ru·bi·con
noun
A river in northern Italy
metaphor
The point of no return. Refers to Julius Caesar's march on Rome in 49 BC: It was considered treason to bring an army closer to Rome than the banks of the Rubicon River. If his campaign was successful, he would rule; if it failed he would be executed for insurrection.
idiom "Crossing the Rubicon"
I have committed the unpardonable act of removing a component that can only be taken out in pieces. The rear main heater wye that routes hot air from the air-cooled engine heat exchangers, combines them into a single 4.75" tube that travels forward to a multi-way splitter and eventually produces a whisp of heat at the dash, or at vents on the floor. The whole affair never was very well insulated which is why the heat exchanger, producing an incredible 400°F, was under-appreciated: it never got a chance to do its job because of leaks, busted fittings, and incredibly poor airflow.
That wye pipe that joined the two exchangers on their way forward is a real stinker. It is welded into place before the decking is welded over top of it. Cutting it out with a Sawz-All (reciprocating saw) or an angle grinder is extremely nervous work since the tight quarters can cause you to cut something that you possibly don't want to.
Like the accelerator cable tube. The clutch cable tube. Nothing important. (Yikes!)
Obviously, this begs the question "Why did you take the heater wye out?" From those in the Bus biz (especially the über-purists) that phrase is essentially screamed because it means that for all intents and purposes, there no way back to an air-cooled engine. It is as one-way as losing your virginity.
The longer I've stared at the Fellows Speed Shop design, the less happy I've been with how low swingin' those coolant pipes are. One good shot and you're bleeding out coolant all over the road. The primary criticism of an underbelly radiator has been the proximity of the radiator to road debris. I had managed to get the radiator up and out of harm's way through a combination of skull sweat and smartly sourcing my components. Now I wanted to get the coolant tubing up above the level of the frame rails as well so all of the compromises for the conversion were removed.
The Fellows Speed Show design requires you to either drill through the side of the right hand frame rail like it was a bulkhead to return coolant to the engine, as well as drilling through the rear main transverse crossmember for the inlet side of the radiator from the engine. While both of these structural insults can be reinforced again...why are we drilling through rear and side of the frame again? To move coolant. The coolant travels through tubing 1.5" Outside Diameter (OD). That's not large....would it fit if ...? Remember what I said about that heater wye? The place where it already passes through the rear main crossmember is 4.5" wide and 3.75" tall. Remove the wye, and there's your way into the 'box' at the center of the frame where your radiator lives. Nothing hangs lower than the frame rail, and the whole run of coolant tubing (alternating with hose) is now very safe.
But if you're consuming the whole width between the frame rails with your radiator...how are you going to route coolant from the radiator outlet back to the engine? Won't you have to go outside of the frame rail and transverse crossmember box?
I spent serious time during the last two weeks freezing my tail-feathers off in that chilly garage staring up and visualizing how the hell I was going to run that coolant return without chopping holes in the frame.
First I noted that you could go OVER the frame rails. There is 1.6" of clearance between the top of the longitudinal frame rails and the decking. That's about an extra 3.5mm. That's close, but doable if I could route the coolant from the radiator tank up and over the frame rail. I ran into one of the major challenges everyone doing these kinds of conversions does: The reason the Bus is so big on the inside is that they really mashed everything together outside. The unfloor area I needed to navigate was as crowded as the bottom of a ladies purse.
Even assuming I could get over the rail, I would then have to run to the rear, and then jump BACK INSIDE the rail to catch the return fitting at the wye. That's too much jumping around, too many corners, too many fittings, and too many chances to spring a leak. No. I blew a week working that idea and concluded the only way it was better was that it didn't put a hole in my frame rail. Otherwise, just as bad.
But this failure did lead me in the right direction: I started thinking vertically and that turned out to be just the thing: I wondered about going over the top of the radiator. Nope: Fans there.
Maybe I could sneak around the edge of the fan? 1.5" isn't much. Nope. I'll be so occluded up there that I won't have a straight shot 1.5" in diameter to the rear.
Then it hit me like a pile of bricks: The radiator (with tanks at the front and back) is about 24.5" wide at the body. It has brackets TIG welded on which takes the total width to 28". The brackets hold the radiator to the bottom of the 'C' shaped frame rails. The bottom edges of the frame rails are 26" apart. The radiator shown below sits above the level of the frame rail and the long, serpentine coolant tubing snake *inside* the frame rail.(Not shown especially well by this overlay. Imagine the front to rear span above that frame rail.)
So what's the distance, when the radiator is centered in the space, between the outside of the radiator body and the inside surface of the left frame rail? I tested it with the best object I had for the job:a piece of 1.5" diameter steel tube. Holy smokes. It fits, and with about that same 3.5mm 'expansion' space as was to be had by going over the frame rail.
There was some occlusion of the steel emergency brake cable conduit on the left hand side. So...close. I got my jack and carefully applying pressure with a rounded piece of wood in the cup of the jack, put a trivial new bend in that tube without kinking it. I checked the occlusion at the rear. Damme. This will work.
All we need now is a single piece of mandrel bent tubing to chase from the outlet at the front right, make a tight turn to the rear, into the space between radiator and frame rail, then emerge at the back and make another 90° turn to be facing right. The space is so tight that there's no way to do it with straight-pipes and elbows and hose fittings. It has to be done with one piece of 1.5"OD pipe.
And where am I going to get that for less than a king's ransom?
I found a fabricator. What you see shown above is the initial cut. Unfortunately, my draftsman (and consulting mechanical engineer with a lifetime of experience in high criticality cooing systems) is bugging out for the warmer climates of Florida for a month. I'm not going to lay around and wait for him to get back, but I'm going to have to put this on the back burner until he comes back and work other aspects of the design.
The point of no return. Refers to Julius Caesar's march on Rome in 49 BC: It was considered treason to bring an army closer to Rome than the banks of the Rubicon River. If his campaign was successful, he would rule; if it failed he would be executed for insurrection.
idiom "Crossing the Rubicon"
I have committed the unpardonable act of removing a component that can only be taken out in pieces. The rear main heater wye that routes hot air from the air-cooled engine heat exchangers, combines them into a single 4.75" tube that travels forward to a multi-way splitter and eventually produces a whisp of heat at the dash, or at vents on the floor. The whole affair never was very well insulated which is why the heat exchanger, producing an incredible 400°F, was under-appreciated: it never got a chance to do its job because of leaks, busted fittings, and incredibly poor airflow.
That wye pipe that joined the two exchangers on their way forward is a real stinker. It is welded into place before the decking is welded over top of it. Cutting it out with a Sawz-All (reciprocating saw) or an angle grinder is extremely nervous work since the tight quarters can cause you to cut something that you possibly don't want to.
Like the accelerator cable tube. The clutch cable tube. Nothing important. (Yikes!)
Obviously, this begs the question "Why did you take the heater wye out?" From those in the Bus biz (especially the über-purists) that phrase is essentially screamed because it means that for all intents and purposes, there no way back to an air-cooled engine. It is as one-way as losing your virginity.
The longer I've stared at the Fellows Speed Shop design, the less happy I've been with how low swingin' those coolant pipes are. One good shot and you're bleeding out coolant all over the road. The primary criticism of an underbelly radiator has been the proximity of the radiator to road debris. I had managed to get the radiator up and out of harm's way through a combination of skull sweat and smartly sourcing my components. Now I wanted to get the coolant tubing up above the level of the frame rails as well so all of the compromises for the conversion were removed.
The Fellows Speed Show design requires you to either drill through the side of the right hand frame rail like it was a bulkhead to return coolant to the engine, as well as drilling through the rear main transverse crossmember for the inlet side of the radiator from the engine. While both of these structural insults can be reinforced again...why are we drilling through rear and side of the frame again? To move coolant. The coolant travels through tubing 1.5" Outside Diameter (OD). That's not large....would it fit if ...? Remember what I said about that heater wye? The place where it already passes through the rear main crossmember is 4.5" wide and 3.75" tall. Remove the wye, and there's your way into the 'box' at the center of the frame where your radiator lives. Nothing hangs lower than the frame rail, and the whole run of coolant tubing (alternating with hose) is now very safe.
But if you're consuming the whole width between the frame rails with your radiator...how are you going to route coolant from the radiator outlet back to the engine? Won't you have to go outside of the frame rail and transverse crossmember box?
I spent serious time during the last two weeks freezing my tail-feathers off in that chilly garage staring up and visualizing how the hell I was going to run that coolant return without chopping holes in the frame.
First I noted that you could go OVER the frame rails. There is 1.6" of clearance between the top of the longitudinal frame rails and the decking. That's about an extra 3.5mm. That's close, but doable if I could route the coolant from the radiator tank up and over the frame rail. I ran into one of the major challenges everyone doing these kinds of conversions does: The reason the Bus is so big on the inside is that they really mashed everything together outside. The unfloor area I needed to navigate was as crowded as the bottom of a ladies purse.
Even assuming I could get over the rail, I would then have to run to the rear, and then jump BACK INSIDE the rail to catch the return fitting at the wye. That's too much jumping around, too many corners, too many fittings, and too many chances to spring a leak. No. I blew a week working that idea and concluded the only way it was better was that it didn't put a hole in my frame rail. Otherwise, just as bad.
But this failure did lead me in the right direction: I started thinking vertically and that turned out to be just the thing: I wondered about going over the top of the radiator. Nope: Fans there.
Maybe I could sneak around the edge of the fan? 1.5" isn't much. Nope. I'll be so occluded up there that I won't have a straight shot 1.5" in diameter to the rear.
Then it hit me like a pile of bricks: The radiator (with tanks at the front and back) is about 24.5" wide at the body. It has brackets TIG welded on which takes the total width to 28". The brackets hold the radiator to the bottom of the 'C' shaped frame rails. The bottom edges of the frame rails are 26" apart. The radiator shown below sits above the level of the frame rail and the long, serpentine coolant tubing snake *inside* the frame rail.(Not shown especially well by this overlay. Imagine the front to rear span above that frame rail.)
 | |
|
There was some occlusion of the steel emergency brake cable conduit on the left hand side. So...close. I got my jack and carefully applying pressure with a rounded piece of wood in the cup of the jack, put a trivial new bend in that tube without kinking it. I checked the occlusion at the rear. Damme. This will work.
All we need now is a single piece of mandrel bent tubing to chase from the outlet at the front right, make a tight turn to the rear, into the space between radiator and frame rail, then emerge at the back and make another 90° turn to be facing right. The space is so tight that there's no way to do it with straight-pipes and elbows and hose fittings. It has to be done with one piece of 1.5"OD pipe.
And where am I going to get that for less than a king's ransom?
I found a fabricator. What you see shown above is the initial cut. Unfortunately, my draftsman (and consulting mechanical engineer with a lifetime of experience in high criticality cooing systems) is bugging out for the warmer climates of Florida for a month. I'm not going to lay around and wait for him to get back, but I'm going to have to put this on the back burner until he comes back and work other aspects of the design.
No comments:
Post a Comment