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Discussion Starter · #1 ·
I've only had my jeep for a week, but it seems very sluggish in 5th gear. i can maintain 55mph in 4th easier than it can in 5th. is this normal? or is there something i need to dig into?

the jeep in question:
1990 with 4.2 6cyl. manual trans. sitting on 33x12.5x15r mud terrains.

i do know it is running a little rich currently, so i either have a vacuum line issue, or the carb will actually need adjusted. (previous owner replaced the carb)

and also, the fuel cap seems wobbly even when tight? is that par for the course? or would a new fuel cap feel better?

thanks for the help, glad to be part of the YJ owners club.
SQUARE HEADLIGHTS FOR THE WIN
 
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Not sure where you are located, But here at 5000 ft. My 4L 6 cyl with 31" tires has a hard time puling 5th gear. With 33" it would even be worse. You probably need to re-gear or just learn to drive in 4th unless going down hill. :D The gas cap should probably be replaced, but you can have it tested to make sure it is working properly. They are cheap. Can't help with the rich burning. Getting that fixed could give you a little more power.
 

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I've only had my jeep for a week, but it seems very sluggish in 5th gear. i can maintain 55mph in 4th easier than it can in 5th. is this normal? or is there something i need to dig into?

the jeep in question:
1990 with 4.2 6cyl. manual trans. sitting on 33x12.5x15r mud terrains.

i do know it is running a little rich currently, so i either have a vacuum line issue, or the carb will actually need adjusted. (previous owner replaced the carb)

and also, the fuel cap seems wobbly even when tight? is that par for the course? or would a new fuel cap feel better?

thanks for the help, glad to be part of the YJ owners club.
SQUARE HEADLIGHTS FOR THE WIN



Whoever put 33" tires on it probbaly did not regear the axles because it is expensive. Jeeps came from the factory with 26" tall tires and the gearing to match them. When you put bigger tires on a jeep you need to regear and hardly anyone ever does they just live with the lack of power for the offroad look. You either need to put new gears in it or put smaller tires back on if you ever want to be able to use 5th gear again.
 

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Discussion Starter · #4 ·
OK. that was what i was assuming was the culprit. But, since i don't know much about jeeps yet, i wasn't sure if it was just an under powered motor, regardless of tires, or if the big mud tires were my main issue.

anybody want to trade me for their 31x10.5's? haha
 

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If you were close to Houston, I might have a deal for ya. Ye hah
 

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OK. that was what i was assuming was the culprit. But, since i don't know much about jeeps yet, i wasn't sure if it was just an under powered motor, regardless of tires, or if the big mud tires were my main issue.

anybody want to trade me for their 31x10.5's? haha



31's are still to big think 26-28" and if the jeep is lifted it will look really goofy with tires that small on it. So you will need to remove the lift or swap gears neither of which will be cheap.
 

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You might be able to find a shop that will do an "Axle out" re-gear for around $300 plus parts.
It's a bit of work on your end as you bring them the bare housings with only the diffs in it but your looking at a better than a half price savings.
 

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Welcome to the Forum 20streetrod06,

There are thee avenues open to you in all practicality.
1)- Find a pair of axles from a 4cyl YJ. They'll have 4:10 gears. Your stock gears are probably 3:07 ratio. Be sure to pull the covers and check the numbers on the ring gear.
Replace your 3:17 axles with the 4:10 axles.
A set of 4:10 axles usually run in the $500.00 range, depending on where you live.

2)- Re-gear to an even steeper ratio, 4:56-4:88. This is a better way if you want to keep the 33s, but will cost more.

3)- Get smaller tires. I'm currently running 31s on stock 3:07 gears but I have a set of 4:10 axles that I'll be installing soon. A 4.2 with standard shift and 31s on stock gearing doesn't get to use 5th gear often.

A combination of #s 1 & 3 will be about the same cost as #2. Decide how you want to use your new toy as you save up for whatever choice you make. Stick around the forum and learn all you can so that you can make decisions that will suit your use and budget. Look around your area for a local Jeep or 4X4 club. Where I live, there's a Facebook Jeep club but the posts are usually about runs or social events (good to participate to meet other off roaders). You'll get great technical information here.

Good Luck, L.M.
 

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5th gear isn't supposed to have any power, it's an overdrive gear.
Right. That is worth noting. 5th gear isn't really an acceleration gear. On relatively flat roads, like the highway, you can maintain a high speed in 5th and that is all it is really good for. It is normal to be in 5th and put it to the floor and not really get too much of a response...obviously some response, but you are in overdrive.
 

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Yep, it just lowers your RPMs to save on gas at speeds above 55mph. That's all it's for.
 

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Discussion Starter · #12 ·
5th gear cant maintain 55mph, i'm not expecting 5th gear to have acceleration, just be able to cruise on flat highway.

what will going from the stock gearing of 3:17 to 4:10 do for gas mileage?

and there is no lift on the jeep, so dropping tire size wont look goofy, just closer to stock, plus make it easier to get in and out for a short guy.
 

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It's 3.07 not 3.17... dropping to 4.10 will have very little effect on mpg but might help a little if you've been lugging the engine....

I find it unlikely that you have 33's on a stock yj....
I have 33's with a 4.5" lift and don't have a lot of extra room...

If it truly is stock tho look for some 235 75 15's...

I recently bought a set of 5 bfg rugged terrain for $420 shipped to my door form walmart.com for my 97 tj... drives soooo nice compared to my other jeeps on 33's
 

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Of course it's 3:07 ratio. I fat fingered that. I'd edit it, but then it'd screw up the continuity of the posts. (Posts #12 & #13)

Good Luck, L.M.
 

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Discussion Starter · #15 ·
here is a picture of her. previous owner said there wasn't a lift, but that these tires were already on it when he got it.

from being under it nothing looks "non-stock" and as you can see in the picture, its not got extended shackles.
 

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'89 YJ 4.2 with MC-2150 Carb & HEI, 2-1/2" Ex. AX-15, NP231 SYE, Adams shafts, F&R ARB, 3
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I lived with 33's and 4.10's for about a month, couldn't take the doggedness on the freeway and went to 31's because I was happy with the stance with a 2.5"suspension lift and 1"body. 32's would probably fit mine better but …… I would suggest you drive it for a while, Learn up on what you are equipped with, and make some informed decisions on what you want to end up with before you start shopping. Do it once, Do it right!

Welcome
 

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Need clarification and advice on the re-gearing option.

Welcome to the Forum 20streetrod06,

There are thee avenues open to you in all practicality.
1)- Find a pair of axles from a 4cyl YJ. They'll have 4:10 gears. Your stock gears are probably 3:07 ratio. Be sure to pull the covers and check the numbers on the ring gear.
Replace your 3:17 axles with the 4:10 axles.
A set of 4:10 axles usually run in the $500.00 range, depending on where you live.

2)- Re-gear to an even steeper ratio, 4:56-4:88. This is a better way if you want to keep the 33s, but will cost more.

3)- Get smaller tires. I'm currently running 31s on stock 3:07 gears but I have a set of 4:10 axles that I'll be installing soon. A 4.2 with standard shift and 31s on stock gearing doesn't get to use 5th gear often.

A combination of #s 1 & 3 will be about the same cost as #2. Decide how you want to use your new toy as you save up for whatever choice you make. Stick around the forum and learn all you can so that you can make decisions that will suit your use and budget. Look around your area for a local Jeep or 4X4 club. Where I live, there's a Facebook Jeep club but the posts are usually about runs or social events (good to participate to meet other off roaders). You'll get great technical information here.

Good Luck, L.M.
Ok so I have basically the same issue, 87 Wrangler, wiring chopped apart by a ‘Nutter trying to do the mod. Had old 33s so I’ve been working to get it working. It runs and drives now, but 50 is all she will do in 4th. Forget 5th, can’t hold any speed on the flat in front of Atlanta Motor Speedway lol. So, I need to re-gear, at least to 4.10, but you recommend lower to 4.56-4.88. What would be the difference be, speed and performance wise? I’d like to be able to run at speed on the interstate (70+). Would it be worthwhile to build the Dana 35 with TracLok, or better to save for a 44 or 8.8? This was bought to be my “short range’ DD and inspection truck for use on and off road, I am a pipeline inspector so I need to get places, off road, but still most of my driving would be on road. I’m trying to save mileage on the F-350 LOLS. I am also looking at freeing up the breathing, has a MC2150 on it, but the adapter leaks. Looking at a 4.0 head swap, and run a 2.5’ exhaust. I made a cold air intake from a Cadillac intake, fits the MC great!

Please any advice, and data would be greatly appreciated. I already ‘discovered’ the LJ Unlimited too late, that is the next build as it will perfectly suit my work needs, and I don’t have to use the CJ-8 in the back yard for work (assuming I can ever get around to building and restoring it).

Thanks in advance.
 

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here is a picture of her. previous owner said there wasn't a lift, but that these tires were already on it when he got it.

from being under it nothing looks "non-stock" and as you can see in the picture, its not got extended shackles.



Shackles look stock to me and it does not look like it has a body lift. My friends YJ had 33's with no lift and factory wheels when he got it. I would find new/used wheels and put stock tires back on it since you have no lift to remove.
 

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Those look like 2 1/2" springs to me from the arch visible tho tough to say from that angle...
(Op's jeep)

BTW... LOVE the K5
 
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