior traction(17" wide tires), and carries 1180 lbs., versus 5" wide tires, and 900lbs. load on the front axle. I have personally weighed each axle separately.
If one looks closely at the front axle on my car, you will see that the brake line which enters at the lower rear, is well below the bleeding valve on the upper front of the caliper. The calipers were switched side to side.
As I posted in my last journal entry, I've heard that the chroming process sometimes invades the bore, and with insufficient honing during reassembly, reduced service life is a definite possibility.
If you use a pressure switch in the line,should it be in the front or rear line? Is there a particular brand of switch that is more reliable than others? NOW this is off of the subject,but on a SBC is there anywhere you can screw the water temp sending unit in that would be more toward the rear of the engine than the normal place?
Thanks
Gary
The pressure style brake light switch should be installed close to the outlet from the master cylinder. It doesn't make any difference whether it is installed in the front or rear line. Be sure to install it before any residual valve or proportioning valve so that full line pressure is present.
i.e. master cylinder, short section of brake line, "t" connection for brake light switch, short section of brake line (or adapter to connect the fittings), residual valve (if needed), short section of brake line, adjustable proportioning valve (if rear line is being used), followed by the remaining line and fittings to rear brakes.
Try to get the hydraulic switch "Made In USA" for best quality. Some non power assist master cylinders work better with a low pressure brake light switch.
As to the water temp sending unit; some Edelbrock (and perhaps other manufacturers) have intakes that have rear outlets in the intake as well as two outlets in the front of the intake. Look at the Edelbrock RPM Air Gap. In most street apps the extra front outlet and the two rear outlets are plugged off with pipe plugs. In some racing apps a line is connected from the rear outlets to the front outlets to assist with the transfer of coolant throughout the engine block.
You could also install the sending unit in the passenger side cylinder head as this threaded hole is towards the rear of the engine. Be aware that if the temp sending unit is installed in either head that the reading will be somewhat higher (about 20 degrees) than if the sending unit is installed in the intake manifold. This is due to the close proximity of the sensor to the exhaust port in the cylinder head.
Thanks for all the info on proper plumbing procedure on the brakes,I'm not using power assist,so I will look for one of the low pressure switches. My intake is an Edlebrock performer (no provisions on the rear of it) I wanted to use a manual temp gage but didn't want the line running along the valve cover ,maybe I'll go with an electric one then I can route the wire anywhere I want to without being limited to a certain length.
thanks
Gary
hey bud i made a big mistake when i welded my mount onmy 37 coupe i never checked the pedal throw i had to extend the pedal are becausei welded it back too far just a little tip have a nice day
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