front differential

[barm]

i believe that my side bearings are going bad in my front diff,, the cv axles have excessive amounts of play,, (up, down, froward, back) inside the front diff,,, the car drives fine, but the half-shaft seals in the front diff will start to leak in just one day of driving,,, (i have replaced them many times, including axles),,, i know that subaru has a way of tightening these bearings,, but i can't seem to find any info on tightening these on my trecel,,, nor can i find any procedure on replacing these if need be,,, any info will be greatly appreciated,, thanks

[Petros]

it seems to me that if the front diff carrier bearings were worn and sloppy enough to cause that, the rest of the diff failing can not be far behind. If the side bearings can shift around, the pinion gear will also be misaligned, and the ring and pinion will grind eachother up. At best, the strain put on the diff input shaft would cause the input bearing to fail, and possibly break off gear teeth. If that is really the case you need to start looking for a new front diff assembly. What year it is?

[barm]

it's my 88,, i'm not sure how bad it really is,, how much play should there be?,, what i can tell you is that the driver side has a lot more play then the passenger side, and this is the side that quickly starts to leak again,, but keep in mind that i drive 20 miles down a hard dirt road (lost of flex) and then travel 60 more miles on a highway at 80 mph 5 days a week,, when the seal starts to leak, it is very little, but gets worse as the months go by, and by that time the passenger side will have started,,, there is no gear noise,, and the car drive very smooth,, i always keep it topped off with gear oil,, it has a new engine, suspension, clutch, bushings, front end, ect,, i like rebuilding these cars, they get great gas mileage, and are good in the snow,, i live at 9300 ft,, this is my forth one, and i never had this problem before,,, is this common? have i just had good luck before? is there not an easy way to change these bearings? or do you really think the diff is done for? this has been a continuous problem for two years,,, the diff has about 220000 miles on it,,, i have driving others way over 300000 and never had a diff problem before,,,,thanks for your reply,, again any and all info is appreciated

adam

[Petros]

The front diff is fairly reliable, a few list members have had problems on very used Tercels, that likely were run low on gear lube, but it is not a common problem based on feedback on this list.

I can not imagine there being much slop in the side bearings without blowing the ring and pinion gears. It is possible that the spline shaft is worked and worn, and the splines are allowing the output shaft to move around?

The bearings are replaceable, but I suspect you would have to have a shim kit to set up the correct gear lash on the front ring and pinion gear set. And unless you know how to set the gear lash I would not recommend it as newbie project. It would likely be easier and cheaper to get a front diff assembly from a wrecking yard and install it rather than replace the diff bearings and reset the gear lash. Though before you do that I would suggest you verify the source of the movement in the output shaft.

Good luck.

[splatterdog]

It could also be caused by side gear to diff case play too. The only way to know for sure is to pull it out and inspect it.Without tools and experience you better follow Petro's recommendations. Otherwise you will need inch and foot pound torque wrenches, dial indicator with base, minimum 10 ton press, bearing separator or dremel to cut off pressed on bearing races, maybe a puller or two, gear marking compound(usually comes with new aftermarket gear sets).

It would seem the lowly old terc has some decent gears in it. I recall somebody here noticed a dealer parts guide showing that our ring and pinions also fit in a Lexus of some sort? That would be so wierd/cool if it were true.

Could be the only way to impress some skeptics. "Hey man, this car has Lexus gears up front"

[ARCHINSTL]

Could be the only way to impress some skeptics. "Hey man, this car has Lexus gears up front"

Call me snooty, but I would prefer pulling into the country club lot and sniffing to my Lexus neighbor in the next parking slot: "Hmmm - your car has Tercel gears up front..."
Tom M.

[splatterdog]

Good one Arch.

Found it- http://www.tercel4wd.com/forums/viewtop ... ear#p26959

[barm]

ok first of all i would like to thank everyone for there replies,, but let me throw a little more info out into this problem,,, i am confident it is my drivers side diff bearing only,, i have been driving nothing but these tercels since 1992,, i have done 4ac swaps, rebuilt heads, carbs ect,, i am pretty manically savey as long as i have directions,,, having changes out numerous half shafts on these cars, i noticed that the drivers side had more play then any other that i have changed on these cars ( first time three years ago on this car) now the play is not a lot, but it is more than any other that i have worked with,,, after continuous changing of the half shaft seals,,,,, the driver side just keeps getting worse,,, now the passenger side after inspection,,, i did not install the seal correctly the last time i changed it,,, so it leeks no more,,, about a month ago i started to here bearing noise (no grinding, just high pitch when climbing hills at high speed) so i changed out all my wheel bearings thinking this was the problem,, that is when i noticed the half shaft leek considerably worse,, since then i have change the seals twice, and the axle once,,, the noise, and leek just keep getting worse,,, there is no metal or contaminants in my GL fluid, just a little of bearing molly residue,, the car still drives very smooth with no signs of gear noise or vibration even at 80+ now my problem is i can't find any service info on changing just these front bearings,, from the service manual, exploited view of the diff,, it seems like all i have to do, take out the half shafts, remove the front diff cover,, and only two bolts hold these bearings in place,,, i should not even need to drop the tranny,,, can anybody deny or confirm this,, do i really need to disassemble the entire differential? i have located the bearings online for $30-$50 each and if changing these are that simple and cheep,, i would like to try this first,,, also could you please elaborate on the gear lash adjustment,,, again thanks for all your help and replies,,

[Petros]

The hypoid gears in the ring and pinion of any differential depend on having the relationship between the two gears be exactly correct. The face of each gear tooth must make contact in the center of the gear face, with exactly the correct clearance to prevent binding when the gears heat up. To accomplish this adjustment there are very thin washer-like shims that are placed on either side of the diff center carrier and on the input shaft. this allows fine adjustment to move the ring gear side to side by removing a shim on one side and adding it to the other, and allow the pinion gear to be moved forward and aft.

On some modern cars they use soft crushable washers instead of the shims, to get the right clearance instead of adding or removing shims. These are good for one time install only, and I understand they are not very durable since over long time they tend to compress and mess up the clearance, these were invented to speed production assembly. I do not know if the Tercel diffs use these or not, I do not think so but I am not sure.

I do not know if it is possible to remove and replace the carrier bearing and not have that adjustment still be the same. That would depend on how precision the new bearings match the old ones installed in the factory. IT seems unlikely to me this adjustment would not change, but I have never had a Tercel front diff apart, nor have any feel for how good the replacement bearings would match the size of the of the original bearings.

If you have one bearing grinding itself away in the front diff, it seems to me there might already be damage to the ring and pinion, and perhaps to the other bearing as well, perhaps not but there is not a lot of wiggle room when it comes to the correct geometry of the hypoid bevel gear engagement. If you are going to attempt this I would replace both bearings on the left and right side, and very carefully inspect the condition of each of the gear teeth no both gears.

Personally I would not attempt it, and I have been inside of just about every part of this car, and many other cars too. It is not that unbolting everything is do difficult, it is getting the gear lash correct after you get it back together. There is this dye in the form of a paste you put on the gears after it is back together, and rotate the diff around. Than you inspect the dye pattern on the gears to verify you have the correct contact patch on the center of each gear tooth. If you get it back together with the right gear lash and correct gear contact than you should be good. If the pattern is not correct, you have to pull it all apart, change the shims, put it all back together, and check the lash and pattern again. And again, and again. And hopefully the wear on your very used ring and pinion allows for correct full contact and will "break in" to the new contact pattern without excessive wear. You likely can find instructions somewhere on the internet from someone hot-rod hobby website, most diffs are very similar design and you will get an idea of the process involved.

It would be I think far more reliable to just find a front diff assembly with your gear ratio and just swap out the whole assembly including the housing. From the FSM pictures it does not look too difficult to remove the front diff housing from the trans, even if does require you to drop the transmission.

Give it a try and see how it holds up. All you might do is end up replacing the front diff and housing later anyway. Getting a used front diff in the housing will not cost you any more than buying two new gears, especially if you have self service wrecking yard nearby.

Where are you located?

Good luck.

[barm]

thanks for all the info,, i live outside black hawk colorado,, but drive to denver on a daily basis

[barm]

anybody know were i can find a thrust washer set for this front diff?

[Petros]

likely a dealer item. they ususally sell them in a kit, try Butler Toyota?

you should be able to reuse the ones that are in the diff as long as they are not damaged.

[ARCHINSTL]

If ANYone can get an OE part, it is Butler - and at a better price than all (or at least most). Dan in its Parts Dept. just recently got me a part that was supposed be out of stock in North America. 1-800-921-2851 or http://www.toyotaoemparts.com
Tom M.