What differance will 1979+ axles make on my 76 fj40 (1 Viewer)

rusty_tlc

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gear ratio is 3.73. Can I simply swape the axles on my 76 with the 79 axles? Or is there more to it?
It would probably be easier to swap the third members than the whole axle.

X2 on what 3_puppies said about flanges.
 

73fj40lc

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I think 79 are large pattern knuckles... Making it better ot swap the complete front axle.:D
If all you are looking for is the 3.73 gears then swap the thirds as mentioned b4. If you are looking for an overall better / stronger knuckles then bikersmurf is right. It all depends on what you want and how much time and $$ you want to spend. You can alway go with the rubber overdrive and leave your axles alone.
 
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If all you are looking for is the 3.73 gears then swap the thirds as mentioned b4. If you are looking for an overall better / stronger knuckles then bikersmurf is right. It all depends on what you want and how much time and $$ you want to spend. You can alway go with the rubber overdrive and leave your axles alone.
Or also do both... Diffs and rubber overdrive.:D
 

allan man

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Larger birfields (shorter ones).......same as 79-85 mini PU/84-85 4runner if your lucky and it is complete hub to hub you get the stronger lockouts (aisin) ......more common readily parts as far as chromoly birfs......if you just swap the outers it will require a little grinding on the 76 case for the birfs to fit......probably easier just to swap the whole thing as mentioned above.......


it never ends does it........
 
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All good info.....but I want to keep it simple the good thing is I already have the rubber overdrive using 33's.

I don't get alot of opertunity to take my 40 off road with the exception of a few camping trips so I'm mainly on pavement. So my goal is not to beef up the axle as much as to reduce the gear ratio to reduce RPM's at speed.

With this said I think just swaping the pumkins is the bast option. In doing so everyone mentioned that I would have to swap the drive shaft flanges. I assume that the bolt pattern is differant.

To do this do I need to swap the flanges on the drive shafts or the pumkins? which ever it might be what is involved? easy? difficult? keep in mind that I have torn this thing down to the frame and rebuilt with the exception of the drive train.
 

3_puppies

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you won't be able to use the 76 flanges on the 79 diffs. different splines

easiest solution would be to get the driveshafts from the 79 or just one end of each and mismatch your existing driveshafts. the slip joints are the same.

it's really not that difficult to just swap the entire axle assmblies. you can go thru both of them, at your leasure, before installation, easy weekend swap.

also the axles may not come with any hubs, could be drive plates, or warn hubs, or if your lucky they would be aisins
 
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Thanks 3_puppies!!

So I have a decision to make either way I will need 79 drive shafts so I can mis match at the slip joints.

Do i swap the axles or just the pumpkins.....I have already rebuilt the front axle and replaced all the rear break cylinders on the rear axle. If I swap the axle then I will be looking at refreshing my rebuild skills....if I just swap the pumpkins then no worries......

Disadvantage is It sounds like the 79 axle may be a beafier axle.
 
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Far less difficult to swap out the axles than the center sections. I had no problems with the drive flanges when I took the diff's out of my 1980 & dropped into my 1975' I changed gears & rebuilt axles when I swapped just far tougher birk,hubs. " front disc's was a big + for me as well."
 
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gotta agree on swapping the axles being easier than the thirds...
 

pbgbottle

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something alse to think about
don't forget the rear axle is also different when it comes to the brakes . 08/1980+ should have e-brake on the rear drums.
 
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3_puppies

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something alse to think about
don't forget the rear axle is also different when it comes to the brakes . .79+ should have e-brake on the rear drums.
negative on that.....the ebrake on the rear axle didn't happen until 1981 model year
 
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When you do a cut and turn what is the desired caster angle??? I set mine at 5 degs both right and left, seems ok
 
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So If I hear everyone correctly there is no issue with the 79 flanges or E brake. just swap the axles and the drive shaft flanges will mate with no issues using my 76 drive shafts?

I get a beefier front axle and lower gear ratio which for me is a + because most of my time is on pavement and occasional off road.
 

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