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torque converter size for 72 javelin

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greenhue View Drop Down
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    Posted: Oct/13/2021 at 8:54pm
Hello, I have a 727 trans  with a 401 and the Javelin has 2.75 rear end from a Ford 9 inch. What was the stall speed and size of a stock converter? The converter I now have is from TCI and a Saturday Night Special, and with the gear ratio at 85 mph, it's turning 2800 rpm. If I change to a stock converter, will my rpm increase due to less slippage? TCI was pretty vague with any answers that helped me, so onto the message board. I want the top end speed so the 2.75s will stay but I want the car to less mushy and hoping it is a converter change to make it tighter.
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purple72Gremlin View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote purple72Gremlin Quote  Post ReplyReply Direct Link To This Post Posted: Oct/13/2021 at 8:55pm
2800 at 85?  Converter isnt slipping very much.
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Post Options Post Options   Thanks (1) Thanks(1)   Quote Heavy 488 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/13/2021 at 9:32pm
I believe that you will find purple is correct.
Welcome to the old car joy of a 1:1 third gear out of the transmission.
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greenhue View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote greenhue Quote  Post ReplyReply Direct Link To This Post Posted: Oct/13/2021 at 9:34pm
When I am on the freeway at 85mph, it comes on the cam and pulls nice, but just putting around on the street, I want it to be crisper. I ran 3.50 gears and it was great up to 85, but I was turning about 3800 and traffic was passing me and it felt like I was in 2nd gear. I just thought a stock converter would be tighter but  buying one and it being close to what I have now, that's a lot of work to be disappointed. I can run 3.0s but the trans is leaking and since I would have it out.... Just wondering what stock was turning at 85 mph for my own records. Thanks 
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rockAMX View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote rockAMX Quote  Post ReplyReply Direct Link To This Post Posted: Oct/14/2021 at 1:21am
Changing the stall speed on the converter does not affect RPM at 85 mph, only when launching from a stop. Stock stall speed is usually around 1500-1700 RPM. Changing fluid, filter and torquing bands should help you.
DWR
1968 AMX

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Post Options Post Options   Thanks (0) Thanks(0)   Quote Buzzman72 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/14/2021 at 6:25am
For what you want to achieve, you'll have to change the gears in the differential. 

You're limited by what's available, of course. 3.50 is too low...2.75 is too high...hmmm.
According to what I see online, Strange offers gears in 3.00 and 3.25 ratios.

If 2.75 gears give you 2800 rpm at 85 mph, 3.00 gears will give you 3052 [+/-] rpm at 85 mph, or 27.85 MPH per 1000 rpm.

And 3.25 gears will give you 3304 [+/-] rpm at 85 mph, or 25.72 mph per 1000 rpm. 

Now you just need to decide which works for you. 

My daily driver is a 2008 PT Cruiser. [Go ahead and laugh]. The way it's geared, in OD with the converter clutch on, it does right at 26 mph per 1000 rpm. So 2000 rpm is 52 mph, and 3000 rpm is 78 mph. So 65 mph is 2500 rpm, and 55 mph is just under 2200 rpm [calculator says 2115 rpm]. The 3.25 gears will put you closest to what I have for gearing.

I did the math for you. Now you have to decide which ratio does the trick for you.


Edited by Buzzman72 - Oct/14/2021 at 6:27am
Buzzman72...void where prohibited, your mileage may vary, objects in mirror may be closer than they appear, and alcohol may intensify any side effects.
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Mopar_guy View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Mopar_guy Quote  Post ReplyReply Direct Link To This Post Posted: Oct/14/2021 at 11:22am
Or maybe it's time to get an overdrive trans..... Wink I know I'll never go back to a 1:1 ratio again!

"Hemilina" My 1973, 5.7 Hemi powered Javelin
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