regearing for larger tires

people keep telling me that i need to regear my axles for larger tires. My question is do can I run 33's on stock gearing?

can you? yes ive been running 33's and stock gears(auto) in my dd for a year, but it does suck big time

Yeah, my 32s are definitely not making my acceleration any better

kastein said:

Yeah, my 32s are definitely not making my acceleration any better

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go to 7-11 and buy some NAWZZZZZZ

With anything larger than 31's I defintely recommend 4.10s or better.

DO YOU think you need to re-gear?

Here is a calculator:

http://www.izook.com/gearcalc.htm

you do if you care about fuel economy (or more importantly, performance)

ROBZ95Xj said:

go to 7-11 and buy some NAWZZZZZZ

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I did, I poured three bottles of this into the gas and it barely runs now:
http://upload.wikimedia.org/wikipedia/en/f/fb/Nos.JPG
did I do something wrong?????? :dunno:

(see http://www.gixxer.com/forums/showthread.php?t=226570 if you think I'm serious...)

I ran 33's on stock gearing for almost a year and while it wasn't the most terrible thing in the world, It was pretty bad. I then found a 29 spline 8.25 and then decided I wanted to regear since I had one axle that was not underneath the truck.
I went with 4.10's because I got a really good deal on them and plus daily driving with 4:56's on 33's I hear wasn't that fun.

Do you have an auto or manual XJ? With the 5-speed (technically became a 4 speed once I went to 33's) I was getting as good of fuel economy as ever. It was great

I heard all the horror stories of 12-14mpg after going to 33's, then I went and did real world testing and I was reading 17-18mpg BEFORE compensating for extra distance traveled over the odometer reading due to the oversize the tires. So it was actually better than that. I was thrilled to say the least.

themangeraaad said:

Do you have an auto or manual XJ? With the 5-speed (technically became a 4 speed once I went to 33's) I was getting as good of fuel economy as ever. It was great

I heard all the horror stories of 12-14mpg after going to 33's, then I went and did real world testing and I was reading 17-18mpg BEFORE compensating for extra distance traveled over the odometer reading due to the oversize the tires. So it was actually better than that. I was thrilled to say the least.

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did you swap out the speedo gear in the transfercase, that would be the real world difference. calculations dont tell the real truth. stcok gearing(3.07) with 33's with a manual trans will not see 17-18mpg with daily driving.

I did not swap out the gear however if I did I would see the speed at which I am traveling (at any given time) increase several MPH. If it is reading a higher MPH (after gear swap) then the odometer reading would increase at a faster rate since it is seeing me traveling at a higher speed.. Aka my Jeep would think I was traveling further off one tank of gas.

So if I reset my odometer at one fill-up, then drive for a tank, then fill again and do the calculation for mpg, that should get me a pretty solid value. I did this and did the calculation with exactly what my odometer read and I got 17-18 (+/- 1) mpg. This is using the same gas station and usually the same pump to attempt and eliminate other variables. And also did this every time I filled up with similar results so it wasn't a 1 time thing.

No clue why I got that, I always just figured I could choose my shift points and let the engine sit in it's sweet spot which let it run as well as possible. I do know my drive back from college was almost exactly 100 miles (100.5 or something like that). I filled up at school and drove home once, then filled up at the station down the road from my house. I had burned 5.5 gallons of gas over a measured 102 (+/- maybe 5) miles. :dunno:

Of all the reasons mentioned here, I havent seen anyone mention trans temps and strain. When I wheeled with 33s and stock (3.55) gears my trans, even in 4-lo, would get quite hot. Put a trans gauge on there and keep an eye on it.

4.56s helped keep it down to a reasonable level. A trans cooler and a switch/relay for the electric fan to run all day got it even cooler.

If I had it to do over, I would have gone 4.88s with my 33s. 4.56 works...but 4.88 would have been slightly better.

J.

ghettocruiser said:

Of all the reasons mentioned here, I havent seen anyone mention trans temps and strain. When I wheeled with 33s and stock (3.55) gears my trans, even in 4-lo, would get quite hot. Put a trans gauge on there and keep an eye on it.

4.56s helped keep it down to a reasonable level. A trans cooler and a switch/relay for the electric fan to run all day got it even cooler.

If I had it to do over, I would have gone 4.88s with my 33s. 4.56 works...but 4.88 would have been slightly better.

J.

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Good to know.. I was torn between 4.56 and 4.88 (not to hijack the thread or anything ). I have 33's now and plan on going to 35" or 36" in the coming years.

With the 5 speed and 3.07s that calculator told me i should be at 3.92s or something in range with my 33's, so probably 4.56 would be OK for stock deep gearing with 36's.. 4.88s to give it a bit more grunt..

..or 4.56s and a stroker... hmmmmmmmm

themangeraaad said:

Good to know.. I was torn between 4.56 and 4.88 (not to hijack the thread or anything ). I have 33's now and plan on going to 35" or 36" in the coming years.

With the 5 speed and 3.07s that calculator told me i should be at 3.92s or something in range with my 33's, so probably 4.56 would be OK for stock deep gearing with 36's.. 4.88s to give it a bit more grunt..

..or 4.56s and a stroker... hmmmmmmmm

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i have 4.10 gearing, 31's, and a 5-speed and i could get away with running 33's. but if i were going to 35's or 36's, i would want atleast 4.88.

i dont put much stock into those calculators, they dont factor in enough variables such as vehicle weight, drag.....

Oh I know not to put too much into them, which is why I typically go at least 1 gearset deeper than it recommends.. or I plan to at least.

However at the same time I dont plan on upgrading for another 6 months at least so I am tempted to pick up a pair of 4.10 axles and swap them in for the time being. Figure 4.10s would be a *bit* better than 3.07s that I am used to. :laugh:

themangeraaad said:

Oh I know not to put too much into them, which is why I typically go at least 1 gearset deeper than it recommends.. or I plan to at least.

However at the same time I dont plan on upgrading for another 6 months at least so I am tempted to pick up a pair of 4.10 axles and swap them in for the time being. Figure 4.10s would be a *bit* better than 3.07s that I am used to. :laugh:

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a "bit" would be an understatement.

if you have never regeared, you dont know what your missing. going from 3.07 to 4.10 is a big difference.

plan ahead as axles and gearing is something i would only want to do once because of the cost.

4.10 is a stock gearing (I believe it was for 2.5 liter engine and some manual tranny, not sure which), so if you currently have stock axles without any trusses, lockers etc it's really not a big deal to find a set in a junkyard and bolt em up.

speaking of which themangeraaad I call dibs on a set of 4.10s in d30/8.25 out of Hollands :roll:

I am almost positive that any XJ with a 2.5 came with 4.10s, or most at least.

89xj: Thats why "bit" was in **'s. I know it will make a huge difference, approx 30% different. haha. I have never regeared but I know the costs associated with it, so I only plan to regear once.. however I may be picking up a set of stock XJ axles. I currently have a 27 spine 8.25 so I would either A) find another 27 spline and just have spare axle shafts if I break something, or B) find a 29 spline and go stronger (but not have spare shafts). Should be able to pick up a pair of axles for < 200$ each. They would be good to get me through the winter since I just want to get the XJ on teh road again for the winter months (and have it be funner to drive again than it is with 3.07s)

kastein: does Hollands have a good XJ selection? I normally go to Everettes (hollands is over an hour drive away from me) but everettes selection has sucked lately. If hollands has a good selection I may have to make a drive up on haloween. If I get to the axles first you can buy them off me if the price is right :laugh2:

I don't know if Hollands has a good selection yet, last time I went there was 06 and I didn't own a car yet... I'll see I guess. Most of NAC Massachusetts is planning on going, it looks like. I usually go to Sam's Pull-a-Part in Worcester.