4.88's w/33's is Outstanding! - JeepForum.com
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post #1 of 38 Old 03-25-2007, 01:46 PM Thread Starter
55willystruck
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4.88's w/33's is Outstanding!

Just regeared the Jeep with Alloy USA 4.88's, picked her up on Friday afternoon and have been working with the heating/cooling cycles since. My rig is an '05 LJ Rubi, heavy with aftermarket bumpers, armor, winch, etc., etc. I'm running 255/85/16 BFG MT's, which actually measured out at 33.5" tall, and the factory 4.11's were horrible with my setup. I'd lost 6th gear pretty much all together, my 1st gear was no longer a granny gear/finesse gear, but became a dedicated "starter" gear. The control I had was gone, the rig was a chore to drive and took constant throttle, so fuel economy suffered as well. I dropped from 18/19mpg on average clear down to 13mpg average with 33's and the stock 4.11's. Performance was horrible. Off-road was really bad.

I am THRILLED to report that despite my horrible frustration and stress, nervousness with the decision between 4.56 and 4.88's, my choice of 4.88's was most definitely the right decision for me. I'm still working on the initial break-in, and won't be done till tonight after I cross the mountain back home, where I'll change fluids out, inspect everything and put some fresh fluid back in.

So far, the rig is a totally different animal. She's "Alive" now, with power across the entire rpm range once again. 1st gear is back to being an excellent all-around granny/control/finesse gear, as well as a good starter-a good mix of everything. I have total control once again, very smooth, very easy to work or play around with-hard to describe, but a HUGE improvement. 6th gear on the highway is amazing-I actually not only re-gained the use of 6th gear, but also actually have power in 6th. I can actually climb hills at highway speed, and still have power in reserve to accelerate even-something I couldn't do even when stock. I'm turning 2500rpms at 60mph via GPS-the speedometer reads about 10% fast, so 60mph via GPS is reading as 66mph on the speedo. I'll correct with a Superlift TruSpeed shortly. Regardless, the rpm range is exactly where I wanted to be-it is absolutely perfect. My fuel economy has increased as well, though I'm not positive on the numbers just yet, I suspect I've gained probably 2-3mpg back. I'll get back with some hard numbers after my return trip home tonight.

Overall, I am THRILLED with the 4.88's-it was definitely the best choice for me, and my rig's setup. The setup is OUTSTANDING to say the least, I am so relieved that it's done and worked out the way it did. I was extremely nervous about this choice, and nearly changed my mind at the last minute to have 4.56 installed instead. Glad I sweated it out-this is definitely the best setup for me, and was well-worth the stress involved with the decision.

I'll report back with actual fuel numbers later, but if anyone has any specific questions regarding rpm ranges/speeds, etc, I'd be glad to try and report back with whatever is requested.

Big Thanks to Ron and Eric at Alloy USA, as well as Dave at Northridge, ytodd and of course, Jerry, for my many questions over the last few months trying to figure this out. 4.88's is Awesome on my setup, definitely worth two thumbs up! I couldn't be happier.

Best of Luck,

Mike

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post #2 of 38 Old 03-25-2007, 01:54 PM
robncar
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Sounds like you're happy! Now for some 35's to go woth those 4.88's... just kidding, enjoy!
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post #3 of 38 Old 03-25-2007, 01:57 PM
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put the 4.88's in mine and couldnt have been happier, however I running 35's and its still strong

2004 TJ | 5'' on 35x12.5's | Currie HD Steering| Smittybilt tire carrier | 4.56's |

1988 XJ | 6'' on 33x12.5's | Locked and Loaded |

Quote:
Originally Posted by bobbert350
you have to stop thinking of miles per gallon its fun per gallon....and in my jeep my fpg is too much to count
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post #4 of 38 Old 03-25-2007, 02:15 PM
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I'm trying also to decide between 4.56 and 4.88 . . . but I have an automatic . . . for comparison . . . can you tell me what your final 6th gear transmission ratio is ? . . . let us know about the gas mileage when you can . . . glad to hear you're happy with your setup

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post #5 of 38 Old 03-25-2007, 04:20 PM
XtremeJeep
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Numchuck..........mine is an auto w/ the 4.88's and its amazing, you wont be dissapointed

2004 TJ | 5'' on 35x12.5's | Currie HD Steering| Smittybilt tire carrier | 4.56's |

1988 XJ | 6'' on 33x12.5's | Locked and Loaded |

Quote:
Originally Posted by bobbert350
you have to stop thinking of miles per gallon its fun per gallon....and in my jeep my fpg is too much to count
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post #6 of 38 Old 03-25-2007, 04:36 PM
Jerry Bransford
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Quote:
Originally Posted by numchuck
I'm trying also to decide between 4.56 and 4.88 . . . but I have an automatic . . . for comparison . . . can you tell me what your final 6th gear transmission ratio is ? . . . let us know about the gas mileage when you can . . . glad to hear you're happy with your setup
When in overdrive, your 4-speed automatic is similar to being in 6th gear, or 5th gear with the 5-speed. It actually has a slightly deeper overdrive ratio so going with the lower ratio would be better.

When you have a choice, buy American made.
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post #7 of 38 Old 03-25-2007, 05:46 PM
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I'm running 4.88's on 33's as well. I am not very comfortable driving on the road. It feels like when I push the gas I am not going anywhere, just revving he engine. I'll feel much better when I get 35's. Based on my experience, if my Jeep was my DD I would have went with 4.56's on 33's.

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Last edited by koheed; 03-25-2007 at 05:58 PM.
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post #8 of 38 Old 03-25-2007, 05:55 PM
numchuck
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thanks guys . . . given the expense of a gear change . . . I should also probably plan on 4.88 . . . and if it proves to be too much . . . I could just "water" my tires

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post #9 of 38 Old 03-25-2007, 06:07 PM
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Auto 4th is .69 to 1. 6sp. in 6th is .84 to 1. 4.88s would be better for freeways for the automatic 4sp.

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post #10 of 38 Old 03-25-2007, 06:13 PM
numchuck
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thanks Tom . . . that settles it for sure.

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post #11 of 38 Old 03-25-2007, 06:55 PM
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Glad to hear it is working out well for you. I am going to be building Dana 44's for the front and rear of my jeep. I will eventually be going to 35's. From the sounds for your results I will be going to 4.88's.

Ron
US Navy 1993-'97
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post #12 of 38 Old 03-25-2007, 07:08 PM
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Quote:
Originally Posted by 55willystruck
I'll correct with a Superlift TruSpeed shortly.

It would be more cost effective to just get a new speedo gear wouldn't it? Isn't the "truespeed" like 180$ vs. 20-25$ for a new speedo gear and about 10 min to change the speedo gear.

Just a thought

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post #13 of 38 Old 03-25-2007, 09:32 PM Thread Starter
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Quote:
Originally Posted by YellowNJTJ02
It would be more cost effective to just get a new speedo gear wouldn't it? Isn't the "truespeed" like 180$ vs. 20-25$ for a new speedo gear and about 10 min to change the speedo gear.

Just a thought

Yeah, it would be more cost effective if I had the 231 t-case, but my Rubi is equipped with the 241OR case, which uses an electronic speedo sender, so unfortunately a gear change is not possible.

Just crossed the mountains and returned home. Man, I LOVE this setup!!! I didn't get a chance to fill the tank yet-will get it tomorrow morning on the trip to the auto parts store for some diff fluid to get my oil change done, however my FIRST tank of fuel on the new gears during initial break-in was actually higher than expected. I got 17mpg on the first tank after the swap during break-in. That's up 4mpg from the 13 average I had with 4.11's and 33's. I'll fill tomorrow and see what I got coming across the pass-though it looks like it's going to be pretty darned close as well.

The trip home consisted of leaving Whidbey Island at sea level, and crossing Stevens pass-I forget the exact elevation. With my rig in STOCK form with 4.11's and factory 31" MT/R's, coming back over heading East over the pass, I could not keep 6th gear-had to downshift to 5th and run 5th over the top. With the 33's and stock gears, 6th was lost entirely, I ran 5th most of the time and had to drop to 4th to cross the pass. I am thrilled to report that now with the 4.88's, I was able to maintain speed at 60mph turning 2500 rpms the entire way over. If I wanted passing power, dropping to 5th had plenty of pep to get up and go if need be-this is a huge change for the better. I'm now able to run exactly as I was hoping to run in the rig, and turning the perfect rpms for my liking. 60mph is right at 2500rpms, 70 is around 2900. I only hit 75 once and didn't pay too close attention, but was barely over 3000 on the nose. The power through the entire range is outstanding. I am SO happy I went this route.

Did I mention I LOVE this setup!!!

Best of Luck,

Mike
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post #14 of 38 Old 03-25-2007, 10:28 PM
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4.88s are a lot of fun with the 33s. That's what I have.

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post #15 of 38 Old 03-25-2007, 10:34 PM
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I have a daily driver 5 speed with 33's, would 4.88's be too much?
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