"On a side note, a 3.73 may be scary

cgc68

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May 4, 2008
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75
Location
Southeast IL
"On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two."

I found the above statement while searching for info about swapping out my TH350 for a 200 4R transmission. My car has the 3.73's. I don't understand the part about "scary" and "feel higher". Please explain.

charlie
 
"On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two."

I found the above statement while searching for info about swapping out my TH350 for a 200 4R transmission. My car has the 3.73's. I don't understand the part about "scary" and "feel higher". Please explain.

charlie

Lower gear = higher engine rpm's. Too low a gear and your engine rev's too high for normal street driving.

:beer:
 
My truck has 3.73 with OD transmission. Hardly what I would call scarey.
 
"On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two."

I found the above statement while searching for info about swapping out my TH350 for a 200 4R transmission. My car has the 3.73's. I don't understand the part about "scary" and "feel higher". Please explain.

charlie

Lower gear = higher engine rpm's. Too low a gear and your engine rev's too high for normal street driving.

:beer:

Exactly, but as always it depends on what you want for the car....for instance, if you drag racing and want to drive it to/from the track for a day's worth of grins.....well your 373 is not so bad....but if you want a town/cruiser you can easily drive cross country and get decent fuel economy....well 373 is on the high side......the 373 will definately get out of the hole quicker, but I see Yankee weather there too....so maybe not so much in the rainey/winter....useless for street driving....
I drive my car daily, but i'm in FLORIDA....snicker......:2nd: only to California for weather....I stuck with the 336 my car came with....

:noworry:
 
"On a side note, a 3.73 may be scary on the street with the 2004r. First gear is lower than your TH350 so the 3.73 will actually feel higher when you combine the two."

I found the above statement while searching for info about swapping out my TH350 for a 200 4R transmission. My car has the 3.73's. I don't understand the part about "scary" and "feel higher". Please explain.

charlie

I believe the First Gear ratio of the 200-4R to be 2.75:1, and combined with 3.73 rear-gears, it would 'feel-like' you retained your THM350, but had 4.11s in the rear while in First Gear

2.75 x 3.73 = 10.2575 div/by 2.52 (1st Gear in THM350) = 4.07, or almost 4.11 gears

I have a 700R4 with a 3.06:1 First Gear and 3.73s out back (equivalent to THM350 & 4.56 gears), and when leaving a stop-light at moderate throttle in-traffic, it shifts almost instantly into 2nd, and sometimes into 3rd before I cross the intersection.

My guess is the 'feel-higher' is a reference to feeling like it had a higher numerical (lower mechanical) rear-gear.

The lower mechanical gearing of 1st & 2nd in the 200-4R & 700R4 will help off-the-line performance, but the spacing of the gears is wider than a THM350 or THM400, so be prepared for a larger drop of RPM on the gear-shift with either A/OD transmission
 
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correct, a "shorter" gear is numerical "higher", that said it seems your gears feel like a TH 350 with 4.11 gears.... lots of fun until you get on the highway... :goodnight:
 
I have that gear ratio behind my M-21 4speed,i don't know about scary but it sure is fast,for short burst anyway,sucks on the highway 70mph/3700rpm.
Oh Well
 
I think sometimes it depends on what angle i look at the needle :push: my speed/o jives with my GPS, but my tach could be off seems to read the same as my timing light tach at idle but who knows.
 
I have a 700R-4 with 3.70 rear gears. @ 70 MPH I'm only running 2000 RPM. It's still ok from a stop, It just shifts into 2nd at about 20 MPH.
 
I have a 700R-4 with 3.70 rear gears. @ 70 MPH I'm only running 2000 RPM. It's still ok from a stop, It just shifts into 2nd at about 20 MPH.

Sounds good but what are your RPMs at say 140mph

Dean, I have the 700-R4/3.73 combination in my '82, and the ratio between the speedo & the tachometer is almost dead-on @ 3:1:
75 MPH = 25 (hundred) RPM in 4th Gear with lock-up, so simple math says 47 (hundred) RPM would be approx 141 MPH, but I doubt the converter would lock-up, nor the transmisssion stay in OD while at wide-open throttle
 
I have that gear ratio behind my M-21 4speed,i don't know about scary but it sure is fast,for short burst anyway,sucks on the highway 70mph/3700rpm.
Oh Well

Keven mine is a 3.73 . 70 Is only 3500 and my speedo and tach are slow ???????


Stock tire size?

Try using Richmonds' gear calculator
http://www.richmondgear.com/101032.html

I get around 3000 to 3200 RPM @ 70 mph with 3.23 rear gears and 27" tall tires - 1:1 5th gear ratio....manual gear box

My new TKO II trans. arrives today!!!!! Overdrive Baby! :thumbs:
 
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3.70 gears with a 25.7" tall tire (p225*60R15) = 3400 @ 70mph in a stick car, in an auto you have 5 to 7 % slip to add to this.
 
Correction on my last post. I have 27.05" diameter rear tires, (255/45-18") and with the 700R-4 and 3.70 rear gears my tach sits at 2200 rpm @ 70 mph.
 
We had a 1995 S10 Blazer with 4.3 v6 700r4 and 4:1x diffs. it was perfect gearing. I wouldnt hesitate to run 3:73's again. Matter of fact my 06 ram cummins has an auto and 3:73's :D
 
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