I've aquired some u-joint half shafts from a small military truck and was contmeplating using them to replace my CV half shafts for more articulation. I've already put on BJ spacers and longer front shocks and the CV are what is limiting the front end now. (1991 extra cab, 3.0 TD, locked F/R). I have access to a machine shop and should be able to modify the axles (length, and adapting the ends to toyota). What I'd like to know is peoples opinion of using U-joints vs. CV's and what the next thing to bind will be. (These are very high angle u-joints).
I'm assuming my next limiting factor will be tie rods-I'm thinking maybe set up bumpstops for this, or possibly fitting a larger tie-rod set up to the truck (such as off an old chevy car?) possibly giving more strength and more articulation due to having a larger ball area.
I'd like to hear people's opinions on what would work/not work. I'm going for a 'long' travel kit without the huge price and I don't want to widen my truck at all with the fiberglass fenders or flares.
And of course eventually the BJ will limit the travel and I guess that is where I'd stop! Thanks for any ideas/opinions, I'm in Afghanistan now and won't be able to try this until March, but it'll be nice to have already planned for some of the future problems

 

OK, seriously? no one has any opinion, on yotatech?
So what is the usable angle for the factory CVs? I've heard about 22* but haven't been able to confirm this. I've been reading about how CV's are way better than u-joints and I know why. I'm just wondering if some u-joints with high angle yokes on them can operate at a greater angle than the factory CV's. I know this won't be a match for the super cool RCV CV's that just showed up, but they won't be $1600 for me either.
I figure if I can get 5 more degrees of usable angle out of them, that can be a significant increase in usable suspension articulation.

and Mods move this to the Fab shop if you think it belongs more in there. Thanks

 

its hard to have an opinion on the subject. there is only one real way to find out if there will be a benefit or not.

All in the end, if it does not work out. you should not have a problem returning to stock or going to a traditional long travel.

Also, it is always cool too try something new. If no body tried new things, we would all be driving stock yota's

 

Do IT ive learned in life to tackle everything with confidence and have been pleasantly suprised when stuff turns out one of a kind and custom, do it and post some pics!!

 

I am going to do it! I was just wondering if people knew for sure that these high angle u-joints would have more of a usable angle than the CV's. It obviously looks like they do/will, but I was worried that maybe I'm not looking/researching something enough or someone else would have already done it. I'm curious about what some of the more experienced/educated guys on here think about the outer joint doing double duty as the steering turns and the suspension cycles. On the stock vehicle this joint performed the same duty though.

 

It will be fine. Downey used to sell a kit that did this same thing. Your tie rods are still the weak point, along with the idler arm.

Stock angle is 22* on CV's.

Go for it.

 

Thanks Ike, after reading some of your threads I was wanting an input from you. The only difference in the Downey was the use of CV outer joints right? What angle would you guess I could get out of u-joints (I realize what I'm asking-tire size? driver finesse? size of u-joint? etc..). I figure even if I keep it at a mild +5* more than the CV's, that will translate into considerably more travel.

 

That will give you more travel.

What were the angles that the factory military set up used? Stick within those parameters, and you should be fine. I'd guess + 5* would be safe, but I have no data or evidence to back that up.

For even more travel, look into increasing your uptravel too. The stock uptravel comes nowhere near stressing the CV's. If you could get the ujoints to get to +5* on uptravel as well, so 27* overall, you would have some very good travel.

 

Go for it and take lots of pics.

 

I'm gonna have to jump in here with another opinion/voice of reason.

Dude! You're nuts! What are you thinking? There's no way u-joints, even "high-angle", are a good idea for this application. You aren't accounting for as much angle as they're going to be experiencing. Sure you have the angles caused by suspension travel. And very high ones at that, if you calculate in use in a long travel situation. But what about the steering axis? There's no way in hell that the u-joints won't bind up when you go to turn a corner. So do you plan on driving in a straight line all the time? No? I didn't think so.

Where u-joints are sometimes used to replace the birfields on solid axle rigs, they only move in the steering axis relative to the rest of the axle shaft. In that case they are only used for their added strength. NOT to improve articulation. The whole theory of trying to use them for that is totally flawed. The more angle you introduce to them the more ineffective they will become at allowing for shaft rotation without speed differentiation between shaft sections and/or avoiding binding. They will try and bind up, and at the very least, vibrate like crazy even with the steering axis angles not applied to the halfshaft assemblies(as in driving in a straight line).

BTW,NO, Downey did NOT create such a ridiculous setup. What they eventually sold for use with their own entirely original 14" LT systems were Porsche CVs modified with shafts splined to fit Toyota hubs and flanges made to bolt to the IFS front axle. Why? Because they were built to handle not only far more HP than stock Toyota CV halfshafts, but being fully CV halfshafts could also handle the added angles involved smoothly and efficiently.

Downey had originally copied, for the most part, the design of Rancho's LT kit that used u-joint slip yoke CV halfshafts. And seeing later that the Rancho kit was so poorly designed and conceptually flawed in that respect, they then went with the most logical replacement for them when they designed their own LT kit based on entirely original concepts and components. Which also solved the inherent problems of the naively employed u-joint slip yoke CV halfshaft system thought up by the Rancho R&D department(as if there were such a thing).

Hmmm, Toyota T-100 CV halfshafts? HINT! HINT!

High-articulation fully u-jointed halfshaft = major oxymoron!

That's even more senseless than the u-joint slip yoke CV halfshaft concept!

Sorry to rain on your parade!

But be my guest, go right ahead and try!

Just don't forget to post the pics of the carnage resulting from it. And for god's sake don't get yourself killed by thinking that it's safe to drive the vehicle as was intended by the manufacturer with such a setup. What do I mean by that? Take 'er slow while your learning how much they won't work for what you're intending. After all, bindage in the steering axis, which will occur to some extent(I can guarantee), means not being able to steer very well(if at all).

PS, have you stopped to wonder why nobody's done this before? Now might be a good time to do that. And this whole notion is borderline "dumbest things someone's told you about cars" material. I'll let it slide though, mostly because the idea hasn't been proved or disproved yet. And is still only hypothetical at this point. Though it's a very poorly thought out hypothesis without a doubt.

Are we through here?

 

Wow! let's see, I wish I was as smart as MudHippy! I mean I have already done my own diesel conversion (with the help of a couple of friends of course), put F150 springs on the back end, and oh yeah I even put BJ spacers on the front and some how knew that I had to get it aligned! I amazed I'm not dead yet!
I'm pretty sure I commented on how nobody as done this before... and I know CV's are better for this application. I wanted to know if u-joints could beat a 22* angle. If they can (which isn't too hard) then I can get more articulation out of them steering axis or not, if they can't then I won't be able to. And this may come as a shock, and it doesn't neccessarily transfer over but all of the large military trucks use a u-joint/slip yoke/CV on the ifs/irs here like the dreaded 'rancho' setup.

 

Oh yeah, and these come directly off of a pickup sized military vehicle and were used as the front halfshafts, the Aussie's use the front to steer just like we do!
In all seriousness though, I don't know the turning radius or exactly the front end travel they had, that is what they make stops for.

 

Soooooo....Downey DID use the ujoint. Contradiction there, wot? I have an old Downey catalog with those shafts pictured and for sale.

No one is arguing that this will work better than CV's. It won't. But it may work off road.

Unless I am mistaken on the OP's set up, the suspension cycling is fine. You sorta had the theory right. A CV joint maintains constant angular velocity through the joint, and thus, are ideal in a front, steering application. The CV's also allow for the axle to plunge as the suspension cycles, making it possible to use a single shaft, and therefore, allowing a lighter, smaller shaft to be used for the same strength.

U joints do not. HOWEVER, if you have two ujoints, which I am assuming the OP does, then angles cancel, and angular velocity is conserved = No vibration. This is because the Knuckle, and the axle mating flange are at nearly the same angle through suspension cycle. This does NOT work for steering, but if the wheels are kept straight, angular velocity will be conserved through the shaft, and it will operate just fine.

If you question this, you are welcome to look at any 85-89 4runner's rear drive shaft. The same principle applies. Because the diff flange and t-case flange are at the same angle, and, if the suspension is designed correctly, those angles change very little throughout the suspension cycle, angular velocity is conserved through the drive shaft, and you get no vibrations.

You can get slightly more angle out of the ujoints, so if the OP wants to fab this up, then good.

As for steering, I would leave the hubs unlocked for street driving. For offroading, it will likely be fine, but there could be some binding at full droop, and full lock on the steering. But, if you got this off of a truck that was already incorporating all of that, then I suppose it works.

I am basing my whole suspicion that this will work based off of the idea that it worked on this military truck, so why not on the toyota?

Given what the OP posted, I say, give it a go.

And good work being a dickhead. Hopefully in the future you can express a dissenting opinion without bloviating and being insulting.

 

Oh..well..you know me. I have to differ, and make that clearly known, when my inner voice tells me it's appropriate. Sure, I don't always manage to do so in the kindliest fashion. IMO I've certainly been more insulting on many prior occasions. (I'm sure you remember the days of yore when I was prone to much font sizing abuse. Atleast I've left that behind me, for the most part.) And on many occassions those whom were the target of such rebuttals may not have seen them as a means to an end. Instead seeing them as just rude, holier-than-thou, snobbery I imagine. I do, however, have my reasons and always have a desired goal I set forth to achieve with them. In almost every circumstance those desires are not selfish in origin. Particularly in this case, where I've nothing to gain from it. What do I care if I'm proven right, or if anyone believes me on this? Doesn't earn me anything. After all, it's not my time/money wasted in it's pursuit. Not my life on the line as the "driver" of a rolling death machine created by the ignorance of basic engineering design principles. Perhaps then I might have someone elses best interests in mind? But, how could that be true? Certainly it's not! I'm just a dickhead right?

Be that as it may, I still must contend that this whole notion of halfshafts without any CV joints is absolutely preposterous. There's no wonder in my mind why it hasn't been tried as a feasible option. And I won't retract any of my prior statements on it. They are what they are, and I have every reason to believe that when this little experiment is concluded, they will be proven correct. And I have no shame, or regret, in having expressed them as such.

Meaning.....

I disagree in full with most of what you've said in regards to it. But it's a free country and I'll respect your right to your own opinions.

So as to not hurt any more feelings too deeply, I'll keep my final exclamation on this matter as brief as possible.

It's an EPIC FAIL in the making. And one should be very cautious in the choosing of the arena in which to perform this ill-advised stunt. If you end up running yourself straight off a cliff while attempting it, then perhaps that's what you deserved. If you end up running someone else off the road/trail, then I hope that you are willing to face the consequences of such crimes. If you come rolling my way in such an out of control contraption...may god have mercy on your soul, because I won't.

Just one more tiny thing to consider before I head out, the possibility that the OP isn't telling the exact truth in regards to the actual construction of these alleged non-CV halfshafts. I've looked high and low for any references to such a thing in use anywhere. And what have I found? Nada. The only vehicle, military or not, that I've been able to find that even uses halfshafts of the type/design similar to the ones Rancho tried, with only one CV joint located at the steering knuckle, is an H1 Hummer. So I do NOT believe that non-CV halfshafts really are used ANYWHERE BY ANYONE for the purposes described in this thread. MMMM K? I desire a bit more proof than hearsay on this one. Sorry!

So there's a perfect opportunity for ya to get a little redemption, and to make me look stupid. Show me! Then you look smart and I look dumb. Good Luck!

 

Looks like we do have one thing in common. Neither one of us cares what the other one thinks. Personally, I don't care which one of us is right either. I have no interest in ever trying this idea.

I'll leave you to continue bashing the OP.

Have fun.

 

Not entirely true. From my POV anyways. I happen to think alot, dare I say most, of what you've contributed to this site to date has been very useful stuff. So I do care what you think, so long as it's not about me I suppose. Even there I can't help but to assign some value to your opinion. You've proven to me that you have real life experience to back up the things which you believe to be true. Such is worthy of honor and respect in my book.

But, as is life, no two people are likely to agree on everything.

This thread stopped being any fun for me before I ever chose to post in it. And my final thoughts on it have been laid out in their entirety. No more do I have, and no more shall I give.

'Till we meet again!

 

Next time I get over to the airbase I'll take a picture of the vehicle these came off. I too have tried searching for the vehicle on line so I could research if it's a f@@##$%d implementation of a bad design or not. So far I have not had any luck finding out what kind of vehicle it is. It appears that the Australians drive it, it has 5 lugs spaced like a Land Rover, 4 wheel drum brakes and a coil spring front end. The back is a FF, center dropout 3rd, with leafs.
Mudhippy, don't you think you're being just a little over the top with this supposed careening death machine rant? If these don't work, then isn't the likely outcome a busted halfshaft and trying to get out of what ever I got into in 2wd? Maybe you think I'm building this up for highspeed running? I'm not, I use my truck as a DD and roughly have it set up expedition style (or getting there anyway). And yes, it has manual hubs that will be unlocked on the street. I also plan on unbolting a torsion bar, removing bumpstops and seeing where the stock CV's and steering start binding up and if these would be an improvement. I'm asking the questions now because I'm not home and can't just go out and get the answers myself.
H1 hummers have CV's at both ends of the halfshaft. And like I said, alot of the big (5 ton type) IFS/IRS trucks have u-joints at the diff and CV's at the end just like the rancho set up, which I find kind of odd to design this on purpose due to the angular momentum problem.

 

Ok, I didn't find it in a conventional google search, but a read of Tom Woods website gave me what I was looking for.
I still don't think I would have run a family off a cliff as suggested by MudHippy but it turns out this would be a waste of time to try. According to Wood's website a conventional shaft with u-joints at both ends is really only good for a 15* angle on the u-joints. So it looks like the toyota CV's have it beat. I was really surprised at how low that angle is and that the information isn't more widely known. (we all know CV's are better.......)
I saw the centered diff thread recently posted and am probably going to try a 2" body lift followed by a 2" engine/drive train lift and see if I can move the front diff in 3" and use T-100 shafts for my better articulation plan. This way I can also scheme it to get more up travel without hitting the fenders.

 

no thats wrong it 38 degrees for 2nd gen 4runner u joints. convetional are like chevy jeep style yokes. my tcase is at 28* at ride height and it doesnt bind even on full droop

 

ill post up a pic in a minute so you can see