Contour Enthusiasts Group Archives Forums Modifications Transaxle Transmission filter? Check out this site....

Hey, Terry, I am curious,

You seem to warn about adding an inline filter quite a bit, so I must admit, my curiosity is peaqued. Do you know something that most people dont about this?

I am not trying to argue, but I fail to see how adding an inline cooler affects the flow of fluid. The fluid is pressurized, correct? It has a set flow based on line size in square inches. I simply cannot believe that adding a filter would restric or affect the flow of fluid in any way. if you look you notice that the size of the filter, and the media is SIGNIFICANTLY greater than the area of the 3/8 inch line that runs to it. So there should be NO loss in pressure, IE, the Pressure per square inch would drop, but the overall volume of fluid is increased. On the way out the volume is reduced so the Pressure per square inch increases. This is exactly how oil filters work, but I certainly wouldnt run without an oil filter.

You may argure that oil systems are deisned to run with filters, but that's just not true. Oil systems are designed around a certain pressure and flow. The fact is, that the math tells us unless the filter is somehow removing energy from the fluid (which it is NOT), the pressure and flow are not affected. 3/8 inch line in at 60 PSI = 3/8 inch line out at 60 PSI. Unless the fluid is going somewhere else? You certainly dont expect me to believe that the thin paper media inside the filter is capable of holding pressure?

Like I said, the filter is not only approved by ford, but FORD actually puts them on cars.

Sounds like a winner to me.

But like I said, if theres something you know that your not telling us, then lets have it.

I am not answering for Terry, as he can do that himself, but I thought I would take a shot...


All filters have a pressure drop. As they collect debris, the pressure drop gets higher. If you look at a filter specs (I do this in my job), they are rated for a given pressure drop at a given flow rate. In addition, a good one has a spring loaded bypass so a clogged filter won't stop the flow entirely. The spring bypass might be rated 3PSID (Pounds per Square Inch Differential). That means when the filter is fully bypassing, the pressure drop across the filter is at least 3 lbs. The poresuure could be 1000PSI in, 997PSI out, a difference of 3PSI) The pumps are rated at a volume/pressure. The pressure is the sum of all resistances in the circuit (Much like electric). The oil passages, orifices, valves, internal filter in the tranny all add up to a pressure drop at a given gpm. Let's say 1000 PSI at 3 gpm (not a rating for our internal tranny pump, but a number to use). If you decrease resistance (clean filter, larger pipes, etc) the pump can deliver 3.2 gpm at 950 PSI. If you increase resisitance, the pump might deliver 1050 PSI at 2.8 gpm. The problem with our cars, is the higher pressure might be good, but the lower flow through the cooler is not good.

In reality, the pump is a fixed displacement pump. There is a pressure regulator that dumps extra oil if the pressure gets high. So while the pump is actually delivering the same GPM at a given rotational speed, the regulator start dumping some of that GPM when the pressure get's higher than it's setting. This is to maintain an even pressure across all RPM input ranges. A low rpm, it is dumping very little. At high RPM, it dumps a lot.

Now I hear your mind thinking, let's up the regulator setting. Good Idea...but, the pump isn't rated for that much higher pressure and the oil pump casing is been known to fail at the pressures it runs now. Since we can't increase the pressure, we really don't want to add any restriction to the present system.

To do this right, you need to redesign the pump housing and gears for more strength at a higher pressure, change the regulator setup, increase some of the passage and tube size. Not so easy. I don't know what Level10 does to improve performance, but is probably along these lines.

FWIW, even a small cooler, which should be a help, can increase the pressure drop and reduce flow.

So that's why you must be careful of the filter. Since I don't know what the flow actually is, and I know that the flow is a little low without an external filter, I would say an external filter will give you cleaner oil at a higher temperature than now. And high temps kill the tranny.

The only way around this might be an external pump, tap into the tranny pan, let the external pump pull oil out of the pan, filter it, and return it to the pan. This would work, but I don't know if it would be really cost effective. I would just change the tranny oil more frequently and put an appropriate sized oil cooler on.

Originally posted by Contouraholic:

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The only way around this might be an external pump, tap into the tranny pan, let the external pump pull oil out of the pan, filter it, and return it to the pan. This would work, but I don't know if it would be really cost effective. I would just change the tranny oil more frequently and put an appropriate sized oil cooler on.

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This isn't a bad idea, except the CD4E doesn't have a bottom pan.

The flow rate of the CD4E through the cooling line is approx 1L every 20 seconds at idle.
I don't know what it is while driving, but it HAS to be tested while driving.
Placing a pump on the line between the cooler and a filter wouldn't be a bad idea.
When the fluid re-enters the tranny, it is directed to spray on the drive chain,
so there is no problem with pressure on the return side.
From there it drains to the bottom and is picked up buy the sump.

The problem, with adding a pump is this...

Cooler flow rate is variable, and if the pump flow exceeded the actual flow at idle,
it could very well PULL oil pressure away from the tranny, via the cooler line outlet,
and that would be bad for the tranny.
If the pump should fail while you were driving, the fluid flow throught the cooler would essentially STOP.
This would back up inside the tranny, and cause a spike in pressure that *could* crack the ATX Case.

So you see, the IDEA has potential, but the pumps we have today, are not really suited for this type of application.

Doesnt have to be into a bottom pan.I haven't looked, do we have a drain plug? We could pull from there and return a little higher up...A bypass setup like this would polish the oil pretty well.

Wasn't really trying to design this, just suggesting the the existing oil loop is probably best left alone except for a cooler. A filter would need a different approach to avoid exceeding the trannies capabilities.

My gut feeling is that a cooler would do more to help than a filter. It looks as though overheating is a more likely failure mode than metal particles.

I see you points on most of this, and I acctually like tha idea of adding an external filtering system, bt I would have to thinka bout that some more, but in theory, it would work great.

Right now I am happy changing the fluid every oil change.

Under high mileage aggressive driving conditions, particularly in European model cars, vehicles were experiencing forward and direct clutch cylinder bushing failures on vehicles equipped with CD4E transmissions. The root cause of the problem was determined to be inadequate flow of transmission fluid under high-speed conditions. A Filtertek engineering team lead by Executive Vice President of Technology, Larry Larkin was requested by Ford to assist in evaluating solutions for this problem. After six months of working alternative design configurations for the CD4E Transmission Sump Filter, Filtertek developed a filter design solution that eliminated the early wear out problem. The improvement results were significant with the overall achievement of extending the transmission integrity to well beyond the limit of the vehicle warranty. There was a 400% improvement in filter integrity at 150,000 miles and increased reliability from 72% to 99.5% at 150,000 miles.

Lets list what we think we know..

• Problem: inadequate flow of transmission fluid under high-speed conditions
• Solution: designed a filter that countered the problem (or so there PR states

Since some poeple have killed the tranny in less than 10k I think it's safe to assume that a plugged filter is not the cause. I doubt that a filter can clog in under 10K and i have read of more than a couple people haveing the tranny die by then If that is the case then adding an addional filter will not help the problem because it will add attional restriction in the sytem. But replacing the current filter with a higher flow less restriction version may work? Or omitting the factory filter (empty filter) all togeter for this brand.

Originally posted by woz:

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Lets list what we think we know..

• Problem: inadequate flow of transmission fluid under high-speed conditions
• Solution: designed a filter that countered the problem (or so there PR states

Since some poeple have killed the tranny in less than 10k I think it's safe to assume that a plugged filter is not the cause.

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It is NOT that the filter is plugged...
The filter also serves as the SUMP PICKUP !
That was the WHOLE IDEA that FilterTek won the award for!!
They improved OIL PICKUP by redesigning the filter !

In reply to:

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It is NOT that the filter is plugged...
The filter also serves as the SUMP PICKUP !
That was the WHOLE IDEA that FilterTek won the award for!!
They improved OIL PICKUP by redesigning the filter !

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A new design is nice....Only question I would have "Did it solve the problem?"

The problem: Tranny Failure.

The pickup may be new, the "problems with the old pickup" solved, but, does the new filter have a lower tranny failure rate than the old?

I have seen new designs that solved a problem, but the problem it solved did not prevent failure.

For instance, some here have put a baffled oil pan on their engine. Solves the oil not being picked up in a curve problem. But they still lost a bearing....So while a baffled oil pan solves the problem, it didn't solve the real problem.

Not saying the new filter doesn't work as promised, just, does it reduce tranny failure? I mean in the real world, not in the lab. Was the oil filter the cause of tranny failure? Or is it something else in the tranny. Since the award was recent, I would rather see a track record on consumers cars than just an anlysis of the problem and voila! a new design filter fixes it, we promise.

FWIW, Ford can't get the dashboard to stick to the dash. Fluid dynamics is harder.

Well to add the ATX filter or not to add the ATX filter that is the question?

This back and forth pros and cons guys will cause group members not to act or rather just to change ATX fluid (properly) at 12K intervals if that is the recommendation under normal heavy duty operation.