Rear axle: unit bearing cups or inner c/knuckle?

[ScottRS]

What do you feel causes the down grade?


Correct. Sidewall to frame.

For a comparison, 60" wide axle with 35s is down to 4" for same frame. The front is closer to 11" with 35s which gives full turn on kingpin 60.

As noted, I'm not expecting full turning angle. My quick math for the 43s says I can pull off between 15-20 degree(~18). With 35s, that goes up a bit more(~22) I don't recall max turn angle but I thought it was 45 degree with extreme clearancing of the yokes.

Stock shafts are typically induction hardened and not very deep. By the time you cut the surface down and then cut splines into that, you're into basically unhardened core, which has much less strength than before. Guessing, 60-70% remaining, but that's just a guess.

60" WMS is pretty narrow. I'd want to be wider on 40's. But I also don't live where fender coverage is relevant and 83" wide overall is fine for what I do; YMMV.

I don't know 1550 joints. 1480 stock will bind around 38-42 degrees. I've clearanced to 48 and run at 45-46. Tire clearance usually becomes a problem on all but the most purpose built tube cars past about 40. 45 is the limit with RCV joints. Kingpin knuckles usually bind around 40, I don't know where the Superduty knuckles limit out.

20 degrees of rear steer would be big for someone who's never had it at all, and disappointing for someone who's run 45. Is your 20ish estimate assuming suspension static at some level position or full-twisted? It makes potentially several inches of difference.

 

[Phil]

What are you trying to do on Rubicon that can’t be done easily with 43s and a drag axle? Hold-my-beer hot laps around Soup Bowl? Why would you even contemplate queer steer?

 

[Bebop]

Bebop Thank you for bringing meat to the table. When I start posts, I am seeking data and not unsupported "opinions". If I'm looking at an idea, I'm looking for why it is bad and not a generic "everyone does it this way". I rarely bring up a thread seeking information with a path 100% set.

You don't need to have built a lot of axles to understand why your idea is for from being a good idea.

Now that I read the comments, I also see that you'll need special 35sp side gears vs the normal 36. I'm assuming there is a cost to that.

Just keep the stock side gears and get you some custom shafts and be done.

Stop over complicating shit that doesn't have to be.

 

[mobil1syn]

Correct. Yes, I'm considering 35sp side gears... my "local" axle guy does 35sp recuts for ~$100 a shaft.

below is from the 9 vs 60 thread that was derailed. so youre $400 into gears and then the labor to install them, so any cost saved for keeping the stock shafts steer shafts seems out the window. i feel like you are trying to justify to yourself that rear steer is cheaper. which it might be intially but will quickly snow ball.

are you building/buying housings or planning on recycling stock ones?

based on my quick research, it would appear the side gear set you are looking for is the ARB pn #728H031 and goes for $464 on summit.

 

[mdogg]

U-joints that never see any angle typically aren't happy for long. The grease on the one needle that sees all the action gets pushed away and nothing happens to move any to replace it. Eventually you end up with a flat needle and/or a dent in the cap & trunion.

I mean, I guess you could add greasing your rear axle u-joints as a frequent maintenance item, but that whole idea seems silly to me in the pursuit of saving a few hundred bucks in the scope of a ground-up vehicle project. One shit experience with a u-joint on one weekend trip and you're by far in the red with that one.

I can confirm this issue you will have running ujoints that don't steer. iv ran d60 joints in a rear steer setup that I never steered for around 200 race miles. Superjoints were seized solid due to no steering use and constant spinning.

They still worked but were not happy when I swapped them out, no idea how long you could run something like that to failure though?

 

[Lil'John]

Stock shafts are typically induction hardened and not very deep. By the time you cut the surface down and then cut splines into that, you're into basically unhardened core, which has much less strength than before. Guessing, 60-70% remaining, but that's just a guess.

Good point. Unsure if my axle guy does any heat treat work after the fact.

60" WMS is pretty narrow. I'd want to be wider on 40's. But I also don't live where fender coverage is relevant and 83" wide overall is fine for what I do; YMMV.

No chance of running 40s with a 60" WMS. I just tossed that measurement since it was one I had handy. Minimum WMS I was considering for 40s was going to be 67".

While I do have fender coverage legality issues, I don't care for 1/2 of tire outside of body.

I don't know 1550 joints. 1480 stock will bind around 38-42 degrees. I've clearanced to 48 and run at 45-46. Tire clearance usually becomes a problem on all but the most purpose built tube cars past about 40. 45 is the limit with RCV joints. Kingpin knuckles usually bind around 40, I don't know where the Superduty knuckles limit out.

20 degrees of rear steer would be big for someone who's never had it at all, and disappointing for someone who's run 45. Is your 20ish estimate assuming suspension static at some level position or full-twisted? It makes potentially several inches of difference.

My 20 degree was just static based upon measurements. I 100% understand that low tire pressure and suspension flex will impact that number "badly".

What are you trying to do on Rubicon that can’t be done easily with 43s and a drag axle? Hold-my-beer hot laps around Soup Bowl? Why would you even contemplate queer steer?

I am considering rear steer for the same reason I swapped a 472 into an FJ40 and one of my current FJ55s; shits and giggles. No other reason.

A secondary "stretch" reason for rear steer is a "single shaft" solution for trail repairs. Yes, I'm doing offset rear axle housing and not centered. Offset will try to match the front.

You don't need to have built a lot of axles to understand why your idea is for from being a good idea.

Now that I read the comments, I also see that you'll need special 35sp side gears vs the normal 36. I'm assuming there is a cost to that.

Just keep the stock side gears and get you some custom shafts and be done.

Stop over complicating shit that doesn't have to be.

For the side gears, the reason I'm considering 35sp is purely for ease of axle shaft acquiring. Several axle shaft places I've called won't do 36sp. I think it was Branik who has a reputation of being VERY slow in producing things but they would do 36sp. Do I really want to lock myself into one or two shops and then wait months for replacement shafts?

Doing 35sp does rule out using open Tundra diffs in any way.

I don't mind investigating complicated solutions which is what this thread is for. The research into other solutions is part of my enjoyment in projects.

below is from the 9 vs 60 thread that was derailed. so youre $400 into gears and then the labor to install them, so any cost saved for keeping the stock shafts steer shafts seems out the window. i feel like you are trying to justify to yourself that rear steer is cheaper. which it might be intially but will quickly snow ball.

are you building/buying housings or planning on recycling stock ones?

See above on 35 spline thought process.

On the axle housing(s), it will depend upon which project. My first attempt will be to modify a stock housing. This will help me dial in measurements. For the "big" project, it'll get Ruffstuff housings. If I end up destroying stock housings, I'll upgrade them to Ruffstuff. FWIW, I had zero issues with the stock FJ40 axle housings getting destroyed while doing Fordyce(31s) and Rubicon(35s) so I'm semi-comfortable running the modified Tundra on 35s.

I can confirm this issue you will have running ujoints that don't steer. iv ran d60 joints in a rear steer setup that I never steered for around 200 race miles. Superjoints were seized solid due to no steering use and constant spinning.

They still worked but were not happy when I swapped them out, no idea how long you could run something like that to failure though?

Thank you for throwing out your experience. The curiosity I would have is how many miles before they locked up... and then how much steer use to reset the grenade.

But your experience does hint that rear steer is only suitable for trailer queens

 

[SLOWPOKE693]

Bebop had the correct answer on page one.


My opinion:

If your wanting to do this to "save a buck" because it's a trail only beater, go for it. If you have any plans at all to street drive this thing I wouldn't even consider it. Some ideas to save a buck are stupid. This would be one of them.....

 

[Bebop]

A secondary "stretch" reason for rear steer is a "single shaft" solution for trail repairs. Yes, I'm doing offset rear axle housing and not centered. Offset will try to match the front.

Good luck with that.

For the side gears, the reason I'm considering 35sp is purely for ease of axle shaft acquiring. Several axle shaft places I've called won't do 36sp. I think it was Branik who has a reputation of being VERY slow in producing things but they would do 36sp. Do I really want to lock myself into one or two shops and then wait months for replacement shafts?

Doing 35sp does rule out using open Tundra diffs in any way.

So you're going to spend $400+ for the day you MAY need a replacement shaft quickly, but you won't spend the money to buy the right axleshafts from the begninning. Got it. 🤦

Build your axle with the same shafts left and right. Use Branik for custom 36sp shafts. With the extra $400, buy a THIRD shaft that you keep as a spare.

Now you have spent the same amount of money, don't have to wait if you ever break and can fix the rig yourself on the trail, and you have an axle that isn't a stupid contraption.

MIND BLOWN !!!!

Blahblah
But your experience does hint that rear steer is only suitable for trailer queens

No it's not. But you're going at it the wrong way.

And I can't point you in the right direction, because you'll tell me that :

Looks like we need a sticky on every offroad board that Bebop says if you don't spend hundreds and thousands of dollars you shouldn't be offroading Thanks for usual non-answer.

Sooooooo, you want to build something to do that job right, without using the right parts for the job, for cheaper than using the right parts for the job and when everyone tells you that you're going at solving your problem the wrong way, you get annoyed ?

Dude...

If there was a way to do it better and cheaper, don't you think that the people we have here, including some that have been doing this for yearssss, would have figured it out already ?

 

[Lil'John]

And Bebop is back to the "I'm right, your wrong" with no support and taking the topic off the original topic. Who would have thunk it. What little meat you've brought to the topic has been noted... the rest of your arrogant bullshit has been put into the appropriate bin.

For those that are actually here for tech, I'll steer it back onto the topic of rear steer that is locked out.

It seems like there are two issues that have been brought up:
1) U-joints with no angles will explode. One user has brought up ~200 miles to blow out a set of u-joints. The last time I talked to CTM on the topic of their bushing'd u-joints, they stated theirs aren't suitable for road speed on drive flanges/slugs. An option to fix this issue is to go with RCV axle shafts. Sure, a $2500 to $3300 price tag so a bit of a reach compared to $1200 plus u-joints for regular 4340 d60 35 spline (Branik)

2) Balljoints... this isn't clear if it is normal accelerated wear due to large tires or if it is due to additional wear/tear due to location. There is replacement HD ball joints that I can't find a link for.