Hello all,
I am an infrequent Yota tech user but it has been an invaluable tool for helping me fix up a 1993 Ext Cab 3.0 4x4 that I bought almost a year ago. I would appreciate any advice with my newest problem with my four-wheel drive.
I bought the truck with a bad engine, so I had to take the previous owners word that the 4x4 works. When it recently snowed here in the KC area I found out it didn't work so good. I have the auto-locking hubs and when I put it in 4-wheel drive a few weeks ago I found that it does engage and turn the front wheels but that it "hops and jerks" badly when going down the road. I incorrectly assumed bad CV joints, so I replaced both CV half shafts but it does the same thing.
It then hit me that the previous owner mentioned that the rear end locked up and that he put a used rear end in it. Now my uneducated guess is that he got a used rear end with gears that don't match.
What do you guys think? And if this is the problem, how do I confirm my gears in the front and back and what is the easiest/cheapest way to go about fixing. I have never messed with an axle replacement or changing gears, but need to get this fixed as I need 4-wheel drive. Thanks in advance for all the help.
Steve

 

find out gearing you have in the rear, check it against factory specs. if it's off, then look for a used factory unit.

Easiest and cheapest seldom go together. Especially if you want it done right.

 

EDIT: Just noticed you have auto hubs, so I'm not sure exactly how those operate, but basically engage them and make sure the d-shaft rotates when doing the test below.

Jack the rear up, put a chalk mark on the driveshaft where you can see it from the side of the truck, turn the wheel 1 revolution and count how many times the d-shaft turns. If you have factory 4.88s (autos only I think), then the shaft should turn almost 5 times, if you have 4.10s then it should turn just over 4 times. Do the same to the front, with hubs locked and see. They should be the same.

You said it was snowing, so I assume the road was pretty slick. Sometimes when driving on dry pavement 4wd will jerk, especially 4lo.

If you have the wrong gears, there are many options. The easiest would be to buy a complete 3rd member and swap it out. However, if you like the gears in the rear, maybe you should swap the front to match the rear.

 

ErikB Toyota differential page

You have ADD not auto hubs

 

Don't know much about your truck but chances are the front is 410.

You need to determine the rear ratio....rig in neutral....jack up 1 rear tire....mark the driveshaft and turn the wheel exactly 2 full turns while noting the number of DS rotations.....
2 tire rotations and 4.1 DS revolutions = 4.10 gears
2 tire rotations and 4.3 DS revolutions = 4.30 gears
2 tire rotations and 4.6 DS revolutions = 4.56 gears
2 tire rotations and 4.9 DS revolutions = 4.88 gears

the above works with a standard open differential....all bets are off if you have a locker

 

Guys,
Thanks for the replies. The posts on how to check ratio were exactly what I was looking for, thanks cory and zuk. That should help me figure out if this is my problem.

Waskillywabbit, I am not sure what ADD is. I have had many 4x4 vehicles in the past and I guess I just refer to anything that I don't have to get out and lock hubs as "auto hubs." Sorry for the confusion.

Cory, yeah it is definitely a problem and not typical 4x4 bite like on dry roads. It is even real bad when driving straight on snow pack.

As for the complete 3rd member, I know that is what the previous owner said he had done before. Excuse my ignorance, but what exactly is a 3rd member. Is that the complete rear end and axles all the way out? Thanks again guys for all the help.
Steve

 

the third member is the Center piece that is bolted into the middle of your axle..lol

yea depending on the gears you got in the back..ya might wanna gear the front to match LOL

if ya got 4.10's in the front and 4.56's (or 4.88's..or 4.30's??) then gear the front to match it! that way you can run a set of 31's (or 33's) without much power loss lol

 

Just an FYI:My 4runner 3.0 auto has factory 4.88's. I'd match it to factory if you go to change it. Most folks don't gear up but down.

As for the ADD that is correct; Automatic Disconnecting Differential. The hubs are always locked and the CV's always spinning its just that the front diff is not engaged.

 

If you have a little mechanical skill you can pull the axle's out front & rear then remove the diffs and count the teeth on the larger ring gear and then do the same on the pinion gear, front & rear and you will find out for sure if thats the problem which it sounds like it is.......after you write down the # of teeth on the ring & pinion gears you could call any rear end shop and give them the count and they will tell you what gears you have...then you can try to find another diff with the right gears on craigslist........That would be the cheapest way to go.............If I were you, depending the size of your tires I would try to find the correct gear ratio and put that diff in the rear-end and drive the truck without 4WD until you can afford to put matching gears in the front diff.......this wont hurt anything unless you engage 4WD............If you have anymore questions feel free to send me a message.........Good Luck!

 

Hey guys,
Thanks again for all the help. According to the plate on my drivers door jamb, my truck came with a "G254" rear end in it. I found on the internet that this would indicate an 8" gear with a 4.556 ration and 4 pinion, open diff. I am assuming the front has never been changed, so this is probably what I need to be looking for. I will get the truck in the garage and double check axles ratios though first as you guys suggested. In your opinion is the 4.556 ration a good ratio for this truck. I am currently running 31" ATs on it and don't do any off-roading. I would like to but some ball joint spacers in front, and maybe shackles in the back to run 33" tires possibly but this would be down the road. Thanks again for all the help.
Steve

 

4.56 manual trans and 33x10.5 = good match.

 

Find out what you have in the back before you make a decision . The PO may just have put 4:88 in the back if so they are better than 4:56. although You may be right about the 4:56 make sure that is what is in the front .

 

i just saw an ad somewhere with someone trying to get rid of a set of 4.56 thirds. I thought about buying them myself as spares cause they were so cheap. I'll see if i can find it again and post a link for ya to see if you are interested.

Again, not my ad, just trying to help.

 

Here it is:
https://www.yotatech.com/forums/f11/...ern-ca-198736/