Installing Stainless Steel brake lines on a 308 GT/4

Thirty years ago I had a front flexible rubber brake line burst on my old Dodge station wagon (sailboat car). It was a harrowing experience - the E-Brake got a workout as I slowly drove home. Since then I usually change them out after a decade or so on all my cars. I've done many, but for some reason I hadn't on my '75 308/GT4. I finally bit the bullet this month.

The connections on these brake lines are different from others I have seen and worked on, so I decided to document the procedure I followed to spare others from the "learning experience." There may be other ways to remove and replace these lines, but this is the procedure I used because I wanted to remove them intact, as they were being sent to a supplier who fabricated new SS lines for me.

The actual flexible brake line connection is threaded on both internally and externally. The external threads are used by a thin 24mm nut to secure the connection to the bracket. The internal threads receive the 10mm DIN flared fitting to the steel brake line. The flexible brake line nut is 17mm.

Don't try to loosen any of these connections without supporting the opposite nut with the appropriate wrench. I used a combination of flare wrenches, crow's foot flare wrenches and open-end wrenches of the above mentioned sizes.

PROCEDURE:
1. Thoroughly clean the connections at both ends. I used an air-powered engine cleaner, degreasing solvent, toothbrushes, etc.

2. Soak the connections (on both sides of the brackets) with your favorite liquid thread breaker (WD-40, P-Blaster, etc.). I used a concoction suggested on another thread: ATF and acetone, mixed 50/50. It seemed to work as well as the other stuff.

I applied the thread breaker twice a day for a week to give it time to do its job.

3. (Optional, maybe not needed) Peen the nut on the connector with a brass drift a couple of times to encourage it to break free.

THE CALIPER SIDE

4. There is a thin sheet-metal piece on the steel brake line side of the bracket. It has tabs bent over to secure the big (24mm) nut, and a 90º bend at the bottom. Bend those tabs away from the nut so it can be loosened.

5. On the inside of the connection (the side connected to the steel brake line) slightly loosen the flare fitting with the 10mm wrench, with the 17mm wrench on the fitting on the flexible brake line.

6. On the inside of the connection (the side connected to the steel brake line) slightly loosen the thin nut with the 24mm wrench, with the 17mm wrench on the fitting on the flexible brake line.

7. Unscrew the 24mm nut (once freed it should come off with your fingers). That little "S" shaped steel line which goes to the bottom of the caliper is very fragile. (Ask me how I know - more about that later). Because this steel line has a sharp bend not too far from the flare nut if you try to back out the flare nut before freeing the flexible line it may bind on the steel line at the bend as it backs out of the fitting. It's hard to see, but if that happens you may break the steel line at the bend.

By removing the 24mm mounting nut, and pulling the flexible brake line away from the fitting the flare nut can be removed without backing into the sharp bend.

8. Unscrew the 10mm flared fitting while pulling the flexible brake line in the opposite direction so as not to displace the steel brake line.

Place the now loose brake line end in a receptacle to catch any brake fluid which hasn't already drained out on your floor.


THE CHASSIS SIDE

Is pretty much a repeat of the caliper side, except now the hose is free to rotate, which makes it easier. Crack the 10mm flare nut, bend the tabs holding the thin (24mm) nut off, and you may be able to unscrew the flexible line from both the flare fitting and the mounting bolt by twisting it off. Otherwise back out the flare nut, then the mounting nut. Clearance is the real problem, especially on the front wheels. It helps if you don't have big fat hands with stubby fingers like mine.

STEEL BRAKE LINE AND FLARE FITTINGS

I called around to all the usual suppliers for Part# 101401 (BRAKE PIPE) and it came back as NLA. Then I found it had been superseded by by a Testarossa part # 143699 (BRAKE PIPE 13 CM LONG), but it, too was NLA.

Examining the flare on the end of the pipe I determined that it was a DIN flare on a 4.75mm steel line. This is a double-bend flare, very similar to the SAE 45º flare. Good luck on sourcing a DIN flare line. You can download a PDF that shows the details of these flares here; http://www.fedhillusa.com/webnuts/common%20flares6.pdf


I did find a SAE 45º flare 3/8" line that looked like it might work. Plus it was made out of Cunifer, which is a seamless, copper nickel alloy DOT approved brake line used for OEM and replacement brake lines, and much easier to bend into shape than the mild steel. The NAPA part number for this line is ATM 8D0611722F. Website: http://www.napaonline.com/Catalog/CatalogItemDetail.aspx?R=ATM8D0611722F_0303050172

My Son, who is a Certified Hydraulics expert examined the fittings and thought the SAE flare would work in the DIN fitting, using the SAE flare nuts. So we decided to give it a try and it worked under pressure with nary a hint of leakage. I'll keep an eye on it for the next year or so.

INSTALLATION OF THE NEW STAINLESS STEEL BRAKE LINES

The installation is much easier than than removing the old lines, especially because the new lines have swivel fittings on both ends, unlike the rigid fittings on the old lines. The procedure we followed was first the chassis side, then the caliper side. The sequence on each fitting was (1) thread the 24mm mounting nut, then the metal bracket with the tabs onto the steel line; (2) connect the flare nut (10mm) to the flexible line, finger tight; (3) position the metal bracket and thread on the 24mm mounting nut, finger tight; then (4) tighten everything up.

The only problem we encountered was the rear lines when installed looked perilously close to the outer CV joint, so we removed the bracket bolted to the caliper and bent it outward (towards the rear) a few degrees. That did the trick, there's over 1" of clearance now.

BLEEDING THE BRAKES

I have a pressure bleeder for my BMW 850i, and the cap fit the 308 reservoir perfectly (the only stroke of luck I had on this project). We bled the calipers RR, LR, LF, RF twice around, then pedal bled them, and pressure bled them once more. I used Castrol LMA - two pints with some left over did the job. The pedal is rock hard. I never had any brake problems over 3 decades of owning this car, and I religiously flushed the system every 3 years or so. It was very hard to tell the new fluid being bled through the system from the old fluid.

I got the new Stainless Steel brake lines from Glenn at exoticcargear.com (610-788-2123), and they were of excellent quality, exactly the right length (I sent him my old ones to be matched) , all the threads and fittings were correct and appear to be much better than the original rubber lines.