I don't know if I should be or not. Did the first service on it at 25k, installed a new shift solenoid and a Mag-Hytec pan. Old fluid looked OK, normal sediment on the pan magnet, trans shifts fine, everything seems good to go. But I could not help wondering how this monster diesel tranny is still getting along with basically the same filter they were using in the 727s back in the 60s. I was astonished to see that Mag-Hytec even recommends using the old style filter as being a better design. ***?

So I got to looking around and found an elegantly simple, neat way to install a bypass filter in the cooler lines using a standard filter mount. There is about an eight inch section of 1/2" I.D. rubber on both lines near the bottom of the washer bottle. The top line is the hot/pressure side:

http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_11.JPG

Located conveniently nearby is a cubby hole behind the bumper with plenty of space and a nice solid place on the core support mount to attach:

http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_12.JPG

There is a .025" flow reducer on the filter input coming from the hot line so most of the oil continues to flow normally through the cooler. But there is enough of a pressure differential across the lines at this location to slowly push a small amount through the bypass filter. Removing the inner fender took all of 5 minutes and made installation a breeze:

http://stuff.is-a-geek.net/PhotoAlbu...ics/CRD_13.JPG

Hopefully with regular service and set up like this, my tranny will last a bit longer than might otherwise be expected.

 

Nice try, especially since did not cost much. Hopefully the filter will cool the escaping fluid enough so don't lose cooling efficency. You will not see any difference in tranny life as the in tranny filter is more than adequate. That is why has stood the test of time for essentially 45 years JMHO

 

I think the real benefit is being able to do at least a couple drain-refill services without having to worry about the internal filter. Clean fluid is never a bad thing, and dropping the pan is somewhat of a PITA, to me at least. Wonder why they finally went with an externally serviceable spin-on filter with the new RFE trans?

 

agreed. it makes a mess.

i just put a drain plug in my pan

 

Yep, gotta have a drain plug. Nice bonus to the Mag DD pan, as well.

I don't know if you understood the part about the .025" flow restriction. Cooling is actually enhanced with this setup. The very "small" amount (2% maybe?) of oil diverted through the bypass is insignificant to the main flow, if anything slowing it only slightly, in a similarly small amount. Cooling happens over time - time in the cooler.

I wonder how many drains/flushes you can do before the stock filter begins to clog? Probably depends mostly on how often you do them to get the dirt flushed out. Sounds like alot of ATF. And I wonder how that affects cooling after it does start to clog?

The race-built 727 in one of my cars doesn't have a "stock" internal filter. It's looks and is shaped kinda like it, but is actually just a brass screen. There's an external spin-on full flow in the cooler circuit, with a pressure tap for checking line pressure to do the real filtering.

You can't change the internal filter through a drain plug.

 

That's the usual purpose of dropping the pan to access the filter: WYSIWYG -
it's the only method of determining what shape the transmission mechanicals are in, rather than just guessing from fluid color and odor - the 68RFE does have an additional filter in the cooler return path, but it is located inside the pan, also having the anti-drainback valve as part of the filter assembly - same goes for it's smaller brother, the 545RFE, behind the HEMI, 4.7, and 2.8L CRD (FYI: bell-housing, torque convertor diameter, shaft-diameter, # of clutches in some clutch-paks, # of planet-gears in some planetary sets, and oil-cooler pipe diameter is only difference in 68 and 545 - case, valve-body, and pan is same dimension throughout) - as the 47\48 series trans have adjustable bands as well as clutches, I would follow factory recs on fluid\filter change intervals, dropping the pan to check the mess, therein - excellent preventive maintenance for a 50yr old gasser (patooie!) slush-box transplanted behind a hi-tork Diesel engine - other than that, no probs with installing an auxilliary external filter

 

I thought I remember hearing one of the newer trannys had an externally serviceable spin-on filter? Was that the Aisin or something like that on the cab/chassis trucks?
FWIW, those early 727s acquitted themselves pretty well behind street hemis and 440 6-packs, so that comment would need a little clarification. AFAIAC, I'll take proven technology, updated and improved over time before the new stuff in most cases. I'm sure the RFE trans family will turn out to be an excellent piece of machinery as well. But only time will tell.

 

That filter setup will never extend the filter replacement times on a 48RE, its in the wrong place to pull most of the contaminants from the system. The bulk of material contaminants come from the clutch packs and are washed directly into the pan. This is WHY you change the factory filter at service time. The only thing it will catch is any clutch material from the TC. If your shedding that much material the problems are much larger.

The minimal pressure differential is not going to help much as the filter saturates and eventually catches any contaminants.

Service times are also for looking for developing problems and you cant do that unless you drop the pan. A 3 dollar drain plug kit and that is a moot point. Gonna have to go farther to improve on a tried and true system.

Gotta rate this with a TAG, a placebo mod.

But hey, if it makes YOU feel better then it did its job.

 

So how do these so-called "material contaminants" get into the stock filter after they are washed directly into the pan? Do you know what the filtering efficiency or micron rating on the stock filter is?

I see you don't know much about bypass filtration.

Ever wonder what happens to pumps and seals flowing fluid loaded with particulate contaminant? Better filtering extends the life of those components and would go a long way towards protecting your investment in all those expensive tranny parts in your sig. Any wonder why the new trans has an additional filter in the cooler return path? Must be to catch all that clutch material from the grenading torque converters, I suppose.

Actually, it makes the trans feel better. Sorry, I but gotta rate your analysis "poo-pooing." But hey, if it makes you feel better... See you at the tranny shop! No wait sorry, you'll probably be there long before me.

 

Group 4 full syntheic fliud is a upgrade.

 

I love a good healthy debate amoung the users.

"quote" I don't know if you understood the part about the .025" flow restriction. Cooling is actually enhanced with this setup. The very "small" amount (2% maybe?) of oil diverted through the bypass is insignificant to the main flow, if anything slowing it only slightly, in a similarly small amount. "end quote"

Yep, I certainlly caught that. So 2% of the atf returning from the converter and or the lube circuit is being filtered after beinbg pumped throughout the tranny. The OEM filter filters 100% of the oil being pumped through the system, in addition to the metal that is cleaned by magnet in pan. Let's see 2% after or 100% before - which is better???????? Oh, yes, it is a good filter.

Next: Quote:
Originally Posted by no_6_oh_no
Gotta rate this with a TAG, a placebo mod... But hey, if it makes YOU feel better then it did its job
And also "gmctd"
Excellent responses!!!!

Yes, the RFE series does have a spin on filter that filters all the converter return and cooling fluid. And has a bypass valve to allow tranny to live a few more miles if the cooler plugs. It still has a regular filter that does all the previous cleaning chores. JMHO of course.
So, I guess if giving up your hard earned shekels for something of little value makes you feel better, than MOPAR to you. Spend your money on occasionally changing PS fluid and brake fluid. the tranny engineers did a good job on engineering and upgrading. If some owners were as prudent in their use of a stock tranny.

 

I'll give this response a "10"!

No way I'd put anything in the cooling circuit that would possibly impede fluid flow.

Screen type filters on race trannys (727) gives up filtering capabilities in exchange for more flow.

 

IMO, the primary reason the 45\545\68RFE trans have the oil-cooler return filter is the torque convertor for the 45 (the 545 and 68 are just same-size enhancements of the 45) was designed with a plastic stator, where the TCM has a Torque Management Request line to the ECM, calling for reduced torque input at various times, all in preparation for when RWAL was replaced by 4W-ABS and ESP was added, such that wheel-spinning acceleration events, heavily dependent on the stator, would be prevented - the plastic stators have a history of crumbling under normal operation, whereupon DCJ replaces the TCC, cooler lines and cooler, transmission fluid and both filters - transmission internals are not damaged, otherwise

As you can tell, I'm not a fan of the quickie back-flush concept, which is minimal-labor fast money for the shops - it all goes back to the fact that if you don't drop the pan for filter changes, you don't know what mechanical shape the transmission is in as mileage accumulates - particularly not, if you know no previous history, having just bought the pre-owned (read: rode hard and put up wet) truck

Drop the pan - that's the plan

 

Fluid exchange such as a BG machine is NOT a flush and nothing backwards about it.Its just a exchange of fliud using the engine and trans in the vehicle to do such.Best thing to happen to a auto trans since its invention.

 

Yep - works real good when selling a truck pulled from a flood, or selling a truck with a damaged transmission: "Lookit the clear fluid, my friend - smell that: gotta real good odor, too - yep, 'at's a good ole transmission - c'mon inta my office, friend, I can work ya a real good deal on 'at ole truck - uh, ya are lookin' ta pay extra fer the warranty deal, right?"