Author Topic: gearing options  (Read 534 times)

Offline gwcrim

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gearing options
« on: June 26, 2019, 12:07:20 PM »
Hi all.  It's been quite a while.  I have a silly question.

When you order a new vehicle and check the box for the limited slip diff, typically you get a higher numeric ratio with the diff.  Example:  standard gear ratio on XYZ truck is 3.55 but order a limited slip diff and you automatically get 3.73 gears.

Why is that?

Online JohnnyPopper

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Re: gearing options
« Reply #1 on: June 26, 2019, 06:15:22 PM »
Wild guess but the LS takes up more space, growing the ring diameter,  that changes the number of teeth?

Someone on this board will know, that just came to mind as I read your question...
1957 Apache 3100 235 Inline 6, 3 on the tree
1973 C-20, 3+3 454 4BBL TH400  Water Injection
1978 K-10, 350 4BBL TH350 NP203 M.M. Part time Kit/Hubs
1980 C-10 under construction

Offline zieg85

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Re: gearing options
« Reply #2 on: June 26, 2019, 10:32:17 PM »
I've only ever ordered 1 new truck in my life and you had to check the box for what ratio and limited slip but that was back in 1991 when I ordered a new C1500
1985 C30 Custom Deluxe Ext. cab 5.7L TH400 3.21 
1985 C20 Scottsdale 7.4L 4 speed 3.21
1986 C10 under construction
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Offline VileZambonie

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Re: gearing options
« Reply #3 on: June 27, 2019, 06:03:03 AM »
These types of upgrades change the meter from economy to performance. There are usually set parameters when it comes to options.
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Offline 75gmck25

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Re: gearing options
« Reply #4 on: June 28, 2019, 05:49:58 AM »
In the old days (70's?) you could usually order a limited slip axle (GM Gov-Lock, Ford Traction-Loc, etc.) with just about any axle ratio, although when buying something a little more exotic (like a Detroit Locker) you would have had only a few choices.  For example, Ford only offered the Detroit Locker in 4.30 ratio in Mustang and Torino, while I believe Traction-Loc came in 3.25, 3.50, 3.91). 

In today's world the car makers reduce cost by keeping fewer parts on hand, so they limit your choices.  I think they assume that you buy a limited slip for towing, so it goes along with a lower ratio.

Bruce