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re-gear worth the cost?

3K views 21 replies 15 participants last post by  roccomonte 
#1 ·
87 YJ 4.2L auto 3.73 gears 33" tires. I'm going to stay with 33's it struggles a bit on the highway but its ok. No tach so I dont know the RPM's. I dont have a lot of experience with what it should feel like so I cant compare it to anything. Eventually I'd like to swap in a 700r4. Should I re-gear? How much of an improvement will it make. I drive mostly on road with some off road time 70/30 id say.

Also the speedo is off I'm sure is there a way to get it accuarate?
 
#2 ·
If it mainly on-road or a daily driver I would suggest going ahead and regearing it to 4:10's maybe 4:56's. You will notice a very large difference. I recently had the gears, tranny, and rear axle upgraded and it made such a huge difference in power. You will be really happy with the gears. You can always go with a granny install into your transfer case later if you decide to get into more off-road driving. I own a 88 YJ sitting on 33's.
 
#3 ·
I have seen complet axles out of a 4 cyclinder sell on craigslist for $200 -$300 for the pair. The 4 cyclinder axles would give you 4.10 gears cheap. Another option is to find an 8.8 with 4.10 gears and a D30 out of a 4 cyclinder to match, this is what I did.

You can buy a new speedo gear to go in the transfer case to fix your speedometer. You just need to know your gear ratio and your tire size. Check Quadratech or 4wd hardware.
 
#7 ·
I have seen complet axles out of a 4 cyclinder sell on craigslist for $200 -$300 for the pair. The 4 cyclinder axles would give you 4.10 gears cheap. Another option is to find an 8.8 with 4.10 gears and a D30 out of a 4 cyclinder to match, this is what I did.

You can buy a new speedo gear to go in the transfer case to fix your speedometer. You just need to know your gear ratio and your tire size. Check Quadratech or 4wd hardware.
I would go this route. Spend the extra $$ now and put in an 8.8 with 4.10's instead of another D-35. It's not even worth unbolting the springs to get that turd under there.
 
#4 ·
theres a guy by my house that has 4.10 gears from an 8.8 for $75 bucks on craigslist.. if you get your axle lol
 
#5 ·
Thats a good idea. I started looking and see prices around 200 300 per axle... probably a bit more expensive then I'd like as I would probably have them cleaned and rebuilt. I'll keep it in mind tho and see what I can find. Its always easier if your not in a rush. And since they aint broke yet I'm not.
 
#9 ·
I noticed a large difference.
1) My jeep rattled crazy in the rear end and for awhile I thought it was my rear tire carrier/ bumper I installed. I even went as far as to weld it to the frame to fix the rattleing sound. The sound finally went away as soon as I read somewhere on this forum that a stock 35 with stock gears sitting on larger tires was known to rattle and decided to switch axles and re-gear. Now my 1988 YJ is rattle free on take off.

2) Goin up hill in 5th gear was a no-go. Any incline caused me to immediatley down shift to fourth. Even in fourth I would slowly lose speed. I could maybe get to 60mph with a head wind. Keeping up with highway traffic was not happening. As soon as the 4:10's were installed I can use 5th gear and my jeep can accelerate past 80mph without blinking.

In short, if it is only a couple of hundred rpm difference then it is the most important couple of hundred rpm in the world. I daily drive mine to work, to pick up the kids from daycare, and to go fishing. I even scheduled to travel from Colorado to Abilene, Texas to pick up my trailer becuase the power difference is that vast for me. My advice is to listen to people here, get quotes for the parts you need and then call some shops and see what their price to regear you stock axles would be. You will see very quickly that the difference in price is extreme and by buying an 8.25 or 8.8 axle with 4:10 already in it you get a stronger more worry free axle and 4:10 gears for half the price of having a store just regear your stock junky axles.

I did my research and decided to go with 4:10's instead of 4:56 or 4:88 because I use my jeep as a DD. Any gearing issues I have out on the trail will eventually be solved by a better transfer case or a gear kit for my np231. Please keep in mind I am no expert and just learning about jeeps but I did spend about a year reading before making any changes to my jeep and when I finally did I was completely satisfied with my decision. Now you need to decide what you think would be best for you and what you plan to do with your jeep down the road. My advice is to regear if you are running 33's but also decide now what you want to do in the future so you don't waste your money later on down the road. If you think it would be fun to start doing trail rides and are not set FOR SURE on staying at 33's then I would definatelly get a different rear axle.
 
#13 ·
Guys, really thanks for all the comments. This site is worth its weight in gold. So regear mine or buy the used 8.8 and D30 regear those to 4.56 and install? Is there a specific vehicle I should look for on the 8.8?
 
#15 ·
95 through 2001 Explorer.

this range gives slip lock diff and disc, and is the best match.

Get a 4.10. Just bought one this week for $250.00.

My issue now is figuring out what is involved with regearing the D30!!!!!!!!!!!!!
 
#19 ·
95 through 2001 Explorer.

this range gives slip lock diff and disc, and is the best match.

Get a 4.10. Just bought one this week for $250.00.

My issue now is figuring out what is involved with regearing the D30!!!!!!!!!!!!!
Regearing is a tough task if you've never done it. I regeared my D30 & D35 (I know its dumb but it was my first install, so if it broke I could get an 8.8) and it was time consuming and not having special tools made the job a little harder. I did tons of research before hand; looked at tons of pictures and tips. That stuff helps but once you start running patterns then you'll find how frustrating it can be. The wrenching is not hard, its the tolerances and tools that were my hurdles. The only tool I bought was a in-lb torque wrench for the pinion preload.

To the OP, I went to 4.10's and I noticed a huge difference. I'm still running 31's but planned for 33's with the gears. I'm just waiting for tax time to get some decent wheels and tires. You can do all the engine mods possible but gearing is where you'll notice the most gains.
 
#16 ·
Get an 8.8 with 4.10 gears. That will cost the same for someone to regear your d35. Remove you front driveshaft. Drive around for a couple of weeks to see if you like the 4.10 gears. If you want more, then you can consider the 4.56's. If you like the 4.10s, then re-gear your d30 and put your front driveshaft back in.
 
#20 ·
If you guys like the 4.10 gears I would hunt for a 4.11 front axle. This would be cheaper than regearing one.The two will work together real good.
 
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