Thinking about getting this 97

[1997ThunderbirdLXV6]

With a 7 tooth output shaft drive gear, an 18 tooth speedometer gear, 3.27 final drive ratio, that would mean the tire needs to turn 786 times to drive the car one mile

Could you explain that calculation?

I was going via the wheel circumference. For 225-60-16, I come to a circumference of 2124.973 mm. That translates to 757.4 rotations per mile.

 

[theterminator93]

The constant is that the PCM, odometer and speedometer treats 1000 rotations of the VSS as 1 mile. All the other math revolves around this relationship constant.

Speedo drive gear teeth = tire rotations/mile * final drive ratio * output shaft teeth / 1000

There are 7 teeth on the MN12 output shaft. IIRC the stock 3.27 VSS drive gear is 18 teeth. Doing the math:

Tire rotations/mile = VSS gear teeth / output shaft teeth / final drive ratio * 1000

18/3.27/7*1000 = 786.37 tire rotations/mile (25.64" diameter - a paltry 195/70/15 tire)

This is when the speedo would be perfectly accurate representation of vehicle speed.

With a 3.08 final drive and a 17 tooth gear, the perfect tire size would be 788.5 rotations/mile.

It does seem odd that the math works out to such a short tire, but the numbers don't lie... unless the formula we've all been using for years is wrong.

 

[1997ThunderbirdLXV6]

I understand. Basically you're not considering actual tire circumference (and resulting rotations/mile) but calculated rotations/mile (and resulting  ideal tire circumference), because that way, the PCM reported speed is most closely aligned with actual speed.

In contrast, for my calculation, strictly speaking I would have to use GPS speed, because I'm starting from actual tire dimensions.

I actually just came back from putting this to the test in my car, comparing PCM speed and GPS speed, with GPS speed being about 2 mph higher (60 and 62 mph respectively).


My mistake was that I mixed the two: PCM-reported speed with actual tire dimensions.

My apologies for creating any confusion. I just felt that a slipping or non-locking torque converter could potentially explain the observed symptoms. I still think transmission temperature should be observed.

 

[CDsDontBurn]

Based on the same calculations, at 60 mph, your revs should be 1,734 rpm.

I'll check again at 60mph and see where the tach is at for that speed

Do you remember when that screen shot was taken? Uphill/downhill? Cruise control on/off?

It was largely a flat area, but there was some slight incline, 0.5° at best, I'd say. This picture and screenshot were about 6 miles after the big hill climb.

@theterminator93 , I am using my sport wheels from my Pearl Bird and it's stock tire size, 225/60/16 on my Gold Bird and not the 205/70/15 tires it came with.

 

[Kidd-7]

In torque settings there is an option for Ford specific PIDs. That's where you'll find the trans temp.
Then you'll have to go back to what to log and they will show up and you have to select them. I'll try to get some screen shots or better direction for you, my torque app is not handy at the moment.

 

[CDsDontBurn]

@theterminator93 , @1997ThunderbirdLXV6

Torque Pro readouts at (almost) 60MPH.



@Kidd-7 , thanks for the support!

 

[1997ThunderbirdLXV6]

Yes, speed and rpm check out. I admit I was on the wrong track.

 

[Kenz]

On the radiator - 187F
View attachment 14039

Odd that the radiator is that much cooler than the rest of the system. Maybe the radiator could be clogged? You already replaced most of the cooling system.

The cooling systems are great on MN12s. With temps like what yours is running, something is seriously messed up

 

[CDsDontBurn]

Odd that the radiator is that much cooler than the rest of the system. Maybe the radiator could be clogged? You already replaced most of the cooling system.

The cooling systems are great on MN12s. With temps like what yours is running, something is seriously messed up

Sounds like maybe I should have also replaced the radiator when I had it all apart?

Today's high also reached 240 like yesterday's high.

 

[1997ThunderbirdLXV6]

Could you do a temperature reading on the ATF cooler lines? Or are they too narrow for a good reading?

 

[CDsDontBurn]

Could you do a temperature reading on the ATF cooler lines? Or are they too narrow for a good reading?

I can definitely try that, yeah.

 

[Kenz]

Sounds like maybe I should have also replaced the radiator when I had it all apart?

Today's high also reached 240 like yesterday's high.

If it's going to be a daily driver it would be good to have a new radiator in it anyway. I keep putting off replacing the original one in my Cougar; it's working fine.... and it gets very hot here in FL. If I ever end up taking it on a long road trip I will replace it. I don't want to be driving on a long trip with a 30 year old pressurized plastic time bomb under the hood.

If your car didn't have the 4.6 maybe head gasket could be a cause, but the head gaskets don't go bad on these engines. Even if the transmission has something wrong and is overheating, I doubt it would cause the coolant to get that hot.

IMO not much left to be causing it but the radiator at this point.

 

[dDUBb]

Today's high also reached 240 like yesterday's high.

Just a couple thoughts ..

Does your app datalog over time or just display current / max readings ?

Id be curious to see for comparison under similar circumstances; what are the temps with the AC on and off ( engine load ) .. and what happens to temps if you roll down the windows and crank the heater on full. If the heater core makes a sloshing sound, you could have an air pocket, or if the heater core effectively removes a lot of heat - it could be due to insufficient flow through the radiator / weak fan.

In my industry; heat transfer through a radiator with air movement is more effective when the coolant moves slower. ( implying that a closed vane pump may or may not change coolant flow versus RPM .. Water moving too quickly has less time to transfer heat.

 

[CDsDontBurn]

Just a couple thoughts ..

Does your app datalog over time or just display current / max readings ?

Id be curious to see for comparison under similar circumstances; what are the temps with the AC on and off ( engine load ) .. and what happens to temps if you roll down the windows and crank the heater on full. If the heater core makes a sloshing sound, you could have an air pocket, or if the heater core effectively removes a lot of heat - it could be due to insufficient flow through the radiator / weak fan.

In my industry; heat transfer through a radiator with air movement is more effective when the coolant moves slower. ( implying that a closed vane pump may or may not change coolant flow versus RPM .. Water moving too quickly has less time to transfer heat.

Drove to see my friend today. On the drive, temps got to 227 and it was at that time that I did what you said; roll the windows down turn off the AC, and turn up the heat to max.

Temps ultimately dropped to 197 and stayed there while I had the heater on. When I turned off the heater and turned the AC back on, temps crawled back up to 215-220 and maintained there the remainder of my trip.

 

[Grog6]

Do you know anyone with a thermal camera? Looking at the radiator with one would tell you in an instant if the rad is clogged.
One informed my decision to replace the radiator in the red cougar. Someone had used stop-leak, and added other bs to that poor car; no wonder a 6500rpm burnout killed it, lol.