It's An OCD Thing, You Wouldn't Understand

[aw12345]

I had seen that at one time or another, way more trouble then it's worth, then there is still the thing that driveshafts should not run at more than 8 degree U joint angle. As fancy and good as that solution is I think the stock pillow block bearing of a 1 ton pickup is a better solution at the speeds you will travel provided the driveline angles are reasonable. They last several 100 thousand miles in pickups. Big rigs use a larger version that generally last close to half a million miles or more without any maintenance . The thing that lills em is running steep driveline angles to get around engines and crossmembers. In your case a set of warn hubs for your front axle would be a very good idea.

[inVERt'D]

David, here is a constructive observation. Since you are plenty creative, lob the front of the frame of in front of your lower control arm mounts will give you better triangulation for the lower arms, lots more room for your creations and just tube the front end. Will make a lot of things in the front easier, including a nice front end stretch. Why limit yourself to the constraints of the frame in the front. Same goes for the control arm mounts, move them to the outside of the frame and you can run a one piece driveshaft. Which will make you a lot happier in the long run. Lot of people have reliability problems with 2 piece front driveshafts. It works fine for crawling, but for hi speed driving it isn't the best solution unless you have select able hubs. Not criticizing, just trying to help you along to the path of the dark side my Swiss cheese brother

Happy to have the constructive observation or criticism, Art!

First, I intend to do a "front-half" eventually, but as silly as it may sound, I can't afford it now. Maybe I'll find my way into a set of coilovers by then and make my life simpler. Second, as far as the crossmember goes, it's part of my overall plan to use this Jeep as an experimental platform for suspension geometry. It gives me more freedom to place and move links than I could ever get by simply attaching them to the frame rails. Except, of course, that I can't place them as far outboard as the frame rails, but doing so creates roll-oversteer geometry, and I don't see any benefit in that at all.

The front driveline was what concerned me most, but in short, I believe I can solve any issues pertaining to it. I don't have any first-hand experience with two-piece front drivelines, but I did do some research before committing to one, and I've done more since. From what I've been able to gather (i.e., the following is not the gospel), the problems are generally due to a number of factors, including, but not limited to:

Alignment/ vibration problems:
1) The overall driveline angle putting the first (t-case side) shaft at an upward angle so screwing up the vertical alignment.
2) Using a two-piece driveline to go around an engine and/ or transmission, and so creating significant lateral misalignment.
3) Using a single pillow-block style carrier-bearing/ slip yoke setup with in any setup where there is misalignment in the first shaft. The proper setup for this type of carrier bearing should have as close to 0* misalignment as possible.
4) Misalignment problems in the second (pinion-side) shaft which may or may not be related to the above issues.

For a long time, the standard way of running a two-piece front DS was to use a pillow-block style carrier bearing (like the one in the rear of my Chebby pickup). Some of the go-fast guys had problems with these because the grease overheats. Seems to be a potential problem with rear DSs too. For a little perspective, it would seem this same group has problems keeping grease in double cardans as well.

Now to give myself a little credit, I started designing a fixed-yoke, double-bearing setup in my head, but before I got too far, I googled it and found the go-fasters had anticipated me by around 2-1/2 years. So I didn't invent anything totally new, but the good part to learn was that I wasn't all wet, and racers have been using similar setups successfully. The other thing I learned was that the more successful designs were using tapered roller bearings in oil baths. I had fully intended to use tapered bearings, but hoped I'd get away with grease, since it works for my wheel bearings. Maybe not, since the DS spins faster.

Several vendors are now advertising these, but here's the earliest thread I've found on the subject. As far as I know this is the original. If you notice, he started with a zerk, but mentions abandoning grease for gear oil.
http://www.pirate4x4.com/forum/gener...aft-vibes.html

EDIT: This thread from 2009 is actually the oldest I've found, I just hadn't realized that:
http://www.pirate4x4.com/forum/gener...l#post10305755

[aw12345]

David, here is a constructive observation. Since you are plenty creative, lob the front of the frame of in front of your lower control arm mounts will give you better triangulation for the lower arms, lots more room for your creations and just tube the front end. Will make a lot of things in the front easier, including a nice front end stretch. Why limit yourself to the constraints of the frame in the front. Same goes for the control arm mounts, move them to the outside of the frame and you can run a one piece driveshaft. Which will make you a lot happier in the long run. Lot of people have reliability problems with 2 piece front driveshafts. It works fine for crawling, but for hi speed driving it isn't the best solution unless you have select able hubs. Not criticizing, just trying to help you along to the path of the dark side my Swiss cheese brother

[inVERt'D]

Scrap metal art/ Front LCA Crossmember (cont.)

Made the basic frame bracketry first, since it would help with checking fitment. Did I already say it's going to be tight in there?


Cut some notches out for the body mount brackets. This is just the rough shape I used for early mockups. They will be more streamlined and the square access holes will be cut into the bottoms.



They go kinda like this. I think I moved the vertical part to the middle after these were taken. There will be fully tied to the frame rails before it's all over.


Drilling holes in tabs. LCA tabs on the left, and v.1 frame-side brackets on the right. At this point I was still entertaining the idea of making the crossmember height adjustable. If I stayed on that course, I would have eventually made 5-hole laminates to go over these. Instead of (5) 1/2” bolt holes, the brackets will have (2) 5/8” bolt holes. Like I said earlier, I decided the adjustability wasn't worthwhile. There just isn't enough room to go higher, and going lower means worse ground clearance. I decided I could later make a higher-clearance crossmember for rock crawling.


My first idea on how to configure the tabs. Ended up changing the tabs a little, and their configuration too. The ones with the thick vertical parts were moved to the outboard and aft sides of the crossmember. I'm just showing you this stuff to cornfuse you.


Some of you may hate this. Not a great pic, but here's a shot that shows an early mock-up. The crossmember is just resting on the bracket, and will be 1/4” lower as per the drawings. The fore-to-aft position is a close approximation. I plan to make ramps for the rears of the tabs to make them more slippery when backing up.


More on its way...

[inVERt'D]

Scrap Metal Art

Floor board for an old fork lift is some great 1/4” scrap.



Some of the nicer scrap metal around here. Left over scraps from a bridge project or something, and the anti-rust paint/primer really works. 1/2" high-quality mild steel = medium-duty tabs. I can't make the rocks duck, but maybe I can make some of them wish they did. Also in view is the 2x2, .250" tubing that will form the core of the crossmember.


Saw a bit of rusty steel in the dirt, kicked it, and up popped some 1/4" plate. Lucky day! It's good to be a redneck.

[inVERt'D]

Another thing I had to work out was the shape of the LCA tabs. Below is an unfinished version 1 drawing. It was designed for to get some decent ground clearance, and hopefully not too much anti-dive geometry (the front counterpart of anti-squat). The larger circle is the outside diameter of a ballistic joint ~3”. This design doesn't protect the joint very well. I drew some different versions of this that protected the joints better, gave better anti-dive (AD) numbers, etc., but I'll spare you. Note that the bottom of the crossmember tubing is flush with the bottom of the frame.


After doing some more research and playing with the 3-link calculator some more, I realized that the best AD numbers (according to prevailing thought) would require me to place the brackets where they would hang up on the rocks. I screwed around with a design that would allow me to raise and lower the entire crossmember, but decided it wasn't worth it. I decided to go with the best AD numbers. Since the crossmember is removable, I could make a high-clearance version later and compare the performance. I'd rather start with better performance and know what I'd given up for better clearance. That would be educational.

As a side-note, another way to improve AD geometry would have been to move the brackets back quite a bit further, but I don't like the options that leaves me with for a crossmember.

Below is the v.2 link tab, which is used on the v.1 crossmember. The v.2 crossmember will probably mount the link ends somewhere in the neighborhood of the v.1 tab's positions.


Comparison of versions 1 & 2

[inVERt'D]

Yeah, a double cardan at each end of that section of shaft. It allows you to wrap the driveshaft into multiple compound angles without vibrations. Look up LP magazine driveshaftology. They have a good example on an offset diff being fed from a Dana 20.

I'll look into it. I have a couple I could probably use.

Worth on the street is that two piece driveshafts on the front suffer from reliability problems.

If that's the case, there's a reason for it, and possibly a good solution too.

[aw12345]

Worth on the street is that two piece driveshafts on the front suffer from reliability problems.

[6spdYJ]

Sorry I missed your reply earlier. I'm kinda out of it today. More out of it tonight. A double-double cardan?? Are you serious?

Well, I'm really tired. I'll try to figure out what you're saying tomorrow.

Yeah, a double cardan at each end of that section of shaft. It allows you to wrap the driveshaft into multiple compound angles without vibrations. Look up LP magazine driveshaftology. They have a good example on an offset diff being fed from a Dana 20.

[inVERt'D]

You can also do a double-double cardan between the t/c and the hanger bearing to maximize the re-directing while allowing the shaft to the pinion to stay as long as possible. If the front section of shaft has the rear u-joint in line with the lca mounts, you should have no issues.

That drawing is sorta conceptual. It's not a contract drawing if you know what I mean. I may clock the t-case a notch to move the front output down. Would be a good thing for a number of reasons. At any rate, I don't anticipate the need for a double cardan on the t-case side, and the pinion side should be sufficiently long. I plan to stretch the front eventually anyway.

So how far along with this project are you? I really want to be there for your break in run. Ooops! Sorry, used the word BREAK. I meant inaugural...

Smartass. The front crossmember is pretty much done. The frame bracketry is probably 3/4 done. I'm screwing with the HP30 now, but I've been putting more time into unrelated projects. I expect it all to be solid, but I can tell you this, if the front crossmember breaks, DON'T follow me

[RAT]

So how far along with this project are you? I really want to be there for your break in run. Ooops! Sorry, used the word BREAK. I meant inaugural...

[inVERt'D]

You can also do a double-double cardan between the t/c and the hanger bearing to maximize the re-directing while allowing the shaft to the pinion to stay as long as possible. If the front section of shaft has the rear u-joint in line with the lca mounts, you should have no issues.

Man, it sure is fun to tell you how to spend your money and time

Sorry I missed your reply earlier. I'm kinda out of it today. More out of it tonight. A double-double cardan?? Are you serious?

Well, I'm really tired. I'll try to figure out what you're saying tomorrow.

[inVERt'D]

Is his name by any chance Rube Goldberg?

Ha ha. Even my Chebby as a two-piece drive shaft. I wanted a fixed yoke setup and was pleased to find I'm not the only one who's crazy.

http://www.pirate4x4.com/forum/misce...ing-mount.html

[6spdYJ]

You can also do a double-double cardan between the t/c and the hanger bearing to maximize the re-directing while allowing the shaft to the pinion to stay as long as possible. If the front section of shaft has the rear u-joint in line with the lca mounts, you should have no issues.

Man, it sure is fun to tell you how to spend your money and time

[RAT]

Here's a diagram. I paid a professional to do this.

Is his name by any chance Rube Goldberg?