Thread: TOTM: Gearing

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  1. #1 TOTM: Gearing 
    ....... Lifetime Supporter rstrucks's Avatar
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    From ratios to installation, tell us what you know.

    If you have a particular ratio that works well for your rig be sure to give info about your vehicle like tire size, engine, etc..
    Thank you to those that serve our country.
     

  2. #2 Re: TOTM: Gearing 
    Senior Member Ken L's Avatar
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    Gearing is the only part of my Jeep that I haven't done myself. I did select the gearing that I wanted though; I went with 4.56 gears. Dana 30 front, Dana 60 rear.

    4.0, 42RE transmission, 33x12.50 tires.

    My Jeep started life with 3.73 gears. They worked fine with the 33s for several years, but when I upgraded the rear axle I was going to have it geared the way I wanted, so after research I decided on 4.56. After moving to Colorado I recognize that 4.88 may have been a better choice, but at the time I was concerned about the small pinion and gear mesh on the D30 and creating a very weak link. Mainly I notice that I could use deeper gearing on the highway going over the mountain passes, but off-road this gear combination works fine.
    Ken L
    '96 ZJ with stuff
     

  3. #3 Re: TOTM: Gearing 
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    I run 4.56's on mine, V8, 35's, HP30 and 8.8. For the V8 with a few small mods, it works very well for me. I wouldn't mind a little better crawl ratio on the trail for some of the bigger obstacles, but the 4.56's are a good all-around fit for me. I can maintain 75mph on the highway no problem, can make it up the big passes in the mountains, and still be able to crawl when needed. I've found that I use my brakes a lot less on the trail now too with the deeper gears as I had been running 3.73's on 31's, 32's, 33's, and 35's.

    We did the gears ourselves, but did have significant help from JpRngr, who has done a bunch of gears. It's a time consuming process, but nothing too bad. Having the right tools makes all the difference in the world though. Without some of the specialty tools that Corey has, it would have been a much harder job.
     

  4. #4 Re: TOTM: Gearing 
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    I have 4.56s with 35s and V8 on 30/44a. Feel the same way about it as Dave does. Sometimes I wish it was a little lower for crawling but for driving it, it is a good set up. My other concern would be putting 4.88s in a 30. When I swap axles later, I may look at going to something lower, but for now, the 4.56s work good. I guess going to 4 to 1 t-case would be the thing to do if I wanted a lower crawl ratio.

    I traded my 3.73 axles for these so I did no work on the regear.
    Brian
    99 WJ - 6" lift w/ Claytons, 231, 4.56, 44 Front, Locked 44a, Custom bumpers, 35 KM2s, Spyderlocks
     

  5. #5 Re: TOTM: Gearing 
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    I'll throw in what I have:

    In the first ZJ build I ran 35" MTR's with 4.56 gears - the gearing came out VERY close to stock, and for east coast wheeling which often involves a mix of slick terrain, rock, etc - I feel that is the best way to go (staying close to stock final ratio). Now if you're going to build a mud rug - go higher, rock rig, go lower!

    In the buggy phase I also had 4.56 gears, but with 42's and an AtlasII 5:1 transfer case. The ratio also worked out not too far from stock - and was good overall, but as I spent most of the buggy time in the rocks, it was WAY TOO HIGH. I think when you go big you find yourself in the rocks more, and crazy-low in first gear is the only way to go. For how big that rig was, I shouldn't have had to bounce as often as I did.
     

  6. #6 Re: TOTM: Gearing 
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    I ran 4.88s in my waggy 44 and ford 8.8 with the 4.0 and 35s. I was very happy with this setup and it would still run 65 on the highway. I am about to run those same axles in a 5.2, so I am hoping the 4.88s are not too low (numerically high just so we are all on the same page ).
     

  7. #7 Re: TOTM: Gearing 
    The class retard Lifetime Supporter ajmorell's Avatar
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    Quote Originally Posted by Ken L View Post
    Gearing is the only part of my Jeep that I haven't done myself. I did select the gearing that I wanted though; I went with 4.56 gears. Dana 30 front, Dana 60 rear.

    4.0, 42RE transmission, 33x12.50 tires.

    My Jeep started life with 3.73 gears. They worked fine with the 33s for several years, but when I upgraded the rear axle I was going to have it geared the way I wanted, so after research I decided on 4.56. After moving to Colorado I recognize that 4.88 may have been a better choice, but at the time I was concerned about the small pinion and gear mesh on the D30 and creating a very weak link. Mainly I notice that I could use deeper gearing on the highway going over the mountain passes, but off-road this gear combination works fine.
    Pretty similar thoughts. There are a few times here and there where 4.88s would be nice, but 4.56s seem to do pretty well even on some of the climbs. If I keep my ZJ (which it's looking like I will) I think I will be sticking with 4.56s and 33s for a while, even with a worked-over 4.0 I think 35s will suck pretty bad - on the road at least. Prior to moving out west, running 3.73s and 33s was tolerable but still not great (no real steep hills or decrease in hp due to elevation in MI). When I first moved out to NM I bought 32s and those were barely tolerable with 3.73s.
     

  8. #8 Re: TOTM: Gearing 
    My avatar isn't animated Lifetime Supporter SirFuego's Avatar
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    I tend to think of "gearing" as the entire package -- engine, transmission, transfer case, and axles. While the need for additional gearing can really come from "any" of those components, most of the gearing discussion is going to be focused on axles since they are a "static" ratio that affects the vehicle in all situations -- and it's also the most practical way to get additional gearing/power.

    I was very happy with the trail performance of my 4.10s on 35s with my 5.2L, rebuilt transmission, and stock 231 tcase. I stuck with 4.10s because they were available in the junkyard and I was also concerned with pinion strength if I went any deeper. I cannot comment on streetability since my rig spent 99% of its time in 4LO. There are times I wish I had a bit more gearing, but there are also times I was very happy with the wheelspeed I could get with 4.10s, so I can't comment on how much more/less I would have enjoyed 4.56s or 4.88s.

    I plan to go as deep as I can go when I swap axles and 37" tires in -- which will be 5.13s for the axle combo I'll be running.

    One other thing to consider is that those "gear ratio" calculators that take tire size into account also do not take the total rolling friction of the tire into account. So even though a gear calculator may say 4.56s are your "stock equivalent" gear ratio -- you may really want to run 4.88s for actual performance similar to stock.

    That said, I specifically mentioned a rebuilt transmission in my specs. The reason is because prior to it getting rebuilt, my Jeep always felt like it was "missing" something in terms of power -- and I assumed it was because I was undergeared. After I finally blew out the transmission and got it rebuilt, it drove like a brand new vehicle and I "found" what I thought it was missing. It was an old transmission that still shifted well, but was just worn out and over time it really killed my power. As a result, I don't consider any assessments of my 3.55/31s and 4.10/33s combos to really be fair since my transmission was really worn out.

    Another thing to consider with a transmission is that if you are considering swapping one out, you might want to look into gear ratios, because you can find some with a lower first gear ratio -- which will help crawling and still allow you to maintain similar highway performance. This is easier said than done, though, since you'd likely need to make your own adapters to run such a transmission.

    Transfer case gearing of course only helps in offroad situations when you are in 4LO. When you are talking bigger tires, it may be your only option to get that additional gearing you want in the rocks. Deeper tcase gearing will allow you to crawl better, but may hinder you a bit in wheelspeed situations such as snow, mud, or hill climbs. I've been happy with my stock gearing on my 231 for the type of terrain I wheel, but it's not perfect in the rocks. Having a 4 speed transfer case would be more ideal (with 2.7ish and 4.0ish available), but for 36s and lower, the stock tcase gearing has worked well for me in the east coast and of course is much cheaper than swapping in a bling transfer case. 4:1 tcase gearing seems to perform more elegantly in the rocks, but it sometimes can be a bit too low for some obstacles.
    Last edited by SirFuego; 01-03-2012 at 02:29 PM.
    Quote Originally Posted by SB406
    I think that's your signature move.
    "The Former"- Lay Jeep against obstacle in trail. Mat gas pedal. Form Jeep to the shape of obstacle.
    Robot
     

  9. #9 Re: TOTM: Gearing 
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    I am running 5.38's in the 60's and also ran it on the front 44. I did the math and it works great. I decided on this by the tire diameter I am running and 5.13 would bring it close to stock, but I wanted to help the 4.0 as much as I could and still maintain highway speeds. I think I hit it perfect for a dual purpose rig. It put the 4.0 in the torque curve where I wanted it. 4.0, 39.5's, and can still go 80mph down the highway, and could still turn the rear tires over on the pavement in 2 wheel squeal (in the rain haha). It was perfect for me.

    Now that my rig is trail only (slugs), I would like to have some deeper gearing in the TC but could not see anything lower than 4:1 working for me.
    I'm still waiting on the inexpensive shit to break!!!

    '02 WJ with 60's, locked, full hydo, ORI's, on 40's, and still have air conditioning!
     

  10. #10 Re: TOTM: Gearing 
    Senior Member Grand Slam West Planner Mtn WJ's Avatar
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    Brief recall of my experiences with different gearing.

    2001 WJ with 4.0. It came with the factory tow package with had the 3.73 gears.

    I drove with the 3.73s on 31s and it was ok but I didnt like the hunting between gears on the highways climbing hills in Colorado. On the trail my craw ratio seemed ok.

    I put 4.10 gears and ran both 31s and 32s for a couple years with them. My shift points were much better on the highway and the crawl ratio improvement was noticeable. I liked the 4.10s with both of these tire sizes.

    I went to 33 inch tires and the gear hunting started all over again. Gas mileage went down etc. Then changed to 4.56s with the 33s. I really like this combination. It seems to put the 4.0 with 42RE in the right power band for highway and trails. My gas mileage went up and I can even use cruise control on the flatter higways.

    I think 4.88s would be nice for crawling but not necessary and I would be a little hesitant to have them in a D30, even with the HP D30. considering on a Dana axle the lower the ratio the smaller the pinion gear. As for the 9 inch and 8.8s its the opposite.

    I really like my 242 tcase but wish someone would build a 4-1 kit for them. Seems everytime one hits the market they stop making them shortly thereafter. Probably some kind of technical issue. Otherwise there are a lot of 242s out there.
    Ask not what your country can do for you; but what can you do for your country. JFK Jan 20th, 1961

    TnT Customs Long Arms, 33" BFG KM2s, Magnum 9k winch, Ready Welder, Custom HP 30/30 front with ARB, Currie HP 9 rear with Detroit
     

  11. #11 Re: TOTM: Gearing 
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    I have 4.56's in my 96 with the 4.0 and also in my 97 with the 5.2, both are currently on 33's but will be happier once I put 35's under the 5.2 to get the revs back down.
    96 4.0 ZJ, 4.5in RE coils with Teraflex arms, Yukon gears, ARB front bumper, 33x12.50 M/TR's, homemade OBA setup....

    97 with stuff....
     

  12. #12 Re: TOTM: Gearing 
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    I think so much goes into this that it is hard to build soley on stats. I have learned this to be a FACT for my builds and those I build for- Go to a deeper gear than the "charts" tell you. To maintain (as much as you can) factory power with a bigger gear you MUST go to a deeper (numerically higher) gear than you "need" to for maintaining the same ground speed at the same rpm.

    When you go to a taller tire than stock, 98% of the time it is heavier. This equals more rotating mass which requires deeper gearing to compensate for the added weight as well as for the obviously the taller tire. GO DEEPER THAN YOU NUMERICALY THINK YOU NEED TO...I HAVE YET TO HAVE THIS PHILOSOPHY FAIL ME.

    Some ratio's that have worked for me-
    ZJ with stock (healthy V8), 231 swap, 3" Skyjacker short arm lift and 31" XTerrains on steelie's- Factory 3.73's- Good for the sand and light to moderate trail wheeling, 4.10's would have been an improvement...but not needed for light to moderate wheeling while "stock" with 3" lift.
    Above ZJ with 7" of lift, 8.8 swap and 4.10's with a welded rear and lock right front on 31" XTerrains- 4.10's were a good move off road with the 31's. gearing was fully sufficient for all but rocks and not quite ideal for sand.
    - Between the above and below setups I had started gutting the vehicle...in the end it was ONLY a windshield and stock leather seats- EVERYTHING else not essential for wheeling was pulled. Reader MUST take this light weight into consideration!
    Above ZJ with 33" TSL's- Gearing was lacking and could have benefited GREATLY from 4.88's. Fine on road, passable off road, but sucked in the sand (tire was to heavy for gearing, wheel spin was lacking), LOVED the tire off road but it lacked control (meaning it was hard to go between idle and wheel spin under high load). Fella I sold it to put some 30" street tires on it and ran it in the sand...he LOVED the performace. Given that in the end it was as light as you could make a ZJ without giving up structure, to maintain similar performace, you would have to go to at least 4.56's to compare to the 4.10's.

    Thats enough on this subject...I'll skip what worked on my other builds...similar results.
     

  13. #13 Re: TOTM: Gearing 
    Senior Member ATL ZJ's Avatar
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    I have a lot of thoughts on this but I think you need two speeds for most wheeling. Something low, a crawl gear. Let's call it 100:1 (varies with preference) and something much higher... say 30 or 40:1. Unless you live in a high traction area I think both are required for different trails. The first for more technical crawling and the second for ledges and rock faces that require wheelspeed. Of course if you have an auto trans you can just let it shift to get the wheelspeed but a good bit of the time you need to launch in that "wheelspeed" gear. Rarely do you really need to hit it that hard but a short burst or bursts of wheelspeed at the right time works absolute wonders.

    If I have time later this month I can work out to work out more precise figures I will. Also talking in terms of crawl speed which takes tire size and into account will translate more universally rig to rig and be more usable.
    Last edited by ATL ZJ; 01-19-2012 at 11:26 PM.
     

  14. #14 Re: TOTM: Gearing 
    Senior Member ATL ZJ's Avatar
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    Also I have always been and remain a fan of "shiftable gearing". What I mean by that is rather than gearing axles super low and getting all my reduction there I would prefer to have deeper transmission or transfer case gears that I can select under certain conditions only. That way you aren't committed to one type of gearing 100% of the time. It also helps you avoid running a super low gearset with a smaller weaker pinion.

    However I think you can take this concept to an extreme. Not only are low-geared tcases expensive but moving the reduction upstream from the axles can put a whole lot more stress on driveshafts and driveshaft ujoints. Like most anything moderation is generally best.
     

  15. #15 Re: TOTM: Gearing 
    Senior Member Grand Slam West Planner Ted_Z's Avatar
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    I'd never run 4.88s on a D30, the pinion is just too small/weak for my tastes.

    I'm running 4.10's with a 5.2L and 33's. I'm sure 4.56's would be better but I found a 8.8 with 4.10's so I didn't have to regear. Once I win power ball I'll regear and put an ARB in front.
    -Ted Z
    '97 Grand Cherokee Laredo w/ stuff
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  16. #16 Re: TOTM: Gearing 
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    I always recommend using the Gearing Calculator at WWW.GRIMMJEEPER.COM to do a side x side comparision of gearing options. It takes the guess work and personal opinion out of the equation.

    It's easy to use. Simply select your drivetrain components from the pulldown menus, enter the tire size and gear ratio you considering then click on the calculate button.
     

  17. #17 Re: TOTM: Gearing 
    Senior Member ATL ZJ's Avatar
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    Quote Originally Posted by SeriousOffroad View Post
    I always recommend using the Gearing Calculator at WWW.GRIMMJEEPER.COM to do a side x side comparision of gearing options. It takes the guess work and personal opinion out of the equation.

    It's easy to use. Simply select your drivetrain components from the pulldown menus, enter the tire size and gear ratio you considering then click on the calculate button.
    That's a good easy to use site. running numbers on it is the absolute minimum I would ever do before making gearing decisions
    but if you only go one place, go there.
     

  18. #18 Re: TOTM: Gearing 
    Senior Member Lifetime Supporter 5.9 ANDY's Avatar
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    i used the grimjeeper.com calculator, i was calculating the best gear ratio to match factory in OVER DRIVE!!! imo many people over look this, so using this figure, because of the "high" or over drive in my tranny, i was able to go to 5.38's and be at speed with comfort on the freeway, and and gobs of low end TQ.

    5.9V8-46RE-241OR-5.38's-37"
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  19. #19 Re: TOTM: Gearing 
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    Don't believe for a second that Timken bearings are the only decent bearing or that they are all made in the U.S.A. I've seen plenty that were marked "Made in India".

    I've used plenty of Timken Bearings (USA and India flavors) and have just as much success with National, Koyo, and SKS.
    Bearing failure is often a result of incorrect preload more than it is of the brand.

    No matter how desperarate you are to get your rig up and running, get another crush collar if you srew yours up during final installation.

    TAKE YOUR TIME SETTING UP YOUR GEARS!
    If you don't have the time to do it right the first time, how in heck are you going to make more time to do it right the second time.
     

  20. #20 Re: TOTM: Gearing 
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    I agree with bearings. Koyo is not bad; fag, ntn, skf are all excellent suppliers.

    Just make sure the bearings HAVE a brand and aren't marked made in china.

    I've learned to start the set up with the shim stacks the previous gear set used. Its made life easier the last few times.

    Used gears are a total pain to dial in.

    My gearing experiences from bone stock to where I am now.
    stock. 97ltd 5.2, 44re, 249, 3.73
    225/70/16 goodyear all seasons.
    Tons of power
    Good fuel economy
    Speedo actually reads fast by 3%
    245/75/16 mtr, 2" bb, 3.73
    Still plenty of highway power.
    Speedo dead on
    Lost about 2mpg combined
    4.5" lift, 32/11.5/15 bfg atko, soft 8's, auto 3.73
    Highway power dropped a fair bit, struggled in some steeper areas at interstate speeds.
    Offroad power was acceptable mileage dropped to about 13-14 combined
    242 swap
    Highway driving was improved with 2wd vs. the seized vc
    Mileage improved a tick
    Offroad was about the same
    engine mods, eq iron ram heads, hughes f1 intake, 1.7rr's
    Highway power was definitely improved
    Offroad low rpm power did suffer a bit as those items were meant for highwr displacement 5.9's
    5spd swap, shortie headers, 8.8, 231, 3.73's
    The manual trans changed the whole feel of the rig.
    Significantly better low speed power, higher rpm possible with the better first gear ratio
    Highway driving was improved as well mileage went back to what I had been seeing with the 245's.
    35" baja claws, 3.73
    Severe loss of observed power.
    Overdrive(5th gear) is useless.
    Around town economy really suffered
    Highway mileage did improve slightly keeping the rpm about 2500-2750 in 4th.
    I don't see how anyone can honestly claim them to be tolerable with an auto.

    New axles, hp44/d60 have 4.56 and are intended to run 37's with my current drive line and with a 408stroker in the future. The extra torque from the long rod motor should more than make up for the slightly less than optimal gearing choice I made on that.
    97 grand cherokee ltd, 5.2, white, many mods of debatable value.
     

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