Non Lock Rpms
- Thread starter j l smith
- Start date
mikestang63
SN Certified Technician
mikestang63
SN Certified Technician
Tell me why you are opposed to a lock up converter.
Did you convert to a 1 piece input shaft
Do you have a trans cooler
Stall speed is only one factor when considering a converter. Contact a good company like TCI or Edge and complete a spec sheet.
@j I smith
This question was answered earlier. Note how fast your eng. is turning while cruising at steady throttle, then take 15% of that number, add it on, and there you have the eng. speed with 3.73 gears. This is all being made so much more difficult than it really is. imp
@karthief
Yes, if the coupling characteristics (i.e. stall speed) are changed, all other things remaining the same, eng. rpms at a given cruise speed will change; however, since the horsepower needed to keep the car moving at that speed remains the same, a different converter will "eat" more or less energy as heat, depending on it's characteristics. Compare to a locked converter, which is basically the same as a clutch, which has a "stall speed" of zero. imp
@ j I smith @karththief
285-40-17 tire has a calculated rolling diameter of nearly exactly 26". Makes 776 revolutions per mile, therefore 776 rpm at 60 mph. 776 X 3.23 = 2505 eng. rpm. @ 60- mph.
For 3.73 gears: 776 X 3.73 = 2894 eng. rpm @ 60 mph.
Note 60 mph = a mile a minute. imp
mikestang63
SN Certified Technician
your calculations are wrong
An AOD has a .70 to 1 ratio in OD
no way are you doing 2900 rpm at 60 mph with 3.73's and a 26" tire in an AOD. I have that setup and at 60 it is more like 2000 rpm
I posted the correct rpm for 3.23 and 3.73 gears
just plug in the numbers here
http://spicerparts.com/calculators/transmission-ratio-rpm-calculator
2025 rpms is what I came up with
1 to 1 was 2687 rpms using similar calculator
Will using a high stall converter like a 3500 cause higher rpms that a stock one at 60 mph?
mikestang63
SN Certified Technician
@mikestang63
Hold on! I'm calculating everything based on 1:1 driveshaft to eng. ratio! Sorry. I forgot we're talking a non -1:1 final driver. So, what is 0.7 of 2900? About 2000.
My apologies. imp
Hummm, I guess I need to learn more about converters, So what gear would j l smith be better off with the 323 or 373?
Lets guess that this is a street car since he didn't say.
A 3500 stall converter at steady speed will only stay there w/o load on the engine.... The car may cruise in a "no load" scenario at 2k, but that'll go straight to hell as soon as you step on the throttle. Depending on how loose that converter actually is, the engine speed could, and probably will flare to as high as 2700 RPM every time you put your foot in it to speed up.
I have a 2700 stall speed L/U 10" converter in my 4R70w. Same high gear ratio as your AOD. (.67) w/ 3.73's and a 315/17 rear tire
My test speed is higher than your's though,(70-75 mph) and there's a pretty good chance that my speedo is off a little.
When I lock up my converter in OD,..my RPMS drop to 2900-3k from about 3300 at a no-load steady state...But,....if the lock up is off....who knows where it goes when I stand on the throttle..
I have a 2700 stall speed L/U 10" converter in my 4R70w. Same high gear ratio as your AOD. (.67) w/ 3.73's and a 315/17 rear tire
My test speed is higher than your's though,(70-75 mph) and there's a pretty good chance that my speedo is off a little.
When I lock up my converter in OD,..my RPMS drop to 2900-3k from about 3300 at a no-load steady state...But,....if the lock up is off....who knows where it goes when I stand on the throttle..
@madmike 1157
We are remembering, I hope, that the AOD converter "lockup" is not controllable, as are the electronically shifted TCCs which I imagine 4R70W has. Moreover, the AOD converter is not in action at all in both 3rd. and 4th. (OD) gears. This is accomplished by having TWO input shafts from the converter; one drives 1st. and 2nd. gears, while the other, being driven by the converter housing (and thus the eng.) provides engine-to-transmission mechanical drive with no fluid converter action at all in 3rd. and 4th. gears. imp
@madmike
But the lockup is solenoid-operated, is it not? The AOD is a non-electronic transmission, Ford's first real attempt at providing an overdrive automatic for rear-wheel drive. It was a reasonably staunch box, but not used universally. imp
I'm guessing that you are pointing out the difference between an AOD and my transmission, and not asking me what I'm using to make mine work.
There are still solenoids in there to actuate the LU in my transmission,..The switches that I toggle are tied to those. The rest of the transmission functionality is controlled through some old crotchedy vacuum modulator installed in place of the EC valve.
I never closely looked at the differences between the AOD/AODe, and my transmission...I sorta assumed that the AODe and 4R70w were similar in respect to the AODe being the less power capable transmission
Yeah, we're talking bananas and oranges. AOD was mechanical, but featured no torque converter action in 3rd. & 4th. gears only. AODE was electronically controlled, shared some components with AOD, but none of the important ones. 4R70W was a revised version of AODE introduced in 1993 in Lincoln Mark VIII.
What might be of value to you in particular is that units used with 5.4 eng. featured stronger gears. imp
