Gear Ratio and 8.8 thoughts

[joeylead]

So here is my build plan, i just got a great set of 35" bfg for a steal so now its time to get the axles done. My plan is to run an 8.8 out back. so, i have heard alot that the 8.8 has a weak carrier, so that would make me lean towards a detroit. But with 35's would it be an issue? I would prefer to run a lock rite because of the cost. In the front i will be installing an auto locker as well. No worries about on road characteristics, i just dont want to install the lock rite and have it explode the carrier. Also, with gear selection, i thinking 4.88 (currently have 3.55). the jeep is used for driving around on nice days and east coast rockcrawling stuff. I am not into mudding or high speed sand runs.

thaanks,
joe

 

[Bounty__Hunter]

The stock carrier in the 8.8 is fine and can handle a lunchbox locker. Be sure to get one without the limited slip so you can fit the lockright. Also have the axletubes welded to the center section to address the 8.8's main weak-point of spinning the tubes in the housing. I did my own with 55% nickel welding rods (For steel to cast).

What year Jeep? Check out this package if it's a TJ: Complete Ford 8.8" Rear Axle Assembly Jeep TJ Ready to Bolt In Axle Swap

 

[joeylead]

I forgot to mention that is was for a TJ. Actually, ecgs is where i was planning to get my axle from. I can save over 300 by getting a lockrite instead of a detroit which will help cover the costs of my front axle work. When i spoke to my local professional his estimate was a little higher. In terms of gearing though, is 4.88 to low considering i am coming from a 3.55? I remember in my old tacoma, i went from a 4.10 to a 4.88 (6cylinder, auto) when i went from 32's to 35's. Any my TJ is a 4.0 5spd. Of course i just saw a set of axles, D30HP and an 8.8 all set up for a TJ, but 4.10 gears. So hence my other question about the ratios.

 

[Bounty__Hunter]

4.88 will be a good ratio for you. Your final drive ratio will be only slightly lower than when stock, which is good as the gear ratio charts and calculations only account for the larger tire size, not the added rotational mass of larger tires. Your RPM will be 200-300 higher than stock at any given speed which is minimal, and the correct side to error on when considering performance.

4.56 will return RPM to where it was with 3.55 and stock tires, but doesn't take into account the extra tire mass and grunt needed to get it moving. I always go one gearset lower than what returns RPM to stock, and haven't been disappointed yet. Go with 4.88.

 

[69jeepcj]

I have a v8 jeep with 4.88,s and a 4spd. It had 35" tires and a warn overdrive at one time, with the overdrive the 4.88,s weren't too bad on the high way, if I remember, it was about 2200 rpms around 60-65. Now, without the overdrive I am at 3000 rpm,s or better around the same speed. I dont have a seedo so I cant tell you an exact speed. honestly without the overdrive I think 4.88 are too low for the street, but I have the extra umph of the v8. I would say your jeep will drive about the same as your tocoma with 35,s and 4.88,s. as far as torque and power go. someone calculated it for me once and said with 35,s and 4.88,s it would put me around a 373 ratio. As bounty said get a 8.8 with open carrier, if you get the limited slip you will have to buy a open carrier to put the lockrite in.

 

[joeylead]

Thanks for the input guys. I did find an 8.8 with 3.55 gears to match mine and an open carrier with the intention of putting that in. But with the 35's I really need better gearing. I will go with 4.88's. What do yoy think of a d30 hi pinion in terms of being stronger than the low pinion version? Just wondering.if its with a few extra bucks to find one.