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Opinions on towing with high mileage transmission


cmattina

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I have a 2003 fx4 auto with 340 000 km (200k miles) on it. The engine and rear diff have about half that.

The transmission seems to work OKAY. Sometimes under hard acceleration from a stop (pulling from a stop sign when cold) it slips and slams into second. but that is very occasional and only when accelerating hard, even less often that occurrence will cause the o/d light to flash, but it goes away on it's own after next start up. The o/d light hasn't flashed for a month. When the light flashed last i had it scanned: i believe i was told the code had something to do with 3rd gear pressure (or something like that). Which of course is odd as the issue has to do with 1st and 2nd.

I have new fluid in there, and the the tranny was serviced with filter recently.

Having said that, i am left with an option of towing about 3000 lbs about 700km or renting a uhaul for 450 bucks.

Of course no one here is psychic, but i wouldn't mind some opinions. Like i said the transmission works great 95% of the time. And very occasionally slips and then slams into 2nd.
 


RonD

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2nd transmission cooler added and off you go.

Heat is what kills automatics not miles, but the more they are driven the more chances they have been run with trans fluid temp at 200 or higher, and that shortens their life.
Radiator trans cooler is marginal at best, when you are going up a long grade the coolant temp goes up normally and so does trans fluid temp, so both are trying to get cooled down by rad....................trans suffers.

Any heat damage that has been done, is done, so life is what it is right now, add the 2nd trans cooler and even a temp gauge to monitor fluid temp, and it will last as long as it would have whether you pull the trailer or not :)
 

cmattina

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2nd transmission cooler added and off you go.

Heat is what kills automatics not miles, but the more they are driven the more chances they have been run with trans fluid temp at 200 or higher, and that shortens their life.
Radiator trans cooler is marginal at best, when you are going up a long grade the coolant temp goes up normally and so does trans fluid temp, so both are trying to get cooled down by rad....................trans suffers.

Any heat damage that has been done, is done, so life is what it is right now, add the 2nd trans cooler and even a temp gauge to monitor fluid temp, and it will last as long as it would have whether you pull the trailer or not :)

So, i believe it has a trans cooler already, so you are saying to ad another?

Thinking about it, after factoring in the cost of the cooler and time to put it in, it may make the most sense to just go with renting the truck. I'd have to rent the trailer anyways.

Just to confirm.

With the symptoms I have already, would putting extra weight be an issue?
 
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RonD

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2003 4.0l Ranger will have 5R55E transmission, hard shift to 2nd is most likely OD shift.
5R is a 4 speed same as 4R, Ford added software to computer that engages OD with 1st still engaged to add 2nd gear and made it a 5 speed.

So flashing OD light makes sense

And slipping shift to 3rd could also be an OD issue when it doesn't disengage quickly.

Could be OD shift solenoid, but could be valve body gasket as well, common issue on 4R/5R's

You can look at this page to see gear ratios of 4R55E and 5R55E: http://www.therangerstation.com/tech_library/AutoTrans.shtml

4R = 2.47 / 1.47 / 1.00 / 0.75
5R = 2.47 / 1.87 / 1.47 / 1.00 / 0.75

5R 2nd(1.87) was added between 4R 1st and 2nd

1st(2.47) x OD(.75) = 5R 2nd(1.85), .02 difference in ratio is transmission shaft

If you have a radiator trans cooler AND a second trans cooler then transmission should be in good shape.

I would rent a truck anyway
 
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don4331

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Transmission shaft better not be winding up by .02 rev per rev. :)

As I was avoiding work tonight, I did some digging.

Issue is number of digits in your calculations: 1st gear is a planetary set driving a planetary set and end result is ratio of 2.474x (where x is <5), so rounds down to 2.47. OD has ratio of 0.75439 again rounds down to 0.75. But, when you use the extra digits, 2nd gear becomes 1.865y, which rounds up to 1.87. Case of the missing 0.02 closed.

The following shows the power flow in a 5r55 (5r55 starts at p.78, 4r70w at p.61) far better than I ever could: http://www.toolcrib.ca/assets/pdfs/power_flow.pdf

My $0.02:

If it is 700km across Saskatchewan, just rent the trailer. If it is 700km over Lake Superior, rent the u-haul. (assuming from distance in km that you are fellow Canuck).
 

RonD

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Transmission shaft was way easier :)
 

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