Fat brake pipe(s)

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Pinger

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Find a part number, I'll send it to you.
Thanks 618 - a very kind offer. But, I'll just source the pipe here and upgrade my flaring kit to cope with 1/4'' pipe. That way I'm also covered if at any time the rest of that pipe run needs changing or I decide to do it now.
I'll keep you offer for something I'm truly stuck with! Thanks again though - appreciated.
 

GoToGuy

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Tubing and pipe is always O.D. , outside diameter.
Hose whether rubber, Teflon, buna, synthetic, is always measured by I.D. inside diameter.
 

Schurkey

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Tubing and pipe is always O.D. , outside diameter.
No.

Tubing is measured by OD, so the fluid path is smaller depending on the wall thickness of the tube. PIpe is measured by ID. Thus a "1/2 inch" pipe is huge compared to "1/2 inch" tubing. 1/2" tubing would be a tight fit INSIDE 1/2" pipe. Of course, most pipe is not precision-made, so the actual fluid path varies somewhat.

Hose whether rubber, Teflon, buna, synthetic, is always measured by I.D. inside diameter.
Not exactly. Hose can be measured by ID in some cases. In other cases the ID is similar to a same-nominal-size tube. In other words, the nominal size minus the wall thickness of the tubing. The actual ID is smaller than the nominal ID.

Examples:
Aeroquip 2807 "Teflon" / "PTFE" steel-braided hose, -4. Nominal 4/16 = 1/4" hose. Actual inside diameter .19 rather than .25. Similar to 1/4" tubing with a .030 wall thickness.

2807 -8 Nominal 8/16 = 1/2" hose. Actual inside diameter .42 rather than .50. Similar to 1/2" tubing with .040 wall thickness.

Aeroquip FC300 -8 reinforced rubber hose with polyester outer braid. Nominal 8/16 = 1/2" hose. Actual ID is .41 rather than .50. Similar to 1/2" tubing with .045 wall thickness.

NAPA NBH H178 "3/8 inch" fuel hose, nominal 3/8", actual ID is .375 = 3/8 inch.
 
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PlayingWithTBI

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Tubing is measured by OD, so the fluid path is smaller depending on the wall thickness of the tube. PIpe is measured by ID. Thus a "1/2 inch" pipe is huge compared to "1/2 inch" tubing. Of course, most pipe is not precision-made, so the actual fluid path varies somewhat.
^^^This - plus, depending on pipe thickness, especially in PVC makes a huge difference, Sch40, Sch80, or, in bigger pipe like IPS100, IPS 125, etc. An example of the difference in pipe diameter, look at CPVC as apposed to Sch40. CPVC is the same OD as Copper pipe where Sch40 PVC is based on ID. Way too many variations to just make a blanket statement :33:
 

Pinger

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In general, each wheel cylinder (including calipers) gets fed with a 3/16 tube. But since both rear wheel cylinders share plumbing from the combo valve to the brake hose...they use a 1/4 tube since it's supplying two wheel cylinders.
Just out of curiosity, was the 1/4'' pipe fitted to GMT400s prior to the introduction of ABS (antilock braking system)?
 

someotherguy

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Just out of curiosity, was the 1/4'' pipe fitted to GMT400s prior to the introduction of ABS (antilock braking system)?
GMT400's have had ABS from the first year model - 1988 - just that it was rear-wheel only. The SUV's introduced in 1992 got 4-wheel ABS, but the pickup trucks didn't get 4-wheel ABS until 1995.

Richard
 

GoToGuy

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Wow, that certainly was a land mine. I don't use plastic pipe on vehicles. Nominal size is reference data, but not what I ask for at the parts dept. Yes the actual size of Aeroquip Teflon is less than what the dash number is. Do you know why?
Why go into the FAA, MS, NAS, AN? Maybe 5 poeple would could understand it.
I was limiting it to SAE type material, truck related.
Hey sorry won't happen again.
 

Pinger

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GMT400's have had ABS from the first year model - 1988 - just that it was rear-wheel only. The SUV's introduced in 1992 got 4-wheel ABS, but the pickup trucks didn't get 4-wheel ABS until 1995.

Richard
I'd have to ask the question of earlier than GMT400 then. I was curious as to whether the larger pipe facilitated quicker dropping of pressure in the wheel cylinders during ABS activation as much as promptly increasing pressure on brake application. It would do both, but I was wondering if the need to drop pressure quickly trumped the need to build it and hence the choice of 1/4''. If the earlier trucks also had 1/4'' - that would knock my ABS pressure release theory into a cocked hat. (Which is probably where it belongs!).
 

618 Syndicate

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I'd have to ask the question of earlier than GMT400 then. I was curious as to whether the larger pipe facilitated quicker dropping of pressure in the wheel cylinders during ABS activation as much as promptly increasing pressure on brake application. It would do both, but I was wondering if the need to drop pressure quickly trumped the need to build it and hence the choice of 1/4''. If the earlier trucks also had 1/4'' - that would knock my ABS pressure release theory into a cocked hat. (Which is probably where it belongs!).
Pretty sure there was no abs on trucks prior to 400's.
 
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