Kilmer

Hello:

I have a 1997 SR5 with 110K on the clock. Had the car since new, never had any issues with it, has been my reliable beast unlike my other car . I blew out the axle housing. Call the dealer and it's ~$1500 new. I unfortunately do not have those kind of funds now to spend on this part. So, i called the local salvage yards, and found out that there are 2 different final drives (FD) for this

4.10
4.30
4.56 (basically 16's on the 4.30 FD)

Now, my FD is listed as 3.73 aka 3.727

I can't find this part anywhere. I've searched car-part and etc. and there isn't even a listing for it. Essentially I have 4 questions:

1. What is auto disconnect? I presume a button type of disconnect vs. auto disconnect for 4WD. I have a lever inside the car that allows me to change from 2WD to 4WD and never leave the car to disengage anything, and I presume this is indicative of having auto disconnect?

2. Where can I find this axle housing with this specific final drive? Links please if you guys have them.

3. Lastly, I am asking a more rhetorical question I think. But, if I install a different FD in the front then the rear, it would just mess up the rear end correct?

4. Lastly, should I replace the drive shaft?

The car currently drives and I don't think the transfer case got messed up at all. I am not sure about a lot of these details as I come from the world of VW's and FWD :wink: , yes please don't hate on the VW's

Thanks for your input guys/gals.

dragr1

iTrader: (3)

Auto or 5spd? Limited or SR5? Locker? Factory 16" wheels or 15's?

It could be a 3.90, 4.10, or 4.30, but not 4.56 unless it was a 2.7 motor.

Is it the front or rear? Please describe what you mean by "blew out"?

Auto disconnect is ADD, basically the 4wd hub disconnect system, it has nothing to do with the 4wd lever. All '96 through '02 4wd 4Runners had ADD.

Kilmer

..............

marko3xl3

From what I am observing, you have the I4 2.7L engine with the small 15" wheels and the 3.73 gearing. Contrary from what dragr1 said, 3rd gens never came with 4.56's from the factory, only 3.73 for the I4 2.7L, and 4.10/4.30 for the non-locked/locked 3.4L V6.

To explain somethings...an e-locker is a device that came from the factory in the rear differential which locked both rear wheels together to spin at the same speed and provide more traction off road. With an open differential, many times one of your wheels is totally useless off road.

Auto Disconnect, the proper name being ADD (Auto Disconnecting Differential) is a vacuum operated system that dis-engages the front differntial from the wheels when not in 4WD to save the drive parts. How exactly it does that, I am not sure. I believe it disconnects one wheel, so the differential still spins but the drive shaft doesn't? But I am not sure...I am gonna get to the bottom of it one day

Where to find the differential you need...Well, if you don't wanna pay full price, just search some dismantlers, junk jards. In my area there is one who specializes in Toyota's, maybe there is one in yours.

I also wanna know what exactly happened, how did it "blow up". Depending on the situation, you might have to replace the driveshaft. Basically, only replace it if it's damaged.

Will you mess up your drivetrain if you install a different FD (aka. gearing). YES, DO NOT DO IT. If you wanna get back on the road, just remove your driveshaft for the moment and let it sit. If you use a different gearing up front than up back and engage 4WD, you will cause MAJOR BINDING in the drivetrain and you will break a lot of expensive parts. Don't do it.

And no, we don't hate on VW's. They have a completely different purpose. All cars have their strengths and weaknesses.

Welcome to Yotatech! And don't forget to tell us what exactly happened. Hope I could help,
Marko

024Runner

Welcome to the club.

dragr1

iTrader: (3)

Steve had 4.56 gears factory on his 3rd gen

Kilmer

4.56 aren't really a type of gear, it's 4.30 gears with 16 inch tires from my understanding after speaking with several dealers.

I have a 3.4 V6 SR5

So, this is my moms ride. I actually helped buy it for her. She has been using it since 1997 when we got her. She was driving down the road and her car started to smoke so she pulled over. Then she ended up with her mechanic and he said her axle housing needs replaced and the driveshaft he would recommend replacing as well I will see the car today as I haven't seen my mom all week (lives about an hour away). I would like to help purchase the correct part and send it to her mechanic. Hopefully, this will save her 1500 bux.

I presume she either drove too fast in 4WD or she tried to disengage it while driving (which I presume is also bad). I don't really know how it all happened those are the details she told me. I found one yard who has the 3.727 aka 3.73's in stock, but I am hesitant to pull the trigger as I am not 100% if that is the correct FD on the vehicle.

Any advice is appreciated.

Thanks

rimpainter.com

It's pretty simple really. Since she blew out the front, just jack up the rear, mark the drive shaft at the flange and housing with whiteout or similar, and have someone spin a wheel exactly two full revolutions while you watch the mark spin around. Count the # of times it goes around. Do it a couple times if you aren't sure. I was able to tell the difference between a 4.10 and 4.30 ratio. Once you establish that, cross-reference it by the code, then go hunting for front differential assemblies in junk yards; housing and all.

Before it is installed, why this happened needs to be established. No sense putting a "new" used diff in place if it's just going to blow again.

FWIW I have done two swaps (front and rear diff housings). The front is by far the worst. If you are mechanically inclined, you could probably do the front swap in 8 hours.

Kilmer

Ok, I'll try and do that tomorrow morning, I have a buddy that runs a shop and I can get on his lift if I get there early. Although i would like to order this part that I found today as it's like the only 3.73's I was able to find from searching car-part.

How can I figure out why this happened? Why do the axle housings fail usually? The car has 110K but that shouldn't be the reason I don't think.

I am mechanically inclined, and have a garage of my own that I could do this swap at, but I also have a friend who does this for a living, and I don't really have the time right now to do this, as I am embarking on my own project completion: (Just got the motor back into my beast not too long ago)




Lastly, I know it's a bit off topic, but see in your sig you are using a perfect power SMT6. What are you utilizing it for specifically? I was looking to use that for my car as a piggy back, but my ECU won't allow me .

rimpainter.com

To retard/advance timing and add fuel where needed. The 5VZFE has a nasty ping problem between 2K and 3K RPM when charged. The SMT allowed me to gain control and eliminate it. If you want more info, search "SMT Perfect Power" and you will find a huge thread on it. Good reading too.

Kilmer

Isn't there some chip that is made for the stock ECU or would you rather control your own timing/fueling I presume? I played around with an SMT unit, but my OEM VW ECU will not let any piggy backs control anything

Kilmer

.....

rimpainter.com

"Chips" do exist, yes. But for the money people have found the gains to be minimal (see www.gadgetonline.com). Besides, with the SMT you have complete control for probably the same cost: You can even flip a switch to another map (literally) for changing conditions such as weather or elevation. A chip will not do that.

As for why this happened to the front diff...well, that's pretty much impossible to say over the net. We could take some guesses and have you check some things, but it sounds like you have a buddy that could do that for you (using a hands on approach vs. virtual). I would highly recommend that root cause be determined before you proceed any further. This is definitely rare on these vehicles...

Kilmer

Makes perfect sense. I guess my ECU is the devil and I either have to go to a standalone of some sort or 'chip' tune as it has adaptation values which i cannot manipulate with a piggy back...



Yeah, that's what I'll be doing tomorrow I guess




So, the rear and front final drives should be the same is what you are saying? I presume that is why I should jack up the rear and rotate it to get the actual final drive?

rimpainter.com

Yep, they should be the same.

Kilmer

thanks for all your help/replies

dragr1

iTrader: (3)

The diff is definitely not 3.73. It is either 3.90, 4.10, or 4.30, but definitely not 3.73. Most likely it is 3.90 or 4.10 as I am pretty positive that 4.30 was only available with the locker.

Kilmer

Well, you won't believe what happened. My Mom decided to take it to a shop which did the work. I found, which appeared to be the correct gearing 3.90 IIRC, and it drove fine for a year and a few months, until it broke AGAIN

This time I am going to do this myself so that there are no issues.

The tranny code on the side of the B-pillar or door says they are 3.90's and the vin says 4.10's. So, I am sort of stuck in a similar predicament.

What I did was remove the front driveshaft to see if I can get it to drive in 2wd mode but the front end still seems to be locked in. This probably means that the vacuum engagement is locked and probably what broke it the second time, so I will have to get a new vacuum pump.

So, my questions are the following:

How do I figure out the correct FD? I am going to pull the front carrier and see how mangled it is. I can count the teeth on the R&P. If I bought the wrong one then it would have broken much faster right?

How do I get it to lock out of 4wd? Is there a manual way to do it or do I have to replace the pump? I will buy the vacuum pump cause I'll probably need it anyway and is probably the main culprit of all this.

I was hoping to pop the rear cover to see what R&P is in it, but it's similar to a Ford 9inch rear with no cover, so I'd have to pull the whole thing apart which seems like a lot of work for no reason.

So, I don't want to buy just another carrier and slap it in and go to see it happen again in a year. Any advice?

Kilmer

Pulled the rear axle housing. It was actually much easier then I thought. It is pretty time consuming. Counted the teeth and its 43 vs 11 so that's a 3.909090909 final drive. Now to order the correct part for the front.

All that work to find out that I had the correct FD the whole time. So, now I wonder if the other shop didn't replace the engagement mechanism and it was always in 4wd since install and that's why it blew out...hmm

Thank god this isn't a daily driver for me

toy_tek

Need to find a new shop. Sounds like the fixed the result but not the problem. Ask your mom if the green "4wd" light was on the entire time... the one that shows 4 wheels/axles.

Also, just so you know, what you're referring to as FD is more commonly referred to as "gear ratio". IIRC "final drive" actually takes into consideration transmission and xfer case ratios as well.