Brakes dragging

[Zed Head]

p.s. And, just because others, apparently, use a residual pressure valve on mixed drum and disc systems it doens't mean that Nissan did.  Despite the extensive descriptions that Nissan put in to the brake chapters, the only mention of a difference at the MC between front and back is about the reservoir.  The closest thing to an RPV is the check valve that they show.  But there is one on each side and they look the same.

 

[Captain Obvious]

Yeah, since most of us here (including the OP) aren't running Wilwood stuff, then that datasheet is pretty much moot About the only thing that Wilwood data sheet did for me was confirm that "residual pressure valves" are really a thing, and (for me) raised the question of "Is Wilwood the only people who do this, or does everybody do it?"

And after some digging "on the internet", the answer appears to be "everybody does it and have been doing it for decades."

So my bottom line takeaways from all this are pretty much identical to yours...

Some sort of residual pressure valve is a good idea if you are running drum brakes with return springs*. And if you are running disk brakes and have your master cylinder mounted lower than the calipers, you should also use one, but it should be a lower pressure rating.

There could easily (probably?) be a difference between F and R outlets on the stock master cylinders and there could be issues if you don't account for that in some way.

I think we're all on the same page!

 

* I can get into my take about the "why" if anyone is interested, but not sure anyone wants to hear it at this point.   

[z8987]

27 minutes ago, Captain Obvious said:

Yeah, since most of us here (including the OP) aren't running Wilwood stuff, then that datasheet is pretty much moot About the only thing that Wilwood data sheet did for me was confirm that "residual pressure valves" are really a thing, and (for me) raised the question of "Is Wilwood the only people who do this, or does everybody do it?"

And after some digging "on the internet", the answer appears to be "everybody does it and have been doing it for decades."

So my bottom line takeaways from all this are pretty much identical to yours...

Some sort of residual pressure valve is a good idea if you are running drum brakes with return springs*. And if you are running disk brakes and have your master cylinder mounted lower than the calipers, you should also use one, but it should be a lower pressure rating.

There could easily (probably?) be a difference between F and R outlets on the stock master cylinders and there could be issues if you don't account for that in some way.

I think we're all on the same page!.

 

* I can get into my take about the "why" if anyone is interested, but not sure anyone wants to hear it at this point.   

I only use wilwood because of their reputation with brakes.  If I could contact the engineer that made the m/c for these cars, that would be better.  I bet there are docs somewhere that discuss that m/c design. I'm just looking for data to help me make a decision.  I'm there now. 

[z8987]

All my brake problems are fixed.  I'm not sure what happened to the rear wheel that was locking up.  After I freed it with a screw driver and removing the wheel, there were no more problems with that. I don't know if it got stuck when I used the e-brake, or something else, but after freeing it, all the problems went away. 


I attached two videos.  PreFix.mov, this one I jacked up the front of the car and spun the tire, the brakes rubbed a little, this was prior to making changes to the master cylinder.   After reconfiguring my master cylinder with the larger reservoir servicing the front I jacked it up and did the same thing and the brakes weren't rubbing.   The second test was done after bleeding the brakes and driving the car for about 80 miles.  A great day driving around.  Just sharing, my results.  

postfix.movPreFix.mov

Edited February 4, 2022 by z8987