Don't understand this rear-end gearing/swap thing

Trying to learn over hear, but from doing some reading on this site, I'm trying to understand my best gearing choices and options. I have a 97 XJ with the 8.25 Chrysler rear-end with the 29 spline, which I have read is pretty close to being as tough as the old Dana 44's and much better than the Dana 35. I plan on lifting it 5.5" and putting on 33's, but for the next year I am going to be running 60% highway/40% offroad. What is my best option...thinking now and for the future..and cost wise?

I just read about that you can only go down to 4.56 gearing on the 8.25 but I have found out that gearing to the 4.56 in the 8.25 Chrysler causes some nasty gear noise and that the 8.25 is really hard to set-up correctly. Then I read that the ford 8" rear swap is easy, cheap, stronger, comes with disc brakes and allows for more gearing options (4.10 geared ford 8.8 with a trac-lock for not much more or even the same price as 1 with 3.55 or 3.73 gears).

I don't know tons about gearing or axle terminology, but I am trying to learn what my best options are and why.

Also, I am guessing that the 8" swap is only for the back axle assembly, what needs to happen to the front...anything? (Here's where my limited knowledge comes into play).

Let me know what you all think...

Thanks,

Beebe (Double Down)

Well, I've done the 8.25 axle gear swap to 4.56 and it took twice to get it right. However, we did this to my daughter's XJ and it was great from the start. The key is to work with a shop that does these a lot and knows what they are doing.
The 8.8 Explorer axle swap is great. Got disk brakes, which is why I did it. The gear swap was pretty easy also.
The 8.25 axle is a good axle so don't be unhappy if you decide to stay with it. Just get a shop that knows what they are doing!

I'm not certain what the question is but I'll explain what I did and why...

I was going to 32" tires and had been told that if I didn't regear I would loose a lot of power and that my overdrive would basically be useless on the highway around here (lots of steap hills). I wanted to keep performace about the same as stock so it looked like 4.10 gears were the way to go for me.

I had the POS Dana-35 rear end. Its reputation was that I could expect to start breaking shafts. I'm the type that would rather do work now then be surprised later. I considered buying a 8.25 to replace it. However, I was having trouble finding one with 4.10 gears, so if I went with that axle I would have to buy the axle and then regear it. Ford 8.8" axles with 4.10 gears were easy to find and only cost about the same amount as paying somone to regear the D35 or Chy8.25". So for me it was simply an economic question. Yeah it would cost $200 +/- more for the Ford 8.8 then regearing the d35. But for that money I get a lot of peace of mind and disc brakes

The Ford 8.8" swap is not bad if you have a place to work and can weld. I didn't have either but a friend of mine loaned me his garage and another friend volenteered to do the welding. I did not buy the MORE install kit but built everything up piece-meal. It was probably cheaper then getting the MORE kit but a pain. If I do this again I will fork out the money for the install kit rather then spend time hunting down everything I need.

You don't have ABS so I'll skip describing how to disable that.

I tried finding a d30 front with 4.10 gears but was not able to for a reasonable price. So I had my d30 regeared.

I am very happy with this setup so far.

-Brian

Double Down said:

Trying to learn over hear, but from doing some reading on this site, I'm trying to understand my best gearing choices and options. I have a 97 XJ with the 8.25 Chrysler rear-end with the 29 spline, which I have read is pretty close to being as tough as the old Dana 44's and much better than the Dana 35. I plan on lifting it 5.5" and putting on 33's, but for the next year I am going to be running 60% highway/40% offroad. What is my best option...thinking now and for the future..and cost wise?

I just read about that you can only go down to 4.56 gearing on the 8.25 but I have found out that gearing to the 4.56 in the 8.25 Chrysler causes some nasty gear noise and that the 8.25 is really hard to set-up correctly. Then I read that the ford 8" rear swap is easy, cheap, stronger, comes with disc brakes and allows for more gearing options (4.10 geared ford 8.8 with a trac-lock for not much more or even the same price as 1 with 3.55 or 3.73 gears).

I don't know tons about gearing or axle terminology, but I am trying to learn what my best options are and why.

Also, I am guessing that the 8" swap is only for the back axle assembly, what needs to happen to the front...anything? (Here's where my limited knowledge comes into play).

Let me know what you all think...

Thanks,

Beebe (Double Down)

Click to expand...

You didn't mention if you had a standard tranny, or an auto... that'll effect what gears you need to put in to go back to stock ratios, at a given tire size.

Example:
I just recently lifted my jeep and put in an 8.8 rear end with 4.10's. Given that tire size, and gear ratio I'm over-geared atm.. I could run 35's, with those gears, and be back in the stock rpm range.

I imagine if you had an auto, with 3.55's. 4.10's might put you back perfectly in the rpm range with 33's. Don't have the link handy off hand, but if you do a search on gear ratios, I'm sure you can find the chart that does compare the tire sizes, and the ratios for you.

PF

My bad, it's an auto.

I will try and look for that article on tire size...but I guess I am just trying to understand what my best scenario is. Should I do the 4.56 or just do the swap which will give me better options. But will that swap be okay for highway use? Like I said, don't know much about gearing.

Thanks,


chris

Here's a couple of sites for you:

http://www.4lo.com/calc/geartire.htm

http://www.enjoythedrive.com/content/?id=25828

Hope that helps

the gear ratio should be matched to the tire size you want and the type of offroading/onroading you plan to do. i run 4.10s and 31"s in the manual XJ and like the performance. Most reccomned 4.56s for 33" tires. I think 4.10s and 33" would be just fine with an auto. until you can re-gear.


If you prefer to have better on road capability you may want to not gear down so much.

wish i had the time to do the 8.8 swap instead of paying up the Ar** for a rebuilt D44w/discs. (had no place/tools/time to fab)
-J

Well myself and a buddy are installing gears in his XJ this weekend, he has done it a few times. I hope everything goes ok after reading I need a pro shop to install gears in the 8.25.

So according to the chart 4.56 is perfect for 33's unless I want more power, then go to the 4.10. So aside from more power and lower gearing, is the only advantage of the ford swap the disc brakes?

If you do the ford swap and don't want the 4.10 (but want the disc brakes, more durability, etc) can you go up to 4.56?

Thanks,

Chris (Double Down)

sorta.


There are many others taht are more experienced than I, but here's my 02.

The 4.56:1 ratio will increase the torque at the wheels giving you better acceleration than the 4.10s. it will feel like you have more power. going from 4.56 to 4.10 would decrease the acceleration and make the performance worse. but it will increase the top speed;this might be better on the highway.

if you want to crawl rocks go with 33s" and 4.56 or 4.88 for the gears. but your top speed may suffer.

the 8.8 is a good rear. It comes with 4.10s and im not sure how they will be with 33"s. I want to know too cause im tired of my 31"s ...


-j

boy this seems to be going round and round here. if you cant afford to regear right now and you have a cheap way of getting 4.10 in your jeep its will work fine but if your footing the bill to regear get 4.56 and don't look back. I sold my old axles to my best friend and with 32"dunlops and 4.56 gears on his 88 with 200k he gets over 21mpg on the highway and about 18 oround town and love the power the 4.56s put down.

go with 456,l just did mine from 410s,an run 33rs,its lot better,the 8.25 is not that bad,get good gears,frt axle nut from d30is the rt size for the side adjusters.