Part numbers or apps for 80 Avanti master cylinder???

[WayneC]

Seems like I once had that info, but I cannot find it now.

I need a part number (EIS, NAPA, etc) for the dual brake master cylinder used on the '80 Avanti

(2-bolt, with brake lines lines to bottom front and side left).

My research on other forums indicates it MAY be a master cylinder used on Ford vehicles with front disk

brakes in the mid to late 60's (66/67 T-bird, 67 Fairlane 500, 68/69 Torino).

Anybody know for sure what was used?

The car has been sitting for a considerable period, and the master cylinder chambers were dry

when I checked it after finding the car had no brakes (the brake pedal goes to the floor, and there's

evidence of fluid having leaked where the M/C meets the booster).

Anybody know how to tell if a booster is bad, when you can't use the brakes because the car is

laid up with a probable bad master cylinder? There's no obvious evidence of copious

leakage around the vicinity of the six wheel cylinders, and it would be strange for both front and

rear to leak dry at the same time (although I suppose that the rears could have leaked

the fluid out some time previously without my knowing it since the front brakes kept working).

The booster may have sucked the fluid past the M/C piston seals; but it may not have, since

after I added fluid it seems to stay in the chambers with the engine running (pedal still goes to floor).

If it IS a bad booster, I probably will need to get it rebuilt before I install a new M/C, but that's

a large expense I'd rather not incur unless it's necessary, because this is not a car I intend to

keep long term... I need to simplify my life in my old age.

I can hear air exhausting (or being sucked in) from somewhere as I push the brake pedal to the floor,

but that might be normal (possibly even a good sign, since the M/C offers no resistance to the

pedal travel)... I'm not sure.

Thanks,

Wayne

Edited April 28, 2007 by WayneC

[Gunslinger]

I don't know the part number for the master cylinder, but I believe you can obtain one from Studebaker International, Nostalgia Motors or Jon Myers.

To check the brake booster, pull the vacuum line while the engine is running. If the booster is good, the engine will suddenly start running badly from the massive vacuum leak. If the engine runs the same, the booster is bad as it must have been leaking internally. Plug the vacuum hose and the engine should start running normally again.

You lack of pedal after adding fluid to the master cylinder could be due to massive amounts of air in the lines that need bled out. Another possible issue is the type of fluid...Avanti Motors back then put DOT 5 silicone fluid in the system...you may have added DOT 3 and the two are not compatible...in fact a very bad and potentially hazardous mixture. Poor brake pedal would be the least of your possible issues if they've been mixed.

If the car has been sitting as long as you say, the entire braking system should definitely be rebuilt...new master cylinder (booster if neceesary), rebuild the calipers and wheel cylinders, new pads and brake shoes as at least some are likely to be fluid soaked and new rubber hoses. You may well need new metal tubing...this would be the time to do it. Safety first...if your car's brakes can't stop you, it doesn't matter how nice the rest of the car is when you hit something.

[geojerry]

Bruce,

If you do accidentally mix a small amount of DOT 3 with DOT 5 Silicone, what is the worst case scenario ? Can you look into the Master cylinder and see any difference in color if the two are mixed ? I may have done this last week after I noticed one of the chambers half filled and could not tell what type of fluid was there. When I poured in the DOT 3, I noticed its color was abit different. Will the brake pedal pressure indicate this bad mix in any way ? I only added a small amount. Should I have the fluid drained and lines bled with new DOT 5 added to play safe ?

Also, My 78 II does not have disc brakes in the rear. Is it worthwhile to convert over ?I saw the ad from JIM TURNER Brake interchange kits. What's your opinion.

Thx,

Jerry

[WayneC]

I don't know the part number for the master cylinder, but I believe you can obtain one from Studebaker International, Nostalgia Motors or Jon Myers.

Well, I'd hoped to pick one up locally.

To check the brake booster, pull the vacuum line while the engine is running. If the booster is good, the engine will suddenly start running badly from the massive vacuum leak. If the engine runs the same, the booster is bad as it must have been leaking internally. Plug the vacuum hose and the engine should start running normally again.

Thanks, that may be a way to tell... actually the engine runs and idles very nicely, just as it always did, so perhaps my worries about the booster aren't warranted.

You lack of pedal after adding fluid to the master cylinder could be due to massive amounts of air in the lines that need bled out. Another possible issue is the type of fluid...Avanti Motors back then put DOT 5 silicone fluid in the system...you may have added DOT 3 and the two are not compatible...in fact a very bad and potentially hazardous mixture. Poor brake pedal would be the least of your possible issues if they've been mixed.

Sure... I didn't add the fluid to fix the brakes, but rather to see if I could cause more leakage to see where it was leaking fluid. Hadn't thought about Dot 5,

usually the M/C has some sort of tag if it uses Dot 5, but I do intend to drain the old fluid before refilling and bleeding.

If the car has been sitting as long as you say, the entire braking system should definitely be rebuilt...new master cylinder (booster if necessary), rebuild the calipers and wheel cylinders, new pads and brake shoes as at least some are likely to be fluid soaked and new rubber hoses. You may well need new metal tubing...this would be the time to do it. Safety first...if your car's brakes can't stop you, it doesn't matter how nice the rest of the car is when you hit something.

Yes, I know... just hard to get psyched up to put money and effort into the car at this time;

I'm getting too old to be crawling around under cars, but I can't get the car out of my steeply inclined driveway to tow it to a shop (not that they'd know anything about Avanti brakes, anyway); I have another Avanti I intend to keep, this one will probably go.

Still would like to know the part number or application of the master cylinder.

[Gunslinger]

Jerry...

I'm not sure what difference in color you might see. Most DOT 5 fluids I've are a purple color. DOT 3 fluid is generally near clear looking. If they get mixed you'll generally see a murky and cloudy mixture in the master cylinder reservoir.

The problem with accidently mixing the two fluids is they're chemcially incompatible and results in a very mushy brake pedal.

Just to make sure...and brakes are so important I wouldn't take the chance myself, I would have the whole system fully flushed and fresh fluid of whatever type added. I would also make a tag (or get a reproduction decal from Nostalgia or Stude Internat'l) that states DOT 5 only and mount it prominently, if you decide to go with DOT 5.

Twenty plus years ago I put DOT 5 in my '63 R1, and knew nothing about the incompatibility of the fluids. I definitely suffered loss of brake pedal and loss of brake feel. Not completely, but enough to cause concern. A few months later my brakes failed completely but I was able to stop the car without incident. In my case the master cylinder went bad suddenly, but I can't say it had anything to do with the type fluid. It may have been coincidental.

If you do flush the system and replace it with DOT 5, make sure the system is completely flushed and dry...no moisture at all leftover. DOT 5 is great, but don't use it in a car with ABS or traction control. One drawback with DOT 5 is it can aerate and the ABS activation can cause that. I'm not aware of any performance car made today that doesn't prohibit DOT 5 in the car's brake system.

As far as adding rear disc brakes to your car, I guess a lot depends on how much you drive the car. For pleasure driving only I don't see any advantage to it. It's a lot of expense and work, plus you will likely have to run different wheels on the car to clear the calipers. I considered adding either the Turner or Steeltech systems to the front of my '70, but having to buy new wheels when my Magnum 500's are like new seemed a waste, as well as the added expense. My car, when it's done, is a pleasure car only and won't be driven hard, so the stock system should be more than adequate.

[IndyJimW]

Remove the two nuts that bolt the M/C to the booster and pull the M/C forward, usually you don't have to remove the brake lines. Look at the rear seal of the M/C, if you see any brake fluid the M/C is leaking into the booster. Replace the master cylinder.

Jim Wood

[WayneC]

Bruce,

If you do accidentally mix a small amount of DOT 3 with DOT 5 Silicone, what is the worst case scenario ? Can you look into the Master cylinder and see any difference in color if the two are mixed ? I may have done this last week after I noticed one of the chambers half filled and could not tell what type of fluid was there. When I poured in the DOT 3, I noticed its color was abit different. Will the brake pedal pressure indicate this bad mix in any way ? I only added a small amount. Should I have the fluid drained and lines bled with new DOT 5 added to play safe ?

Also, My 78 II does not have disc brakes in the rear. Is it worthwhile to convert over ?I saw the ad from JIM TURNER Brake interchange kits. What's your opinion.

Thx,

Jerry

It may be impossible to tell if the existing fluid is mixed... Dot 5 starts out with a light purplish hue, but over time in use it turns clear; Dot 3 and 4 start out slightly yellowish, but also turn nearly clear. Supposedly Dot 5 doesn't mix with Dot 3 or 4 but floats on top... but maybe the purplish dye from Dot 5 will mix with Dot 3/4, so there may be no way to easily tell if you have a mix. You could try pouring a fresh sample of each type in a glass container to see if they separate into layers (stratify) after a few hours (purplish color on top); if they do, then you could do the same with fluid from your M/C... pour a bit into a glass container and mark the level, then add some fresh Dot5, wait a few hours, then see if the purplish color stops at the line you marked. If you do the experiment, let us know how it turned out.

I'd advise you to drain the lines and refill to be certain.

A Google search turns up lots of opinions on Dot 5 versus Dot 3/4, like this: http://tinyurl.com/ysjl8v

Other Google hits claim a mix of Dot 3/4 and Dot 5 will cause deterioration of seals; I doubt that, and in fact the opinion above says the seal issue probably occurs because some people flush their brake system with petroleum-based fluids like mineral spirits before refilling with Dot 5, and that it is likely the exposure to mineral spirits that causes the seal problems.

My opinion on upgrading the brake system:

The Avanti brakes were state of the art in the US in 1963, and are fine for normal driving as long as they are kept in good condition. If you can lock up the wheels in a panic stop, the brakes are doing all they can, and the rest is up to the tires and road surface; better disk brakes and/or better pad/shoe materials and rotor design reduce fade tendencies due to heat effects on pads under sustained braking conditions (like panic stops from very high speeds, or road racing, or carrying heavy loads down long steep hills), where the brakes lose their ability to grip as they heat up.

Remove the two nuts that bolt the M/C to the booster and pull the M/C forward, usually you don't have to remove the brake lines. Look at the rear seal of the M/C, if you see any brake fluid the M/C is leaking into the booster. Replace the master cylinder.

Jim Wood

Already made that decision, Jim, it is leaking, the question is on the identity of the M/C.

Wierd! I replied to two separate posts, but the software kept appending the second post to my first post, like an edit, despite my re-editing and re-posting several times, trying to separate the two replies, even leaving and re-entering the forum once... must be some sort of glitch in the website software. This post may get appended, too. (and it did)

Edited April 28, 2007 by WayneC

[Gunslinger]

Wayne...

I've also read where the dual master cylinder on Avanti II's were either a Ford unit or a Mopar unit, depending on model year. I believe the change came about the '71 model year. My '70 is an August '70 unit, and it has the earlier 4-bolt master cylinder, so the change to the 2-bolt and different booster must have come after that. There were some changes to the rear brakes after that as well, so I'm assuming the master cylinder and booster were changed at the same time.

Somewhere I may have the information on what the specific application was. It might take a day or so but I'll see what I can come up with for you. That way you can check price from a local supplier against what the Stude and Avanti suppliers might be asking.

[WayneC]

Wayne...

I've also read where the dual master cylinder on Avanti II's were either a Ford unit or a Mopar unit, depending on model year. I believe the change came about the '71 model year. My '70 is an August '70 unit, and it has the earlier 4-bolt master cylinder, so the change to the 2-bolt and different booster must have come after that. There were some changes to the rear brakes after that as well, so I'm assuming the master cylinder and booster were changed at the same time.

Somewhere I may have the information on what the specific application was. It might take a day or so but I'll see what I can come up with for you. That way you can check price from a local supplier against what the Stude and Avanti suppliers might be asking.

Yes, thanks, I'd appreciate that.

I believe the change came in late '71.

My other Avanti IS a '71, and takes the earlier 4-bolt M/C.

For posterity, my old notes say the application for 65 to early 71 Avanti was 67-69 Chrysler with

power disk brakes, EIS #64874 or Wagner #64874 or NAPA #36259; rebuild kit Wagner #59053

And my old notes say 63/64 Avantis used Wagner #F27047; rebuild kit Wagner #F19372

Front brake pads: NAPA #5702, Ferodo #DDB704, Mintex #GDB704

I just found a note on a post I saw in 1998 from someone saying the AOAI Issue #80 pp32 says

"Brake Booster Master Cylinder 76-82 is Bendix #2510302", but it's unclear as to

whether it's referring to the master cylinder or the booster.......

....WHOA!!!!, I just tried typing that Bendix number into a Google search and came up with this

page that I somehow missed in my earlier Google searches:

http://studebaker-info.org/parts/NEW/mc.txt

that caused me to do more searching which led me to this page of illustrations

at Bob Johnstone's website:

http://tinyurl.com/2g2f45

The top one (67 Ford Fairlane 500), and the bottom one (68 Ford Galaxie) do look a lot like mine,

I need to compare a little more closely, because those two have very different brake line

fitting threads and I don't know what my car needs, but it appears like the issue may be close

to being RESOLVED.

Thanks, everyone, for your help.

[Gunslinger]

Wayne...

Looks like you found your solution. The best I've come up with is a refernce that states the master cylinder is either from a '70 Dodge Polara or a '68 Dodge Charger with drum brakes, and I'm pretty sure they're both the four bolt variety.

The only other thing I've come up with so far is a master cylinder rebuild kit, but the list doesn't say if it's for the four bolt ot two bolt style. The number is Bendix 2800.

Either way, it looks like you've got the information you need.

[SBCA96]

So the master turned out to be leaking after all? You didnt get back to

me or I would have sent that Johnstone page to you. His pictures really

help in finding the right M/C. Too bad I have the 4 bolt LAST one on the

other page which is 70 bucks for a replacement!! OUCH! Though its very

possible that the larger bore size is why I dont have any issues with my

Cobra brake install?

http://www.studebaker-info.org/tech/repstuavMC.html

But you need to look on Bob's other page which has the two bolt units

pictured :

http://www.studebaker-info.org/tech/repavIIMC.html

Tom