With 33s you'll find you're still underpowered at 3.73. You'll need 4.56 minimum. Good looking jeep.
What did you do to your TJ today?
- Thread starter LJRubiconGuy
- Start date
NicKnack
TJ Enthusiast
Even for a DD? I have a 60min commute, mostly highway and it only bogged down a little with the 31s.
Thank you, it’s definitely been a work in progress and far from finished.
I had to downshift to 3rd in town to go up a hill. On the highway I had to downshift to 4th on a hill. Now, granted, I'm in Washington State and we have some formidable "hills". With 4.56 gears it makes the effort easier.
NicKnack
TJ Enthusiast
I have a stick as well with 33s. I went with 4.56 because if I want to go off-roading, it’s a 1.5 hr drive. It’s less than 3K RPM which i find pretty good.
NicKnack
TJ Enthusiast
I have to be honest, I’ve heard so many different views on this that my brain hurts lol. Originally, 4.88 was suggested, then XT said I’d be fine with 4.10s. This seemingly very knowledgeable fellow on YT gave a formula that calculated out to 3.73s. Before watching that video though I had somewhat settled on 4.56. It seems as though there’s a perfect ratio lingering out there somewhere... now, how to find it without regearing multiple times.
NicKnack
TJ Enthusiast
I like that answer. So far that’s three votes for 4.56. It’s currently in the lead.
4.56 will be perfect if you have the 6 speed manual. I have the 5 speed and will be jumping to 4.88s in the next month or so.
Don't listen to that YT guy.
Also, once you have your 33's, measure to the center of the wheel (or center of axle) and double that number. that is your effective rolling tire height and will give you more accurate numbers. My 33's have a "rolling height" of 31.5"
at 70 mph I'll be at 2841 rpm in 5th gear
NicKnack
TJ Enthusiast
Crap, I have the 5spd. What’s causing you to make the jump? Where are your RPMs at 60mph?
I currently have 3.73 and at 60 mph I'm doing around 2600 rpm, in 4th gear. 5th is pretty much useless at the moment.
NicKnack
TJ Enthusiast
Strange... I’m similar to that with the 3.09s on 31x10.5, but I could cruise in 5th. Haven’t had it on the highway with the 33x12.5s yet.
Part 2 of my “I’m getting one more summer out of my top” I flex sealed the inside flap and seams of the zipper and Velcro on my rear windows to hopefully stop the water seepage.
I'm assuming you'll have the tires before the gears? You'll definitly see what I'm talking about as soon as you take it out for the first time. You won't hate 4.56 by any means. But I've been stalking this topic for a good while now, and have settled on 4.88s for 33s with a 5 speed as being the best combination.
Dont feel crap. I understand...it’s though as you feel you only get one shot to get it right.
If it makes you feel better, I’ve yet to feel like I should have to went to 4.88.
Kermit1911
New Member
Just as any other day, I took the jeep out for my Saturday running. Today, It finally warmed up a bit so I rolled the windows down. I noticed a chirp coming from the right rear that increased with speed. It was much too slow of a chirp to be coming from the drive shaft. I'm thinking its the rear end. Possibly a spun race. I'm partially deaf on my left side and with the wind rushing into the cabin, I couldn't hear it when I got over 40, so it sounded like it went away. It's definitely there at low speeds though. I've noticed a steady decrease in MPG (9 to 11 MPG average) and deceleration when I'm coasting. The diff fluid was topped off before winter and hasn't been leaking. My jeep is a 2004 4.0/ Auto/ stock suspension/ and 31s . Stock drive train Dana 30 and 35. I jacked it up and noticed some slop in the rear open diff. It's dark now and I'll attempt a more in depth look tomorrow. I'm hoping its a simple fix since I've never had to mess with a rear axle before. Yay me!
It's definitely daunting, and carries that feeling of needing to get it right the first time.
You have more hills and such, so a high numerical ratio makes sense to me.
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