What gear ratio should I go with?

m1gu3l

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Denver, CO
I sold my 2000 2.5L manual and purchased a fully decked (cosmetic stuff ) 2000 4.0L auto (I wanted a manual, but my wife now can also drive it and it has the inline 6 I wanted) Looks like the previous owner keep it in good shape but only did cosmetic changes, like road armor front and rear bumper, warn winch, painted the hardtop to match the body, new Corbeau seats rear and back, and 35"s

So I took it for a drive the other day and I hit a hill and the poor thing could not go up, I felt like getting off and pushing it. After cleaning the Dana covers seems that is geared at 3.07 front and back, which I think it's the reason it can't crawl uphill.

Looks like my first mod will be to re-gear, and after doing some research seems that I might want to go to 4.88 or higher if I want to tow a small teardrop trailer. Do you have any recommendations on gearing at 4.88 or should I go to 5.13 ?

The rear is a Dana 35 and front a Dana 30

Thank you
 
Welcome to the forum. Well, based on your rear Dana 35 axle, its present 35" tires are too big for that axle to support for long. Its axle shafts are not really strong enough for 35's. And if you regear the axles to a suitable lower ratio to bring the power back up where it belongs, that would make it even easier to break one of its axle shafts.

This is what can happen to a Dana 35's axle shaft with 35's as happened to this friend of mine while we were on the trail together.

Marianne640x480.jpg


You have a couple choices, see what you think about the following. You can downsize the tires to 33" and regear to 4.10 which would be an awesome combination. That ratio would be ideal with your transmission. A Dana 35 axle is ok with 33's. Least costly way to make it driveable.

Or if you want to keep the 35's you can strengthen your Dana 35 by replacing its axle shafts with stronger larger diameter shafts via a Super 35 kit from www.revolutiongear.com. With 35's I'd recommend a 4.56 ratio. A more expensive way to make it driveable but at least it's an easy proven upgrade that will hold up to 35" tires even on difficult trails.
 
I have 4.88s with a 42rle 4.0 dana 30/35 and sometimes I wish I went with 5.13 and I don't tow so there's my opinion. I know what you mean about it struggling uphill so the 4.88 is millions better than the previous gearing, just not AS great as I wish also i'm on 33's
 
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Welcome to the 3.07 club lol, Go down to 31,s I think 35,s may kill your axils?
Must suck when getting rid of a lower powered TJ only to find the 4.0 sucks just as bad with bigger tires because of the gearing :(
 
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I have 4.88s with a 42rle 4.0 dana 30/35 and sometimes I wish I went with 5.13 and I don't tow so there's my opinion. I know what you mean about it struggling uphill so the 4.88 is millions better than the previous gearing, just not AS great as I wish.
Good advice, just be aware m1gu3l that his transmission is a 4-speed automatic and correct axle ratios for it are totally different for your older 3-speed automatic. Don't get confused with those ratios that are only appropriate to his particular/newer transmission. :)
 
I had a dream the other night that I was going up our steepest hill in Perth Australia and I kept changing down until struggling in second then I had to stop and put it in first! The que behind me was long and angry lol That was just after the poll on worst factory TJ decisions "3.07" lol
 
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02, 4.0 5 speed, 4.10s and 33s….I wish I had went with 4.88s.
 
Welcome to the forum. Well, based on your rear Dana 35 axle, its present 35" tires are too big for that axle to support for long. Its axle shafts are not really strong enough for 35's. And if you regear the axles to a suitable lower ratio to bring the power back up where it belongs, that would make it even easier to break one of its axle shafts.

This is what can happen to a Dana 35's axle shaft with 35's as happened to this friend of mine while we were on the trail together.



You have a couple choices, see what you think about the following. You can downsize the tires to 33" and regear to 4.10 which would be an awesome combination. That ratio would be ideal with your transmission. A Dana 35 axle is ok with 33's. Least costly way to make it driveable.

Or if you want to keep the 35's you can strengthen your Dana 35 by replacing its axle shafts with stronger larger diameter shafts via a Super 35 kit from www.revolutiongear.com. With 35's I'd recommend a 4.56 ratio. A more expensive way to make it driveable but at least it's an easy proven upgrade that will hold up to 35" tires even on difficult trails.

I agree with Jerry on this. Definitely upgrade to the super 35 kit, or move down to 33's.
 
Thank you everyone for the help and info! I called a few shops but man they were busy and I was on hold for a while. One of the shops quoted me $650 for the 30/35 4.88 gear set, and $1200 for labor, which I think is about normal for Colorado prices. Another shop quoted $2600 total.

The shop owner told me that the 4.88 gears should be ok for the 35"s or even 33"s if I decide to go a little smaller. I honestly do not like super tall jeeps and I like to keep the center of gravity lower + I'm not doing any big boulder crawling.

So if I go for the 4.88 do you think it would be ok to go down to 33"s in the future?

(I really miss the fun of manual transmission, but driving an auto is nice during rush hour traffic)
 
Again, you have a 3-speed automatic which requires different ratios than most people and shops are used to recommending for. For 35's you want 4.56 NOT 4.88. But unless you will install the Super 35 kit I mentioned in post #2 above I'd drop down a size to 33's and gear to 4.10. 35" tires are too big for a stock Dana 35. If you didn't actually read my post #2 above, please do so.
 
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Again, you have a 3-speed automatic which requires different ratios than most people and shops are used to recommending. For 35's you want 4.56 NOT 4.88. But unless you will install the Super 35 kit I mentioned in post #2 above I'd drop down a size to 33's and gear to 4.10. 35" tires are too big for a stock Dana 35. If you didn't actually read my post #2 above, please do so.
@Jerry Bransford

Sounds like Super 35 kit in addition to the new 4.56 gears it is, thank you again for the information.
 
@Jerry Bransford

Sounds like Super 35 kit in addition to the new 4.56 gears it is, thank you again for the information.
@Jerry Bransford I was also looking at the 33's from a Jeep Gladiator, for about $1K with only 500 miles on them. Looks very tempting since I had 33's PROComp on my previous TJ and I loved the body to tire ratio looked a lot better proportionally, so I could just get some spacers to fit the new bolt pattern. Oh man, I love Jeeps because of the options but sometimes can be really difficult to decide.
 
Just my 2 cents.
I have a 2004 X 5 speed NV3500 that came with 3:07 gears. It ran 33’s most of its life on the stock axles until December 2020. I had a local shop upgrade the Dana 35/30 with 4:56 Motive gears and the Eaton TrueTrac in the rear. Best $2600 I’ve ever spent. It has plenty of power and I have 5th gear now 😂. Interstate speed of 75 is running around 2600 rpms.
 
Jerry, I have taken your advice on other posts regarding the 3 speed automatic but also have a question relating to this topic. I anticipated a re-gear when I upgraded to 37" tires earlier this year. The axle combo is Dynatrac Pro Rock 44/60 in 4:10 gear ratio which was originally set up for 35" tires with a Golen 4.6 stroker (270hp) and an Atlas 4.3 transfer case. Surprisingly, the on road performance with 37" tires seems even better than it was with 35's. Cruising down the freeway at 70 and just under 3k rpms. It isn't gonna win any drag races from a stop light but off road crawl ratio also seems to be ok. Haven't taken it anywhere serious yet but just playing around on some hillsides doesn't seem to be struggling at all in the lower range when the transfer case is engaged. I know you are an advocate of what a torque converter brings to the table when evaluating gear ratios. My question is with the 3 speed auto, the 4.3 Atlas and the higher horsepower would a gear change (let's say to 4.88) really be beneficial with this set up? I have a 50 mile commute (one way) when I take this thing to work and I don't drive aggressively on road. The cruising speed now is pretty nice. Took it to Tahoe last week and although I had to keep my foot in it, still maintained 70mph up the grades loaded with gear. I know it's all about personal preference as many have stated here. Just wondering if the added horsepower, torque converter advantages and lower gearing of the Atlas vs. stock transfer case makes a gear change an unnecessary expense? 3 speed auto's are pretty tough but a challenge to achieve a street worthy rig capable of both on and off road performance.
 
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I wish I had some validated recommendations for your 270hp engine and 3-speed automatic and 37's but I just don't have any personal experience with it. I'd think 4.88 would give a great experience with 37's but that's just a gut feel without personal experience to back it up.
 
Can’t speak to exactly what 4.88 would be like with the auto and all the extra power, but if you’re happy with street performance at low speeds, then just leave it alone. 4.88 would get you scooting along even easier but with the power you probably don’t need that and it would come at the expense of a decent amount of more highway rpm which while that won’t hurt anything, it could hurt gas mileage possible especially on a more powerful engine that isn’t struggling to pull grades as it is already. So unless it feels bogged down leaving a stoplight, I think you’re good, as crazy as 37’s and 4.10 may sound regardless.

I am all for low gears and run my manual 4.0 at 3000 @ 75 but with a stroker and an auto, I don’t think I’d do the typical ratios unless I felt it needed it.
 
Thanks for the input, never heard anybody here recommend 4:10's with 37" tires...ha. So far I'm liking the on road part, I may have a totally different opinion after some trails. The Atlas cleans up a lot of the mess but idling downhill in 4 low does seem tad bit too fast now with the larger tires.
 
Thanks for the input, never heard anybody here recommend 4:10's with 37" tires...ha. So far I'm liking the on road part, I may have a totally different opinion after some trails. The Atlas cleans up a lot of the mess but idling downhill in 4 low does seem tad bit too fast now with the larger tires.
Lol, felt weird to say for sure. I mean if I were to set one up I’d probably do 4.56 but if you already have the 4.10 and the stroker is doing well?? I don’t see a reason to change it. If you had a higher ratio like 3.73 or something then I’d be pushing more for a regear.

I’m sure 4.88 would be a blast though.
 
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