Difference in differential gear ratios

[smitty1259]

Hi:

Am looking at buying an '86 Tercel 4WD wagon. One of my favorites. Have had 3 different ones in the past.

But, this one has a kink. The guy bought it with a 3AC and auto tranny. He pulled the 3AC, installed a 4AC, and later replaced the auto tranny with the 6-spd. manual. Turns out, the new tranny was from an '83 and the gear ratio is different. He has 3.8:1 in the front and 4:1:1 in the rear.

My question is: will the 4WD even work with these differing gear ratios?

Thanks,

[keith]

It could pull you out of a very slippery situation, like sand or ice. If you hit a hard surface while in 4wd, you will do some damage to the drivetrain.

[Mattel]

Depending on where you are located the best thing would be to replace that rear dif with one out of a tercel 4wd wreck (83-84) if available. Not to hard or expensive a job mine got changed over from the 4wd selector back in one peice. if the rest of the car is good (especially the body) then it would be worthwhile. Might help you get a reduction in the price. Replace the wheel bearings if needed and changeover the oil in the gearbox and dif whilst your there with some good synth oil.

[SynthDesign]

Yes..... 4WD will work but your risking blowing up a trani, grenading a diff or throwing a driveline. Neither is fun and all can total a vehicle in a few minutes. I speak from prior experience and all it takes is a moment from loss of traction to traction in 4wd w/0 matching ratios and boom.... ,that could be it....
A catastrophe that can be easily prevented.

Labor wise ,it only takes a 3 hours to swap a rear diff., unless you have a stuck axle or about two hours to swap a rear end depending on how fast you can bleed the brakes.
Tool wise, it only requires basic stuff; sockets, jack stands, hammer, a rectangular street sign pole w/ the hole punches(Cheapest toyota axle removal tool out there) and a few other things. FSM will get you thru it quick. http://tercel4wd.com/fsm/1985_Manualindex.html

If you do decide to buy it but can't get it swapped over, I recommend disconnecting the 4wd engagement shifter underneath the car so the vehicle can't be put into 4wd by an unaware driver.

[Highlander]

Hey Smitty- I've still got the rear end from the '83 in the car, I was planning on pulling it and putting it up. If you need the third member, let me know, It'd probably be easier than changing the whole of the rear axle out. BTW I'm in CO.

[gearhead313]

noooooo!!! it will not work!! Do NOT engage 4wd if you have missmatched diffs! if it does engage, then one end will be binding severly against the other and probably break something very quickly. I built a grand cherokee and re-geared the back before the front and tried it once and it as horrific, luckily i got it back out within a second or two and didnt do any damage.