Auto Trans Filter / What About a Bypass?

[TheLoneRanger]

I have read a lot about the Perma-Cool tranny filter, and I know some of you use it in line with the cooler. I'm considering this, but am worried about the pressure drop through the filter.

What about installing it in bypass mode? It would be simple to tee it into the cooler lines, and this would prevent any pressure drop because the original plumbing would be unobstruced. Of course the filtering wouldn't be full flow; maybe only 20-30%, but this should be enough. Any thoughts on this???

 

[Ken2]

I've been considering the Racor LFS22825 full-flow transmission filter. Racor told me that the pressure drop of warm ATF through this filter is 0.25 psi, the filtration is 6 microns, and the internal bypass setting is 20 psid.

Ken

[ December 23, 2002, 11:47 PM: Message edited by: Ken2 ]

 

[TheLoneRanger]

Ken2, after reading your post, I looked at info on the Racor filter. That looks like a good one. I am impressed by the 6 micron filtering and the ability to clean it yourself. Also the stainless steel filter media is not suseptible to the "punch through" of a metallic particle, as is a pleated paper element.

There are a lot of choices out there; full flow vs bypass, paper element/cotton vs stainless steel, etc. I am going to install a filter on my Cherokee tranny, just not sure of the type yet......?

 

[Ken2]

The Racor LFS22825 uses a replaceable spin-on filter element with micro-glass media. The other filter elements shown on that page are for replacement in OEM filter housings.

Ken

 

[Al]

The concept here has me interested. Some things give me pause to think however. What about the warranty issue? I have an extended waranty on my vehicle and in all likelihood I won't be keeping it beyond the warranty. Its easy and cheap to drain 1 gallon once ot twice a year and refill with Mobil 1. Total time to drain and fill is well under 1/2 hour at most. I wonder if filtering down to that range is much better in terms of longlivity? Maybe-maybe not. I'd also like to see some oil analysis reports before and after the conversion. Of course we are still in the dark because no-one has yet to demonstrate the penalty on engine or trans life with respect to different level of wear metal in the oil.

Also after 25K on the Mobil 1 the viscosity dropped from 7.6 (Mobil's numbers) to 5.32 (oil analysis) So it looks like extended drain intervals-even with the filtering system is NA. for me anyway.

Not arguing one way or the other-just questioning out loud.

 

[RalphPWood]

If the transmission filter you use doesn't restrict the oil it also doesn't clean it. When you use a filter that cleans oil it always should be used with an element bypass orifice. My ATF filter is rated at 0.01 micron. It has the element bypass orifice of 1/8" in the filter itself. Some filter companies use an external fitting with a 1/8" or smaller orifice. The spin on ATF filters can usually be used with no orifice. They don't clean fluid very well but they are better than the stock filter inside the tranny. I change my Motor Guard submicronic bypass filter about every 20,000 miles .
You will probably get a lot of abrasives the first filter change so I wouldn't go very far on the first change. If you don't require submicronic filtration any pleated paper filter will work on the ATF. Even a big inline fuel filter will work.
About 40 years ago I put a Motor Guard filter on a Buick dynaflow transmission. I found a test plug in the high accumulator with about 80 psi. I returned the clean ATF to the pan. When I shifted into drive 80 psi hit the filter. That's all I needed. 5 psi is enough. ATF is sometimes a lot dirtier than motor oil. There is just no carbon to turn it black. My white element turns grey. We have the same thing with modern gas engines. There is little soot to turn the oil black. It's still very dirty using only the stock filter. You can't see the abrasives.

Ralph

 

[deepsquat]

I bought a used Frantz filter , and was thinking of adding it to my tranny ..already have a Gulf coast on the engine ..

 

[TheLoneRanger]

Ken2, yeah, I was looking at the wrong filter. That pressure drop of only .25 psi sounds remarkable. I would think it would be more.....

Al, you have some good points. Regular fluid changes might just be the way to go. I'm not trying to extend the fluid life, only the tranny life.

Ralph, I was looking at a Gulf Coast Filter that had an adapter similiar to what I was thinking of installing. It simply plumbed into the cooler line, and had one "in" and one "out" for the filter. This would bypass the original fluid flow, and shouldn't restrict the flow or pressure in the original line. The filter itself would have some restriction, but since it was in bypass mode, it wouldn't matter. If I install a tranny filter, I want to be sure it dosen't do more harm than good.....
Thanks for everyones ideas.
Don

 

[Giles]

I have the Perma-cool on my vehicle and was concerned about pressure drops. I decided to use a K&N Oil filter since it is a high flow filter but only gets 20 micron with any efficiency. The bypass valve kicks in around 8-11psi. I called B&M who also makes a bypass filter and asked about the pressure drop and they "guessed" around 4psi, but that since it was on the "loop" side and not the "pressure" side it shouldn't be a problem. It is working fine so far after around 3000 miles.

 

[RalphPWood]

The Lone Ranger,
All the adapter is is a orifice with a port upstream of the orifice for supply to the bypass filter and a port downstream for the clean ATF to return. Gulf Coast uses a 1/8" orifice. I measured a Frantz ATF adapter. It was 7/64".
I drill an internal orifice of 1/8" in the Motor Guard submicronic bypass filter. 1/8" is probably a little larger than you would need for a small tranny. Gulf Coast does a lot of big Allison military trannys. They feel that 1/8" will handle the range down to small cars.
The Motor Guard is the easiest and least messy to change but all of the TP filters work equally well. If you are going to purchase an ATF filter you may as well get one that cleans ATF.

Ralph

 

[RalphPWood]

Deepsquat,
Frantz didn't put an orifice in the ATF filter. I've drilled the orifice out for ATF and fuel. It's better to remove the screens before drilling them. If the filter heats up you are in business. The old timer that uses the Frantz without an orifice makes sure he changes the Frantz before it reaches it's capacity. The 1/8" orifice is the safest way to go. You can make an orifice adapter with a couple of brass tees. One time when I was young I put a Frantz in the return line of the power steering without an orifice. It was not a good idea I broke my Frantz. It couldn't take 1200 PSI.
There is little or no pressure on the return unless you put a restriction in it. The oil always has to find a way around a restrictive filter. The PermaCool sandwich adapter works the same except the orifice can get larger and smaller as the flow changes. It has a relief valve that opens and closes.

Ralph