Gear selection and tranny code. Who knows their stuff. (1 Viewer)

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Can someone tell me the tranny code on this gear calculator I need to use for my 1991 cruiser with auto and 3fe. I'm not sure which tranny and Tcase I have by the codes they are using. Basically I want to turn 3000 rpm at 75 and I need to know what gears to slap in the pumpkins to make that happen. BTW I will be running 31 inch tires. Here is the calculator
http://www.dfw-tx4wd.org/Tech-Dept/Tech-Dept/gears.html
 
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You have an a440, not listed on that little database.
not sure on the transfer case model number.

at 31 inch tires, leave your gearing alone. 75 mph shoudl put you at around 2600 if I remember correctly, been a while since I was stock.

Dave
 
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I've got to do something because I can't even pull 75 on flat ground. Hell I can't pull 60. I can in third but not in 4th. I think I could use 4th if I could actually be a 3000 at 75mph. It pulls hard through third but won't pull unless its above 2600. Engine runs fine, doesn't smoke, its just a gutless pig.
 
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I took a look and I think its the A44D tranny listed. It is a 4spd auto and turns 1950 at 65 mph in high gear. I need to be around 2400 at 65 so I can actually accelerate to 75. Looks like I would need 4.88's or 5.13s to make that happen.
 

ginericLC

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You've got something else wrong. My 91 with 35s would easily pull 75mph on the flat. I'd usually set the Cruiser Control at 82mph between MH and Boise. That is pretty flat and I'd stay in OD.

You have an A440F tranny and a HF2A transfer case. The transfer case ration is 2:48:1 for figuring low range. The tranny ratios are 4.081:1, 2.29:1, 1.50:1, 1:1, 0.88:1, 4.31:1R . Also for using these gear calculators you need to use true tire size and not tire man. stated size.
 

ginericLC

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You've got something else wrong. My 91 with 35s would easily pull 75mph on the flat. I'd usually set the Cruiser Control at 82mph between MH and Boise. That is pretty flat and I'd stay in OD.

You have an A440F tranny and a HF2A transfer case. The transfer case ratio is 2:48:1 for figuring low range. The tranny ratios are 4.081:1, 2.29:1, 1.50:1, 1:1, 0.88:1, 4.31:1R . Also for using these gear calculators you need to use true tire size and not tire man. stated size.
 
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I don't know what else could be wrong. Runs good just has no torque. I seriously can not pull anything above 65 on flat ground. If it shifts down I can and accelerates well a from 2600 to 3300 rpm but below that it won't. Timing?
 
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Another thing I noticed was it shifts from third to 4th and immediatly into overdrive. It won't shift into fourth for more than a second. If I'm reading your post correctly it goes 1,2,3,4 overdrive. Basically five forward speeds.
 

ginericLC

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No I'm sure it is a 4speed. Hmmm! Maybe the site I cut and pasted the ratio information from was wrong.? 3rd is 1:1 4th is the OD. I pulled the info from Marks4wd.com
 
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Ok I found this calculator http://mail.tlca.org/trails/techexchange/rpmtbls/index.html#Define_The_Gearing_Yourself


And it has the specific tranny and T case for my application. I'm turning 2400 rpm at 75 mph. To do what I want to do I would need to be running 5.20 gears so I could turn 3000 rpm at 75. Are these trucks very sensative to exhaust. I just put one on and seems to have really hurt my fuel economy. I think I got just under 200 miles on my last tank of gas. Where as before I could get 270 miles on 24 gallons. I haven't filled it yet so maybye my gauge is screwy. But another issue is the power. If anyone with a 91 cruiser is driving near Twin Falls let me know and I'll give you the keys so you can take it for a test drive and see if the performance is sub par.
 

CJF

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DJForrestA said:
Another thing I noticed was it shifts from third to 4th and immediatly into overdrive. It won't shift into fourth for more than a second. If I'm reading your post correctly it goes 1,2,3,4 overdrive. Basically five forward speeds.
Above ~47mph, If you shift from third to fourth (which is overdrive), the torque converter should lock, which is what you're feeling a second later. If you are in fourth ("D") at 40mph or so and accelerate without letting it downshift, you should feel the torque converter lock up at ~47mph.

As for your power, if by saying you "can't pull over 65" you mean that without towing anything, you simply cannot maintain a speed of over 65mph when in "D", then something is definitely wrong with your engine or possibly drivetrain.

Curtis
Stock 91FJ80, 31" BFG AT
 

CJF

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DJForrestA said:
I'm turning 2400 rpm at 75 mph.
That doesn't sound quite right... I know 60mph is at very close to 2000rpm for our rigs; use that to verify the calculator's readings.
 

ginericLC

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Yes the 91 is sensitive to exhaust. I changed the exhaust on mine twice. First time it was too restrictive. Second time it was a lot freer flowing. Power went up a lot after the change. Mileage and power were horrible with that exhaust. Actually it wasn't the entire exhaust that was bad, it was too small of a cat.

2400 rpms at 75mph is about right. 60mph =1917 on the chart. I think that chart is accurate. When I went to 35s I could run at 80mph at a smidgen over 3000 rpms in 3rd gear and that is what the chart shows. I remember 2400 was about right at 75 with the stock tires.

Peak torque is at 3000 rpms for the 3FE so you should feel pretty good power at that point. What is strange is for the NA non injected 3f peak torque is at 2200 rpms.

Just so you know your mileage is going to suck if you are running at 3000 rpms all the time.
 
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eric,
did you have the issue on exhaust after using the dodge type cat or something else.
Dave
 

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