35's with 3.21?
03-06-2011, 03:43 PM
#12
JK Freak
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Im running 33's and 3.21's right now and Im always in 6th. Even through the hills of TN and KY I just drop it down to 5th. I constantly drive 70+ without a problem.
03-06-2011, 03:54 PM
#13
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I just put 35's (315/70-17s) on my 6-speed with 3.21 gears this week (put the BB/lift on this weekend in the snow!) and it's not the worst thing ever.
I have always wondered what folks compare their Jeeps to when they say it's gutless, needs a Hemi, etc. Mine has the tallest gears you can get and is normally the quickest away from stop lights. It's not a sports car, but certainly can get out of it's own way... at least with 32's.
With the 35's it still gets up and goes - just slower. I'm not trying to race anyone so who cares?
I haven't wheeled it yet to any great extent... mostly just getting in and out of my driveway. Now, before you
, you need to know this: we have snow on the ground here Dec-April and I stopped shovelling my driveway when I bought the Jeep in '09. 
The entrance to my driveway is the height of my mailbox!
Can you do it? Yes. Will you like it? Only you will know. I can live with mine for now - no problem!
I have always wondered what folks compare their Jeeps to when they say it's gutless, needs a Hemi, etc. Mine has the tallest gears you can get and is normally the quickest away from stop lights. It's not a sports car, but certainly can get out of it's own way... at least with 32's.
With the 35's it still gets up and goes - just slower. I'm not trying to race anyone so who cares?
I haven't wheeled it yet to any great extent... mostly just getting in and out of my driveway. Now, before you
, you need to know this: we have snow on the ground here Dec-April and I stopped shovelling my driveway when I bought the Jeep in '09. The entrance to my driveway is the height of my mailbox!Can you do it? Yes. Will you like it? Only you will know. I can live with mine for now - no problem!
03-06-2011, 04:38 PM
#14
JK Junkie
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Thanks guys. In the time it took me to drive to work I got 15 responses.
YES I have an AUTO. So I guess she will automatically decide what gear she wants, haha!
So...let's say I go ahead and do the 35's and keep the 3.21 for awhile. Thoughts on a 2 1/2" budget boost?
Here's the thing, I have to do everything on a budget. I have had her since Sept and haven't done anything to her. SO What I do I want to be right. I don't want to go off half cocked and just mess something up. I know it's all about learning, etc, but being my DD and my only vehicle, I can't have her out of commisssion for long if I do mess something up.
BTW...you guys rock! I am leaning towards the 35's just want to do it all correctly.
YES I have an AUTO. So I guess she will automatically decide what gear she wants, haha!
So...let's say I go ahead and do the 35's and keep the 3.21 for awhile. Thoughts on a 2 1/2" budget boost?
Here's the thing, I have to do everything on a budget. I have had her since Sept and haven't done anything to her. SO What I do I want to be right. I don't want to go off half cocked and just mess something up. I know it's all about learning, etc, but being my DD and my only vehicle, I can't have her out of commisssion for long if I do mess something up.
BTW...you guys rock! I am leaning towards the 35's just want to do it all correctly.
03-06-2011, 04:47 PM
#15
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Turn OD Off and you will be ok.
Have you found the faq's yet? In the drivetrain area is a great rpm chart. Measure the tires (don't use the misleading mfg's propaganda height), then play with the numbers. That will show you the OD On rpm's. To get OD Off, divide that number by .69
An example:
Auto, 3.21's, 31" tires (guessing on the actual height of your stock tires)
= 1681 rpm @ 70 mph
Auto, 3.21's, 34" tires (you're new 35's could be anywhere from 33.5-34.5 when mounted)
= 1533 rpm @ 70 mph
then /.69
= 2221 rpm @ 70 mph OD Off
This is a much more freeway friendly rpm.
My opinion is that JK Auto's are undergeared straight from the factory, and a mid-2k rpm range on the freeway is what you want to shoot for.
And another comparison:
Auto, 5.13's, 34" tires
= 2450 rpm @ 70 mph with OD On
So your OD Off with 3.21's and 35's won't be horrible. Not optimal, but livable.
Have you found the faq's yet? In the drivetrain area is a great rpm chart. Measure the tires (don't use the misleading mfg's propaganda height), then play with the numbers. That will show you the OD On rpm's. To get OD Off, divide that number by .69
An example:
Auto, 3.21's, 31" tires (guessing on the actual height of your stock tires)
= 1681 rpm @ 70 mph
Auto, 3.21's, 34" tires (you're new 35's could be anywhere from 33.5-34.5 when mounted)
= 1533 rpm @ 70 mph
then /.69
= 2221 rpm @ 70 mph OD Off
This is a much more freeway friendly rpm.
My opinion is that JK Auto's are undergeared straight from the factory, and a mid-2k rpm range on the freeway is what you want to shoot for.
And another comparison:
Auto, 5.13's, 34" tires
= 2450 rpm @ 70 mph with OD On
So your OD Off with 3.21's and 35's won't be horrible. Not optimal, but livable.
03-06-2011, 05:20 PM
#18
JK Junkie
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My paperwork says it's a 3.21 and I thought without the tow package it had a 3.21. I plan on calling in my VIN tomorrow to double check because I got under the Jeep and couldn't find a ratio tab with the numbers and the sticker was well worn and unreadable.
Not too worried about MPG....it's a Jeep. I don't drive very far. I drive to work and back which is 42 miles daily. Small runs here and there...Then I go on a big road trip once in awhile when I need to clear my head, but that's about it.
I'm also not worried about being fast off the line! I get pulled over plenty for some reason. So, being slow off the line will just help keep me out of trouble...ha...no I know, long shot.
I'm also not worried about being fast off the line! I get pulled over plenty for some reason. So, being slow off the line will just help keep me out of trouble...ha...no I know, long shot.
03-06-2011, 05:20 PM
#19
JK Super Freak
I don't have 3.21s but I have been running 35s on 3.73 gears with an auto for 2 years and its OK but obviously not ideal especially considering its a DD for me as well. Get a 2.5 lift and 35s, you won't regret it.
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03-06-2011, 05:22 PM
#20
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Yep, Auto. I had a manual with my YJ, decided to try auto this time. I actually enjoy driving a manual, but...always have to try something new.