Wrong Gear Ratio!!

Hi there! I will keep this short and sweet. I have just completed my pre-runner 2wd to 4x4 swap using a prerunner 4x4 conversion guide on here. I used an Fj transfer case and have deleted the ADD system. I have ran into a HUGE problem. I just tested you my truck for the first time and something is not right. The truck lunged in 4x4 and cant and the front tires seem to me skipping...I didn't dare push it. I just did a rough check of my front gear ratio its 3.73....and my rear is 4.10. I bought it used from LKQ and they said it was 4.10 but its not... and I foolishly assumed it was..

I was doing to install an Eaton truetrack in the rear end would this alleviate my problem with the wrong gear ratios?? As you have probably guessed I am new at this but I love my Taco and need to see this through

Any help is much appreciated! I am very bummed out..

Thanks

 

Welcome to TW

 

You definitely need to have matching ratios front and rear. I'd start looking around for a new 3rd member for the front or rear to swap in to match which ever ratio you want.

 

I would recommend going to 4:10 in the front axle. Then u have a little leeway if u go with bigger tires in the future. Good luck

 

Checkout the assembled 3rd members from East Coast Gear Supply.

 

Please edit your title to illustrate that you need Technical assistance.

We reserve "Help" and similar for folks who are broken down on the side of the road or stuck out in the boonies.

Thank you! And good luck!

 

Thanks for every ones quick response!

I am going to pull the trigger on a Eaton true track for my rear end. Ill keep my eye out for a proper 4.10 front diff and ill definitely check to make sure it is 4.10... I cant believe I made that mistake but live and learn..

Sorry! Title has been changed

 

Pull the front driveshaft and see if it still does it. There's a lot of diagnosis that's not happening and a lot of guessing that is happening.

 

I did just that the truck drives fine in 2wd but does not like 4x4

 

^^^this, unless there was more diagnostic done that is in the first post, you have way jumped to conclusions. How did you “roughly check the get ratio”

 

Use a jack to get the driver side front tire off the ground. Put a mark at TDC on the front diff flange and the tire. Have someone turn the tire 2 rotations. Count the number of rev's the flange makes. That will get you close to the diff ratio.

 

I marked the tire and drew a line on the front drive shaft and slowly rotated the tire 10 times. Came to 18.6 turns of the drive shaft x2 was 37.2 so I'm guessing that's 3.73 gears but I could be wrong

 

LOL That’s funny. I ain’t never seen anyone turn the tire 10 times. 2 is enough. Since you are sure you have 4.10 rear gears, you must have a 4 cylinder, right?

 

Sounds like you got a front clamshell out of a v6 truck. You need one out of a 4 banger to match the stock 4.10 ratio of your rear axle. FYI all 6 lug 4 bangers whether it be a 2wd or 4x4 truck came with 4.10. I WOULD NOT go n change the rear to a 3.73.

 

I just had a thought. You mentioned that you deleted the ADD. Did you get a front diff out of an AWD FJ. Did they even make a FJ with 4.10 gears? I doubt it. So, it seems like you you need a 4 cylinder Taco diff and then transfer the FJ right axle and diff tube onto the Taco diff. Or did you just lock the ADD engaged?

 

This ^^^^ is wrong.

Let’s start from the beginning.
-You had a V6 prerunner and kept the original rear axle in it?
-You installed a used 4wd trans?
-You installed a used tcase from an FJ cruiser?
-You installed a Tacoma front clamshell you ordered as a 4.10 but did not ever 100% confirm it as 4.10?
-You deleted the Tacoma ADD tube front the above clamshell for a solid FJ tube?

Let us know if any of those things are wrong and it will help us help you diag it

 

x2

No FJ shipped with 4.10's.

OP, if you want to match the front to the back you need the front diff from a 4 cyl 2nd gen Tacoma if you want 4.10 gears.


If your going to order new 3rd members from ECGS, and you plan on bigger tires with a 4cyl, i would plan ahead and go with 4.30's. Also be aware going with TrueTrac is a commitment TrueTrac is great at what it is designed for, but if you drive mostly on the street I would think twice about going with TrueTrac. It takes getting used to and plan on rotating your tires alot! I have both, one with TrueTrac and one with a real TRD Mechanical LSD. For normal use and occasional off-road the TRD wins hands down. For off-road use, TrueTrac wins hands down.

 

I road course race with my TruTrac. It works exceptionally well on the streets.

Less wear than clutch style. Aside from biasing, that is the main difference.

 

... not just bias, TruTrac locks when you apply power and one wheel starts to spin at a different speed. The problem comes in when you need to pull out it traffic while making a turn..... it does its job and locks tight, which drags the rear tire facing the side in which your turning. lol, i drive 100% or 0%, on the throttle, and trust me it rips up off road tires dragging them when turning. the other issue is driving on wet or ice roads. its takes getting used to with TruTrac.

Your absolutely right that clutches can wear out on the TRD LSD diff's, i have just never had it happen before. Ive bent axles with TRD LSD, never had clutches fail.

All that being said.... on my daily driver i run TruTrac.