Manual brake master cylinder

[65fastbackresto]

Yea the bleeders are on top.

I bought only the front disc brake assemblys at a swap meet, and none of the related parts which is what caused all this to start with.

What got me to wondering about this issue was looking at CSRP`s list of parts related to their Granada disc swap. They show the RPV in their kit. And I am sure of one thing, these brakes aint right, I have to pump them twice while driving just to get any pedal pressure worth pushing on, the brakes always engage fairly well right at floor level, but.......that makes me real nervous.

And to clarify, what I ment by bleeding the brakes, when I bleed the front disc, the pedal goes all the way to the floor when I bleed it at the line coming out of the mc, which means the rear brakes aint causing any pedal pressure at all, cause I would have at least SOME pedal pressure, which I dont.

And you 2 keep up your discusion, I`m finding this pretty informative, keep em coming. I`m gonna print this whole discusion and bookmark once resolved, I know another guy having the same issue here at home.

 

[ultrastang]

Steve,
I agree that there is nothing resembling the "duck billed" rpv inthe comb valves. On top of that, numerous articles I've read (especially during the last couple days ) make no mention of it at all. You think then that it's just kinda been decided it's not necessary at all...? Dennis

This is just my guess, but I think the reason the RPVs were installed in the vehicles through the 60s & '70s was because that was just the auto manufacture's mind set that "this is the way we have always done it." However, since the vehicles of the pre-60s largely had MCs that were mounted under the floor, it probably was needed on them, but after the MCs were moved to the firewalls in the '60s, it would seem it was not needed (as far as I can see) --eventhough they continued to install them in the MC ports during the decades of the '60s & '70s.

Sometime by the '80s, I guess Ford figured out that since the MCs were on the firewall (above the plane of the calipers/wheel cylinders, the RPVs were pretty much no longer needed (except maybe for some isolated instances) --as evidenced by the '90 5.0L Mustang GT disc/drum MC and the Fox Mustang stock valve I had posted earlier, where there were no RPVs present anywhere within it, nor are there any in-line in the brake system between the MC to the rear drums themselves, and they work with no problems --(and you have to remember that the Fox Mustang ran for 14 years --1979-1993. With the exception of the '84-'86 SVO and '93 Cobras, all had discs front/drums rear, and there were thousands upon thousand of these Fox Mustangs produced during that time that didn't have brake problems from the lack of an RVP in the brake system.


There's something else I thought of, while I was at work today, regarding the problem of getting the air out of the system and getting a firm pedal... Several years ago, I did a disc brake swap. I got everything on and began trying to bleed the system out, but it would just never get a firm pedal! After searching and searching for the problem, I finally discovered the brake pedal-to-MC pushrod was a little too long and was slightly pushing in on the MC's pistons even when the pedal was at rest (not being applied).

With the pistons slightly pushed in, it would not allow the pistons inside to return to the "home" postion, and I could not get all the air out of the system. Once I addressed the pushrod length, and had no force on the MC pistons when the brake was at rest, I was able, then, to completely bleed the system out and finally get a firm pedal!

I'm not sure what push rod is being used (??), since I didn't see any mention of it, but if the (manual) Granada MC came from the parts store with a pushrod, it is too long. The original '65/'66 MC pushrod is the one that is required in this swap if you are using the Granada MC in a manual application on the '65/'66 Mustang.

 

[dharrelson]

I'm not sure what push rod is being used (??), since I didn't see any mention of it, but if the (manual) Granada MC came from the parts store with a pushrod, it is too long. The original '65/'66 MC pushrod is the one that is required in this swap if you are using the Granada MC in a manual application on the '65/'66 Mustang.

No, I can definitely say that I used the rod supplied with the Granada MC when I did mine, so that ain't it.
In fact, I checked it next to the '67 dual MC I had on the bench and it was the same.
So there ya go.
Later,
Dennis

 

[dharrelson]

I bought only the front disc brake assemblys at a swap meet, and none of the related parts which is what caused all this to start with.

What got me to wondering about this issue was looking at CSRP`s list of parts related to their Granada disc swap. They show the RPV in their kit. And I am sure of one thing, these brakes aint right, I have to pump them twice while driving just to get any pedal pressure worth pushing on, the brakes always engage fairly well right at floor level, but.......that makes me real nervous.

And to clarify, what I ment by bleeding the brakes, when I bleed the front disc, the pedal goes all the way to the floor when I bleed it at the line coming out of the mc, which means the rear brakes aint causing any pedal pressure at all, cause I would have at least SOME pedal pressure, which I dont.

And you 2 keep up your discusion, I`m finding this pretty informative, keep em coming. I`m gonna print this whole discusion and bookmark once resolved, I know another guy having the same issue here at home.

If you have the discipline (something I never had) do one change at a time and try it out. I always get in a hurry and do a bunch of things at once, and don't know what did what.
Later,
Dennis

 

[ultrastang]

No, I can definitely say that I used the rod supplied with the Granada MC when I did mine, so that ain't it.
In fact, I checked it next to the '67 dual MC I had on the bench and it was the same.
So there ya go.
Later,
Dennis

Hmmm...

Ok, 65fastbackresto is dealing with a '65 Mustang. You have a '67 --I'm guessing? --I have a '68, myself. I owned a '66 fastback, but that was a long time ago, so I don't have it anymore to compare.

I don't have a '65/'66 manual brake pedal pushrod in the shop to compare by, but I don't think they are the same length as '67/'68. '67/'68 body is not the same as '65/'66. The '65/'66 brake pedal is also not the same as the '67/'68 manual brake pedal, and the pedal pin on the '67/'68 models is in a different location on the brake pedal compared to the '65/'66's pedal.

Eventhough the '75-'80 Granada/Monarch & '77-'80 Lincoln Versailles are not built on the same platform as the early Mustangs, they do share the same track width and the same basic front end structure layout as the '67-'70 model Mustangs. So, there's a very good chance a '67/'68 brake pedal push rod may be the same length as a '75-'80 Granada's, but may not be the same length as a '65/'66's.

This is why when you swap Granada front discs onto the '67-'70 models, you do not have bumpsteer problems (at least no more than what it was with its stock spindle/brake setup), but on the '65/'66 models, some people do experience this problem, because the '65/'66's track width is two inches narrower vs. the '67-'70 Mustangs and '75-'80 Granadas.

Since the front end geometry of the Granadas is very close to that of the '67-'70 Mustangs, I can only guess that the distance and mounting points from the MC to the brake pedal is also very similar to the '67-'70s, but may be more of a difference when you compare it to that of the '65/'66 models(?).

--Additionally, a cheap performance upgrade for a '67-'70 Mustang is to use the 15/16" sway bar off a V-8 Granada/Monach/Versailles. It's only 1/16" under a 1" diameter sway bar, and they are cheap from the wrecking yards --I've bought 4 or 5 of them over the years for ~$10.00 each. NOTE: The Granada sway bar will not work on the '65/'66 Model Mustangs.

 

[dharrelson]

Ok, 65fastbackresto is dealing with a '65 Mustang. You have a '67 --I'm guessing?

No, the swap I keep refering to is a '65. I just happened to have a '67 MC sitting around (years ago I was gonna use it to get a dual system. Never did). I threw the '65 MC in the trash without ever comparing anything. Buit the NAPA Granada MC worked with its supplied rod.
FWIW,
Dennis

 

[ultrastang]

No, the swap I keep refering to is a '65. I just happened to have a '67 MC sitting around (years ago I was gonna use it to get a dual system. Never did). I threw the '65 MC in the trash without ever comparing anything. Buit the NAPA Granada MC worked with its supplied rod.
FWIW,
Dennis

I felt like I was getting Altzheimers or something there for a minute, but after I went back and re-read your post, I could see that you were saying that you had a '67 MC sitting around that you compared and not that you had an actual '67 Mustang. Ok, it makes more sense now.

Welp, since 65fastbackresto lives in the north-western part of the state, and I live in the south-central part of the same state, the logistics aren't practical that I could just bee-bop right over to his place to actually see what all is there, and to physically check the components to track the problem down.

I guess I'm all out of suggestions and I just don't know of anything else I can add, from hundreds of miles away, through the presence of typed text on a computer screen (?????)


--what's left of ultrastang.

 

[dharrelson]

I guess I'm all out of suggestions and I just don't know of anything else I can add, from hundreds of miles away, through the presence of typed text on a computer screen (?????)

Yeah, me too. Just have to wait and see.
Later,
Dennis

 

[65fastbackresto]

The brakes are already better then before...

I changed the mc out with the one the dharrelson suggested, so we are making some headway. Now I`ll address some of yalls questions.

Yes its a 65 mustang.

I used the original 65 pushrod that goes into the mc. And I think the length is right, cause I can pull the pedal back toward the steering wheel about 1/4 inch, which shows some slack, but not too much.

And if this RPV dont help yall can have all the pics ya want, cause I`ll be at a loss to what to do then for sure.

BTW, when you buy a mc off the shelf, it dont have the pushrod in it anyway. At least mine didnt from napa.

And I will keep pecking at this one part at a time, cause I really dont want to blow any more money then I have to at this point.

 

[65fastbackresto]

The 10 lb resdiual pressure valve fixed it.

Had a firm pedal even before bleeding the lines.

Just so ya know, these valves are hard to find, Mustangs Plus carrys a Wilwood RPV for $22 and it was the only one I could find.

Now......off to the next bug.....driveline vibration.....but thats another thread maybe.....

 

[dharrelson]

Cool. Glad you found the problem.
Driveline vibration? Don't talk to me about driveline vibration:

drive shaft broken in two and collateral damage

 

[65fastbackresto]

LOL, this job looks a little more important now

Me and a buddy broke a drive shaft while racing when we were kids, it broke at the yoke where it comes out of the transmision and almost turned the truck over couple times when it was slamming the pavement.

Your pics reminded me of some of the damage we did to dads truck that day....