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1929 chrysler replaced brake fluid with silicone problem

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i replaced brake fluid with silicone and now i have leaks that i didn't have before. the wheel and master cyl. where rebuilt the lines flushed and reassembled. the lines are copper with flair fittings, the flairs that were not touched know seep, the bleeders seep. has anyone had this problem with silicone.

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I've had leakage problems with brake systems, especially after opening fittings and bleeders. I have a theory about brakes: spending money on brakes is better than spending money on font end collision repair (or hospitalization).

Are you reusing the old wheel and master cylinders, running them on silicone now? I like using NEW components, new wheel cylinders, or matching up the innards of a new cylinder to the housing you have (when there is no new wheel cylinder that just bolts on) . The old style wheel cylinders used ally pistons that form electrolysis over time, the new type are steel against steel. The newer rubber parts are made to withstand the newer fluids. I like to take the new cylinders apart, clean off the cosmoline (anti-corrosion goo the cylinders are shipped in) coat the parts in the fluid you will be using after the rebuild, and coat the threads of the bleeders with never-sieze. Make sure your bleeder screws are clean and that there is no gunk or corrosion internally where they seat. Silicone is more viscuious (thicker) than DOT-3, but it will leak just like DOT-3 if it is given a chance.

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I've had leakage problems with brake systems, especially after opening fittings and bleeders. I have a theory about brakes: spending money on brakes is better than spending money on font end collision repair (or hospitalization).

Are you reusing the old wheel and master cylinders, running them on silicone now? I like using NEW components, new wheel cylinders, or matching up the innards of a new cylinder to the housing you have (when there is no new wheel cylinder that just bolts on) . The old style wheel cylinders used ally pistons that form electrolysis over time, the new type are steel against steel. The newer rubber parts are made to withstand the newer fluids. I like to take the new cylinders apart, clean off the cosmoline (anti-corrosion goo the cylinders are shipped in) coat the parts in the fluid you will be using after the rebuild, and coat the threads of the bleeders with never-sieze. Make sure your bleeder screws are clean and that there is no gunk or corrosion internally where they seat. Silicone is more viscuious (thicker) than DOT-3, but it will leak just like DOT-3 if it is given a chance.

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i have had the master and wheel cyl rebuilt by white post they been on the car two years i have great brakes just can't get the seeping to stop out of the bleeders, i will try the never-sieze. is the never-sieze act like a sealant on the threads, if so maybe i should do all the flair fittings what do you think.

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i have had the master and wheel cyl rebuilt by white post they been on the car two years i have great brakes just can't get the seeping to stop out of the bleeders, i will try the never-sieze. is the never-sieze act like a sealant on the threads, if so maybe i should do all the flair fittings what do you think.

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No, the never-sieze just keeps the bleeders from becoming stuck in the cylinders, the original bleeder seats and ends have to be clean in order to do their job properly. One little bit of corrosion or gunk will keep the bleeder from seating all the way at the bottom and they will leak.

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No, the never-sieze just keeps the bleeders from becoming stuck in the cylinders, the original bleeder seats and ends have to be clean in order to do their job properly. One little bit of corrosion or gunk will keep the bleeder from seating all the way at the bottom and they will leak.

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Silicone brake fluid is normally used in extreme temp apps. Motorcycles do DOT5. Silicone also makes your pedal feel a little spongy, and it costs a lot more than DOT3 fluid. For a family car, there’s no need to switch.

The biggest caution is, never mix DOT3 & DOT5 fluids. If you do, the combination will congeal into a gummy mess and your brakes will certainly lock up. Then the lines are nearly impossible to flush.

If you pull all the pistons out of the brake cylinders, and flush the brake line with alcohol real well, you should be good to go. Make sure the master cylinder is flushed real well. Sand the glaze off the inside surfaces of your wheel cylinders using 400 grit sandpaper and DOT5 brake fluid. Cylinders that have a ridge or are real smooth (glazed) leak more than ones with a nice cross-hatch... just exactly the same as piston rings on smooth bores (they hydroplane and use oil).

If you use Anti-seize, do it BEFORE you flush and re-install. Petroleum solvents ruin brake seals. KEEP ALL PETROLEUM PRODUCTS AWAY FROM YOUR BRAKE SYSTEM!!! Brake fluid IS NOT made from oil, but is alcohol based, and it sucks up water faster than Scotch-on-the-rocks. Instead of Anti-seize, buy a small tube of silicone grease. (They use it inside faucets on delrin nylon and neoprene parts.)

Putting the pistons back together using DOT5 fluid should be same as before. I always replace the neoprene piston cups. They usually have a size imprinted in the mold, and some parts stores order them by the bag at ~25¢ each. For a couple bucks, you can do your whole car. Just before putting the dust boot back on, I like to smear a little silicone GREASE (not sealer) around the inside of the cylinder. It’s thick, heat resistant, and flexible, to keep moisture and dirt out (to avoid rust). Bleeder valves have a metal-to-metal seal, meaning, if they leak, there is an obstruction in the seat. Pull the bleeder valve out and inspect the seat carefully. Tightening them just past 'snug' exerts a thousand pounds on the seat, and nothing should leak.

Four or five-year-old brake fluid is full of water, causing your steel brake lines to begin to rust from the inside. If you flush your old fluid, you will see the color is rusty-red, not clear. Flushing old fluid is easy; just keep enough fresh fluid in the master cylinder, and do every wheel. The whole system doesn’t hold a pint of fluid, besides that, it’s a good idea to crack those bleeder valves every few years so they don’t seize.

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Just a comment. I own a 29 Chrysler Model 75. The bleeders for that car have a slightly different flare than modern bleeders. Using a replacement bleeder will leave you with a slight leak. I had to polish my old bleeders and seats, and theey work just fine.

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pat did you use silicone if so how is your pedal, and have you had any problem with the silicone. pat The model 75roadster gas cap what was in scripted on the cap, and do you have one for reference if I need a size dimensions. mike

mike

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I have a model 65 with silicone fluid and the pedal is perfect. The brakes work better than I ever expected. I don't know what the one gentleman was refering to when he said silicone brakes are spongy?? Perhaps he had a bad experiance with silicone at one time with air in the line.

Go with silicone. You won't regret it.

Dan

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I don't know how right this is but i was told some years ago by a brake man , never to use copper for brake lines as it is to soft and liable to blow the flairs ,and also that all brake lines should have double flairs.

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I have a 1936 Airflow Coupe with silicone fluid in the brakes and it has been in the system since 1987.

I have no leaks and it has a perfect full pedal.

All lines were replaced and every reference to the conventional brake fluid was removed before hand.

A spongy pedal can be caused by airation of the silicon fluid during the filling process.

This is caused by the fluid being poured into the master cylinder too quickly.

The fluid will hold minute air bubbles in it in suspension which are extremely hard to remove during bleeding.

I suggest that the fluid be poured down a 1/8" diameter wire when filling the system so that the fluid does not aerate.

The manufacturer does caution the user about this problem

Regards

john Spinks

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