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3.21 or 3.55 gears. Which to use?
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Author:  Tim_K [ Tue Jan 14, 2003 9:03 pm ]
Post subject:  3.21 or 3.55 gears. Which to use?

I'm trying to decide what gears to put in my Duster and can't make up my mind. I've got the 3.21 Sure Grip 8-1/4" axle in my Valiant now, and the plan is to swap it into the Duster when the time comes. But I've had a nice set of 3.55 gears laying around for about 3 years now and want to use them. Don't even remember where I got them.

With a moderately built /6 and a 4 speed (2.66 low, non O/D), what would you think? It'll most likely get 14 inch wheels with a 26" tall tire.

This car is to be used for drag and street racing, and some daily driving. I've been running 3.21's behind automatics for years, but I know that lots of factory Mopars with manual gearboxes came with lower gears standard.

I wonder what kind of difference in 1/4 mile times I would get between 3.21 and 3.55 gears.

Author:  Doctor Dodge [ Tue Jan 14, 2003 10:41 pm ]
Post subject: 

With the 2.66 "close ratio" 4-speed, use the 3.55.
This gives you a 9.4 start-off which is actually a little "steep" for a Slant.
3.21 will give a 8.5 start-off ratio, basically a "clutch burner" to get the car moving.

Either gear will not be real fast on the open highway so why not give it some off the line spunk.
DD

Author:  Dart270 [ Wed Jan 15, 2003 6:23 am ]
Post subject: 

I'm with Doc. You might see one-two tenths gain depending on how your motor and trans are set up.

Lou

Author:  Tim_K [ Wed Jan 15, 2003 6:45 pm ]
Post subject: 

Yes, I'm thinking of the 3.55's also. With 25.5" tires and 3.21's, I'm pretty much limited to 75 mph @ 3200-3300 rpm on the highway, which is borderline for the rush hours around here.

Since I want to move up to a full 26" tire for the Duster (maybe a 215/70/14 or a 215/65/15, depending on what kind of "slot" wheels I can find), I think 3.55's would be best. I figure I'm losing 3%-5% in the torque converter (stock 2000 stall) right now, and the clutch won't slip at all on the highway. So it all should come out about even.

Author:  slantzilla [ Wed Jan 15, 2003 8:42 pm ]
Post subject: 

Don't be a wussy Tim. Put some 3.91's in it and be done. I thought you were gonna build a race car??????? :twisted: :roll: :D :shock:

Author:  87ram [ Thu Jan 16, 2003 10:17 am ]
Post subject: 

Stick in the 3.55!!!!

You don't have to worry about being at 6000rpm at 70miles with the 4spd. I would go with the 3.55s. If you put the other set, give me the 3.55, I'll make good use out of them! :twisted:

Author:  Ron Parker [ Fri Jan 17, 2003 3:55 pm ]
Post subject:  gears

Tim my man bagel is right put the 3.91 in and go for it. I put in a 3.91 when my car was a street /strip car. The car had not been driven in a while so driving down to my local strip i decided to clear things out. At 5400 rpm on the tach and 102 on the speedo the chrome windshild pieces flew off. I went back but colud not find them thats when i knew i wanted a \6 race car. Ps the car had 78000 miles on it and has gone 5000 miles down the drag strip scince then. Thanks Ron Parker :D








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