Transmission cooler question

[Mr. Pockets]

I have a B&M SuperCooler in my car. I only recently installed it in front of the AC condenser, as was suggested to me. The reasoning was that this would allow the cooler a lot of air with which to cool off, both while in motion and while at rest with the fans on.

Jeff from Hodges Subaru just called. Among the tech's suggestions (which I'll detail in my tranny thread) was one concerning the cooler. He doesn't like where it is and wants to hook up the stock cooler again. According to him, the condenser gets really hot and just acts to heat up the fluid.

Which is exactly what I thought the stock cooler did. So which gets hotter and causes more problems - the condenser or the radiator?

[svxistentialist]

I would not agree with your tech on this Cubes. With the B&M out front, the reverse is happening. Your tranny cooler is dumping hot air into the condenser rad, and that in turn is having to work hard to get rid of the heat that it is being fed from it's own system and the additional heat from the B&M.

Personally, I would not consider having the Supercooler physically in touch with the AC rad a good idea. An air gap of a few mm would help avoid heat transferring by conduction. Also, it is important that air can get feely right through the three matrices.

Where I would agree with your tech is on the point of the original stock cooler. You should be running fluid through this. The original is a liquid and air cooled device, and square inch for square inch is a more efficient dumper of heat than the B&M. If you force feed it with an air line, you will see it is not clogged completely. Can't have been, else your tranny would have burned up on a run to the shops with the amount of heat ours produces.

Connect up the stock cooler as well, feed them in parallel. If the stock one ever clogs completely, you will still have safe cooling with the B&M auxiliaryin place. Also, and your tech will like this, with two devices doing the cooling, there will be less heat dumped back at your AC condenser from the B&M, which will then be better able to cope with it's own job of keeping the driver cool.

All systems happy!

Joe

[Mr. Pockets]

Well, either way, I drove a 1,000mi road trip with the cooler in place and had no problems either with the transmission or the AC. I checked the fluid frequently to make sure that it wasn't getting burned.

The cooler isn't in direct contact with the condenser - there are some foam pads in between the two that amount to a few mm of clearance.

I'll give you my reasons for putting the cooler in and taking the stock one out of the system:

1. Enough members here saw significant ATF temperature drops with the same set-up. Temperatures in all sorts of driving were dramatically lower with the B&M replacing the stock cooler.

Admittedly, I did not verify this myself, but I am now planning on doing it. If I find that the B&M keeps the fluid consistently cooler, even by a few degrees, I'm taking my data straight back to you naysayers.

2. I did not want to add too much path to the system by running the coolers in parallel or series. I was concerned that this caused even a slight pressure drop, of which I have now felt the effects through a different cause.

Why would you plug the coolers together in a parallel fashion? Wouldn't the fluid basically just take the path of least resistance, so you'd see one cooler with fluid barely moving through it at all? It'd provide a little redundancy, I guess, but I question whether that's worth it.

[svxistentialist]

I have[had?] the same misgivings, and asked the same question on Yahoo soon after I got my car.

Yours being a '93, if it has a '93 rad, it will probably have the turbolator in the tranny cooler. The upgrade did away with that in later models, so grunge did not collect, reduce pipe diameter and reduce flow.

The oil will follow the path of least resistance. In a parallel set-up, that would imply most oil will travel through the B&M, it not being grunged up. In a series set-up, the pump has more work to do pushing through the two coolers. So the pressure increases. I don't like this. If the stock cooler ever completely jammed, no oil would get cooled, your tranny would melt.

With two coolers plumbed in parallel, the pressure at the pump will be reduced. However, both coolers[assuming no complete blockage] will be doing work, getting rid of heat. This is a GOOD THING. As the B&M is rated at 19000 lbs, I would not do parallel if you drive in a Northerly cold climate. If you drive in a Southerly warm climate, you bet I would use two. A good compromise would be to plumb in parallel, but include a manual valve in the circuit to the stock cooler. That way, you could let the oil flow through it for additional effective cooling in the summer, close it off in winter. You could even use the valve to balance flow through both coolers, if you had it on the B&M circuit, and I am presuming without measurement that the B&M would have least resistance to flow.

Although this post doesn't read like it, I am a fan of simple and elegant solutions, don't like to over-complicate things. However, the high final drive, and all the high gear ratios in the SVX causes the torque converter to multiply up a lot, stupid amount of heat created, and so the engineers seriously underestimated the amount of cooling required, IMHO. And if you look at the WRX, they do not make too many mistakes of that magnitude. But that is how I see the problem. Seriously and fundamentally undercooled tranny oil.

Joe

[oab_au]

Joe wrote
>Although this post doesn't read like it, I am a fan of simple and elegant solutions, don't like to over-complicate things. However, the high final drive, and all the high gear ratios in the SVX causes the torque converter to multiply up a lot, stupid amount of heat created, and so the engineers seriously underestimated the amount of cooling required, IMHO. And if you look at the WRX, they do not make too many mistakes of that magnitude. But that is how I see the problem. Seriously and fundamentally undercooled tranny oil. < Quote from Joe.

I agree with you Joe, mainly on the high final drive ratio, causing heat from the converter action.

But the main cause of failure, is the type of linings used, on the clutches. In the early models, (up till 94 Models) the linings flaked off in large pieces, Subaru weren't the only ones to have this problem, It was just the type of facing that was used in many autos of that era. The Australian Holden had the same type of trouble till the linings were changed.

The cooler in the radiator used an internal finning in the tube to cool better. The theory is that when a fluid flows through a cool pipe the oil next to the metal cools and forms a boundary layer that prevents the cooling of the oil in the middle of the tube.
Having the brass mesh in the tube, Conducts the heat from the center of the flow, There being more cool metal to conduct the heat away.

Unfortunally the big flakes blocked the cooler, which in turn restricted the flow of cool oil, that is used to lube the gears. The end result as everybody knows, is melt down of the gear train.

What is needed by all the early models, is a coarse strainer type filter to prevent the lining flakes from entering the cooler. The original cooler is the best, maintaining the oil at the best temp.

If the box has been rebuilt it should have the later type linings, Which don't flake off, Problem solved.
Harvey.