Steering, Suspension, & Brakes

I tossed my brake lines when I stripped the car... I have the dual circuit, non-servo assisted master cyliner from the early '70's. Are the fittings sized for 3/16 or 1/4" line?

Any reason I should plan to use 1/4" for the main lines for each circuit from the master to wherever I T off to the wheels?

Also, 1/4" line is typical for the clutch line, right? That's what I recall from years ago so even though I haven't decided which clutch master to use, I'm thinking 1/4" will fit most of them out there... and it fits the slave I'm using (a '56 Ford truck slave of all things).

Thanks in advance.

Rob



Edited 1 time(s). Last edit at 02/03/2009 11:53PM by rficalora.

Rob, 1/4" line will work. Line size isn't too important, but the larger line will allow fluid transfer a bit quicker, which is nice both to allow the brakes to release quickly and also the clutch action smoother. I used 1/4 or AN -4 lines throughout my car, brakes and clutch. If you decide to use the MG clutch master I found that an AN male bulkhead union would screw right into the output port and seal allowing me to use AN (or JIC) fittings and line directly from the master cylinder to the slave. I used the same from the ports on the brake pressure switch and ran AN lines to the front and rear brakes from there. 10 years, no problems.

Rob, your MGB tandem non-servo master cylinder is designed to accept British bubble flares on 3/16" line. You probably don't have proper tools to make bubble flares at home, but that's not a problem! Bubble-flared tubing is readily available at local auto parts stores. My local Auto-Zone had a big inventory of them to choose between last year.

This is what a British bubble flare looks like:


Note that the store will probably also have European-style "metric" bubble-flared tubing. (It will probably be color coded green.)

Suppose you want to mate to something new... For example, Ted Lathrop recommends installing Wilwood residual pressure valves near the master cylinder. Well then, you'll need to start with a British bubble-flared line at the master cylinder, and then put an American-style "inverted" flare on the opposite end of that same line.

An American-style inverted flare looks like this:


With a decent quality, readily available tool, you can make great inverted flares at home. The key is to buy a good American-made tool. If you buy a Chinese tool for this, I'll have to come down and kick your butt. The Sears Craftsman tool is pretty good. (I actually have a Chinese flaring tool too, and it makes really crappy flares no matter how carefully you use it.) Note: I found that it worked out to buy (mostly) long pieces of "British" tubing and short pieces of "U.S." tubing, since the only part of the U.S. tubing assembly I was actually using was the threaded fittings.

With regard to the clutch lines... I agree with Bill that braided-steel covered flexible line seems to be the hot ticket. Get yourself a Pegasus Auto Racing catalog and study the three or four pages of fittings.

Incidentally, I just noticed that the Pegasus catalog recommends 3/16" line instead of 1/4" line for the brake circuit because they say it provides a firmer pedal.

I made all new brake and clutch lines for my conversion (retaining the original 3/16" brake and 1/4" clutch sizes) and using the afformentioned $9.95 "Chinese" flaring kit from Harbor Freight. If you have a couple of practice runs, you can get acceptable flaring results - at least mine haven't leaked yet! If I was contemplating doing a lot of flaring, I'd buy something a little more robust as Curtis suggests.
If you are mixing and matching brake/clutch components from various sources make sure to determine if they use bubble or double flare ends.

Quote:

I'll have to come down and kick your butt.

Studying martial arts, Curtis? :)

I'll go one better. I'll feed Steve Carrick a 12 pack of Labatt Blue Light & sic him on ya. :)

Actually I've been studying Pegasus on-line which is what led me to the questions... I've only found two fittings that are designed to work with the spring clips to transition from braided to hard line...

3265-12 3AN/Female 42 degree Inverted Flare 3/8x24 Brake Adapter $4.49 In Stock
3265-13 4AN/Female 42 degree Inverted Flare 3/8x24 Brake Adapter $4.59 In Stock

So with those I can transition from either AN3 or AN4 braided brake lines to 3/16 hard line -- at least the research I've done so far says standard "american" 3/16" brake line mates to female 42 degree inverted flare with a 3/8x24 thread.

Oh, & thanks for the bubble flare info... I knew about european bubble flares, but it never occured to me that the MG master cylinder would be bubble flare & a British version at that! So I'll need ra couple of elatively short length of British bubble flare lines to go from the brake master to the residual valves, cut off the residual valve ends & re-flare them (w/the right fittings too) to 42 degree inverted flares... then on the other end of the residual valves, I'll use 3/16 hard line to the tabs... That takes care of the brakes.

Now, on the clutch, my slave has a 7/16 x 24 female fitting. Pegasus has a 4AN/42 degree inverted flare 7/16 x 24 adapter that'll let me go from the slave to AN4 braided line. But, I need to find a way to go from the braided line to 1/4" hard line & haven't found that fitting. (I prefer to use hard line from the clutch master to get close to the slave, then transition to a shorter length of braided -- I just think the hard line is neater & can be routed more cleanly up in the engine bay.)

To mate to 1/4" line, it looks like the fitting would need to be female 42 degree inverted flare 7/16 x 20... but I don't see a fitting in Pegasus' catalog that has AN4 on one side & 7/16 x 20 on the other & is designed to work with a tab/spring clip to make the braided to hard line transition.

I did notice pegasus has a pre-made weldable tab/fitting combination that doesn't use the spring clips...


I don't know whether that approach will stay tight w/o the regular maintenance stuff like this gets in a racing application so am hesitant to use it. But if it will, I'm sure I can find a 1/4 x 1/4 or 1/4 x AN4 fitting that I could set up the same way for the clutch. What do you think about that threaded through/nut retainer approach?

If that's not a good idea, it looks like I have to go with 3/16" line for the clutch or drop back to using braided all the way to the clutch master... unless someone has another idea?

Ran into the same problem with flares and the sort because of different components ( Toyota calipers, Nissan Calipers, Wilwood master, and stock clutch ). I was able to get all the fittings that I needed using Earl's or Russell fittings. I was able to do away with some hard lines to braded lines.

Your local performance shop will have all the fittings you may need to convert over to AN.

Oooops. When I picked the Wilwood residual pressure valve example earlier... well, it's a little bit screwy example because actually Wilwood's valve has pipe threads, so you'll need converter fittings on each end, as shown pretty well in this photo of Terry Schulte's GT:



In other words, if you order two residual pressure valves from Speedway Motors, then you might also want to order four of their 910-31831 IFF-to-NPT Straight Fittings (3/8"-24 IFF to 1/8" NPT male) at $2.99 each.

By the way, not sure what parts chains you guys have around you, but around here O'Rieley's & AutoZone "loan" tools. They have all the typical special automotive tools. The way it works is you pay for the loaner tool & as long as you bring it back within 90 days you get a full refund. the tools are good quality & typically more professional grade than most of us can justify for infrequent use stuff. They have flaring tools, steering wheel pullers, A/C & Alternator pulley pullers, gear pullers, etc., etc... Not that I'm afraid of Curtis or Steve... ok, Steve after a 12 pack of Labatt's is a bit scarey!

Curtis, thanks for the part numbers on the fittings for the residual pressure valves. Speedway is where I'd tagged to get the valves so you just saved me a bunch of time finding fittings.

While we're talking brakes & clutches, any thoughts on whether this clutch master would fit...

Similar to Standard Tilton Master Cylinder but extends only 3.2" from mounting surface to outlet port. Provides a full 1.1" stroke and comes in a 1" bore version which matches the slave I have.



Edited 1 time(s). Last edit at 02/04/2009 11:00PM by rficalora.

Rob, a lot of sources I've seen don't recommend aluminum AN fittings for brake systems, especially for a street car. I found that the industry standard hydraulic fittings called JIC are the same as AN in thread and flare but made in steel or stainless steel and the steel ones are quite a bit cheaper than the race car parts. I used them on my Midget and haven't seen any signs of corrosion on any of them, so the gold iridite (sp) coating is pretty good.

Rob, you can also use the standard double flare tool to make acceptable bubble flares (I recommend Rigid brand, they have an excellent kit that sells for somewhere around $60-80. As the name suggests it is rigid, and it works quite well.) By making the first step of a double flare and then not the second, you end up with a belled flare that is extremely similar to a bubble flare. I've not been able to find any significant differences in them and I've been using this method for almost 30 years now without any failure or leakage issues.

But you better pay heed to these guys, I wouldn't want Steve Carrick all loaded up with Labatt's sic'd on me either!

Jim

Edit: I used hydraulic fittings on my I-H truck which saw all of the worst weather, salt, etc. Those fittings do rust badly under those conditions so I would recommend the stainless if you can get it. JB



Edited 1 time(s). Last edit at 02/05/2009 09:42AM by BlownMGB-V8.

Advance Auto has the same tool loaner program.

Didn't look like you were having any problem, Jim. ;)

Wasn't MY idea.

Jim

Thanks guys. On that pegasus tab bracket with the aluminum fitting, I wasn't planning on using that tab or fitting specifically, just asking if using that style of fitting -- threaded with a nut to retain it in the tab vs. the type that uses a spring clip to retain it in the tab -- is appropraite for a street car.

I'd picked out the fittings I'll need but didn't think about rust; I'll have to double check that they're coated or switch to stainless. Good tip Bill.

That type of fitting is essentially a bulkhead fitting. It is eminently suitable for transition from hard line to flexible, provided it is solidly mounted.

Jim

Thanks Jim... that solves my clutch transition problem because there are bulkhead type fittings for 1/4" hardline to AN4 braided.

So - bubble flare for fittings and couplings, double flare for brake cylinder connections?

Don, the easiest way I've found to figure out what flare you need is to look inside the fitting that the brake line flare is mating with. This pic shows it pretty clearly.

Thanks, Rob