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Wanted 3.52, but turns out to be 3.79; Wrong transmission from junkyard...
Topic Started: Mar 6 2010, 03:14 PM (8,488 Views)
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Duct tape heals all wounds

:gp 3rd'ed.
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Yeah, I understand that difference. I thought maybe the width along with the 1" difference, going from 12's to 13's, was just too much to get out of the "sweet spot". I guess I didn't realized 155 to 175 doesn't really make that much of a difference which is good to know. What I meant was if he went to 13's & stayed with 155, I thought he might still be in the "sweet area" haha, maybe not "spot". I was simply going off that chart Dgeo posted with MetroMPG's Firefly. Either way, I've learned quite a bit from this post. Thanks for all the great info!
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Are you experienced?
[ *  *  *  * ]
Now that all the blah blah blah has died down, I'm hoping to clarify some of the 'technical' statements previously stated:
"I counted the pinion, and it was 18 teeth"
-this is highly unlikely.
(For you to count the pinion, you need to split the case.)
You can read my DIY Split the Case thread if you are in doubt.

:news :news :news :news :news :news :news :news :news :news :news :news :news

Next I would like to simplify the 3.79 vs. 3.52 gear ratio mumble jumble:

:smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface :smackface

Put the car in 5th, lift one front tire off the ground and rotate the crankshaft.

Rule #1:
For a 3.52 gear ratio: 4 crank revs = 3 tire revs. (74 ring/ 21 pinion teeth=3.5238095)
Rule #2:
For a 3.79 gear ratio: 3 crank revs = 2 tire revs. (72 ring/19 pinion teeth= 3.7894736)

If you can remember 4/3 and 3/2, you can easily figure out the gear ratio.
It doesn't get any simpler than that...any tire size, any wheel size, spark plugs or no......even if the head is off!!!
^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o) ^o)

This information was presented in a now-locked thread:
but is buried on page 2. Sadly, we had a member who felt I was either kidding or withholding information and the thread digressed terribly. Nevertheless, there is valuable information offered, if you hunt for it. For the GeoMetroForum members, I've extracted some easy to understand information in case you want to check a car's gear ratio. The gear count (ring and pinion)? Those are direct counts on actual gears not calculated values or something I read in a brochure.

With so many people asking about their final drive ratios, maybe this buried information could be :type 'pinned' :type so that threads like these won't turn into an unhappy read. I haven't read any other threads which provide this information in an easy to understand and easy to retrieve format and maybe someone (moderator?) has the computer/literary skills to present it in the most acceptable form for our readership. Who knows, maybe someone could start a 'post your gear ratio' thread????
Now, to answer the initial question: I agree that a 72/19 final drive will provide you with many happy hours of fuel efficient driving and you should install it instead of looking for the expensive (and rare) 3.52.

Even though I've been here since day one I rarely post, but with all the smoke and mirrors, this thread seemed like it could use a little 'help'. Anyone who has counted their 4.11s hopefully will be motivated to add rule #3 etc. etc. as I'm not going out and jack up another car.

Finally, I welcome any corrections.

:popcorn :popcorn :popcorn :popcorn :popcorn :popcorn :popcorn :popcorn
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