4:11 to 3:73 third member swap questions

[cronic]

Ok, Since I am going to have to have the rear end rebuilt in my 73 I am wondering what is involved with replacing the 4:11 with a 3:73? This is a daily driver with a 327v8 ,700r4 with 3 speed toyota transfer case, and 31" tires. I don't take it offroad. I turn 2600 rpm with the 4:11 at 70mph. What could I expect to turn with a 3:73? Other than the third member wihich I am going to pick up rebulit from Iron Pig Offroad what else will I need?

 

[Mr. Toad]

Direct swap. Easy.

The only difference will be the pinion flange bolt pattern, but Kurt at Cruiseroutfitters can set you up with replacements that will match your driveshafts. Pretty cheap, and the pinion seals on the 3.73s probably needed replacing anyway.

 

[All Four]

Remember that you have to change the gears in both ends of the truck in order to prevent some serious drive line wind-up in 4wd mode.

 

[cronic]

Remember that you have to change the gears in both ends of the truck in order to prevent some serious drive line wind-up in 4wd mode.

Yep, I will. I don't use 4wd at all, so I will swap the front later when money allows and will be sure not to use 4wd in the meantime.

 

[Poser]

Remember that you have to change the gears in both ends of the truck in order to prevent some serious drive line wind-up in 4wd mode.

wind up?


Is that what they call it when your transfer case fractures into two pieces?

 

[35inchoverdrive]

Is that what they call it when your transfer case fractures into two pieces?

I think that would be the unwinding.

 

[jtoro]

Windup because you wind up looking for a new tc.

 

[Pin_Head]

what else will I need?

Bigger tires.
Then you won't need the 3.73s
Easier, cheaper, better on road and off.
Win, win, win.

 

[thecrazygreek]

what the hell is wrong with 70 at 2600? What else do you want? Leave it as is. I WISH i was at 70 at 2600 rpm... I have a 327 with the stock 4 speed and I havent seen 70 yet.,.. Bastard..

 

[dgangle]

I tried a 3:73 third from a 60 in the rear of my 40 and loved it. Bought another and swtiched the front too. Got both for $100. With 33's, 55MPH indicated is ~70 acording to GPS and ~2800 RPM. To me this was easy, inexpensive and by far the best mod I have ever done. Made the truck almost tollerable to drive on the highway. That one extra pinion tooth makes a WORLD of difference.

 

[Vicm]

I will trade you 2 (3.7) for a one 4.11 you pay for the shipping.
I will even send you 2 matching slip joints to match the pinion flange. Sice it will have the fine splines and the different bolt patren.

 

[amaurer]

The better question is - how are you at 70mph @ 2600 with 4.11s and 31's?

I run exactly the same combo and only get 60mph at 2900.

dgangle has the 3.7's already, and hes got 70mph at 2800 - and thats on 33's!!

 

[BC40]

The better question is - how are you at 70mph @ 2600 with 4.11s and 31's?

I run exactly the same combo and only get 60mph at 2900.

dgangle has the 3.7's already, and hes got 70mph at 2800 - and thats on 33's!!

700r4 od

 

[amaurer]

700r4 od

Ohhh. Must be nice....

 

[cronic]

Ohhh. Must be nice....

It is, thanks

 

[ken_79-fj40]

3:73's and 33's is actually pretty nice with a mild 2F also on the road. I run mine down the highway at 70 no problem with traffic. Off road it kind of sucks though. Can't go slow enough for some stuff. I'm hoping for an orion someday to solve that.

 

[Mr. Toad]

3.73s are fine in my very stock 1975 fj40. 29-ish inch tires. Nonetheless, I'd never drive it 70 mph when other people might be on the road.

 

[cronic]

3.73s are fine in my very stock 1975 fj40. 29-ish inch tires. Nonetheless, I'd never drive it 70 mph when other people might be on the road.

Neither would I in a stock fj40. However, when your steering is right and with 4 wheel disc brakes it is possible and as safe as you can be in a 30 plus year old vehicle.

 

[dargreg]

I just took the 4.11s out of mine and put 3.73s in ,Whith the 6.2 diesel it made the world of differance I love it on and off road .Mine is a DD also.

 

[ken_79-fj40]

Neither would I in a stock fj40. However, when your steering is right and with 4 wheel disc brakes it is possible and as safe as you can be in a 30 plus year old vehicle.

With a proper saginaw conversion, correct caster angle, and all fresh suspension it's really not that different than driving any other late model short wheelbase mildly lifted 4x4. Besides the lack of any hi-tech safety doodads of course. I would be far more likely to cause or be in an accident if I drove 10-15mph slower than traffic, and I would think this would be the case pretty much anywhere there is any kind of population.