Colorado Olds

My sons '66 F85 has the single cylinder MC. The car has power brakes, and drums on all fours.

Is there an easy way to switch over to a dual reservoir style? This is his first car, and since we are replacing most all of the brake system anyway, this seems like a good time to upgrade, if it is easy enough to do.

Any ideas?

Dapapadon

I've got a 66 Jetstar 88 and I'm considering the same upgrade. My plan is to use 67 88 brake parts. In your case you'd use 67 Cutlass parts. Booster & master cylinder should be a bolt on. I don't think the 67 MC's will fit the 66 booster. Your 66 brake pedal should be OK. Wheel cylinder should be the same, but get a parts store to check it.

Brake lines are where the problems are. On the 66's the line from the master cylinder went to a four way connector block. (MC, 2 front lines & 1 rear) On 67's the block is a 3 way for the front only. (front MC & 2 front lines) This 3 way block is not reproduced that I know of. I plan to get one from a salvage yard. Then order 67 brake lines from Inline Tube (www.inlinetube.com) About $100 if I remember right.

Some people believe the single reservoir systems are safe.

If you are considering front disc brakes this might be the time to do it.

This is the major safety feature on your car and your son will be driving it. Please research whatever plan you decide on. I'm just passing along my plan for my car and how you might adapt it to your car.

Don

Barneyo

If you cant get a three way block is it possible to plug the opening on
the four way that goes to the rear line? Because of the flare opening it
might be necessary to cut a line off short and have the stub welded shut!


Is it possible to upgrade a 62 F85 (without power assist) to a dual MC?
If so does anyone have suggestions as to what years/cars would fit?

joe_padavano

Don is correct, you need 1967 parts. The boosters used on the single MC cars (66 and older) have a different pushrod length and won't work properly with a dual MC. Brake distribution blocks are very easy to get from either 67-up drum brake cars or the brake repro houses. Also, plugs for flare fittings are readily available. DO NOT try to crimp a piece of tubing to plug that fourth port.

The 67 parts will fit on any 64-67 A-body. The 61-62 cars do not have that option and would likely need an aftermarket brake booster and MC for the conversion. I do think this is an important safety upgrade.

Barneyo

Thank you Joe, Ive been kinda afraid of that from not finding anything anywhere.
I was still hopin Id missed somethin.

I dont think there would be room for a booster between the engine and the
structural member that runs down to the fender well (dont know the right
terminology). But even then I havent found a non-power dual master cyl
that Im sure would work. I agree it is an important upgrade Id like to do.


No -never- crimp the tubing - definitely WELD it shut if you go that route!!
I included that because I wasnt sure about plugs being available for double
flare type openings.

njot33

I'd like to caution you when you try to make the switch from a single to a dual reservoir master cylinder... you need to be careful about how you hook the brake lines up. I'm trying to save you time here and much of the #!@$#% aggravation I went through making this swap... though in the end it was worth it since making this conversion could ultimately be the difference between life and death. I ABSOLUTELY think you should make this conversion and should not even consider continuing with a single reservoir master cylinder. On a 42 year old car you could break a brake line easily and have no way of stopping.

I just did this conversion on a 65 F-85 with manual drum brakes. I believe the '66 would be almost identical to the '65's braking hydraulics. I know you said you had power brakes, but if you can't use the original power booster from your '66, and want to try manual brakes, you can do that. You will, of course, need the correct pushrod to connect to the brake pedal.

The main thing you will need is a master cylinder with a 1 inch bore. You will also need to make sure that you get a master cylinder off an all drum brake car, not one with disks in the front and drums in the rear. A disk brake master cylinder will not have the correct check valve in the port that would go to the front brakes.

You will need to make sure that if you decide to go with manual brakes, that the pushrod can pivot properly in the little notch in the back of the master cylinder.

My recommendation is that you go online to Year One, go under Oldsmobile > Cutlass > brakes, and select part number BM679. This is the master cylinder I got for my '65 and it works well. It cost $85 + shipping, tax, etc.

On this particular master cylinder, the front lines hook up to the rear reservoir, and the rear lines hook up to the front reservoir. NOT ALL master cylinders are like this!! Some go front res to front lines and rear res to rear lines. If you get a different master cylinder than this one, just make sure you check before putting it on the car, that you make a note of which port has more fluid flowing out. It is this port that you want to hook up to the FRONT brakes. This is because the wheel cylinders on the front brakes will have a larger bore than the rear wheel cylinders.

What may be easier to notice is a delay on one of the ports when the brake fluid comes out. One port will spurt fluid first. This one that goes to the FRONT brakes. You want the front brakes to engage slightly before the rears.

You should use 3/16" brake lines to hook the master cylinder up to the system. For the rear brake line, use a universal connector to hook the new brake line coming down from ther m/c to the existing rear brake line.

For the front lines, use a steel block off cap to block the old port in the junction block that used to go to the rear brakes. You can get one at an auto parts store. DO NOT simply cut the line, clamp it shut and try to weld it. You are asking for a brake failure if you do that.

For the line coming down from the master cylinder to the top of the junction block, you'll need to use a 3/16" line but one that has a larger than normal fitting so it will screw into the junction block.

For any line you screw into the junction block, start the threads by hand, and screw in the nut by hand as much as you can... reason being the junction block is brass and the threads will be stripped if you cross thread by accident and screw in with a wrench. Only use the wren ch for the final tightening.

You should be using line wrenches to tighten these. You can purchase these at Sears. You should also buy a tubing bender and a flare tool to make new flares on the brake lines (if necessary) if you don't have them already.

I forgot to say that to hook generic lines up to the master cylinder, you will need adapters that screw into the outlet ports on the m/c so that the fittings on the brake lines will conect to them.

You should check the brake lines carefully and if you have an doubt about any of them, NOW is the time to replace them.

Also, make sure to bench bleed the master cylinder, or bleed the air out of the master cylinder on the car by pumping the pedal, by using extra brake lines that curl up over into the reservoirs themselves, with the open ends submerged below the fluid level. This is the best, and perhaps only real way, to get all the air out of the master cylinder bore. THEN hook up the brake lines. THEN bleed the system using the bleeder screws on the wheel cylinders.

That is everything I can think of to tell you to do. I went through a lot of work and trial and error trying to get things to work, but hopefully you won't have to if you can follow some of what I said.

njot33

Someone wrote in asking about whether a 62 F-85 could be converted to a dual reservoir master cylinder.

I would think that you can use the master cylinder I mentioned... #BM679 from Year One. The reason I say that is because I know a 62 Buick Skylark had a 1 inch bore master cylinder, as does my 65 F-85. Your car, like mine, has manual brakes, which actually makes this conversion easier.

It cost $85 +hipping & tax. Why don't you try it and report back to us whether it worked or not?

As I as saying above, the REAR reservoir on this one goes to the FRONT brakes, and the front res goes to the rear brakes. It WON'T WORK the other way.

I am not sure of the bore size of your wheel cylinders on a 62 F-85, but mine are 1 1/16" for the fronts and 15/16" for the rear. If yours are similar for a '62, I think this same master cylinder would work for you.

You just have to make sure the pushrod will hook up correctly and all that.

Colorado Olds

After the answers I received above we are seriously considering making the change to dual res MC. Thanks for all the info. Maybe someone can verify this recap:

The MC and booster from a 4 wheel drum '67 F85/Cutlass will work.
The existing pushrod will still be correct for the '67 parts.
I can plug the fourth hole in the existing dist. block, and that plug is easily available.
I can connect the new rear line from the new MC to the existing rear line using a commonly available adapter. I will need to make a few bends.
I should use 3/16 inch line from the new MC to both the front block and to the rear lines, but the fitting for the fronts will need to have the larger fitting on the dist block end - is this line with different fitting sizes commonly available?
The rest of the system needs no change - can anyone confirm that the existing wheel cylinders will not need to be changed? I can have the parts house check the #'s, but maybe someone here knows?


It all seems pretty straight forward to me, assuming the adapters and the line with different size fittings on either end are common.

Does anyone see a problem with using a remanufactured MC as opposed to an all new one? Price diff is significant - $30 vs $90. Of course that goes out the window if they are not generally considered safe.

KQQLCAT

I was told by a guy in California (I think it was Karps) that there is no need to do this. You will loose all your brakes if any leakage happens. When you bleed the brakes on your modern car the brakes go to the floor when you bleed one wheel am I correct? Same thing. Now if you are going to go to disc brakes in front you have to make the change. I called them to find out what I needed to do what you want to do.
Pat

joe_padavano

Do what? Convert to a dual MC? I certainly get all my technical info from "some guy".

(see, I'm getting close to channeling Norm )

No, not correct. In a dual system, if one half leaks you will still have the other half. Yes, the pedal will go further, but the car WILL stop.

Colorado Olds

Yes, I thought that was the whole point - if there is a leak on one circuit the other circuit still gives you some braking capability.

Anyway, can anyone verify my recap is correct?

joe_padavano

Yes, you've pretty much got it covered. I've had no problems with quality rebuilt MCs, by the way.

ijasond

inlinetube.com only has the front line sets for the 67's.

joe_padavano

Actually, Inline Tube has a very cool deal for tubes that they don't currently carry. If you send them a good original to use as a pattern, they'll start stocking that pattern and give you a new tube for free for your trouble. A friend of mine did this for his 67 GTO. Also, the owner of Inline Tube has a 442.

ijasond

If I have a 66 and I'm going to try and get 67 lines to convert to the dual master cylinder it wouldn't do a whole lot of good to send my old lines, would it?

joe_padavano

That was intended as an FYI for everyone. More to the point, I usually just bend and flare my own tubes when doing something like this. The factory 67 installation would have used a distribution block on the frame, so the 67 rear line will still be a short one that goes from the dist block to the rear axle. A separate line runs from the M/C to the dist block. Since the 66 in question doesn't have a BRAKE indicator light, there's no reason to run a 67-style dist block with the brake pressure switch in it.

ijasond

I would have to agree. As much easier as it would be to have a kit, it's really not that difficult to run all new lines with parts you can buy at your local auto parts store.

Red Delta

Is this what I'm looking for to do the conversion on my '66 Delta?

http://www.diypartscatalog.com/ShopB...Switch&mode=PA

I'm not afraid of bending my own tubes.