Brake work - Tilted Forum Project Discussion Community

Painted · 06-25-2007, 10:08 PM

Hi! I recently bought a 1985 BMW 635CSI (picture at bottom just for fun). It's a nice car but the brakes aren't the greatest. The pedal has a lot of play and it's not very responsive. So I was wondering where I should start to make the brakes as safe and as reliable as I can (without spending too much). I was thinking of changing/flushing the brake fluid first thing, but then there might be another component that I should change before/during messing around with the fluid. Well, anyways I'd love to hear what the others on the TFP say. Thanks!!

PS.

Martian · 06-26-2007, 01:07 AM

Unresponsive brakes are usually indicative of either low fluid or air in the lines. Pop the cap of your reservoir and take a look. If it's full and the fluid is clean, then you'll just need to bleed the lines. It's a fairly simple procedure, but you'll need and assistant. While you're bleeding the brakes you can check the other components for wear and replace anything that needs it.

BadNick · 06-26-2007, 05:48 AM

Fluid is the simplest thing to check first. But if that looks good, I expect that car to have "well above average" brakes so it could be the master cylinder or calipers are worn; look for signs of leaks at those components. They might need rebuilding. If you are not sure how to do that work (relatively simple with instructions) get one of those repair manuals for that specific car. For example

Chilton BMW Paper Repair Manual - BMW 635CSI
Fits: 1985 - 1988 BMW 635CSI Repair Manual
Brand: Chilton Paper Repair Manual
Part #: Chilton C1018300
Description: Total Car Care Paper Repair Manual, Model Specific Coverage, Simple Step By Step Procedures For Engine Overhaul, Chassis Electrical, Drive Train, Suspension, Steering And More, Including Trouble Codes And Electronic Engine Controls, GROUND SHIPPING ONLY Price: $27.95

http://www.stanscycle.com/bmw-repair-manuals.html

shakran · 06-26-2007, 05:54 AM

let's check the master cylinder first. Pump the pedal several times and then stand on it. If it slowly sinks to the floor, you probably have a bad MC, and should replace that before you swap the fluid.

Then swap the fluid with Ford DOT 5 hi-temp fluid.

Get Porterfield R4-S compound brake pads.

Your brakes should be incredible after that.

And if you really wanna go nuts, swap in stainless steel brake lines.

QuasiMondo · 06-26-2007, 06:08 AM

DOT 5 is silicone based, which is incompatible with glycol based DOT 3 and 4 fluids. If you use DOT 5, you must make sure that all lines are completely flushed of the old brake fluid. Cross contamination between the two creates a gelatinous sludge which clogs up the lines and makes brake repair a nightmare.

My personal opinion is to stick with DOT 3, or if you have a predisposition to 'high-spirited' driving use DOT 4 (higher boiling point).

Plaid13 · 06-26-2007, 05:17 PM

With a car that old i highly suggest you get the car up in the air on a lift or jackstands and get a really good bright light and trace the lines from the master cyclender all the way to each wheel. make sure theres no wet spots on the lines or any cuts in the flexable parts or dents or gouges in the metal lines. Any severe rust or anything like that. If you see any of that stuff replace the line just for safety sake. after that of corse check the fluid like everyone else said. but before you do that just pull the wheels off and take a look at the conditions of the rotors or drums or whatever it is that car has. make sure theres no wet spots where the seals are or any gouges in the surface of the rotors or drumb. and if the brake pads are showing wear you might as well just replace them now. its cheap insurance basicly. Depending on the car a set of pads can cost anywhere from $10-$100 but for a car that old i doubt they cost much. If the rotors or drums are looking kinda worn you can take them to a parts store and they can measure them and recut them if theres enough metal left. if not you just buy new ones. I honestly think when it comes to brakes dont cut any corners. if theres the least bit of a chance something could fail just replace it. Basicly the only thing that effects how responsive your brake pedal feels is the fluid. If its mushy the fluid needs to be replaced and bleed or the car has a crappy design and has too much flexable hose. But since its not a dodge i wouldnt worry about that being the problem. With cars that old Most of the cost of doing the brakes is the labor you pay someone else to do it. If you and a friend can do it it should be cheap. So money shouldnt really be a problem. Stopping is worth spending it on.

06-25-2007, 10:08 PM	#1 (permalink)
Painted Pleasure Burn	Brake work Hi! I recently bought a 1985 BMW 635CSI (picture at bottom just for fun). It's a nice car but the brakes aren't the greatest. The pedal has a lot of play and it's not very responsive. So I was wondering where I should start to make the brakes as safe and as reliable as I can (without spending too much). I was thinking of changing/flushing the brake fluid first thing, but then there might be another component that I should change before/during messing around with the fluid. Well, anyways I'd love to hear what the others on the TFP say. Thanks!! PS. __________________ I came across a nice rack at the department store

06-26-2007, 01:07 AM	#2 (permalink)
Martian Young Crumudgeon Location: Canada	Unresponsive brakes are usually indicative of either low fluid or air in the lines. Pop the cap of your reservoir and take a look. If it's full and the fluid is clean, then you'll just need to bleed the lines. It's a fairly simple procedure, but you'll need and assistant. While you're bleeding the brakes you can check the other components for wear and replace anything that needs it. __________________ I wake up in the morning more tired than before I slept I get through cryin' and I'm sadder than before I wept I get through thinkin' now, and the thoughts have left my head I get through speakin' and I can't remember, not a word that I said - Ben Harper, Show Me A Little Shame

06-26-2007, 05:48 AM	#3 (permalink)
BadNick Riding the Ocean Spray Location: S.E. PA in U Sofa	Fluid is the simplest thing to check first. But if that looks good, I expect that car to have "well above average" brakes so it could be the master cylinder or calipers are worn; look for signs of leaks at those components. They might need rebuilding. If you are not sure how to do that work (relatively simple with instructions) get one of those repair manuals for that specific car. For example Chilton BMW Paper Repair Manual - BMW 635CSI Fits: 1985 - 1988 BMW 635CSI Repair Manual Brand: Chilton Paper Repair Manual Part #: Chilton C1018300 Description: Total Car Care Paper Repair Manual, Model Specific Coverage, Simple Step By Step Procedures For Engine Overhaul, Chassis Electrical, Drive Train, Suspension, Steering And More, Including Trouble Codes And Electronic Engine Controls, GROUND SHIPPING ONLY Price: $27.95 http://www.stanscycle.com/bmw-repair-manuals.html Last edited by BadNick; 06-26-2007 at 05:51 AM..

06-26-2007, 06:08 AM	#5 (permalink)
QuasiMondo Wise-ass Latino Location: Pretoria (Tshwane), RSA	DOT 5 is silicone based, which is incompatible with glycol based DOT 3 and 4 fluids. If you use DOT 5, you must make sure that all lines are completely flushed of the old brake fluid. Cross contamination between the two creates a gelatinous sludge which clogs up the lines and makes brake repair a nightmare. My personal opinion is to stick with DOT 3, or if you have a predisposition to 'high-spirited' driving use DOT 4 (higher boiling point). __________________ Cameron originally envisioned the Terminator as a small, unremarkable man, giving it the ability to blend in more easily. As a result, his first choice for the part was Lance Henriksen. O. J. Simpson was on the shortlist but Cameron did not think that such a nice guy could be a ruthless killer. -From the Collector's Edition DVD of The Terminator

06-26-2007, 05:54 AM	#4 (permalink)
shakran Tone.	let's check the master cylinder first. Pump the pedal several times and then stand on it. If it slowly sinks to the floor, you probably have a bad MC, and should replace that before you swap the fluid. Then swap the fluid with Ford DOT 5 hi-temp fluid. Get Porterfield R4-S compound brake pads. Your brakes should be incredible after that. And if you really wanna go nuts, swap in stainless steel brake lines.

06-26-2007, 05:17 PM	#6 (permalink)
Plaid13 I want a Plaid crayon	With a car that old i highly suggest you get the car up in the air on a lift or jackstands and get a really good bright light and trace the lines from the master cyclender all the way to each wheel. make sure theres no wet spots on the lines or any cuts in the flexable parts or dents or gouges in the metal lines. Any severe rust or anything like that. If you see any of that stuff replace the line just for safety sake. after that of corse check the fluid like everyone else said. but before you do that just pull the wheels off and take a look at the conditions of the rotors or drums or whatever it is that car has. make sure theres no wet spots where the seals are or any gouges in the surface of the rotors or drumb. and if the brake pads are showing wear you might as well just replace them now. its cheap insurance basicly. Depending on the car a set of pads can cost anywhere from $10-$100 but for a car that old i doubt they cost much. If the rotors or drums are looking kinda worn you can take them to a parts store and they can measure them and recut them if theres enough metal left. if not you just buy new ones. I honestly think when it comes to brakes dont cut any corners. if theres the least bit of a chance something could fail just replace it. Basicly the only thing that effects how responsive your brake pedal feels is the fluid. If its mushy the fluid needs to be replaced and bleed or the car has a crappy design and has too much flexable hose. But since its not a dodge i wouldnt worry about that being the problem. With cars that old Most of the cost of doing the brakes is the labor you pay someone else to do it. If you and a friend can do it it should be cheap. So money shouldnt really be a problem. Stopping is worth spending it on.