Mustang Brake Master Cylinder

[t8fanning]

I'm upgrading my brakes, and ordered a CENTRIC 13061062 Master Cylinder for a 1994 Mustang GT from Rockauto. I also ordered a new cheap 240 master cylinder reservoir from IPD. I've seen people say that you should use an oring to space the Volvo reservoir because the nipples are longer, but that's not what I've found.

What do you think, did I get the wrong master cylinder, or is the cheap Volvo reservoir made incorrectly? I'll probably use my old ATE reservoir now, even though it's a bit yellowed.

[740atl]

Why not use the mustang reservoir on the mustang mc?

[t8fanning]

Looks ugly and won't fit my car.

[Homer]

The o rings are to help land the barb in the meat of the seal. The spacing on the 240 res. is slightly different and I think the barbs are a little smaller. I had the same question, but it holds 20 psi with the o-rings.

[Homer]

Originally Posted by 740atl

Why not use the mustang reservoir on the mustang mc?

They leak too.

[t8fanning]

Originally Posted by Homer

The o rings are to help land the barb in the meat of the seal. The spacing on the 240 res. is slightly different and I think the barbs are a little smaller. I had the same question, but it holds 20 psi with the o-rings.

Do you remember how the length of your Volvo reservoir barbs compared to the mustang barbs?

I would understand why o rings are necessary for positioning the barbs in the seal if the Volvo barbs were longer, but that's not the case for the parts I have, which makes me think I may have ordered something wrong.

[J_pelchy]

Side question about the master.
So that master is a bolt up with no issue or does it require modification of some sort?

[Homer]

Originally Posted by t8fanning

Do you remember how the length of your Volvo reservoir barbs compared to the mustang barbs?

I would understand why o rings are necessary for positioning the barbs in the seal if the Volvo barbs were longer, but that's not the case for the parts I have, which makes me think I may have ordered something wrong.

Honestly I didn't pay attention. I used a cheap reservoir too and just went with what TB said. Tom sent me some spare o-rings from when he did the same swap.
The tank you ordered looks correct
Here's the PN for the one I have.
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Homer]

Originally Posted by J_pelchy

Side question about the master.
So that master is a bolt up with no issue or does it require modification of some sort?

You need to extend the pushrod ~0.8" using a 1/4-28" coupling nut and step down one of the outlets from m12 to m10.
Page 8
https://drive.google.com/file/d/0B70...ew?usp=sharing

[11BC2]

There was a Korean stripper on Fort Benning that had nipples as long as your thumb. That’s my only experience with long nipples and it was frightening.

[t8fanning]

To extend the push rod I got this, and turned it down to an effective length of 0.8"

https://www.wilwood.com/Hardware/Har...emno=300-13885

[2turbotoys]

The outlet adapter thread is 1.0 correct?

[dbarton]

So . . . What makes this an upgrade over a normal 240 master?
Dave

[2turbotoys]

Larger piston with more volume for R brakes is why I have one, the 4 piston calipers require that, it's even hard to bleed the brakes with the factory master cyl. Just trickles out. I have the r brakes but didn't install the Mustang MC yet, so they feel slightly better than brand new factory brakes.

[2turbotoys]

Anyone have a link for the outlet adapter?

[dbarton]

Originally Posted by 2turbotoys

Larger piston with more volume for R brakes is why I have one, the 4 piston calipers require that, it's even hard to bleed the brakes with the factory master cyl. Just trickles out. I have the r brakes but didn't install the Mustang MC yet, so they feel slightly better than brand new factory brakes.

But doesn't a 240 already have 4-piston calipers in front? I understand if more volume is needed. I didn't notice that issue when I had R calipers on my 245.

Anyone know the Mustang versus 240 MC bore diameters? Some 240 masters are STEPPED.
Edit: Found it. 1994 Mustang GT MC: 27 mm bore. Stock 240 MC: 22 mm bore.

From Homer's brake thread:

The rear port is M10 bubble flare, front is M12 bubble flare so a reducer is needed.

Dave

[dbarton]

So please correct me if I'm wrong.

My searching tells me stock 240 front 4-piston calipers have 38 mm pistons x4. R calipers have 38 mm x2 and 34 mm x2. That doesn't tell me you need more volume for R calipers.

Edit: Corrected below:

What I found with a quick look at a couple of sources is that R calipers have 42x2 and 38x2 front, 30x2 and 28x2 rear.

Dave

[2turbotoys]

The rears? Also I am pretty sure my '79 didn't have 4 piston calipers, and the rears definitely weren't. The problem became pretty obvious when I tried to bleed them, there was barely any pressure at all 4 corners. I installed a new brake booster, stock MC and all rubber lines at the same time as doing the brakes just to have everything fresh. After looking into it, there are a few threads that talk about this, and they used a Mustang GT master cylinder to fix it.
Also the car doesn't stop nearly as well the S60R the brakes came from.
I don't know, just what research here lead me to.

[Lankku]

Originally Posted by dbarton

So please correct me if I'm wrong.

My searching tells me stock 240 front 4-piston calipers have 38 mm pistons x4. R calipers have 38 mm x2 and 34 mm x2. That doesn't tell me you need more volume for R calipers.
Dave

What I found with a quick look at a couple of sources is that R calipers have 42x2 and 38x2 front, 30x2 and 28x2 rear.

[DrZiplok]

Originally Posted by 2turbotoys

Anyone have a link for the outlet adapter?

You can get an M12x1.0 to M10x1.0 adapter from Brake Hoses Unlimited / goodbrakes on eBay:

https://www.ebay.com/itm/Brake-Line-...-/331605500736

or if you're making your own lines, you can just use an M12x1 nut sized for 3/16 lines.

[DrZiplok]

Originally Posted by dbarton

So . . . What makes this an upgrade over a normal 240 master?
Dave

For me, aside from the anecdotal evidence that it provides better pedal feel with the R calipers, the principal motivating factor was the availability of new parts.

I wasn't able to locate stock of either 240 ABS masters or rebuild kits for same, and building a race car with a master pulled from a ~30 year old derelict did not seem ... responsible.

[dbarton]

Originally Posted by DrZiplok

For me, aside from the anecdotal evidence that it provides better pedal feel with the R calipers, the principal motivating factor was the availability of new parts.

I wasn't able to locate stock of either 240 ABS masters or rebuild kits for same, and building a race car with a master pulled from a ~30 year old derelict did not seem ... responsible.

So you're using the Mustang master on a 240 with ABS? Do you know if the original ABS master had a stepped bore or are front and rear the same?

Can you confirm if the Mustang master has stepped bore or not? Does anyone think it makes any difference?
Dave

[dbarton]

Originally Posted by 2turbotoys

The rears? Also I am pretty sure my '79 didn't have 4 piston calipers, and the rears definitely weren't.

Yes, the rears have always been 2-piston, but every 240/260 from 1975 onward had 4-piston fronts. Some early cars (approx pre-1983) had thinner non-vented rotors with different calipers, but they are all 4-piston.
Dave B

[Texas240]

Originally Posted by dbarton

So you're using the Mustang master on a 240 with ABS? Do you know if the original ABS master had a stepped bore or are front and rear the same?

Can you confirm if the Mustang master has stepped bore or not? Does anyone think it makes any difference?
Dave

It does make difference. Im still using the mustang master on the stock 240 calipers. R calipers did brake better except the squeal was horrible on my car and turned into a slight grinding sound here and there after the brakes would get warm. But it does make a difference

[DrZiplok]

Originally Posted by dbarton

So you're using the Mustang master on a 240 with ABS? Do you know if the original ABS master had a stepped bore or are front and rear the same?

Can you confirm if the Mustang master has stepped bore or not? Does anyone think it makes any difference?

I haven't looked, sorry. In our case it's actually more interesting for the front / rear bore ratios to look completely non-Volvo as we're attempting to get the EBFD in the ABS to think it's in an E46 M3.

As a datapoint, we did about 15 hours of our last 24-hour race on just the front brakes after breaking a rear caliper bracket. It made late trail braking a bit weird, but didn't seem to affect our lap times or overall enjoyment. So, probably not a huge difference.