3.9FD on a 5AT
09-26-2007, 01:51 PM
#4
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I wouldnt worry to much about it. I used to DD a 82 chevy p/u w/ a souped up 350 w/ 4.10 gears on a TH 350. It was not that bad. You got two more additional gears.
09-26-2007, 02:04 PM
#5
Originally Posted by Thanh386
Has anyone done this on the board? I tried teh search nothing came up as always. Would it a better feel?
09-26-2007, 02:11 PM
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Somewhere between 3000 and 3500rpm. I suppose, I would say the lower end of it. You can always lower your cruising speed on the highway. If your worried about gas mileage, dont do it.
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09-28-2007, 10:50 AM
#9
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I don't really care about gas milage much lol. But I do care about engine wear and what not. Will it affect reliabilty? Present problems in teh future?
09-28-2007, 11:05 AM
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I'm not to sure. I can tell you my cousin had a fox body stang w/ 4.10 in it when he had over 75,000 mi in it and drove it like that for 2 more years before selling it.
He did not have any problems come up. Only thing was his fuel pump, but that was for another reason. I had my gears in my pickup for close to 2yrs before removing them due to throwing a 454bb into it. I had no problems whatsoever. Both engines ran strong.
He did not have any problems come up. Only thing was his fuel pump, but that was for another reason. I had my gears in my pickup for close to 2yrs before removing them due to throwing a 454bb into it. I had no problems whatsoever. Both engines ran strong.
09-28-2007, 01:29 PM
#11
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Here's a cool gear/MPH calculator that will help you figure out RPM points for different final gear ratios.
http://www.f-body.org/gears/
.
http://www.f-body.org/gears/
.
09-29-2007, 07:41 AM
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I got the 3.9 in my 5at...at 80 mph I am around 3700-3800 rpms...its high up there...gas has gone down, but I knew that would happen
Last edited by WhiteOnWhite350z; 09-29-2007 at 07:44 AM.
09-29-2007, 12:27 PM
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Originally Posted by fern14
I got the 3.9 in my 5at...at 80 mph I am around 3700-3800 rpms...its high up there...gas has gone down, but I knew that would happen
Is it a "substantial" gain, or just a "little" gain ?
...or I should ask, was it worth the time and effort (and expense) ???
Last edited by OH6 G35; 10-01-2007 at 05:16 AM.
09-30-2007, 08:57 PM
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Originally Posted by OH6 G35
How acceleration, from you "stock" gears ??
Is it "substantial" gain, or just a "little" gain ?
...or I should ask, was it worth the time and effort (and expense) ???
Is it "substantial" gain, or just a "little" gain ?
...or I should ask, was it worth the time and effort (and expense) ???
09-30-2007, 09:23 PM
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Ide love to at least get the 3.5 from a manual. Would hate to lose cruise control even though i never use it, maybe one a month if i visit a friend. I love how long the gears rev out but would be nicer to be a little quicker in the low end. I'm not a big top end guy, not looking for big speeding tickets.
10-01-2007, 05:13 PM
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Wait, if you get a high FD, you'd lose teh cruise control function? Ergh...
but that aside. What brand are you guys using. And about how much was the cost of installation?
but that aside. What brand are you guys using. And about how much was the cost of installation?
10-06-2007, 12:22 PM
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The loss of cruise control, from what I have read and considering I have an AT, is only on the AT's.
As I have said to others; it is the best NA mod in imo.
The only drawbacks with this mod are:
1. Getting a hold on the actual 3.9 gears ( I waited roughly 6 months for the Central 20 gears)
2. If you have an AT, swapping pumpkins with a MT.
3. Install takes time and should be installed by a gear specialist. And in some cases extra parts may need to ordered. My car was in the shop for 7 days.
4. Gas mileage varies. I'm averaging 17mpg in the city.
5. If it's an AT the cruise control will more than likely not work.
As I have said to others; it is the best NA mod in imo.
The only drawbacks with this mod are:
1. Getting a hold on the actual 3.9 gears ( I waited roughly 6 months for the Central 20 gears)
2. If you have an AT, swapping pumpkins with a MT.
3. Install takes time and should be installed by a gear specialist. And in some cases extra parts may need to ordered. My car was in the shop for 7 days.
4. Gas mileage varies. I'm averaging 17mpg in the city.
5. If it's an AT the cruise control will more than likely not work.
