How to bend aluminum cooling tubing?

[shermer-high]

I'm trying to figure out my cooling system in my Subaru fiberglass dune buggy with the radiator in front. How is everyone bending their aluminum cooling tubing without kinking? Also what type of aluminum tube works best? I don't have a tig so I want to do as much one piece as possible. I've been doing a ton of research but would like input from people who have done theirs. I still have to find the right radiator but don't want to spend $700 on a custom one to fit my tight front end. I found some that might work but I'll see haw the tube works first.

[Ol'fogasaurus]

https://www.aaluminum.com/anodized-alum ... -here.html One site does recommend 6000 series of AL tube as this alloy is softer and easier to bend as long as the bend radius isn't too tight. It also talks about the thinning of the metal on the outside of the bend and the thickening of the material on the inside of the bend. The thickening gets to a point where it will collapse (like bending a straw) or will fold into what looks like a "Pittsburg Lock".

I did look at the first part of a video on bending AL tube and they did the old sand packed in the tube (to hold the round form of the tube) trick but used small rocks instead. Not sure if this is that good of an idea for smoothness but they did use it.

Basically you block one end of the tube so when pouring and packing the sand in place it does flow out (you you need to use washed and dry sand for several reasons) Once you make a jig for the minimum radius you want (I think there are tables for this so a search might be a good idea) using "some" heat does work but you have to be careful... very careful. Also the radius part of the jig needs to be formed in a radius also so to slow down the chance of the tube ovaling or collapsing/kinking.

I have bent both round and square steel tubing this way but not AL.

Lee

[Andy Somogyi]

Aluminum comes in many many different alloys and grades.

Aluminum “tube”, stuff you buy by the OD, I.e. 1.25” tube is almost always T5 or T6 hardened. You have to anneal it to bend. Basically heat up to about 600° and let cool.

You can also get “aluminum rigid conduit” or ARC, this is used for electrical conduit. It comes annealed, usually at T1 hardness, and is designed to be bent. It had a thicker wall so it resists deformation and buckling. Basically it’s designed to be bent with a normal conduit bender.

You can also get pre-bent elbows.

I’m going with a mix of ARC and conduit bender for the larger radius bends, and using pre-bent elbows for the right bends, and TIG welding them together. Note, as this is a cooling system, you have to use 4000 series rod, 5000 series is not designed to run at extended hot use.


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[Ol'fogasaurus]

Bending tube, especially AL tube is more difficult than one thinks that is should be and for several reasons. I have been retires for almost 20 years now so from memory: AL tube comes in 1000 to 9000 series of AL which is due to the mix of other metals in the AL. Within each of those series are also other mixes and all the mixes were created (usually) for specific uses. In my almost 34 years working with a lot of AL designs I used 2024, 6061, 7076 mostly along with periodic 5052 AL. Since what I was doing we usually bent in a -0 condition then heat treated it to the toughness needed. The 5052 dealt with corrosion better than other materials, the 2024 was easier to form along with the 6061 and the 7076 could be pretty tough when heat treated to a -T6.

https://www.nalco.co.nz/sites/default/f ... minium.pdf

If you go to the box stores they have tubing benders for the most common alloys used in houses but their size of tube dia. they are designed for might be too small. I do not recommend going to an exhaust shop and using the benders that they usually use as the bend of the tube gets deformed too much but if you don't care... it is a way.

I play with glass buggies myself but my blue buggy is AC and my black buggy (in progress for a long time now) is a water cooled V6 but still in the rear. If you are using a stock pan where is the tubing going to run, under the pan or where? Also, what is the use: street, racing, off-road or sand for example and what is the dia. of the tube? The reason for asking is that AL may or may not be the best choice depending on several things.

Lee

[shermer-high]

I plan to run the cooling tube under the tunnel under the pan. My car is strictly street use and not lowered I won't even need to change the Subaru oil pan. My radiator is set up for 1.25 hoses https://www.appliedracing.com/cooling-s ... ision.html . I know I could use steel for cooling but hate mixing metals if I can help it that being said the factory heater tube to the thermostat is steel. Here is a quick video of my car a couple months ago. https://www.youtube.com/watch?v=3_3A3xQhXDg&t=29s

[Ol'fogasaurus]

The green inside is about the same color as my first short wheel base dune buggy which I still have and use.

https://en.wikipedia.org/wiki/Aluminium_alloy

This is a discussion on AL and it's alloys. I don't know if you will get much out of it or not but just in case... I can only once remember doing any design work with AL alloy tube and it was so long ago (in the late 60 or early 70's) that I don't remember which alloy the engineer I was assigned to at the time told to use (it was for an additional toilet location on an airplane and the whole thing was complicated as I had to add a Teleflex cable that is used to drain, clean then refill the holding tank from the bottom side of the fuselage).

Since you are planning on running the tube under the center of the pan, not inside the tunnel, and your buggy looks to be sitting high enough you might be OK with AL. The chemicals in the cooling system I am not sure about over the long run in AL: e.g., if there might be any problems with them in the AL alloy.

Looks like a nice build and you should be happy and proud of it.

Lee

[Andy Somogyi]

Ah, you’re using a T3 motor.

Friend of mine just Subaru swapped a T3, fits perfect under the deck lid, but has a shortened intake.


If you want, I can weld up a shortened intake, shoot me a PM.

He’s using 1” electrical conduit, steel and works fine, that’s about 1.1” ID.

That scirocco radiator will work fine, lots of people using them for Beetle swaps.

For tube, either steel EMT or aluminum ARC will bend fine with a conduit bender, you just can’t make a very sharp bend.

As for corrosion, both steel and aluminum have similar electrochemical potentials, and very common to mix them (iron block, aluminum heads). Just don’t use stainless, as it has very different potential and will cause galvanic corrosion with the aluminum, if it is NOT electrically isolated.







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[Ol'fogasaurus]

More info:

http://irontite.com/additives/about-coo ... -your-car/

https://www.streetmusclemag.com/tech-st ... chemistry/

I'm old and there were (and maybe still are) problems with coolant and different metals. This is just for information and I don't mean to be a big know-it-all, just had problems with coolant myself over the years.

Lee

[Andy Somogyi]

All materials have what’s called an electrochemical potential, this is essentially a measure of how much work is required to add or remove an ion from that metal.

Moving ions needs three things to occur:

(1) the two materials are electrically connected, thus providing a path for electrons to flow

(2) are immersed in an electrolyte — that is a liquid that has ion forming salts

(3) have different electrochemical potentials which drives the movement of ions

If you remove any one of the three, you will NOT get galvanic corrosion.

Tap water contains dissolved salts, and most antifreeze have certain compounds that essentially sequester those salts preventing corrosion.

If you use metals with similar potentials, like steel and aluminum, you will get little or no corrosion even in the presence of salts.

Of the metals are electrically isolated, you will not get corrosion.

The important thing is to avoid tap water if possible. But the best route is to simply use metals with similar potential and never have an issue to start with.

Whatever you do, do NOT use stainless steel. It had a very different potential, and can be difficult to ensure that the stainless line never touches any grounded part of the car.

More info:

http://irontite.com/additives/about-coo ... -your-car/

https://www.streetmusclemag.com/tech-st ... chemistry/

I'm old and there were (and maybe still are) problems with coolant and different metals. This is just for information and I don't mean to be a big know-it-all, just had problems with coolant myself over the years.

Lee

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[Ol'fogasaurus]

I thought that most of that info was to be found in what I posted. I looked at a lot of other URLs that also had more information but it would have been pretty busy just to do a simple read.

Tubing to radiators or the inlets or outlet on engines usually have a non-metallic tube joining them together and most of the time there is no touching of the pieces only fluids flowing.

The other day on one of the TV car build shows they were talking some similar cooling things on smaller engines (I think he/they were using a V6). They showed the radiator and the bungs that were being used and they looked way larger than 1' dia. Another option I have seen done, and I also don't recommend using, is short metal angles then soft tubing clamped the full length of the pan. One of the reasons being that the soft tube will eventually want to sag and that is a place for air pockets to form.

Lee

[shermer-high]

Ah, you’re using a T3 motor.

Friend of mine just Subaru swapped a T3, fits perfect under the deck lid, but has a shortened intake.


If you want, I can weld up a shortened intake, shoot me a PM.

He’s using 1” electrical conduit, steel and works fine, that’s about 1.1” ID.

That scirocco radiator will work fine, lots of people using them for Beetle swaps.

For tube, either steel EMT or aluminum ARC will bend fine with a conduit bender, you just can’t make a very sharp bend.

As for corrosion, both steel and aluminum have similar electrochemical potentials, and very common to mix them (iron block, aluminum heads). Just don’t use stainless, as it has very different potential and will cause galvanic corrosion with the aluminum, if it is NOT electrically isolated.




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That conversion looks nice I like the idea of keeping the engine low. I didn't want to sacrifice my bed but I am going to loose some bed space. I'm using a Subaru transmission and could drop the engine to the lower holes in my mount with different axils and shortened oil pan but I already bought everything to set it up this way. Everything is a trade off here is the engine fitted. https://www.youtube.com/watch?v=YVmVXDyB4Bc

[Ol'fogasaurus]

Have you figured out what you are going to do? Two tubes from front to back or just what. It is an interesting dilemma.

DSC00647 (2) copy.jpg

001.JPG

This is the bottom of the pan after I put new floors in. The forming of the main structural center section (in the first pix) shows the stiffening of the bottom of the tunnel (the tunnel is two pieces; the underside you see here and the tunnel it's self) so it isn't really that flat.

I added some 1 X 1 tubing down the body mount area for some additional structure but I would not use the 1 X 1 square tube again, maybe a 1 X 2 but the area might be usable for the two coolant tubes. I think I remember of some using the area but I could be wrong as it was so long ago.

Anyway, I posted this just to show what you have to play with and maybe an option.

Lee

[Piledriver]

The long rubber tube setup holds up to rocks, curbs etc pretty well...
Its all at the lowest point of the car.

That being said, if I was going to do it myself I would probably run it through the center tunnel or heater channels.

[Ol'fogasaurus]

The long rubber tube setup holds up to rocks, curbs etc pretty well...
Its all at the lowest point of the car.

That being said, if I was going to do it myself I would probably run it through the center tunnel or heater channels.

The long rubber tube can get torn loose or damaged very easily on rocks especially. For a street car it is the curbs and the large turtles indicating turn lanes you need to be concerned about.

I have seen/ heard of the two tubes run through the tunnel tried and to do it becomes a pain because of the other stuff inside like the shifter rod, the gas pedal cable tube and the e-brake tubes and the heater control handles.

Remember the tunnel (top and bottom assy spot welded together) is the back bone of a bolt on body style of unibody pan. Also there is going to be heat going through those tubes and heat rises.

The heater channels might be better but then you have other compromises mainly heat plus the two firewalls you have to pierce.

Remember, I am building a rear V6 engine buggy so I have spent more than 3 seconds looking into it but it was the low front hood (no room for the radiator) of the body that nixed it so quickly.

Lee

[shermer-high]

I finally figured out my aluminum cooling tubes and am almost finished mounting them. I used 1" aluminum electrical conduit. The outside is a hair over 1 1/4 the inside is 1". It bends easy on my JD Squared tube bender. I went under the center of the tunnel I have plenty of ground clearance, so they are fine there. If I were starting from scratch, I would do things different but it's a retrofit.