I currently own a 1981 FJ 40, it is mechanically perfect, but the tub and the rest of the body are no good, completely rusted. I have the opportunity to buy a 1977 which is in very good condition, can't say much about the mechanical. Are their major differences between the years? I have automatic locking hubs, I also noted the transfer cases are different. The biggest question actally is, are the transmission ratios very different? Anything else I should know. Thanks for the help!

Welcome Newbie!
:D :flipoff2: :D

The tubs are very different in the way they mount to the frame. If that is what you are asking. You can switch them though. I did.
Gearing is similar with your split Tcase being slightly lower. Transmissions should be identical. Your axle gears should be 3.70's and the 77's are 4.11's

What else do you want to know?????

I really appreciate your time, since you are willing to answer questions I guess I will just list them. Here is the premise, I would really like to keep my '81 because she is mechanically perfect, but the '77 is in such good aesthetic condition (assuming all mechanical conditions are the same). So I am debating over what should I do, change the tub and the good body parts from the '77 to the '81, or should I take some of the nicer features (i.e. automatic locking hubs) from the '81 and place them on the '77? (long question huh?) Here are some other small questions I have, your time is greatly appreciated.

1. You changed the tubs....what was the level of difficulty?
2. Can I, or should I, change the front manual locking hubs on the '77 with the automatic locking hubs from the '81?
3. The '77 has a regular transfer case, and the '81 has a "split" transfer case, what is the difference? Is one better than the other?
4. I also have a concern with top end speed (lots of highway driving to get to the woods) are the tranny gear ratios different, or is the 4th gear ratio the same?
5. You mentioned the differential ratios, which ratio would be better?
6. Finally, I read somewhere, the '77's had a strange wheel offset and was difficult to find rims or tires, combinations were different from front to back, I use 15"x10" 6 lug by 5.5 rims with a 4" backspace, and 33"x12.50"R15 tires, will these fit?

I really appreciate your time. Thanks

The low gear of the '77 transfer case is 1.992:1, the '81 is 2.276:1, a difference of 14%.

The gearing of the '77 differential is 4.11:1, the '81 is 3.70:1, a difference of 11%.

Combination of '77 differential and '81 transfer case is 9.35:1, your stock '81 is 8.42:1, a difference of 11% (same as the differential gearing difference - make sense?).

For off-trail use, I'd go with the '81 transfer case and the '77 differentials.

Yeah, the '81 case is stronger.

I would ditch the auto hubs and use the manual ones. They are more reliable and allow you to lock out the front.

The 4th gear on both trannys is the same. As mentioned, you should use the '81 t-case to get the lower gears and stronger case. Also as said, you should use the '77 3rd members because of the lower gearing. With the 4.11s you should be OK at 60-65mph. If you really do a lot of highway driving, you can use the 3.70s to keep the RPMs down or to get a higher top speed.

I don't think '77 had any different or unusual backspacing, or differences front to rear. You will probably not be able to fit a 4" BS rim very well. It might work, but with 12.5" wide tires you would rub the body very badly in the rear and probably in the front. I ran 4"BS rims with 10.5" tires and they rubbed everywhere. My rims were 16" so they cleared the steering arms, 15" 4"BS might not clear them. You can always get wheel spacers to get a little better fit.

FJFJ-

The 1981 has a simplified 6 bolt mounting for the tub vs the 12 mount system for the 1977. That makes fitting the tub a bit tough. You will not find a late (1979 up) tub in good shape w/o buying a whole truck-period.

The 1977 steering column is different than the 1981 ('81 is floating, better). Fitting is not bolt in to '77 tub, but you can make it fit.

The 'auto' hubs are garbage. I do not think the '77 hubs will work well. Buy yourself a set of new or used Aisins (OEM type) for the 1981. Larry Miller Toyota in the Salt Lake area still has new ones for $65 ea.

As was mentioned in another post, the 1977 will have course spline pinion (fine spline axles) 4.11's. The 1981 has fine/fine w/ 3.70's. While you could swap diffs or use 1977 axles, I would rebuild your existing diffs to what you would really like/need (either 4.11's or 4.56...). All in all, your running gear is better in the 1981 than the 1977 (bigger head steering arms, bendix rear brakes w/ e-brake, bigger birfields) so keep those axles. The frame also has 'big eye' shackle mounts (using FJ60 size equipment) so don't write that off (unless you go sr w/ another spring style).

Back to a 1977 tub on 1981, ...can..be done, or you could look into a replacement tub (Al, fiberglass, TLC/metal) and diss the whole conversion headache.

Originally posted by FJFJFJFJ
I really appreciate your time, since you are willing to answer questions I guess I will just list them. Here is the premise, I would really like to keep my '81 because she is mechanically perfect, but the '77 is in such good aesthetic condition (assuming all mechanical conditions are the same). So I am debating over what should I do, change the tub and the good body parts from the '77 to the '81, or should I take some of the nicer features (i.e. automatic locking hubs) from the '81 and place them on the '77? (long question huh?) Here are some other small questions I have, your time is greatly appreciated.

1. You changed the tubs....what was the level of difficulty?
2. Can I, or should I, change the front manual locking hubs on the '77 with the automatic locking hubs from the '81?
3. The '77 has a regular transfer case, and the '81 has a "split" transfer case, what is the difference? Is one better than the other?
4. I also have a concern with top end speed (lots of highway driving to get to the woods) are the tranny gear ratios different, or is the 4th gear ratio the same?
5. You mentioned the differential ratios, which ratio would be better?
6. Finally, I read somewhere, the '77's had a strange wheel offset and was difficult to find rims or tires, combinations were different from front to back, I use 15"x10" 6 lug by 5.5 rims with a 4" backspace, and 33"x12.50"R15 tires, will these fit?

I really appreciate your time. Thanks

First of all dump the Auto hubs. They do not work when you need them the most.....

Now to the Questions..

1: Depends on you. All in all it was not hat bad. But you shoudl be able to weld and fabricate additional cab mounts. Which is a lot easier with some of the fabricating sites on the web. There is a nice site on the general board right now. If you want to know specifics then PM or E-mail me and we can talk...

2: Again, dump the auto hubs. Manual is much better IMHO..

3: You can get lower gearing with the "split" tcase. Stick with that.

4: the tranny's are the same. So the 4th gear is the same. The difference is in the axles. Your 81 has a 3.70 gear ratio the 77 should have a 4.11 ratio. With my 32" BFG's I pulled everywhere I wanted at speed with the 3.70's. I would stick with them if you are running on the street a lot. And not running really hard trails.

5:it all depends on what you do. If you feel that your low range is adequate then go with that. I really liked the combination of 3.70's and 32"tires...

6: The offset should not be much different but you want to keep your later axles. They have bigger birfields than the older axles. so if your 4" BS rims work then keep them!!! Although I would run a 15x8" rim with a 12.50 tire. But that is me...

Anything else???



:D

Originally posted by FJFJFJFJ

1. You changed the tubs....what was the level of difficulty?
2. Can I, or should I, change the front manual locking hubs on the '77 with the automatic locking hubs from the '81?
3. The '77 has a regular transfer case, and the '81 has a "split" transfer case, what is the difference? Is one better than the other?
4. I also have a concern with top end speed (lots of highway driving to get to the woods) are the tranny gear ratios different, or is the 4th gear ratio the same?
5. You mentioned the differential ratios, which ratio would be better?
6. Finally, I read somewhere, the '77's had a strange wheel offset and was difficult to find rims or tires, combinations were different from front to back, I use 15"x10" 6 lug by 5.5 rims with a 4" backspace, and 33"x12.50"R15 tires, will these fit?


Body swaps are work regardless....and dealing with the different mounts just add hassels.
IMO, use the manual hubs. Much more reliable. The Aisin hubs are another upgrade, but the Warn's are workable too.
Split case is stronger than the earlier cases....a nice upgrade to keep.
IMO, 4.11 ratio is more than sufficient, and with the inline 6 and the Spring-under stock-type suspension, you shouldn't have pinion concerns.
IIRC, 3.5" offset is best for Cruisers...and like mentioned, the 8" rim will keep the tire on better offroad.

I really appreciate all of your time, I have learned more the last couple of days than I have in the last year. I decided to keep the '81 original and not ruin a good thing. I am however going to restore the '81. If anyone knows someone selling a complete '81 (the tub, or more importantly the door and roof), any information would be greatly appreciated.

Thanks again!:beer: