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Diff ratio - compare revs 3:15 v 3:54 |
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Greyhounds_AMX
AMC Addicted Joined: Nov/14/2009 Location: Kansas City Status: Offline Points: 1268 |
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But you can have both if you run 3.54's with a T5.
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1968 AMX 390 w/T5
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vinny
Supporter of TheAMCForum Joined: Jan/05/2012 Location: Calgary Status: Offline Points: 2837 |
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I had a few GM vans with I think 3.54 and 700R4 or newer so not bad, couldn't fault them. With 1 to 1 in the Rambler I like the 3.15 as a compromise.
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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A 1:1 transmission high gear doesn't have to suck. It doesn't have to force a compromise axle ratio...if the lower gears in the transmission are a high enough (numerically) ratio. That is where AMC screwed up.
Most AMC manual and automatic transmissions have a 2.5:1 low gear and a 1:1 high gear. That sucks. The ratio spread simply is not wide enough to allow for one axle ratio that produces good low speed performance and good high speed performance. Most cars end up with a compromise gearing that doesn't make them truly good at anything. ...unless you bought Borg-Warner overdrive. Low gear is the same 2.5:1 but the high gear is now 0.7:1. You can run a high axle ratio for good low speed performance but drop into overdrive for high speeds. That 3.54 axle ratio becomes a 2.50 after the overdrive is engaged. It's absolutely perfect. AMC got smarter in later years too. Starting in about 1975 they switched to 3 speed manual transmissions with low gears around 3.2:1 and 4-speed transmissions with low gears around 4.2:1, all with 1:1 high gears. These transmissions got themselves off the line very well with axle ratios in the 2.5:1-3.08:1 range and produced excellent highway cruising. They got smarter on their automatic transmissions with the Eagle when they introduced the wide ratio lockup TC A998. A 2.7:1 first gear and a true 1:1 high gear. A 2.35:1-3.08:1 axle works perfectly with these. My Eagle gets itself off the line just as well with it's A998/2.35 as my Hornet does with it's A904/2.73. Wide ratio 3 and 4 speed transmissions are your friend. AMC engines have a broad torque curve that works well with wide ratios. |
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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