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#1
03-10-2014, 06:59 PM
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3.42 down to 3.08 (27.4 inch tires) with 455
Any of you running a 3.08 gear with a 455? With 27.4 inch tires? I know years ago HO racing stated their best running street combos were 455/TH 400/ 3.08 gears.
 My is quite the beast of the line with 3.42 gears and 225/70r15 tires, but the 3.42 ring and pinion is worn out (whines). Was considering using a nice 3.08 setup I have in its place. I also have a Gear Vendors overdrive (should cruise all day at 85 with a 3.08 in there) . I don't think I will loose a whole lot of "low end" with the gear change, It is a lot of fun now, just wondering if any of you have had a similar combo and stepped back on the gearing on it. Just trying to get some opinions of people who have done similar things. The 3.42 isnt completely "objectional" yet, but being a wagon (even with all the insulation and carpet I have in the car) amplifies the noise somewhat.
Last edited by goatwgn; 03-10-2014 at 07:29 PM. |
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#2
03-10-2014, 07:06 PM
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I have a 3.23 posi in my firebird with 455/TH400 and I can tear the tires free when ever i'd like in 1st gear. 255/60/15. 3:08 would be fine for the street.
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#3
03-10-2014, 07:26 PM
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458, t400, 308 drive before you ante for the o/d o get 70 @2000 100 @ 3000 we dont need no stinking overdrive also uncontrollable from a light
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#4
03-10-2014, 07:29 PM
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also dont use 10" rins if you get it hooked up better have plenty u- joints and a spare driveshaft
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#5
03-10-2014, 07:33 PM
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Already have the GV in there. It has been in there for a couple of years.
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#6
03-10-2014, 08:39 PM
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3.31:1 ran strong, so I'd say a 3.08:1 would be smart with same or better converter:see 12.0 ET sig.
__________________
12.24/111.6MPH/1.76 60'/28"/3.54:1/SP-TH400/469 R96A/236-244-112LC/1050&TorkerI//3850Lbs//15MPG/89oct Sold 2003: 12.00/112MPH/1.61 60'/26"x3.31:1/10"/469 #48/245-255-110LSA/Q-Jet-Torker/3650Lbs//18MPG 94oct Sold 1994: 11.00/123MPH/1.50 60'/29.5"x4.10:1/10"/469 #48/245-255-110LSA/Dual600s-Wenzler/3250Lbs//94oct |
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#7
03-10-2014, 09:01 PM
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A properly built 455 makes sooo much low end torque, at such low RPM's that a dyno can't read power at that low of a RPM.
A 3.08 gear will still be a rip snorter, gitterdone!!!
__________________
1977 Black Trans Am 180 HP Auto, essentially base model T/A. I'm the original owner, purchased May 7, 1977. Shut it off Shut it off Buddy, I just shut your Prius down... 
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#8
03-10-2014, 09:47 PM
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I have seen a 455 turbo 400 3.08 axle 70 Grand Prix run 13.05 all day long without breaking a sweat. Almost a 12 second driver that was totally streetable with a 3.08 gear.
Just saying. Tom Vaught
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"Engineers do stuff for reasons" Tom Vaught Despite small distractions, there are those who will go Forward, Learning, Sharing Knowledge, Doing what they can to help others move forward. |
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#9
03-10-2014, 10:12 PM
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Back in 82-84 my 73 TA had a 455 with 3.08 gears and a stock converter.
Made for a nice street gear, but was more European acting with a long pull through the gears. The biggest downfall was once you got the tires spinning with the 3.08's they kept spinning and you went no where. With the 3.42's the car would spin, but still move out pretty well too. I wish I had the car back, it was an original Brewster Green car... |
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#10
03-10-2014, 11:04 PM
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I'M BUILDING THAT COMBO NOW IN MY 78 TA, WILL LET YOU KNOW HOW IT WORKS IN A FEW MONTHS! NOT SURE ON MY TIRE SIZE YET (COULD CHANGE) DEPENDING ON MOOD & MONEY.
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#11
03-11-2014, 01:30 AM
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Last year I changed the whole 3.42:1 posi rear end in my 1976 Firebird TurboForce Revival Project car to a 3.08:1 posi rear I had around. The Bird has a 400 in it, but with the turbo probably has more torque than a 455 especially after the turbo spools up which is almost immediately. The 3.42:1 was too much torque multiplication as you couldn't go anywhere near WOT until moving about 25MPH in 1st.
I like the 3.08:1 much better. You still can't WOT off the line, but can get there sooner with the 3.08:1. The converter (reinforced TCI) is unchanged at 2200 stall. If I ever have to pull the (built) TH-350, I'll put a stock converter in it. |
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#12
03-11-2014, 01:59 AM
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My old 69 Bird had a 4:10 until I ripped the ring gear out. Dropped down to a 3:55 because that's all I had laying around and wasn't happy at all. It was an extremely built 428 with a T-400.
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#13
03-11-2014, 05:04 AM
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I had a thread last year 3.08's vs 3.42's...two different 80 Trans Ams but the same drivetrain and go fast goodies swapped from one to another...the 3.08's gave up a little initial acceleration,but the car is so much nicer on the highway..and is more consistant at the track....old car with 3.42's ran a best of 11.48 at 118 something...new one 11.52 at 118 something.I will bump up my old thread so you can check it out!
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#14
03-11-2014, 08:01 AM
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I appreciate all the feedback so far guys.
I have 3.08s in my Cutlass and even with the Olds 350, it seems a nice all around compromise. I have stepped back to an 1800 stall from 2500, and a cam with 219@.050 intake/ 228@.050 exhaust/.462/.480 110 lobe seperaation from the 041 cam I had. Much more "low end" than before, so I think this could be a good move. The 3.08 gears are GM gears as well vs aftermarket. I originally had 2.56 in the car years ago with the 326. Need to check out your thread ta man.
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