brake line size
 

Here is some info on my build. 53 1/2 ton pickup. Wilwood 12.88" drilled and slotted rotors. Rear cable drive emergency brake. 4 piston rear and 6 piston front. Frankland QC rear end and leaf spring front and rear if that matters. So here's the deal. I build factories for a living and we have thousands of feet of high end stainless steel tubing from 1/4" to 1/2" in my buildings. We end up with a lot of scrap sometimes 15 to 20 feet long. Wilwood tells me I need 3/16" line for my brakes and not to use 1/4" line. I don't understand why. Same in same out? In the big picture buying 3/16" tubing wont make much difference but I just don't understand why. Any advice would be helpful. I also have pallets of fittings for 1/4". Thanks for any help.

Re: brake line size
 

I know that GM has started using quarter inch lines on their trucks for a while now. They're also running big 2 and 4 piston calipers on some of their stuff. I am thinking the larger line has something to do with the added volume that they're moving. I'm planning on running quarter inch line on mine just because I've had some systems it before that were all 3/16 and you could almost feel the Restriction in the lines as you push the brake pedal down. Myself personally I just didn't care for it.

I really don't know why they would recommend against using larger line. On a hydraulic system you get out whatever you put into it.

Re: brake line size
 

I hadn't thought about the restriction being less. That would be a plus. Someone told me that 1/4" tube would stretch more but this is really high quality tubing polished inside and out. I'm learning a lot about the importance of flow on an engine lately, why would brakes be any different.

Re: brake line size
 

Not saying I know everything but I can't picture steel or stainless tubing stretching.

Re: brake line size
 

Me either I'm going to use it. I think i'll run my frame wiring in the 1/2"

Re: brake line size
 

Sounds like a good plan to me.

Re: brake line size
 

The ONLY reason they could say that is if the the caliper will only take fittings for 3/16" tube. The amount of fluid that is being moved is small, so fluid restriction is not a factor. Remember, a caliper piston only moves a few ten thousandths of an inch when applied.

Brake pressure can be around 2,000 psi and there is more total force being applied to the inside of a 1/4" line than a 3/16" one, but typical brake tubing (both tinned steel and stainless steel) can easily handle it. The tubing IS flexing when you brake, but you'd be hard pressed to measure it in your garage. The first place you would notice is the bends will try to straighten out like an air hose, just on a smaller scale.

Re: brake line size
 

Thanks for your input. This tubing is used for very high pressure liquid CO2 . My engineer assures me it will more than handle a brake system. they will make me any fitting I need for free including sweeping t's or 90's in stainless. I think one off fittings would be cool. It has nothing to do with cost we just like the idea of my guys being a part of my truck project. I have other people making parts for my truck that follow me around the country and work on my construction projects. Everybody likes to help and it's a lot of fun. Thanks again.

Re: brake line size
 

Simply a case of fluid displacement. Factory pieces are engineered to work together to achieve a specific pedal travel and feel. An extra 1/16th in diameter over the length of the line is significant-relatively speaking. If your using calipers with larger or more pistons, the difference in size won't really matter. I'm not saying it won't, it just won't be a big deal. You might notice a small change in pedal feel. I've run large calipers and wilwood 4 piston calipers on the rear of my car for years without issue. And I replaced all the lines with 1/4".

Re: brake line size
 

Thanks again for the input. I'm running Wilwood 4 piston rear and 6 piston front on 12.88" rotors.

Re: brake line size
 

It may be fine, but they need to cover there back side. They may not have tested all the parts with 1/4 line. They will not be liable if you don't follow what they say. That doesn't mean it won't work.