front axle spline counts and corresponding years, identifying an axle (1 Viewer)

[calen]

Hi, so I posted a question yesterday and got the answer i needed but it opened up some more questions.

trying to determine the year of this axle. when i bought it aI was told it was from an fj40 85. it has discs, the reason for buying it. the upper diff hugging u bolt perch is round, and the outer axle splines are 30, and the tip of the straight shaft that goes into the birf has 27. any idea what year this axle is? i was told the gearing is 4.11 but now being told that that upper spring perch being round is actually an older style im questioning the gearing.

 

[charliemeyer007]

What's its been like 38 years, that's almost 2 generations of folks that could have been wrenching on it - they could piecemealed anything in that amount of time. Easy enough to check the gearing - make some marks on the shafts and rotate the drive line 4 and some change should rotate the axle once.

 

[calen]

What's its been like 38 years, that's almost 2 generations of folks that could have been wrenching on it - they could piecemealed anything in that amount of time. Easy enough to check the gearing - make some marks on the shafts and rotate the drive line 4 and some change should rotate the axle once.

true. ok, so for the inner outer splines, is it normal to have 27 on the shaft and 30 on the birf end? I was tryna read on it but was still unclear.

 

[jim land]

Gas 40 get 4:11 and change to 3:70 from jan 1979
But the diesel keep the 4:11 until 1984

Also, from Jan 1979 the steering arm bolt patern is larger and birfield is bigger with a shorter outter shaft

 

[calen]

Gas 40 get 4:11 and change to 3:70 from jan 1979
But the diesel keep the 4:11 until 1984

Also, from Jan 1979 the steering arm bolt patern is larger and birfield is bigger with a shorter outter shaft

im not so concerned with the gearing as I currently have an axle on my car with the correct 4.11 diff that can swap into the new axle if i need to. but I would like to have the most up to date and strongest axles that came in a 40. I haven't really heard people mentioning mismatching spline counts on a shaft and birfeild so Iawanted ot confirm this was normal. 27 on the end that goes into the birf, and the birf has 30 on the end.

 

[pb4ugo]

Stk birfs have 27 spline inner cage, and 30 spline outer on the lockout.

 

[calen]

Stk birfs have 27 spline inner cage, and 30 spline outer on the lockout.

I dont know what an STK birf is? short for stock? assuming your saying OEM is 27 inside 30 outside, is that for all years? or was there a change at some point? I read about aftermarket upgrades (chromoly birfs) that talk about 30 spline inner shafts, what do you do about the carrier that needs to receive the now 30 spline inner shaft? I assume you need to get a different diff carrier?

 

[jim land]

Aftermarket chromo axle are 30 splines in the cage too

 

[peesalot]

OK, Calen, the birfs have had different spline counts on the outer end where hub/lockout goes , old have 6, newer have 30.
The outer end of inner axle that goes into the star inside birf have 27. Unless you have super old front axles.
The inner end of inner axle that goes into the third have 30 , again unless you have a super old axle which is doubtful.
Strength - 30, 27, 30 is the deal with aftermartket making improved birfields still 30 spline. If you really want stronger there are aftermarket axles that improve the birfield inner star material & spline count so those are 30, 30, 30.

 

[pb4ugo]

Stk=stock. You can purchase aftermarket alloy birfs only, with 27 spline cages if you decide to use your stk inner axles. If you decide to purchase alloy inner axles and birfs you can get 30 spline inners axles and birfs. Checkout RCV axles. 27spline inners started some where in the early 70's on drum brake frt ends. Fine spline outer birfs started in 1976 on disc brake frt ends. As @jim land mention in 1979 the stk birf is shorter and slightly stronger and bigger and the Knuckles are large pattern with larger studs. All this info is in the websight.

 

[calen]

OK, Calen, the birfs have had different spline counts on the outer end where hub/lockout goes , old have 6, newer have 30.
The outer end of inner axle that goes into the star inside birf have 27. Unless you have super old front axles.
The inner end of inner axle that goes into the third have 30 , again unless you have a super old axle which is doubtful.
Strength - 30, 27, 30 is the deal with aftermartket making improved birfields still 30 spline. If you really want stronger there are aftermarket axles that improve the birfield inner star material & spline count so those are 30, 30, 30.

@peesalot Thank you, this was very clear and exactly what I was looking for. could not find this info laid out this clearly. thank you

 

[calen]

so now that its been questioned that the year Iwas told might be incorrect. i figured I should confirm the gearing before slpping this thing infront of my rear 4.11 gearing. tried for an hour doing the whole turn the axle and count the pinion turns and evry which way I did it got 1.9 rotations of the pinion? I had the one side axle clamped so it wouldnt move. marked the other axle and the pinion and rotated the axle. every time 1.9? what am I doing wrong? cause theres no 1.9 gear ring for these is there? lol

 

[peesalot]

I did same thing, x2 can not figure that out. Someone please splain ?

 

[charliemeyer007]

I would turn the drive line input shaft (pinion) and count the axle rotation. 3:7 / 2 is 1.85 which is close to the 1.9 you are measuring which implies to me its not a 4:11 unit. Nice that you checked first.

 

[calen]

I would turn the drive line input shaft (pinion) and count the axle rotation. 3:7 / 2 is 1.85 which is close to the 1.9 you are measuring which implies to me its not a 4:11 unit. Nice that you checked first.

thanks! im still a little unclear on how i was doing it wrong. if im turning the pinion and count the axle turns its the same, one full rottion of the axle equals aprox 1.8/9 turns on the pinion. im so confused. I mean, I was hoping not to pull the diff off but now it seems like im swapping my old diff in any way so I guess Ill count the teeth when its open, but I would still love to know what m doing wrong with this pinion/axle turn count method.

 

[peesalot]

Nevermind, figured it, when doing it open you turn wheel 2 revolutions as the side gears have reduction vs. when its locked.
So I would redo your spin test as 1.8 and 2 will be 3.73 or 4.11 and that isnt much difference thats noticable while spin testing so careful measurement of rotation is critical because the suspect ratios are so close.

 

[pb4ugo]

It because its an open diff. try this.

 

[calen]

So ended up just pulling the diff and counting teeth. its not 4.11 so now im really pissed at the PO as nothing about what he claimed it to be is correct. its a pre 79 not an 85, and its 3.7 not 4.11. which is strange no? shouldn't the pre 79 have 4.11 in it? to confirm, 4.11 would have 10 teeth on the pinion yeah? this one has 9.

so im feelin pretty torn now on what to do. I have spent a ton of time tearing this axle down and prepping for blasting, and buying rebuild parts. and now i find out that i need to buy new smaller stud steering arms cause my current ones wont swap on. the "new" axle didnt come with arms. I here people complain about breaking steering arm studs, so I would obviously have preferred a newer axle with bigger studs, but Im this far in on this axle now that it is heart breaking to start all over again down to searching for new knuckles

how much weaker are the 11mm studs? am I loosing sleep over nothing? or should Ijust bite the bullet. scrap this axle and just start looking for 80+ 40 disc knuckles?

 

[Malleus]

It all depends on you. If I paid someone for a 4.11 axle and he sold me a 3.78 axle he'd have it back, with interest. But that's just me.

Toyota replaced the 4.11 gearset in '79 to increase fuel economy and reduce road noise. My first 40 was a '76 and I drove it from Charlotte, NC to Sierra Vista, AZ and back without any trouble. There was more wind noise than I could use; I couldn't hear the axles whine. It ran 70+mph the entire way. I loved it.

I temporarily traded it for an '83 and immediately hated it. After driving the '76 for years, the '83 seemed weak. It just had no torque response. Having said that, it still ran like a 40.

 

[calen]

It all depends on you. If I paid someone for a 4.11 axle and he sold me a 3.78 axle he'd have it back, with interest. But that's just me.

Toyota replaced the 4.11 gearset in '79 to increase fuel economy and reduce road noise. My first 40 was a '76 and I drove it from Charlotte, NC to Sierra Vista, AZ and back without any trouble. There was more wind noise than I could use; I couldn't hear the axles whine. It ran 70+mph the entire way. I loved it.

I temporarily traded it for an '83 and immediately hated it. After driving the '76 for years, the '83 seemed weak. It just had no torque response. Having said that, it still ran like a 40.

i mean, thats talk, i don't think you'd be getting anything back at all, as much as I would also love to throw this through his front window and physically extract 600$ from his person, which no one has, so it would involve what?, holding a knife to guys throat while he paypals me the money on his computer? lets be realistic here. buying on craigslist is a gamble. I am aware of the existing gearings hence my perturbation in finding it is not the gearing I need. I am also talking only about the front axle. I am not trying to change the gearing of my truck. I am just trying to replace the front axle (or knuckles) with disc brake knuckles. and the gearing needs to match the gearing in the rear. no biggie as the car obviously has matching diffs currently in it.

so what i would love to know is how weak really are the 11mm arm stud combo then the larger pattern 12mm arm stud combo? am I knit picking? I mean toyota thought it was worth upgrading right?