Transmission Bypass Filter Progress

[kd5byb]

Good evening all,

Almost ready to mount the incredible Wix 57401 filter into my Toyota Tundra. Have made a bracket, gathered up the right fittings, bought some Thermoid transmission hose, and bought a variety of OEM-style spring hose clamps. Even made up a fitting for putting a dial-type pressure gauge on the inlet side of the filter to check input pressure. (differential drop across the filter would be better, but the LubeGard mount only has a high-side pressure port)

Initially, I had thought about plumbing this filter in parallel with my cooler. Then, looking at the low pressure drop ratings of this filter, I decided to plumb it in the inlet line to the cooler.

Then I got to thinking - what's the only spec I've not checked? Answer - maximum temperature rating of the filter. It is designed as a tranny filter for an Allison tranny, but did Allison plumb it so it was getting 200 deg F ATF?

I don't know. I know the fluid in the Tundra will run at 200 deg F, as the fluid is plumbed from the tranny through a water-cooled (and heated!) heat exchanger. It heats up the fluid in the cold and will cool it a bit if tranny oil temp exceeds coolant temperature. I assume the thermostat in the 5.7L engine is around 200 deg F - so I'm guessing that's going to be the operating range.

I've got access to several K thermocouples and a dual channel reader and plan to mount the thermocouples on the cooler input/output lines to confirm/deny my 200 deg F suspicions.

Anyone know what temperature rating a 57401 might be good for? I've e-mail Wix in the past to no avail...

Perhaps I'll just plumb it after the cooler and not worry about overheating it.

thanks,
ben

 

[bmwtechguy]

Does the filter or mount have any bypass capability? Just curious. I don't know for sure, but am thinking that your filter should be good for those temps..PM Gary Allan-he gets info others can't somehow.

 

[kd5byb]

Nope - neither the filter or the mount have any sort of bypass.

I struggled with that for some time, worrying that not having a bypass would be a big problem. Then I was concerned about at what pressure should the filter bypass? 15 psi? 5 psi?

After a lot of thought, I came up with two facts that made me feel a lot better about not having a bypass in the mount or filter:

1) I found a limited sampling of transmission oil cooler flow rates that showed an average cooler flow would be under two gallons per minute. Some Ford trannies were rated at half a gallon per minute. At 2 GPM into a filter rated for 13 liters a minute at less than half a bar pressure delta (one bar is about 14.7 psig more or less), I'd be hard pressed for the pressure delta across the filter to rise anywhere near 5 psi at typical tranny flow rates. 5 psi seems to be the smallest bypass valve out there of any type. (plus, it would seem that the 10mm ID line that snakes from the tranny all the way to the front of the truck is going to have more pressure drop than anything else in the system)

At some point I need to redo my drop calculations and publish them here. Somewhere I crunched the numbers for the smaller Northern Tool filter and it was like a 3 something psi drop - this filter is bigger (more area) and is rated for about twice the flow.

2) The filter is rated to hold 13 grams of crud - that's a ton of crud, maybe 100,000 miles worth. Of course, being a BITOG'er, I'll change this filter yearly, and it will never ever come close to clogging. For around $30 from FleetFilter, a site sponsor, that's not a big yearly expense.

I'm sure Gary will reply shortly - I know he reads this forum pretty regularly. At any rate, I e-mailed FleetFilter, hoping they had (or could get) a contact inside Wix who would know. FleetFilter has GREAT customer service and they are really responsive to e-mail inquiries.

I e-mailed Wix from their webpage, but no response after a two month wait. It probably blew the mind of the poor folks who sift through it all...

thanks,
b

 

[mudsling]

I installed the wix 57401 inline on my 85 Jeep CJ 7,it has a chevy 350 engine and turbo 350 tranny.I put it after the cooler.Heat was not a problem.Ithink the filter has a magnet in it also.

 

[kd5byb]

An update - spent about an hour this morning putting two thermocouples on the input and output lines of the ATF cooler, to see how hot they do get.

Interesting, there is very little flow through the cooler when the lockup-clutch is locked-up, but once you've stopped, hot fluid circulates through it.

This is an interesting design. Driving it to work tomorrow with the thermocouples and reader in place to see what the temps go to while driving around...

later,
b

 

[Gary Allan]

kd5btb - don't you have the laminar cooler with auxiliary cooler option? I would imagine that's why the flow drops when lock up occurs. They must have need/desire to retain engine coolant temp when the converter isn't producing excess heat unlocked.

 

[kd5byb]

Hi Gary - exactly. I have the towing package on my Tundra, which includes the cooler mounted in front of the radiator.

Or, we're you referring to the coolant/transmission heater/cooler that's separate? It has one of those too - heats the ATF when the tranny is cold. But, it seems like it doesn't heat it too hot - top temp I saw today was about 130 deg F going into the cooler. (It was only 55 deg F out today, though.)

Going to run with the TC's and reader all this week and will be watching temps.

thanks,
ben

 

[Colt45ws]

Where did you get the filter head for this?

 

[kd5byb]

Got it off of ebay - it's a Fleetguard (now Cummins Filtration IIRC) head, believe it's p/n hh6932. I'll check next time I'm in the garage - have a box with the p/n on it...

 

[Steve S]

The torque converter is what generates most of the heat in an auto trans. So if it is locked up ????

 

[kd5byb]

Originally Posted By: Steve S
The torque converter is what generates most of the heat in an auto trans. So if it is locked up ????


That would suggest to me that there's not much heat generated when the converter is locked.

My on-road testing with thermocouples on my tranny cooler input/output lines confirms this - when I'm locked up, both input/output temps fall slowly as theres little cooler flow and it's slowly cooling off. (thermocouples are insulated from cooling air so they really show only fluid temp and cool slowly. When I'm unlocked, input temps rise quickly. Especially in stop/go traffic like I was driving home today. Once I was moving but not locked up, cooler input temp was hot, with output temp being dependent on speed (airflow over cooler).

I saw a record peak of 180 deg F cooler input temp this afternoon in traffic. It was about 82 deg F today.

Well within Wix's max of 250 deg F and the suggested Allison rating of 180 deg F max when this filter is used on an Allison MT500/AT600 series tranny in school buses and the like.

ltr,
b

 

[Ken2]

Originally Posted By: kd5byb
I know the fluid in the Tundra will run at 200 deg F, as the fluid is plumbed from the tranny through a water-cooled (and heated!) heat exchanger. It heats up the fluid in the cold and will cool it a bit if tranny oil temp exceeds coolant temperature. I assume the thermostat in the 5.7L engine is around 200 deg F - so I'm guessing that's going to be the operating range.
I don't think that's a valid assumption.

The transmission cooler is in the bottom of the radiator. The 190° coolant is in the top of the engine. The coolant in the bottom of the radiator is cooler than that in order to maintain a steady temperature in the engine heads. In the winter that coolant in the bottom of the radiator can be darned cold! The thermostat will put very little flow through the radiator, and it'll cool a lot.

 

[Gary Allan]

Ken2: A Tundra has a heat exchanger at the transmission that circulates bypass coolant (like the heater core circuit) to regulate trans fluid temp. If it's equipped with an auxiliary cooler, it gets a radiator type that's out front. It has some interesting diverting modes (more complicated than I think necessary if I understand it correctly).

This will tend to keep the trans at or around coolant temp. As long as the cooling system is up to snuff, everything is fine.