9.5" FJ40 compared to 8" or other options.

[ErikB]

Originally Posted by Blue-Beard

The pinion on a FJ40/60/80 (taco/t100/tundra) rear is nearly d60 sized. (as long as you use a fine spline pinion)
fj40/60/80 pinion shaft dia. 1.575 splines 27 (the t100/taco/tundra pinion is the same I think)
Ford 9" pinion shaft dia. 1.313 splines 28
Dana 60 pinion shaft dia. 1.626 splines 30

If 35 spline lockers were cheap and more readily available for the 9.5 I'd say that would be a great hybrid to run. The Rasin/Pipebomb runs that combo.
ARB has some 35spline side gears for 9.5 air lockers but I'm sure that they aren't cheap.

The taco/t100/tundra 3rd has a 30 spline pinion (same spline size/count as D60, not the same pinion gear size as D60 since pinion gear size is directly related to ring gear size). Aftermarket gears for this diff also have 30 spline pinions.

4cyl and V6 diffs have 27 spline pinions, BUT...
Starting around '01 or '02 Toyota changed the V6 diffs (4runners and e-lockers) to 30 spline pinions. If you regear them, you have to swap the pinion flange and nut for the 27 spline size because all the aftermarket V6/4cyl gears are still 27 spline.

That's more of just an FYI because, AFAIK, the pinion spline count has not been known as a weak point on these diffs.

[smewhtguy]

Originally Posted by Dirty Harry

There is a tech article on Ben's rear axle in the new (Nov/Dec) Crawl.

I'd like to see that article, hell I'd like to see the nov/dec issue period still haven't found one here in nothern Va.

[Blue-Beard]

Originally Posted by ErikB

The taco/t100/tundra 3rd has a 30 spline pinion (same spline count as D60, not the same pinion gear size as D60 since pinion gear size is directly related to ring gear size). Aftermarket gears for this diff also have 30 spline pinions.

True that on the splines, I am pretty sure the pinion shaft is the same size on the 9.5 and the taco though.

[85yota350]

x2 on the heat treat and cryo.

[TBItoy]

.

[Wellsy]

Hey All. I am in this exact situation myself.. Trying to figure out what to do for a rear axle. Running FJ80 in the front right now - its bent so getting a Diamond this winter. But same thing I keep blowing ring gears in the rear end. 2 this yr..

I'm trying to decide between a newer 8" out of a Taco or T100, or put in a matching FJ80 rear axle and going with the bigger ring gear. Which ever way I go I will have Bobby treat the gears first.

Like others have said above, pinion failure has never been an issue for me - its always just the ring gear. So am I better off going for the larger ring gear on an FJ80?

Also anyone know what locker options there are for an FJ80? I'll I've seen is Detroit, ARB, and factory Elocker Anyone make a spool for it? This is a trail only rig. Any option on just welding it up?

And yes I know I should just go D60/D70 - but I have just too much $$ invested into that front FJ80. (Bobby Long FJ80 set, Hi-pinion Elocker, OTT Hi-steer, etc etc)

Thanks

[TachedOutOffRoad]

Ive been scratching my head about this for a while now too.
I wanted swapable 3rds so it was either 9.5" front and rear or the "8.4"s front and rear. I already have three Taco diffs, so that is what I was going to run. A Diamond is still a little while away, so Ive got a HP 8" front and the factory Taco rear for now.

There are a few threads about this, and the general consesous is that they are both stonger than the 4cyl or v6 diff.

-The Raisin/ Pipebomb has the custom 9.5" and is holding up to a V8 and 44"s in a buggy

-the new Slee truck and the ShortBus have the 9.5" rear and run 39"s and a FATASS truck and doesnt break . . . .ring gear

-JRT runs heat reated 5.29s in Taco diffs in a Comp buggy with 37"s and didnt break one.

-Propane buggy runs 42"s on the Taco diff and 4.10s and hasnt broken it.

-The ORS 4runner has 42" TSLs and a taco rear diff in a not-so-light rig.

I think either would be good, but the Taco is a lot easier to find and they are cheaper.

I can tell you in a few months how they 8.4 holds up to some 39.5" IROKs

The '91-'93? Fj80 rears are less desirable because they are not full floating.

[Shefron]

There is one more plus to using a taco rear up front. Only need one spare diff on the trail. I blow my rear diff then I will just install the front in its place so I can get home.

[TBItoy]

.

[TBItoy]

Ok, so I'm 5 years into this HAHA

I'm sellin the stock runner which is on built mini truck axles.

I've gathered:

1 FJ80 front
1 Semi Float FJ80 rear
1 Full Float FJ80 rear

I'm planning to build a light 2 seat buggy "pro-mod" style, all business. Only storage will be an ammo can and a small cooler.


My "plan" was to build a FJ80 9.5" hybrid with the 80 knuckles and the semi-float rear housing.

BUT, with some recent thinking, I'm starting to question my choices.

The FJ80 inner shafts are 24 (large coarse) spline inside the birf.

I currently have broke several 30 spline Longs (busted birf), but I've never twisted a shaft.

If I run FJ80 Longs in the 9.5/FJ80 hybrid will I be gaining "that" much strenght?


I don't want to go through all the trouble to build a hybrid axle, links, steering, etc then start twisting off FJ80 inners.

Drivetrain will be 22R/w56/Toy crawl box/D300, 37 stickies?, ~2500lbs

[Brian Ellinger]

Originally Posted by TBItoy

The FJ80 inner shafts are 24 (large coarse) spline inside the birf.

I currently have broke several 30 spline Longs (busted birf), but I've never twisted a shaft.

If I run FJ80 Longs in the 9.5/FJ80 hybrid will I be gaining "that" much strenght?

fj80 is 24 spline at ~1.250
30 spline is closer to 1.290
Not a huge difference, but the splines are deeper on the 24 spline as well.

All aftermarket fj80 shafts continue with 24 spline. Where the 30 spline birf is so common now. strength wise put it this way:
stock mini weakest
stock fj80
moly 27spline
moly fj80
30spline mini strongest

[zukijames]

tbi i know you already saw this but yeah..

[jeaton]

I am in the same situation but headed down the path that I think will give me a very strong but light front that can take a pounding!

I put fj60 diffs under my pu 2 yr ago, with hot 5.3, th350, 208/300, 4.56 diffs. I have beat on the stuff and no breakage, oh and it weighs 3400 lbs.

Now running mod class I really never worried about my longs with only 37" tires but the knuckles taking a pounding was my biggest concern. I have chatted with Billy and thought about putting fj 80 balls and knuckles on and running that stuff. Bobby told me that the 24 spline stuff at the birf is the same size as the mini 30 spline stuff so there is really no strength lost there. Billy felt that my rig being light hes knuckles would hold up and I was almost ready to pull the trigger and then I went down the dark side.

I had a friend give me a SD dana 50. the C's out are the same as the 60's. I know with out a doubt that the sheer mass of the C's will hold up and I am excited to build my front, the cruiser ring gear is right at 9.5".

I spoke to tech time and he sells 35 spline side gears for my arb. A cursier arb is damn big and I would bet its probably stronger than the 9" and close to dana 60 but not quite there and its ok because when Im finished my front wont weigh 600 plus lbs but more like 3-350 lbs. If an arb is not to your liking you can put a 35 spline spool in your diff also with a lil work.

Shafts will be some cut down 35 spline stuff with sd outers with long ujoints. I will always have some longs on my toy for as long as I wheel! I have two sets of longs that im going to sell to recoup some money so I am really not going to be out of pocket a ton and thats really the best part. I have a buddy thats going to machine the UB and rotors for my 6 lug pattern and build me some high steer.

I am also meeting up with Carl Jantz next week and dropping a cruiser diff off to him. There is room to run a load bolt on a cruiser ring gear and hes going to build a kit so we are able to do it our self's so in the front we will be able to help even more keeping the ring gear where is is suppose to be. I dont think people have ever looked at how toyota designed the bearing caps on cruisers. If you look at the you will notice that the have a machined radius that is the same as the diff radius. when you install your diff, those caps set inside another ring, thus not allowing the caps to deflect, its slick and very effective!

Now I know people are going to tell me that the pinion is going to break! I have watched two buddies that I wheel with ALL the time in rigs weighing 4500-5000 with healthy v8 and one is 220-1 and neither has ever broke a fine spline diff...works for me!!!

I will be updating my 4509 build with this and hoping to get it finished before the Toole utah event.

[WarEagleToy]

I was breaking a mini truck front r&p ever other trip on 39.5 tsls. Went to a hybrid fj60 center, 80 outer and ff 80 rear and 40 cc stickes and im 4 trips in with no breaks on stock birfs fwiw. Trucks whats left of a 92 xcab 3slow duals w 4.7 rear stock 4.10s

[zukijames]

thanks for all the info..im intrested in the 35 spline spool ! i went the hillfire knuckle route but now im realizing i should have just got some reid racing c's and knuckles.


the hell fire stuff is super bad ass and i have no doubt it will hold up just fine.

but im worried about the axle shafts..

if i could i wonder if there is any way to get anything stronger than what is currently out there.

the stock fj80 spindles can probably can not fit anything bigger correct?

could you run a bigger spindle and bigger rcv shaft?

Originally Posted by jeaton

I am in the same situation but headed down the path that I think will give me a very strong but light front that can take a pounding!

I put fj60 diffs under my pu 2 yr ago, with hot 5.3, th350, 208/300, 4.56 diffs. I have beat on the stuff and no breakage, oh and it weighs 3400 lbs.

Now running mod class I really never worried about my longs with only 37" tires but the knuckles taking a pounding was my biggest concern. I have chatted with Billy and thought about putting fj 80 balls and knuckles on and running that stuff. Bobby told me that the 24 spline stuff at the birf is the same size as the mini 30 spline stuff so there is really no strength lost there. Billy felt that my rig being light hes knuckles would hold up and I was almost ready to pull the trigger and then I went down the dark side.

I had a friend give me a SD dana 50. the C's out are the same as the 60's. I know with out a doubt that the sheer mass of the C's will hold up and I am excited to build my front, the cruiser ring gear is right at 9.5".

I spoke to tech time and he sells 35 spline side gears for my arb. A cursier arb is damn big and I would bet its probably stronger than the 9" and close to dana 60 but not quite there and its ok because when Im finished my front wont weigh 600 plus lbs but more like 3-350 lbs. If an arb is not to your liking you can put a 35 spline spool in your diff also with a lil work.

Shafts will be some cut down 35 spline stuff with sd outers with long ujoints. I will always have some longs on my toy for as long as I wheel! I have two sets of longs that im going to sell to recoup some money so I am really not going to be out of pocket a ton and thats really the best part. I have a buddy thats going to machine the UB and rotors for my 6 lug pattern and build me some high steer.

I am also meeting up with Carl Jantz next week and dropping a cruiser diff off to him. There is room to run a load bolt on a cruiser ring gear and hes going to build a kit so we are able to do it our self's so in the front we will be able to help even more keeping the ring gear where is is suppose to be. I dont think people have ever looked at how toyota designed the bearing caps on cruisers. If you look at the you will notice that the have a machined radius that is the same as the diff radius. when you install your diff, those caps set inside another ring, thus not allowing the caps to deflect, its slick and very effective!

Now I know people are going to tell me that the pinion is going to break! I have watched two buddies that I wheel with ALL the time in rigs weighing 4500-5000 with healthy v8 and one is 220-1 and neither has ever broke a fine spline diff...works for me!!!

I will be updating my 4509 build with this and hoping to get it finished before the Toole utah event.

[zukijames]

Originally Posted by WarEagleToy

I was breaking a mini truck front r&p ever other trip on 39.5 tsls. Went to a hybrid fj60 center, 80 outer and ff 80 rear and 40 cc stickes and im 4 trips in with no breaks on stock birfs fwiw. Trucks whats left of a 92 xcab 3slow duals w 4.7 rear stock 4.10s

thats awesome keep us posted

[TBItoy]

Originally Posted by Brian Ellinger

fj80 is 24 spline at ~1.250
30 spline is closer to 1.290
Not a huge difference, but the splines are deeper on the 24 spline as well.

All aftermarket fj80 shafts continue with 24 spline. Where the 30 spline birf is so common now. strength wise put it this way:
stock mini weakest
stock fj80
moly 27spline
moly fj80
30spline mini strongest

Originally Posted by zukijames

tbi i know you already saw this but yeah..

Good info guys, Brian, your post is the reason I started questioning my choice of axles.

BUT I'm not breaking shafts, just birfs. That is where the confusing/frustration arose.


Since Bobby is making 30/30 FJ80 Birfs I WILL buy a set. No questions asked. That sealed my axle choice for THIS rig.






I considered the D50 outers with all 35 spline stuff, but it is more $ than I want to spend, considering I would want smaller/lighter brakes. and honestly I'd do a 35 spline Ford 9" with an aftermarket carrier and the Super Duty outers, just for the fact that I can pick up the phone and order a Nodular 9" 35 spline in pretty much whatever gear ratio for a decent price.

[zukijames]

I'm not sure if rcv got what i was saying but hopefully because 30 spline fj80 's would be sweet.

and like you said toyota breakage is usually 8 inch ring and pinion and the birfs..

9.5 center and fj80 longfield shafts and birfs is the best of both worlds..

but it is alot of money to spend to think the pinion is about the same strength

and inner shaft is weaker than 30 spline longs( unless bobby is really making 30 spline fj80 stuff)

Originally Posted by TBItoy

Good info guys, Brian, your post is the reason I started questioning my choice of axles.

BUT I'm not breaking shafts, just birfs. That is where the confusing/frustration arose.


Since Bobby is making 30/30 FJ80 Birfs I WILL buy a set. No questions asked. That sealed my axle choice for THIS rig.






I considered the D50 outers with all 35 spline stuff, but it is more $ than I want to spend, considering I would want smaller/lighter brakes. and honestly I'd do a 35 spline Ford 9" with an aftermarket carrier and the Super Duty outers, just for the fact that I can pick up the phone and order a Nodular 9" 35 spline in pretty much whatever gear ratio for a decent price.

[jeaton]

Originally Posted by TBItoy

Good info guys, Brian, your post is the reason I started questioning my choice of axles.

BUT I'm not breaking shafts, just birfs. That is where the confusing/frustration arose.


Since Bobby is making 30/30 FJ80 Birfs I WILL buy a set. No questions asked. That sealed my axle choice for THIS rig.






I considered the D50 outers with all 35 spline stuff, but it is more $ than I want to spend, considering I would want smaller/lighter brakes. and honestly I'd do a 35 spline Ford 9" with an aftermarket carrier and the Super Duty outers, just for the fact that I can pick up the phone and order a Nodular 9" 35 spline in pretty much whatever gear ratio for a decent price.

This is very true but I have arb and gear set up and my front is already linked and ready. I was going to have to cut the balls off to go the 80 route so its really not anymore work.

I look at it this way, I will have the shafts and outers ready if it warrents a change in the future but I think that I will be able to run this a long time.

[TBItoy]

Originally Posted by jeaton

This is very true but I have arb and gear set up and my front is already linked and ready. I was going to have to cut the balls off to go the 80 route so its really not anymore work.

I look at it this way, I will have the shafts and outers ready if it warrents a change in the future but I think that I will be able to run this a long time.

Yep, it makes sense for you to do the 35 spline conversion on the 9.5"

For me, not so much.

[steve_925]

i've had fj80s on my truggy for about 3 years, welded rear, spool front, 2rz. never had any problems with the rear, i've heard about the pinion shaft being the weak point of the 80 third, but i've beat the shit out of it with no issues. in the front i had a detroit with bobby inners, i was spotting my girl into a hole/ ledge and i wanted to see what the axle was capable of. low low, let out the clutch, pop. broke the short side inner, exploded the detroit. i would like to see an upgraded inner fj80 shaft, the bobby seems to be just a cromo version of stock. just stepped up to a Lexus v8 and am going to start racing so we'll see how they hold up to that kind of abuse.

[zukijames]

Originally Posted by steve_925

i've had fj80s on my truggy for about 3 years, welded rear, spool front, 2rz. never had any problems with the rear, i've heard about the pinion shaft being the weak point of the 80 third, but i've beat the shit out of it with no issues. in the front i had a detroit with bobby inners, i was spotting my girl into a hole/ ledge and i wanted to see what the axle was capable of. low low, let out the clutch, pop. broke the short side inner, exploded the detroit. i would like to see an upgraded inner fj80 shaft, the bobby seems to be just a cromo version of stock. just stepped up to a Lexus v8 and am going to start racing so we'll see how they hold up to that kind of abuse.

looks like we will have similar rigs with similar goals

[Electric-Mayhem]

If we are talking about having Longfield make different shafts for the FJ80, then its definitely worth pushing for 35 spline ones rather then 30 spline. Someone would have to make new side/spider gears for the diff (or you would have to talk to ARB and get a hybrid locker carrier). I know this got brought up in the "Want an FJ80 axle?" thread but it never went any further.

I've seen plenty of Mini-truck longfields break at the spline, and since the FJ80 birfs are a bunch larger I would think they could fit 35 spline inner shafts too. Going with a Dana 60 35 spline shaft would very likely solve a lot of issues people have been having.

Doesn't necessarily have to be Longfield....maybe RCV would be interested since they already make both Dana 60 and Toyota stuff.

[jeaton]

Originally Posted by Electric-Mayhem

If we are talking about having Longfield make different shafts for the FJ80, then its definitely worth pushing for 35 spline ones rather then 30 spline. Someone would have to make new side/spider gears for the diff (or you would have to talk to ARB and get a hybrid locker carrier). I know this got brought up in the "Want an FJ80 axle?" thread but it never went any further.

I've seen plenty of Mini-truck longfields break at the spline, and since the FJ80 birfs are a bunch larger I would think they could fit 35 spline inner shafts too. Going with a Dana 60 35 spline shaft would very likely solve a lot of issues people have been having.

Doesn't necessarily have to be Longfield....maybe RCV would be interested since they already make both Dana 60 and Toyota stuff.

I talked to Bobby about this and the problem with a 35 spline 80 birf star is that there is not enough material left to be strong. A person would have to redesign the balls and stars and then your left with a 30 spline stub. Now if you could get the 80 birf built like a Dana 60 birf where the outer stub is separate you could essentially move the fuse in your drive train to the out side with a 30 spline stub.

Tech Tim has 35 spline side gears on the shelf for ARB's and I am working on getting the part number for a LC 35 spline spool now.

I thought about trying to fit a dana 60 birf in the 80 ball but there is not enough room and then I am back to the knuckle issues and having to retro fit some kind of spindle to accommodate the 35 spline stub.

[drewp]

i dont really see the point in making fj80 birfs 35 spline, time and money and a guy could just do some ried knuckles and be done, i do see the intrigue in 35spline for the 9.5" side gears, it would be a nice alternative to the 609 id definiteley like a 609.5",
that being said im still wanting to do all fj80 for my 94singlecab truggy, however all this talk about the 24spline not being any upgrade from the 30spline minis other than the 80 birf is bigger/stronger, so if for sure there was 30spline chromo inners for the 80 then im still in to build me a 9.5" front with hellfire knuckles.
is there any numbers on an axle breaking machine comparing 30spline mini chromo to 24spline 80 chromo