Differential woes

[challenger]

Hello, I bought my 4runner back in fall and have now gone through two front differentials since its purchase. A new one is en route to be installed yet again.

My mechanic now tells my that my front tires (Even though they are in the same like new condition and the same brand and type as the rear ones) are 3/4 of an inch different from the rear tires, and it may be the cause of these issues. Could it really be something this simple?

 

[Singtoe]

Is your truck in 4 wheel drive all the time? In reality, the front diff hardly gets used, and only when in 4wd.

Tire size will play apart but only if it is in 4wd. Check you transfer case to see it it is functioning correctly.

 

[J-money$$$]

Hello, I bought my 4runner back in fall and have now gone through two front differentials since its purchase. A new one is en route to be installed yet again.

My mechanic now tells my that my front tires (Even though they are in the same like new condition and the same brand and type as the rear ones) are 3/4 of an inch different from the rear tires, and it may be the cause of these issues. Could it really be something this simple?

i think the mechanic sounds shady, What exactly broke in the differential. The entire thing did not break lol. Knowing the details will help you narrow it down. I doubt the tire size has anything to do with it. You have open diffs so its not really an issue.

 

[challenger]

i think the mechanic sounds shady, What exactly broke in the differential. The entire thing did not break lol. Knowing the details will help you narrow it down. I doubt the tire size has anything to do with it. You have open diffs so its not really an issue.

I am a little bit ignorant of how a differential works exactly, so forgive me.

Both times it has been something about the same shaft on the inside shearing its teeth and it makes this god awful clunking sound when 4hi or 4lo are engaged. I have only paid for it to be fixed once and they are not charging me again hopefully. I don't know, they had it fixed for a week then the same issue happened again, so maybe something else is running a muck inside the 4wd system.

What really pissed me off, was that when I talked to him the guy basically accused me of lying and asked me if I had taken it off road. I haven't, there is still 3 feet of snow everywhere up here, but I would sure as hell hope I can take a 4Runner offroad without this nonsense coming up.

 

[Big John]

I am a little bit ignorant of how a differential works exactly, so forgive me.
.

This is a great video to help understand how an open diff works. You'll think it's a joke in the beginning, but watch it and you will seriously learn a lot.

http://www.google.com/url?sa=t&sour...25iMBg&usg=AFQjCNGTL7lDv67MJU2Wj5zSw9CLv3b4cg

 

[challenger]

This is a great video to help understand how an open diff works. You'll think it's a joke in the beginning, but watch it and you will seriously learn a lot.

http://www.google.com/url?sa=t&sour...25iMBg&usg=AFQjCNGTL7lDv67MJU2Wj5zSw9CLv3b4cg

Thanks for throwing that up here, even though the video had some goofy nature to it, that helped out in understanding it. Now I just need to figure out how the teeth are getting destroyed :redbrick:

 

[JohnsD90]

This is a great video to help understand how an open diff works. You'll think it's a joke in the beginning, but watch it and you will seriously learn a lot.

http://www.google.com/url?sa=t&sour...25iMBg&usg=AFQjCNGTL7lDv67MJU2Wj5zSw9CLv3b4cg

I knew what it did, not how it did it, thats pretty simple!

 

[brian2sun]

What really pissed me off, was that when I talked to him the guy basically accused me of lying and asked me if I had taken it off road. I haven't, there is still 3 feet of snow everywhere up here, but I would sure as hell hope I can take a 4Runner offroad without this nonsense coming up.

It sounds like it wasn't set up properly the last time and so it grenaded. Like Jason said, find out what exactly broke and you'll get even better advice.

BTW, why would the mechanic care if you took it off road? That's what front diffs were made for. There are plenty of gear installers that warranty their parts and labor for 5 years regardless of how much you go off road (like eastcoastgearsupply.com). Hell, I even got a 3 year P&L warranty from 4WheelParts on my diffs. Your mechanic's work lasted a week and he thinks it's your fault? riiiiiiigggghhht. I would definitely not pay him to fix it again.

It sounds like it may be the jackshaft that broke (scuba on YT just snapped his), but that is rare. I've never heard of anyone breaking 2 of them, much less in 1 week.

 

[J-money$$$]

Yeah thats some serious BS. i think he had set the backlash or something off. It sounds like its maybe binding up and grnading the diff. maybe he forgot oil..... GO SOMEWHERE ELSE> trusty mechanics are hard to come by. If someone accused me of lying like that it would be time for a beat down....

 

[brian2sun]

If someone accused me of lying like that it would be time for a beat down....

Yeah, that's no way to treat your customers. :boxer:

 

[challenger]

Yeah, I definitely will not be returning there and paying more. Its at the shop now and as far as I know, a different differential is being shipped and they will only be charging me for the seals and lube (Wheres the oka sil dumb diddly dookio I'm an idiot face?)

It is a used differential I had them put in, so that is probably why there is not a long warranty. Thinking back on it, it seems like a reputable shop would be able to rebuild the thing or I should have just put up the extra cash for a new differential. But oh well, I guess the worst that can happen is I get it back and the same thing happens and I find a better shop.

I really do not see how a fragment of a difference of a measurement in tires could destroy solid metal in a differential, after reflecting on it for most of the day. I may be wrong, though

I might call up tomorrow and figure out exactly what it was that was broken in it.

 

[BrianSD_42]

Both times it has been something about the same shaft on the inside shearing its teeth and it makes this god awful clunking sound when 4hi or 4lo are engaged.

I hope that sound isn't from you shifting from 4-HI to 4-LO when the vehicle is moving!

Assuming it was due to vaugeness of your post:
Despite what the manual says you should not try and shift with the vehicle moving, you should stop the vehicle put it in neutral then shift.

I have only moderate knowledge of gearbox/transfer cases but the first time I tried to go hi -> low I could feel the resistance and grind so I abandoned the idea until I could talk with someone.

I was told that while Toyota designed the vehicle so that you CAN shift while driving & it is true that the manual says you can, after the vehicle gets some years on it doing so is a terrible idea. You will likely feel resistance, hear grinding ect and eventually break something. He even told me about a guy who broke his vehicle doing just that, only the guy didn't know that was what did it, so he broke it a 2nd time as well a few weeks later.


Also, your mechanic sounds like an @hole. Get a new one, preferably one who specializes in Toyotas, hopefully Tacomas & 4Runners.


Wikipedia search for "differential". BTW if you are ever in San Francisco there is a great display of a differential at the Discovery Museum; it really is quite cool to look at and educational.


:zoom:

 

[challenger]

I just talked to them and it was the ring and pinion that ended up being destroyed both times. Any ideas?

 

[brian2sun]

Nothing should destroy a ring and pinion in that short of time besides a really bad setup (not setting the backlash properly). The fact that your mechanic was trying to say you lied and took it off road is completely irrelevant - even if you did. It's his way of trying to get out of fixing it for you. You should be able to off road everyday for 5 years without problems on a well-setup diff. 100% install error.

 

[challenger]

Nothing should destroy a ring and pinion in that short of time besides a really bad setup (not setting the backlash properly). The fact that your mechanic was trying to say you lied and took it off road is completely irrelevant - even if you did. It's his way of trying to get out of fixing it for you. You should be able to off road everyday for 5 years without problems on a well-setup diff. 100% install error.

That makes sense, if they want me to pay anything more at this point they are going to get one hell of a fight. Hopefully, they set it right this time.

So just the be sure, if a entire used differential is installed, the backlash would need to be adjusted properly?

 

[brian2sun]

That makes sense, if they want me to pay anything more at this point they are going to get one hell of a fight. Hopefully, they set it right this time.

So just the be sure, if a entire used differential is installed, the backlash would need to be adjusted properly?

If an entire used diff is installed, then the gears would not need to be set up, the diff just bolts in. If they just swapped diffs with a used one, you must have got a diff that was already "blown".

 

[challenger]

If an entire used diff is installed, then the gears would not need to be set up, the diff just bolts in. If they just swapped diffs with a used one, you must have got a diff that was already "blown".

I've concluded that I have been been had, if they don't fix it this time then it will really make me angry

 

[techno]

To help you understand the process of installing a diff, here's a link to the factory service manual for reassembling and installing the front diff.
http://www.ncttora.com/fsm/1996/SIL...toypdf/02rmsour/2002/024runne/sa/fdc/reas.pdf

Or, if you send me a pm with your email address I can email you a copy of the ARB airlocker instructions for a differential that has some very good pictures and details of the basic tasks and also explains the importance of correct backlash settings.(although there is a lot of airlocker specific stuff too.)

I agree with brain2sun, this sounds like an incorrect backlash scenario. This pic will help you understand exactly what that is, if you don't know. When the diff is rotated back and forth a little bit while the pinion is held fixed, the dial indicator will produce a measurement of how far the ring gear teeth can move before they contact the teeth on the pinion. If the value is too high, then the teeth will smash into each other too much and probably not at their strongest points, or if the value is too small then they can become tight after thermal expansion and be subject to high stress. Either way, stripping the teeth is the usual result.