Replacing Transmission cooler lines

[GMJimmy]

I need to replace the cooler lines in my 68 C10 SB. I'd like to use something easy to bend and corrosion resistant. Most of the steel and Cupro Nickel line I've looked at is .028" wall thickness. I've replaced the cooler lines in my 06 Silverado with factory replacement lines and they seem a lot lighter. I know they're steel because the old ones where rotten rusty. I don't drive the 68 in winter weather so not too concerned about them rusting out. What is everyone using?
Thanks

[roboticjunky]

Just did this on my truck. I used 5/16" nickel-copper tubing and Inverted Flare, 5/16 in. Tube, 1/2-20 in. Stainless Steel Nuts.

I found the stainless steel tube nuts at Summit Racing and the nickel-copper tubing from O'reilly, but you can get the tubing from a lot of different places. Make sure it says nickel and copper, not just copper.

[Steeveedee]

Any parts store should have the b-nuts, and roboticjunky is right about the NiCop line. Straight copper will work harden and crack, probably at the worst time. Steel doesn't work harden in your lifetime, and it's cheap, which is why the general ran it.

[GMJimmy]

Originally Posted by roboticjunky

Just did this on my truck. I used 5/16" nickel-copper tubing and Inverted Flare, 5/16 in. Tube, 1/2-20 in. Stainless Steel Nuts.

I found the stainless steel tube nuts at Summit Racing and the nickel-copper tubing from O'reilly, but you can get the tubing from a lot of different places. Make sure it says nickel and copper, not just copper.

5/16"? I thought 3/8" was what I should use.

Originally Posted by Steeveedee

Any parts store should have the b-nuts, and roboticjunky is right about the NiCop line. Straight copper will work harden and crack, probably at the worst time. Steel doesn't work harden in your lifetime, and it's cheap, which is why the general ran it.

I was thinking steel or Cupro Nickel but was trying to find the same wall thickness stuff the factory uses.
Thanks

[roboticjunky]

Originally Posted by GMJimmy

5/16"? I thought 3/8" was what I should use.

I needed 1/2-20 in. inverted flare tube nuts for my radiator and transmission and the biggest tubing that worked with that thread size was 5/16" tubing. I couldn't find any tube nuts for that size for 3/8" tubing.

[GMJimmy]

Originally Posted by roboticjunky

I needed 1/2-20 in. inverted flare tube nuts for my radiator and transmission and the biggest tubing that worked with that thread size was 5/16" tubing. I couldn't find any tube nuts for that size for 3/8" tubing.

I understand! One of the fitting threads in my rad is stripped so I installed an external cooler. The plan was to pull the rad to fix it but decided to use just the external cooler. I was thinking to run 3/8 line to it and use two inches of rubber to connect the cooler for each line. It has 5/16 copper (previous owner) line on it now and I thought it was too small and restrictive and want to get rid of the copper anyway. I didn't have any cooling issues with the 5/16" line though?

[tim_mc]

I used Right Stuff pre-bent lines from Summit (P/N RSD-TTC6803). They went on with minor tweaking. They're $45, but saved time and frustration, for me anyway.

[Andy4639]

I cut lines of out of the transmission. Used double flare tool made dimples on them. Put rubber hoses on them ran to radiator used correct fittings with barbs on them to attach to radiator. Simple easy and the hose will route a lot better than tubing. Over 5 years never touched it yet.

[Accelo]

Factory lines are 5/16"

[GMJimmy]

Originally Posted by Accelo

Factory lines are 5/16"

My 68 has a 4.8 and a 4L60E transmission out of a 2002 Silverado. The factory lines were 3/8". The ID of a 5/16" line is too small to cool the transmission in heavy use but my 68 won't be doing any towing so 5/16" might be ok.

[jimijam00]

https://www.summitracing.com/parts/sum-230320

[Accelo]

I should have qualified it. The 68 C10 SB lines were 5/16.

[GMJimmy]

Thanks everyone for all the suggestions. I went with the 5/16". I couldn't find the fittings I needed for the 3/8" right away and needed to get it done. The copper lines I took off were 5/16" and I didn't have any issues so on to another project.

[EagleChief]

Originally Posted by Andy4639

I cut lines of out of the transmission. Used double flare tool made dimples on them. Put rubber hoses on them ran to radiator used correct fittings with barbs on them to attach to radiator. Simple easy and the hose will route a lot better than tubing. Over 5 years never touched it yet.

This was the question I initially had... why not use flexible lines instead of tubing? Stainless flex lines, or something like that. I would think it would be much easier to route the lines.

I'm slowly working on swapping an LS into my truck and will eventually have to look into it.

[GMJimmy]

Originally Posted by EagleChief

This was the question I initially had... why not use flexible lines instead of tubing? Stainless flex lines, or something like that. I would think it would be much easier to route the lines.

I'm slowly working on swapping an LS into my truck and will eventually have to look into it.

Flexible tubing/hose is easier to route but you have to hang it in several places so it doesn't sag. Metal tubing is harder to install but only needs support in a couple of locations. The advantage to flexible hose is you can fasten it to the frame out of the way.

[LS short box]

The nicop lines are rated for brake line pressures so cooler lines are no where near that. The nicop lines flare like butter and bends much easier than steel lines.
You need to keep in mind rigid lines need some flex due to engine movement.

[GMJimmy]

Originally Posted by LS short box

The nicop lines are rated for brake line pressures so cooler lines are no where near that. The nicop lines flare like butter and bends much easier than steel lines.
You need to keep in mind rigid lines need some flex due to engine movement.

The copper lines I replaced were fastened to the frame not allowing for movement. I replaced them with nicop and fastened them to the engine right up to the rad support where they change to rubber to the cooler. The nicop lines are easier to bend than steel but still pretty tough.