2nd Gen four wheel drive hard shake and violent steer (1 Viewer)

[SimplyTanner]

Hey, I'm new to the site and forum. It's obvious there are some smart people here! Hopefully someone can help me, I Just picked up my first 2nd Gen four runner. Truck drives and steers great in 2H. But in 4H or 4L it's hardly drive able. It shakes and shimmies hard and will pull the steering hard enough to try and veer you into the oncoming lane or the ditch! Here's the interesting part: when on snow or even loose gravel it is hardly noticeable, but hit the pavement and all hell comes back. Almost as if it is related to the spider gears, acting more like it wants to 'lock'. Transfer case seems just fine. Shifts well. Stays in gear. I have repacked and tightened the front wheel bearings, replaced the worn out idler arm. The tie rod ends seem decent but could use replacement. I've read about the needle bearings going bad on the axle outputs?? Possibly just a bad ring and pinion mesh? SOMEONE HELP! I really like this truck and want it to be reliable! Thanks in advance.

 

[KLF]

You really shouldn't be using 4WD on pavement.

Are you absolutely sure the gearing is the same in F&R?

 

[SimplyTanner]

While I agree about the pavement driving. I only mean 4H on an icy or snowy road and come to a dry patch and grab some traction. But thank you for what could be a very obvious answer to my problem. I'm kicking myself for not ever checking the gear ratio! Thanks again, I'll report back after checking tonight.

 

[Kris]

I'm with KLF, sounds like a mis-matched ratio set.

 

[SimplyTanner]

Well, I'm kicking myself for not thinking of something so damn simple! You are both correct. Using the turn and count method, it looks like the rear is 4.10, and the front is somewhere around 3.8 or so. What would that high of a ratio come from? I know there was option but it seems like 4.10 would be stock?? Thanks guys, really enjoy finally finding a problem to fix!

 

[MItchell17]

there was a 3.73 available but its rare. Nice thing is 4.10s are easy to come by.

 

[pappy]

Nice bit of sleuthing and diagnostics by the Mudders here.

 

[Kris]

I'm going to assume that you still have IFS on your truck? I'm also going to assume it is a pre-95 truck?
So maybe someone destroyed the R&P and replaced it with what was available. That probably being the R&P from a 2wd truck - since 3.73 was an option in those according to :
http://www.off-road.com/trucks-4x4/tech/toyota-differential-identification-18588.html

 

[SimplyTanner]

Yes still IFS, not for too long. I'm already building it's solid axle on the bench. I'd say all signs point to what Kris is saying about a 2wd diff. Lame, but easy to fix. Thanks for all the sleuthing, and advice.

 

[jgranthevagrant]

Scary that someone would do that. Maybe we should put this in the horror wiki.

 

[Kris]

Yes it's scary, but really it's a dick move.

 

[SimplyTanner]

Absolutely a dick move. But I'm the a****** for only testing the 4wd in a gravel driveway! I'm going pull my rear gears for a tightening and take a real count of the ratio. I was thinking it is 4.10. But I looked up my axle code which says 4.30. But that was more commonly automatics. Mine is a manual... Maybe started life as auto? The mysterys are developing

 

[Kris]

Wow. No kidding. The plot thickens...

I was going to say that a 4.30 front might be hard to find. But I really don't have any data to back that thought up.

For how many 4wd toyota's I've owned, I feel like I should have come across one - thankful I didn't though.

 

[SimplyTanner]

Well I've done quite a few turn and count ratio finds. So I'm pretty confident the rear is 4.10. Sloppy gears makes it a little less accurate. So it'll be nice to count actual teeth.

 

[SimplyTanner]

I need to retract that last statement, apparently I had too many friends around and I was a little too intoxicated to be confident in my ratio finds the other night. I just rechecked in a much clearer state of mind. Who knows how I could have been so far off. The front is a 4.30. The rear is a 4.556. So the story is more likely that the front is the original stock gears and the rears were swapped out incorrectly at some point which sounds much more likely. I apologize for the misleading information, and I realize how stupid this makes me look. I'm still curious if it started life as an automatic

 

[Mudder]

All I can say is screw paint codes. Some people have found them to be wrong. Counting is the only way to be sure. But if you want to know what your rig started with Gearratiosanddiffs is pretty accurate.

 

[SimplyTanner]

Looking at my vehicle codes again, truck started life as a manual, R150f. But with 4.30 gears which most commonly came with autos. Guess it's just an oddball.

 

[Mudder]

I know my 89 22re pickup came with 4.556 with the auto. But with how old they are people have changed stuff. Glad you've probably figured out your problem. If you weren't doing an SAS I have a 4.56 7.5 sitting around. But the SAS will be nice.

 

[SimplyTanner]

I figure the easiest route for now is to find a 4.30 for the rear just to have 4wd for the winter. Then I'll pick a ratio when the SAS happens. I have a really nice tight set of 4.10s in the solid axle. We'll see, This truck will never see more then 33" tires, and more likely around 31" so 4.10 might be the number.

 

[Mudder]

@SimplyTanner