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Mustang Brake Master Cylinder

t8fanning

t8fanning

8v are still cool, right?
Joined
Oct 10, 2010
Location
Vancouver, WA
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.

fvfywEAh.jpg
 
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 said:
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.
Click to expand...

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.
 
Side question about the master.
So that master is a bolt up with no issue or does it require modification of some sort?
 
t8fanning said:
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.
Click to expand...

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/B009A2U7ES/ref=ppx_od_dt_b_asin_title_s00?ie=UTF8&psc=1
 
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.
 
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 said:
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.
Click to expand...

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.
Click to expand...

Dave
 
Last edited:
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.
Click to expand...

Dave
 
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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.
 
dbarton said:
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
Click to expand...
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.
 
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