4:10 to 4:30 gear ratio diff swap

Can anyone out there tell me if I can change out the chunk on the rear diff and have no issues? the current tire set up are 31x10.5x15 mud tires and I'm trying not to change any other item such as computer setting, odometer gearing. I am in need of a new E locker as mine seems to have been compromised. 2wd 6 cyl xc prerunner
Feedback is appreciated. Thanks

 

4.30 locker is hard to find, only certain PreRunners had it and 4Runners. 4x4 Tacomas only came in 4.10

 

I'm being told that this 4:30 came out of a 99 Taco prerunner 4x2 what I need to know If I can swap without issues.

 

Dear Gene,

So if I understand you correctly, you want to change out the gears in your rear differential. You want to go to a drive ratio of a 4.30 gearing from a 4.10 on 31 x 10.50 inch mud tires. You want to know if the there will be any changes in the way your Tacoma drives after making this swap. Are you unhappy with the way your Tacoma drives with 4.10 gearing, or are you doing this because your rear differential has seized?

The 4.30 gearing will increase your low end power incrementally, and you will rev a little bit higher in top gear on the freeway compared to your 4.10 gearing. This is taking into consideration that you are still going to use your existing tires.

Good Luck,
Paul

 

You can use any rear locking differential pumpkin regardless of gear ratio. It will bolt right up. You're 2WD so you wouldn't need to match the front.

The only difference is you cannot use a non-locking differential pumpkin on a TRD axle and vise versa.

 

you are correct, the diff I presently have 4:10 has been compromised by the pinion gear bearing being improperly preloaded and possibly causing metal shavings to be distributed thru out the rear end. This being an issue I was going to get a replacement but the only one I can find is a 4:30. Since the bearing has been replaced once I can't find anybody willing to go in behind somebody else as they are afraid to be hung out to dry. If they offer a warranty.

 

4.30 will work fine if it's a locking one

 

It is, thanks.

 

Changing the gear ratio in the rear differential will change your final drive ratio. This will effect speedometer reading, shift points, RPM at a given speed, low end torque, etc.

Going from 4.10 to 4.30 will make the speedometer read higher. You will also run higher RPM at given speed and gear. So will it work?... Yes. Will it work exactly the same?... No.

You can counter these changes buy increasing your tire size slightly but that can have other undesired effects.

 

Ahhh!, there it is. That's exactly what I was wondering. I am not interesting in investing more and more money into a conventional mode of transportation. It seems counter intuitive to me. So this means I need to continue to search. Thanks. I appreciate that which is what I had a slight fear of.

 

You won’t even be able to perceive the difference from 4.10 to 4.30 if somebody didn’t tell you they were different. If the 4.30 is a good deal, go for it. There are a lot more 4.30 lockers out there because it was a relatively common option on limited and SR5 4Runners combined with 4Runners not getting bought back and crushed like Tacomas

 

You're right that the difference would be subtle. The different between the two (4.10 & 4.30) will be about 4.6%... if I did the math right... That means when your speedometer reads 65 (assuming it was accurate to begin with) you will be actually going about 62. This is not a huge deal, might even save you from a speeding ticket some day, LOL. Most cars have about a 1% variance from the factory and little things like air pressure in the tires and tire wear can make small changes. Up to you if 4.6% it too much.

 

Well, I finally removed the 3rd member from the axle, all is in tact. Now since I will need a new set of bearings I'm finding that there are 2 different differentials made in the 4:11 ratio. They make a 27 spline and a 29 spline. So since I see that there are no identifying marks on this thing how do I decifer the difference so I can order the correct rebuild kit? I counted the pinion spline and there are only 10. the ring gear has 41. So where does these 27-29 numbers come into play in identification? I'm totally stumped at this point.

 

It’s the pinion spline for the flange. Why rebuild instead of finding a good used diff?

 

because there are none to be found here in N.C., the closest is Cali and I am fearful of ordering it having it shipped and it be the wrong one. The rebuild will cost just as much as a 2nd hand one. And it seems that the only problem so far is the preload on the pinion bearing was incorrect and ate the bearing up.

 

Should have just bought a used 4.30. After I swapped my 4.30 diffs in and removed the 4.10 diffs my speedo was just as accurate as it was before just error in the opposite direction. Did you ever verify your speedometer against a GPS?

 

Sorry for the delayed response, no I haven't checked against a gps.

 

UPDATE:
After looking unsuccessfully for a 3rd member I decided to order a rebuild kit ( All the Bearings and shims,crush sleeves,) I brought it to a very well known machinist here in Greensboro who works on some of the NASCAR drives personnel race cars. I had him look the diff over and he found that the large bearing on the fork side was worn, the race was actually spinning on the collar, it wore it down 4thousands. So, I had to replace the carrier unit with the spider gears in it. And of course that was no ware to be found but at the dealer. That set me back $875.00. The sunnier side of all of this is he only charged me $125.00 to swap and change all the bearings and set the pre load on the pinion. I feel a whole lot better knowing that the machinist doing the work had a history of 45 yrs of working on all this type of stuff. So now I should be back on the road after tomorrow.
*********Now all I need to know is does this unit take synthetic 75-90 oil or regular 90 weight oil?************
I bought Valvoline syn-power oil full synthetic. (limited slip) oil.
Please advise so I can finish this monster.... I asked the dealer parts dept. and they were useless
Thanks

 

I've used (and generally see recommended) Lucas 80W-90 non-synthetic gear oil in the diff.

 

cool, thanks. I did find that same info in the manual I found online.