I have a '73 body that I am rebuilding with mostly '70 parts. It will look like a '70 and be mostly '70 mechanically too. But, I am going to use the front mounted porportioning valve. I can't figure exacly how it mounts. It has two holes in it for bolts, but I only see one hole on the firewall. Can anyone please post a pic? Thanks Pete

 

heh? like, brake proportioning valve?

 

Page 136 of the Haynes 240z-280z manual... (if you don't have one, buy one asap).

 

ok that makes more sense, when he said proportioning valve i was like... you have to install that! lol.

 

what other proportioning valve would there be ?? :O) Yes that is it in the pics. I have a couple manuals, but none have a photo, only some line drawings. But that pic helps. It clearly shows only one bolt although there are two holes as I described. So this helps. However, any other pics? The photo there isn't the same as the line drawing. The actuall part is the exact same as the line drawing. There have to be 4 lines, two in and two out of the valve. The photot there only is showing two lines. What gives? Any other pics? Actuall cars ? I'm wondering, the hole that isn't used, is it indexed off ofg something? If you use only one bolt, what keeps it straight? I would assume something goes in th eother hole , even if only from th eback?? Any ideas? Thanks guys

 

proportioning valve is an aftermarket adjustable valve that allows you to put more or less braking power up front or in the rear.

 

Well here we go. All I wanted was placement info, but if I must teach I will. First, I am an automotive instructor and own a small restoration business. So, I know what I'm talking about here. A proportioning valve doesn't have to be an aftermarket piece. It is rediculous to think that. Every car that has disc on the front and drum on the rear has a proportioning valve. Without it, your rear brakes would look up first and basically you would have no front brakes. Disc brakes, by design, need more pressure to operate, whereas drum brakes do not. For that reason the pressures must be altered. Many cars have this valve built into a larger piece with is commonly known as a combination valve or a distribution block. Inside this piece are usually several valves. One being the proportioning valve, another being the metering valve and finally the pressure differential valve. Now I am referencing generic automotive designs here. However, these are the basics that all must follow, however they do it differently. Many cars have come with a seperate proportioning valve and the other valves are built into the combination valve. Mustangs built before 1970, F-Bodies before the mid 70s and the early Datsun Z are all cars that used a seperate proportioning valve. Now this valve isn't the adjustable type, as the aftermarket ones are. But it is a valve that lowers the pressure to the rear brakes. You have to be careful when discussing brakes, because many people, incorrecly, use different terms for different brake parts. But I have used the correct "generic" terms for the valves. If you want more info, I can give youmore. But really, I just want to know how it mounts.

 

Did you look at the first pic I posted??? Middle & lower right has the 4 line valve.

An auto instructor working on a car w/o a Haynes manual? That's blasphemy!

 

im not arguing its function or what it is, just simply how i was used to seeing it, its more semantics. in all the manuals etc. that i read it uses regulating valve. which in basic theory is teh same as proportioning valve. but any where when you shop for Z parts you get proportioning valve for the aftermarket adjustable option. simple semantics my friend and it was an explanation as to why it didnt click in my head. never did i say you were wrong so i dont know why your pulling the "im and automechanic teacher" card out already..... touchy touchy

 

well because I wanted was to know how it mounts, and you provided ina ccurate infor mation about that term being used only on aftermarket parts, which is totally untrue.

yes I did see that pick in your posting Nismo, unfortunately, that doesn't show where it mounts. That is the same pick I have in my manual, but yours is clearer. I can tell it uses only one of the bolt holes, if that line drawing is accurate. I want to know exactly how it attaches to the firewall. What is the other hole used for , indexing? and on what ?

 

So you want to know where and how it's mounted?

-From the pics in the manual, and from pics online, looks like it mounts to the firewall right below the throttle linkage coming out of the firewall (to the left of the brake booster).

-How is attaches is w/ a 10mm bolt.

Pics:

 

i do happen to have a 260Z sitting out in my drive way but since your so insolent to be understanding or apologize in any fashion, i think ill just hold off on getting a picture for you.

 

Dude... don't be ghey.

 

dont tell me, some guy is trying to give my his life history lecture and all i said was oops, semantics caused me to misinterpret what he was asking for, and then i get grief for even that.

 

I'm giving you grief for making the non-issue an issue....

 

i know, but it wouldnt be like this if he woulda not given my another lecture when i said my bad semantics got me. its like digging for a fight or something. and quite simply, im done posting in here. if i see a "sorry for the misunderstanding" which is good enough for me, ill get a pic. otherwise, i wont be seen in this thread any more :P

 

I am a facts kind of guy, I just like the facts to be correct. Not trying to insult anyone, just the facts sir )
Those two top pics are beautiful engines!! I see the valve in one pic only. I do have a hthreaded hole in that location and that is what guessed would be the place for it, but I'm still stuck on it having two mounting holes and only one bolt used. Without the other hole being used in some fashion, it would tend to move as you attach and tighten lines to it. Doesn't that make sense to anyone? I know I seem to be amking more out of it than it seems is needed, but it just seems weird using only one hole on something like this with lines attached.

 

Why not attach the lines to it, THEN bolt it in place?

And it shouldn't move much at all if you have one hand holding it, while you tighten the line w/ the other.

 

you said your using 240Z valve in a 260z? might be the prob..... i doubt it though. it shoudl mount right on the firewall almost behind the engine block. ill see if i got a pic in my photobucket account that elaborates more. otherwise id say either do without, or make your own mount there. simple self tapping screw if you wanna do it cheap and easy.










none that are straight on unfortunatly i might be able to snap one later

 

The hard steel lines keep the PV stedy and the one bolt simply clamps it to the firewall. '74, '77 are on the firewall for sure. My '70 is in the rear. The valves are not made by Nissan so there are other cars that use the same valve which is why there are two holes.

 

My '78s is on the firewall, too.
Dave

 

The location of the valve in a 71 240Z is above the rear diff. When I put on the rear disc brakes. We had to remove it and just moved the line over and bolted it back together. On the late model 260Z and 280Z it is located right below the MC and a little to the passenger side on the fire wall. It was held on by one bolt. Most people that have gone to the rear disc brakes have just gutted the assemble or gone to aftermarket part to replace it. Only have seen the two hole assembly in the rear, but they could have been used in the front to. Just mount the lines up and try to use one of the holes to mount it and drill out the other hole, should work.

 

no I'm not using my '70 valve, I'm using the '73. I am using the brake lines from the '73, thus using the front mounted PV.

 

we gave you your answers so did you get it? or you still fighting with it?

 

got it, thanks