Author Topic: Residual Pressure Valve won't fit into repro master cylinder!  (Read 503 times)

X33RS

  • Hero Member
  • *****
  • Posts: 769
    • View Profile
Re: Residual Pressure Valve won't fit into repro master cylinder!
« Reply #15 on: December 01, 2016, 08:49:14 PM »
Dave,
  What I haven't seen in all that reading is the people who complained of poor braking didn't make any mention of whether or not the car had rear wheel cylinders replaced in the recent past.  So they make it sound like install the RPV and problem solved.    Without that information we can't possibly make an informed decision that wheel cylinders are the cure, or aren't for that matter.

I personally can't put a lot of stock in that simply because, I'm not there, I don't know the history of the car itself and I feel there is a lot of missing information.   I also feel rear wheel cylinder relplacement was never mentioned in any of those posts because the updated wheel cylinders weren't brought to light until the very last post,,,then the posts go dead.   As if that's almost like an "AHA!" moment.

While all this effort is admirable, I don't see it as necessary just based off what I've found.  I listed my experiences, that was just on some of my personal cars.  I've also done complete restorations on customer cars, all kinds of brands, including complete revamps of disc/drum brake systems and I've never once experienced any of these issues that are being discussed here.  I would never let a car out the door with subpar brakes for obvious reasons.  At the same time however, I'm also replacing wheel cylinders.  That says a lot to me but of course you have to make your own decisions.

1969Z27

  • Member
  • ***
  • Posts: 164
    • View Profile
Re: Residual Pressure Valve won't fit into repro master cylinder!
« Reply #16 on: December 02, 2016, 09:40:13 PM »
First off, I appreciate all of the replies and thoughts on this.

It is going to be a while before this car is actually running on the street so no matter which way I go, I wouldn't know the results for a while.

So now my question is......if rear wheel cylinders were redesigned with cup expanders starting in 1970 eliminating the need for the RPVs.......when you order new wheel cylinders for a 1968 car, what are you getting? The original 1968 design which would mean you still need an RPV......or an updated design meaning you would not?

And if all replacements wheel cylinders were updated, then what happens when you install the updated design (not requiring an RPV) on a car that still has it's original master cylinder that has an RPV. Could that push the brake shoes out too far? Those are just the thoughts running through my head.

This seems to be one of those many subjects where there are two distinct camps. I went through it with silicone vs regular brake fluid and stainless vs regular steel brake lines. In this case we have the folks who have no RPV and have great brakes......and we have the folks who had had poor braking, found out they didn't have an RPV and installed one, and had a great improvement in their braking......It makes it hard to make a good decision on which way to go.

Dave


I'm getting ready to purchase parts to repair the brakes on my '68. It has a '72 Ventura rear end. Checked on O'Reilly site. 68 & 72 show same part number. So if I get a mc without the rvp's it should be same '72 factory setup. IMO that last Chevelle post sure does make the most sense.


http://www.oreillyauto.com/site/c/detail/BHH1/WC45873/01324.oap?year=1972&make=Pontiac&model=Ventura&vi=5146760&ck=Search_01324_5146760_1225&pt=01324&ppt=C0066#compatibilityTab_
Russ 
68 RS L22/M20
69 SS L48/MC1

blackss69

  • Member
  • ***
  • Posts: 46
    • View Profile
Re: Residual Pressure Valve won't fit into repro master cylinder!
« Reply #17 on: December 10, 2016, 02:22:45 AM »
Information on RPV on a 69 Camaro SS 396 with a build date 02D.  I am the original owner and have done all the maintenance since delivery.  The master cylinder US code 309 casting does not have a RPV in the rear brake circuit.  I have the master off and put a drill bit into the seat.  It went in 2 1/8 inches and finally hit the end of the hole.  Np restriction like a bad RPV that had a hole or deteriorated.  The car has the round pressure hold off valve on front brakes and the proportional valve on the subframe below the drivers door on the rear brakes.  I'm sure it never had a RPV.  The brakes worked fine. 


DAVEN1256

  • Member
  • ***
  • Posts: 281
    • View Profile
Re: Residual Pressure Valve won't fit into repro master cylinder!
« Reply #18 on: December 10, 2016, 03:25:04 AM »
Thank you for checking that and posting that information.

From everything I have seen written about the proportioning valve located on the frame, it wasn't used on that many cars and even the experts aren't sure now why some cars got them and others didn't.......I wonder if when that frame mounted proportioning valve was used, that maybe the RPV was eliminated.

I do not have the frame mounted proportioning valve in my car.

The RPV mystery continues.

Dave

BillOhio

  • Hero Member
  • *****
  • Posts: 800
    • View Profile
    • photobucket
Re: Residual Pressure Valve won't fit into repro master cylinder!
« Reply #19 on: December 10, 2016, 08:30:26 PM »
My z has frame valve and RPV
1969 Z28, Burgandy, numbers matching, 12,900 miles
1967 Plymouth GTX Hemi, 4 speed, dana
1961 Chrysler 300G convertible