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-   -   Has anyone upgraded their gear ratios on lifted big tires? (http://www.jeepforum.com/forum/f9/has-anyone-upgraded-their-gear-ratios-lifted-big-tires-1668329/)

Pentara 10-09-2013 08:24 PM

Has anyone upgraded their gear ratios on lifted big tires?
 
Howdy folks.

Haven't owned my 05 LJ for 2 weeks even but already I'm putting together a list of upgrades and mods. One thing I was told by a local Jeep shop was that my LJ was out of it's power band.

The previous owner put a 4" suspension lift and bigger, wider 33" tires, along with a 1" wheel spacer on the Jeep. No complaints, I love how it looks and drives. But... it is slow to accelerate.

Moving from a Honda Accord to a Jeep, I expected a reduction (It is a truck after all) but had no idea if the degree of acceleration was normal or not. The Jeep expert said it is not and I should upgrade my 3.73 gears to 4.10 ratios. But this costs $2,200+ for parts and installation on front and rear, so it's not a cheap upgrade and money's a bit tight right now.

I have no plans for off-roading any time soon, this is a street driver. I also haven't done anything significant to the I-6 engine.

Has anyone had similar experiences? Actually done this mod or a different ratio upgrade? What were your results? How do you feel now after doing the upgrade, worth it?

Appreciate all inputs and comments, thanks. :cheers2:

DezertTJ 10-09-2013 08:29 PM

Yes it does drastically increase performance, but I'd go 4.88 with 33s and that auto tranny

Jeffro06 10-09-2013 08:30 PM

I wouldn't upgrade from 3.73's to 4.10's....4.56 or 4.88's, but not 4.10's. 4.10's are livable, but not that big of an improvement over 3.73's.

dodgethejeep 10-09-2013 08:48 PM

Pee on the tire you have to establish dominance!!! Anyways, I got rid of the tj I had but I lifted it put on 33's and regeared it with a little help. Quadratec and many others sell the gears and swap kits. If your not scared to get hands dirty, I paid bout 200 to 300 for my gears and installed them in the garage with someone mechanically inclined. This was a couple years back but it made a huge difference. Before with a 4" lift, and 33's I could forget bout 5th driving on hiway. After 4.56's I could fly down the road with a boat on the back. Drove bit better than stock even with lift and rubbers. Dang thing would pass anything but a gas station. I went a bit deeper than Ineeded to on my gears, 4.10s would probly do the trick. Enjoy it while you can.

CommonSense 10-09-2013 09:38 PM

lol YES!! Pee on those tires and let them know whos BOSS. As far as the 3.73s go, my opinion is they are "livable" for 33s personally. If you do re-gear, 4.10s are only the right answer if YOU ARE CERTAIN that you will only keep 33s on the rig and NEVER go bigger. That is because 4.10s will restore your factory power band but that is it. Personally, truth be told, I wouldn't re-gear for 33s... just my .02 cents though

Knuckelhead 10-09-2013 10:03 PM

Quote:

Originally Posted by CommonSense (Post 16703673)
Personally, truth be told, I wouldn't re-gear for 33s... just my .02 cents though

Coming from someone using 31" tires... :shhh:

rchase559 10-09-2013 10:05 PM

Learn to use the OD off switch frequently or gear it to 4.88. You will probably still end up using the OD off switch due to the large gap between third and fourth gear and how early the TCM makes the transmission shift and the torque converter lock up.

I'm assuming that the guys that recommend 4.10s must not have much if any experience with the 42rle behind the 4.0L.

Knuckelhead 10-09-2013 10:09 PM

Quote:

Originally Posted by rchase559 (Post 16704457)
I'm assuming that the guys that recommend 4.10s must not have much if any experience with the 42rle behind the 4.0L.

Ya think?... :teehee:

Rrw600 10-09-2013 10:16 PM

I certainly would not spend the money to go from 3.73 to 4.10s. If you are going to spend the money, go a little deeper. As your post indicates, you've only had it for a couple weeks. Spend some more time with it, you'll soon see you want to do more with it. I ran 3.07s on 31s, then on 33s (not fun), then 4.10 on 33,s and then 35's. Now it 4.88s on 35s.

Jerry Bransford 10-09-2013 10:58 PM

4.10 would be the wrong ratio for 33" tires and your 42RLE automatic transmission, you really need 4.88 for that size tire.

Don't make the mistake of listening to someone's 4.10 or 4.56 recommendation, they simply don't have experience with Jeeps with your particular transmission... go with 4.88 which is the ideal highway ratio... not to mention being superb off-road too. Yes I know 4.88 may seem to some to not be appropriate for 33" tires... but it is when you have the transmission you do.

Also, I've regeared twice... the first time for $1300 and the last time when I negotiated better, slightly less than $1100. :)

bobjp 10-10-2013 06:04 AM

I would have a hard time spending $1000-2000 for a re gear on a street Jeep. Heck, I have a hard time spending that on a Jeep I do take off road. Have you considered getting smaller tires? It would be a much cheaper option, and TJ's look good on 31's if you don't have a big lift. Just a suggestion.

hokahay 10-10-2013 06:37 AM

I started out with a stock X 3.73 and 27" tires. Then I put 31" MTRs on and it was sluggish. Then I re-geared to 4.56 and it was sporty. Finally I went with 33 " tires. It runs fine setup like that. I went thru 4 speedo gears. Now I am back to the original speedo gear so I am back to the factory power range and the speedometer is spot on.

Jerry is right in saying 4.88 is the way to go. I didn't lose any fuel mileage with 31s and 4.56s. Drove 2300 miles out to AZ and back even.

Math is your friend here. New Tire Diameter / Factory Tire Diameter * factory ratio = new ratio for the factory power band. And like the 31s with 4.56 a little deeper is better. I have a 42rle and fooling with the OD is a waste of time. Even worse is it starts shifting in and out trying to be happy.

If spending a grand on your jeep is crazy you're likely going to be back in a honda soon. lol. I am just finishing spending 10 times that on mine. And I am sure over the last nine years I have spent that ten grand already once before.

CommonSense 10-10-2013 08:13 AM

Yup. My fault. I overlooked the fact that OP has the auto tranny. Sorry OP, was going off my 5-speed when I said that!

Unlimited04 10-10-2013 08:18 AM

I run 4.88s w/ 42RLE & 33s. before the regear, 3.73s was horrible on the highway. constantly downshifting...basically lost an entire gear.

Skold 10-10-2013 08:34 AM

Quote:

Originally Posted by Unlimited04 (Post 16713081)
I run 4.88s w/ 42RLE & 33s. before the regear, 3.73s was horrible on the highway. constantly downshifting...basically lost an entire gear.

You think that's bad? Mine has 33's and 3.10 on the AX15. I have 2.5 usable gears it seems.

You recommend 4.88s? Is there any drawback to going with that? Who did yours for you and how much can I expect it to cost? I have D30/D35s.

Thanks!


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