1978 k30 Brake lines

[DBear]

Hey there, redoing a 78 k30 crew cab. Years ago, I stripped the frame bare, and now have no brake lines. Looking for some pre-bent lines for the front main lines and front to back inside the frame rails. I've been finding some for 3/4 ton but not 1 ton. Is it possible that the 3/4 and 1 ton are the same? Just not sure how similar the 2 frames are? Any leads or advice would be appreciated. Thanks in advance

[wildwilly4x4]

Lines will be the same from 1/2 ton to 1 ton (except for that goofy load valve that 1 tons had at the rear...which needs to be deleted anyways)

[DBear]

Originally Posted by wildwilly4x4

Lines will be the same from 1/2 ton to 1 ton (except for that goofy load valve that 1 tons had at the rear...which needs to be deleted anyways)

I talked to inline tube and told me their 3/4 ton stuff wouldn't work for me. So, what you're saying is all the hard brake lines up front of the frame that 1/2 ton 4x4 stuff will work on my 1 ton 4x4?

[DBear]

Originally Posted by wildwilly4x4

Lines will be the same from 1/2 ton to 1 ton (except for that goofy load valve that 1 tons had at the rear...which needs to be deleted anyways)

https://www.inlinetube.com/products/sctb7343

[DBear]

Originally Posted by wildwilly4x4

Lines will be the same from 1/2 ton to 1 ton (except for that goofy load valve that 1 tons had at the rear...which needs to be deleted anyways)

Do you have a picture of the load valve that is not needed? Could you also tell me what it did and why it is not needed? Inline tube and other sites have 1/2 and 3/4 ton pre-formed lines, and you said they will fit the 1 ton 4x4 correct? Thank you for your help sir.

[Keith Seymore]

Originally Posted by DBear

Do you have a picture of the load valve that is not needed? Could you also tell me what it did and why it is not needed? Inline tube and other sites have 1/2 and 3/4 ton pre-formed lines, and you said they will fit the 1 ton 4x4 correct? Thank you for your help sir.

That height sensing valve was a Rube Goldberg-esque attempt at a mechanical anti lock brake system, before there was an electronic version.

It was specifically added to help meet MVSS Federal standards for stopping distance. Some test scenarios (combinations sorted by model, brake series, wheelbase, rear axle, tire type and curb vs GVW) were so tenuous that we would ask for a specific driver to run the test. We would run multiple tests and classify them as "development" until we got a pass and then categorize that one as "validation" and submit it to the Federal Government.

If you are not trying to meet federal stopping distance requirements by a within few inches then you could probably leave it off completely or, as suggested above, add a manual adjusting prop valve back there.

K

[DBear]

Originally Posted by Keith Seymore

That height sensing valve was a Rube Goldberg-esque attempt at a mechanical anti lock brake system, before there was an electronic version.

It was specifically added to help meet MVSS Federal standards for stopping distance. Some test scenarios (combinations sorted by model, brake series, wheelbase, rear axle, tire type and curb vs GVW) were so tenuous that we would ask for a specific driver to run the test. We would run multiple tests and classify them as "development" until we got a pass and then categorize that one as "validation" and submit it to the Federal Government.

If you are not trying to meet federal stopping distance requirements by a within few inches then you could probably leave it off completely or, as suggested above, add a manual adjusting prop valve back there.

K

Good info...I think I cut that off years ago when I starting stripping the frame down...i.e. the reason I am looking for pre-bent brake lines LOL.

Another member stated that I could use 1/2 or 3/4 ton pre-bent lines on my 1 ton 4x4, which he's definitely smarter than I on this situation. Have you seen that done before?

[GRADYS Performance]

Keith, Does this valve increase or decrease rear brake pressure as it operates thru it's height range?

Originally Posted by Keith Seymore

That height sensing valve was a Rube Goldberg-esque attempt at a mechanical anti lock brake system, before there was an electronic version.

It was specifically added to help meet MVSS Federal standards for stopping distance. Some test scenarios (combinations sorted by model, brake series, wheelbase, rear axle, tire type and curb vs GVW) were so tenuous that we would ask for a specific driver to run the test. We would run multiple tests and classify them as "development" until we got a pass and then categorize that one as "validation" and submit it to the Federal Government.

If you are not trying to meet federal stopping distance requirements by a within few inches then you could probably leave it off completely or, as suggested above, add a manual adjusting prop valve back there.

K

[Keith Seymore]

Originally Posted by GRADYS Performance

Keith, Does this valve increase or decrease rear brake pressure as it operates thru it's height range?

Yes.

So fully extended - it limits brake pressure above 150 psi at 43%.

With the linkage compressed (via suspension load) - it allows full pressure.

Assuming it is adjusted correctly and operating as it should.


K

[Keith Seymore]

Originally Posted by DBear

Good info...I think I cut that off years ago when I starting stripping the frame down...i.e. the reason I am looking for pre-bent brake lines LOL.

Another member stated that I could use 1/2 or 3/4 ton pre-bent lines on my 1 ton 4x4, which he's definitely smarter than I on this situation. Have you seen that done before?

When I did lines on my GMT800 I used prebent for the front portion, but the rear portion needed to be straightened and re-bent in order to feed through the rails. I would have been as far ahead to use a straight section and then bend in place.

K

[DBear]

Originally Posted by Keith Seymore

When I did lines on my GMT800 I used prebent for the front portion, but the rear portion needed to be straightened and re-bent in order to feed through the rails. I would have been as far ahead to use a straight section and then bend in place.

K

So, the front portion, which would include the crossover lines, the master cylinder lines, etc. would work (1/2-1ton) 4x4?

[cerial]

Get some 3/16 nicopp, 3/16 flare tool off amazon, 4lifetimelines kit with the fittings. The 25 foot front and 25 foot rear kit with the fittings. Also get some 3/8" cable clamps with rubber insulation and some bolts and nuts from your local hardware store.

Good time to replace your front rubber and middle rear rubber lines. Get those off rock auto.

Now you can easily route and bend the nicopp off the valve to the rest of the truck. My lines off my master going to the valve were good so I kept them for now. But you can easily wrap 2 or 3 wraps around a full red bull can then cut and flare to have nicopp lines going to the valve.

That rear valve is a failure point. If your not required to run it don't.

Nicopp is better in almost every way vs steel. I run it as 3/16 brake and 3/8" nicopp fuel line. Easy to bend, flare, and holds good amount of pressure. Support it every 12-18" along the frame using the clamps so it can't rub and forget about it for 20 years.

[Keith Seymore]

Originally Posted by DBear

So, the front portion, which would include the crossover lines, the master cylinder lines, etc. would work (1/2-1ton) 4x4?

I can't answer that with any authority. I don't have brake line information for '78.

K

[DBear]

Forgive me for my ignorance on this, but isn't there some kind of block that sits inside the front frame to which the brake lines connect to? Didn't think it is the proportioning valve, but I could be wrong.

I am talking about the the block that connects the crossover line, master cylinder lines, etc.? Thanks

[wildwilly4x4]

yes, there is "block" on the front of engine crossmember. That "block" is called a combination valve. This is combination of proportioning valve and a residual valve. They are a pretty generic part typically designed for either Drum/Drum, Disc/Drum, or Disc/Disc systems...front/rear respectively. A quick search on ebay will usually find you one for less than $50, I've found it difficult to lookup at local part stores sometimes. Obviously if you are going back with stock stuff, you will need Disc/Drum for a K30.

[DBear]

Originally Posted by wildwilly4x4

yes, there is "block" on the front of engine crossmember. That "block" is called a combination valve. This is combination of proportioning valve and a residual valve. They are a pretty generic part typically designed for either Drum/Drum, Disc/Drum, or Disc/Disc systems...front/rear respectively. A quick search on ebay will usually find you one for less than $50, I've found it difficult to lookup at local part stores sometimes. Obviously if you are going back with stock stuff, you will need Disc/Drum for a K30.

I did search propositioning valve, but when the part shows up, it doesn't say anything about combination valve or residual valve? Thank you again for your input sir

[DBear]

Originally Posted by wildwilly4x4

yes, there is "block" on the front of engine crossmember. That "block" is called a combination valve. This is combination of proportioning valve and a residual valve. They are a pretty generic part typically designed for either Drum/Drum, Disc/Drum, or Disc/Disc systems...front/rear respectively. A quick search on ebay will usually find you one for less than $50, I've found it difficult to lookup at local part stores sometimes. Obviously if you are going back with stock stuff, you will need Disc/Drum for a K30.

This is what I have found...seems that it is the combo proportioning valve/residual valve


https://www.ebay.com/itm/32552557136...CPbhbX8AaDRgQk