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| | | | Joined: Dec 2010 Posts: 14 New Guy | | New Guy Joined: Dec 2010 Posts: 14 | I just read that a 55 car with three speed trans w/overdrive has a 4.11-1 ratio but a 55 truck with three speed w/overdrive has a 3.9-1 ratio. Is that right. I would think most trucks would have a higher ratio than a car. Any thoughts? | | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Depends on the year of the truck. '55 trucks did have a 3.90, but a 4.10 became an option in '56.
Also, just a quick gear ratio term explanation; 3.90 would be a higher gear than 4.11. A low number would be a high gear, larger numbers are a lower ratio.
Bill Burmeister
| | | | | Joined: May 2006 Posts: 8,351 'Bolter | | 'Bolter Joined: May 2006 Posts: 8,351 | Oh, and the 3.9 gear works great with the overdrive. I'm running mine with 30" tires and the 3.90 gear. I can rung 80 MPH all day long at around 2700 rpm.
Bill Burmeister
| | | | | Joined: Dec 2010 Posts: 14 New Guy | | New Guy Joined: Dec 2010 Posts: 14 | I ment lower when I said higher. lol Just been running lots of numbers in my head. I got the info from the 55 truck 1st series sheet. I have the original rear end in my truck but haven't checked the ratio by turning the wheel method. It's not road worthy yet so don't know how it acts with the overdrive. | | | | | Joined: Jan 2008 Posts: 4,964 'Bolter | | 'Bolter Joined: Jan 2008 Posts: 4,964 | You can't really notice the difference in a 3.90 and a 4.11 with an overdrive. Both ratios make for a real sweat running machine. I've been running Borg Warner overdrives for almost 50 years. | | | | | Joined: Apr 2005 Posts: 2,102 'Bolter | | 'Bolter Joined: Apr 2005 Posts: 2,102 | It is my understanding that factory equipped 55-57 pass cars had 3:36's for the powerglide, 3:55's for all 3 speeds except OD, and 4:11's for OD. 1/2 ton Trucks had 3:90's for 3 speeds and 4 speeds, and 4:11 for OD's. I'm sure that some special orders were made and of course many changes were made over the years. Trucks with 3:90's work great with OD's. I have installed OD's in cars with 3:55's and they make outstanding highway cruisers.
Fred
1956 3100 Pickup/Red/350/3sp OD/PS/Disc Brakes
1957 Bel Air Sport Coupe/Red/355/TH350/PS/Disc Brakes
2017 Silverado LT Single Cab SB/Black/5.3/6 Speed Trans
1947 Willys CJ2A w/F-Head engine
| | | | | Joined: Sep 2001 Posts: 29,270 Bubba - Curmudgeon | | Bubba - Curmudgeon Joined: Sep 2001 Posts: 29,270 | | | |
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