FWD differential

[arbskynxnex]

Ok, so Red is dead. I went to fix a leak on the front cover of the diff housing and when I pulled the drain plug, a big hunk of differential gear fell out. It had been run a lot with low fluid by the last owners. I pulled the transmission and had my uncle the mechanic look at it, he said the wear on the diff, it looked like at least half the teeth on the ring were in immediate danger of breaking like the one did, plus the was a bearing failure somewhere in there too. The transmission leaks, and just looking at 5th gear, it was fairly worn. Transmission still works, but the entire diff is toast. I haven't had any luck at the junkyards, the only 4wd terc I found had a totally frozen transmission. In my desperation I looked at a hatchback, we weren't sure of the diff ratio, it was an 85 too, but we decided to go for it and mount the whole housing up to my tranny and limp by. Pulled it and found out that a 4spd diff housing will not work on a 5speed, it is missing a few vital bearings to do a straight swap, and everything in my diff housing was toast. Which really sucked, because the diff housing on the junkyard one was beautiful. Does anyone know the axle codes for the differentials on the fwd wagons, sedans, and hatchbacks? I forgot to write the code down, (I think it was a 3Y-something, but it was 100+ degrees in the junkyard so I can't rule out heat stroke affecting my brain) but I know of a few more fwds that I might check out. If I can find a 5spd and have an idea of what the front diff gearing is, I should be able to frankenstein a workable car into existence.

[Petros]

The front diff is 3.73:1 for the 83-84 model year, and 4.1:1 for '85 and later. I do not know if the 2wd version uses the same ratio. IT seems to me that you should be able to just swap the front diff into the 4wd housing, presuming you can repair the 4wd housing acceptably. The 4wd housing might be different from the fwd 5 speed because of the EL first gear, but I have never compared them. As a temp measure you could take out the drive shaft and just put in the fwd trans, so you will not have 4wd until you can locate another trans.

No 4wd trans are available in any of the yards here, but I will keep an eye for you.

[ARCHINSTL]

As to differential compatibility - you might check the EPC sticky in the Parts Forum. Compare/cross check the numbers between the 5S FWD and the 4WD.
Tom M.

[xirdneh]

the 3.73:1 has 11 teeth on the pinion and 41 on the ring
the 4.1:1 has 10 teeth on the pinion and 41 on the ring
the hatchback that i took apart had 12 or 14 (i cannot remember but i know its more than 11) teeth on the pinion and 41 on the ring

[Petros]

sounds like you will need to swap in the whole FWD trans until you find the right year 4wd trans to replace the old one. What year TErcel4wd do you have? You now live in George UT?

[arbskynxnex]

sounds like you will need to swap in the whole FWD trans until you find the right year 4wd trans to replace the old one. What year TErcel4wd do you have? You now live in George UT?

Its an 85. I found an 83 with what looks like a good trans, but I don't want to swap to the 3.73 gears, but I'll suck it up and deal I guess. I'm still in Washington. My dad and I were down in Portland and the thermometer on his truck said 106 in the sun, and we were in the sun a good long time.

[Petros]

You can put in the '83 trans and swap out the rear diff (just the third member of the axle, easy swap, takes about an hour). I happen to have a 3.73 rear diiff in the carrier that I have no plans for you can have cheap if you want it. It will get your Tercel running with 4wd at least, and give you time to find an '85 4wd trans at a good price.

For steep terrain the 4.1:1 ratio is better, but the 3.73:1 is quieter on the hwy since the engine runs noticeably slower at fwy speeds, and it might get slightly better fuel economy.

[arbskynxnex]

Thanks, Petros. I've done the swap before and I was pretty unimpressed with the 3.73s but there are no 4.10s around so I have to do it.

[Petros]

Me too, that is why I am converting over my '84 to the 4.10 transaxle and rear diff

[arbskynxnex]

Well it is all a moot point at the moment. The junkyard transmission had more gear bits come out of it than mine and that was the last one I was able to find anywhere around. I've got the old tranny in for a rebuild quote. I think my wallet is going to curl into the fetal position and cry for a few hours once I get the price.

[arbskynxnex]

Urgh. Got the quote for the tranny $2100 for the rebuild, so I'm not doing that. Synchros were crap on the tranny, but the gears are in good shape so it isn't toast and I may attempt a rebuild myself if I can find a diff and have no luck locating another tranny. Which could prove to be interesting. My dad counted the teeth on the ring and pinion and came up with 41 and 18 which would be essentially a 2.28 gear ratio. So I'm totally in WTF-ville right now on that. I'm going to have to have him quadruple count it, since Red drove like it had 4.10s in it, I'm not even sure a terk could move under its own power with with 2.28s. I have a line on terk with a bad engine so hopefully that all works out and I can just turn one of these beasts into a parts car, or save until I find a tranny and sell... or keep and have 2 cars...

[xirdneh]

41 and 18 cannot be right
the tercel 4wd trannys had either
4.1 with 10 teeth on Pinion and 41 teeth on Ring
or
3.73 with 11 teeth on Pinion and 41 teeth on Ring

the 2wd hatchbacks had 12 or 14 (do not remember for sure which) on Pinion and 41 on Ring

[arbskynxnex]

I knew it wasn't right. Dad din't know what he was counting and I have no clue what he did count, but it is a 4.10 diff, so that crisis is averted.

[toughtercel]

Thanks, Petros. I've done the swap before and I was pretty unimpressed with the 3.73s but there are no 4.10s around so I have to do it.

As a fast driver , I choose the 3.73s ,

[arbskynxnex]

Well I solved the problem. I found a terk for $350 with a good tranny but a bad engine. I ended up putting the engine from Red into this one. it has surface rust on the back, but when I was looking at Red I found a large rust hole under the battery box and since I can sand, but can't weld the new car became the good car. I'm going to end up parting Red out since I don't have dedicated storage for it.