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Old 07-30-2015, 09:39 AM   #1 (permalink)
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CV/Double Cardan geometry and Radius Arms

I’m nearly finished setting up new axles and powertrain under my DII, but still retaining the factory radius arms. I’m at the point where I need to make a decision before finish welding and having my 1350 CV drivelines made. The High Angle Driveline website shows to actually point the pinion down a couple degrees from the TC, so that’s how I set it up. It is true that this allows the bearing caps to rotate slightly allowing for better lubrication of the needle bearings. But I’m also thinking now that this full 2 deg down recommendation is probably for a leaf spring suspension that will twist while under throttle. With a radius arm setup I don't think the bushings will allow the axle to twist much at all, so I’m thinking of rotating the pinion back up so it’s pointing directly at the TC.

Once this is burned in it will be a huge bitch to cut apart and re-weld it, so I would rather do it just once. Thoughts?
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Old 07-30-2015, 03:12 PM   #2 (permalink)
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Because you have a double cardan joit at the transfer end, the normal U-joint at the diff end, needs to have a small operating angle of about 1 (min) to 3 (max) degrees to reduce driveline vibration, but still ensure that the needle rollers get rotated, as the driveshaft turns, to share the load between all of the rollers.

If the U-joint was perfectly straight, it would be good for eliminating vibration, but the needle rollers would not turn so the few carrying all of the load, all of the time, would become damaged and the joint will wear/fail prematurely.

If the pinion points up a little, rather than down, it will reduce the operating angle of the double cardan joint, which is a good thing, plus it gets the driveshaft a little higher out of the rocks.
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Old 07-30-2015, 03:44 PM   #3 (permalink)
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I'd be a bit nervous about pointing the diff up past zero, unless I put another DC joint at the pinion. I already have good pinion clearance with the 37's.

I just double checked and the DC joint is at 14 deg at ride height. I have the pinion pointed down a little over 1 deg. Maybe I'll leave it alone.
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Old 07-31-2015, 07:12 AM   #4 (permalink)
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Your running 37's and have the pinion pointed down…

biggest problem your gonna have is the the radius arms are to short
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Old 07-31-2015, 03:20 PM   #5 (permalink)
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I'd be a bit nervous about pointing the diff up past zero, unless I put another DC joint at the pinion. I already have good pinion clearance with the 37's.

I just double checked and the DC joint is at 14 deg at ride height. I have the pinion pointed down a little over 1 deg. Maybe I'll leave it alone.
Either your not understanding what are required/acceptable operating angles for a driveline with double cardan and normal U-joints, or I'm not understanding your descriptions/terminology.
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Old 07-31-2015, 03:28 PM   #6 (permalink)
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Either your not understanding what are required/acceptable operating angles for a driveline with double cardan and normal U-joints, or I'm not understanding your descriptions/terminology.
I understand fully. The pinion needs to be pointed directly at the TC output to run a DC driveline, within a few degrees.

The point of this thread is to determine if the diagram on the high angle drivelines website only applies to a leaf sprung vehicle (leaf springs twist under load, altering the pinion angle), or if I should consider it on a vehicle with radius arms as well. Click the link and look at the diagram. My setup is almost exactly as drawn.
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Old 07-31-2015, 03:58 PM   #7 (permalink)
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I understand fully. The pinion needs to be pointed directly at the TC output to run a DC driveline, within a few degrees.

The point of this thread is to determine if the diagram on the high angle drivelines website only applies to a leaf sprung vehicle (leaf springs twist under load, altering the pinion angle), or if I should consider it on a vehicle with radius arms as well. Click the link and look at the diagram. My setup is almost exactly as drawn.
There's a strange device called a telephone…if you use it correctly, you can actually talk to the vendor and have them answer your question

Still curious about your set-up using stock radius arms
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1983 110 RHD Pick-up

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Old 07-31-2015, 04:21 PM   #8 (permalink)
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There's a strange device called a telephone…if you use it correctly, you can actually talk to the vendor and have them answer your question

Still curious about your set-up using stock radius arms
Yea you're right. It probably doesn't make sense to ask a question about the geometry of a specific type of radius arm from the guys who run them everyday

The axles are D70S rear, D60 front.
H1 wheels/tires
NP241c TC
Duramax Diesel
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Old 07-31-2015, 04:46 PM   #9 (permalink)
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You can count on one hand the amount of guy's on this forum running d2's, which are nothing like a D1 or 90...

doing a axle swap and retaining anything from the original suspension isn't exactly the smartest thing

running a DC driveshafts front and rear…this should help…(stolen from Tom Woods site www.4xshaft.com)
Attached Images
  
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1983 110 RHD Pick-up

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Old 07-31-2015, 05:11 PM   #10 (permalink)
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Did not one person click the fucking link in my first post?

My driveline is setup as shown in your second pic, but the diff is pointed down from the TC just slightly over 1 deg... ah fuck it. This is clearly a waste of time.
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Old 07-31-2015, 05:23 PM   #11 (permalink)
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link doesn't work asshat…
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Old 07-31-2015, 05:32 PM   #12 (permalink)
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link doesn't work asshat…
Works for me dick...

I'll break it down for you

High Angle Drivline-Call Jesse at 530-877-2875 - My Buildup
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Old 07-31-2015, 05:51 PM   #13 (permalink)
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So your building a suspension that doesn't allow you to adjust the pinion angle a couple of degrees once the brackets are welded up.

Shear brilliance…
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Old 07-31-2015, 05:53 PM   #14 (permalink)
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So your building a suspension that doesn't allow you to adjust the pinion angle a couple of degrees once the brackets are welded up.

Shear brilliance…
Have you seen a Discovery Radius arm before? There is no adjustment.
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Old 07-31-2015, 06:00 PM   #15 (permalink)
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Exactly…and they are too short if you run anything bigger that 3" lift spring. To go thru all the work to do a axle swap and not improve the limited design of the stock suspension is retarded.

So are you running a watts linkage on the rear axle also with the stock rear arms too
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Old 07-31-2015, 08:23 PM   #16 (permalink)
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Exactly…and they are too short if you run anything bigger that 3" lift spring. To go thru all the work to do a axle swap and not improve the limited design of the stock suspension is retarded.

So are you running a watts linkage on the rear axle also with the stock rear arms too
I disagree completely. The discovery suspension is actually very good compared to jeeps or any other factory off road suspension with short stamped steel links. The suspension is an area I have to give LR some credit. I'm only running 10" travel shocks, which keeps the geometry well within the working range of a 1350 DC joint. I could have gone though the trouble to build a link suspension (4 or radius), but I quickly realized that would be a waste of time with such short travel shocks and my intended uses. I don't drive over the terrain that Buck does. This is an overland/trail rig. If I wanted to climb rocks I wouldn't waste my time with any full bodied vehicle, I'd build a buggy from scratch.

I've got a 1.5" .250 wall panhard in front, but yes, the factory Watts out back attached to a truss over the rear diff. I set up the watts to have more travel than my shocks will allow by far. I'm never going to punch holes in the body for longer shocks, so the watts is perfect.

The frame has been plated with 1/4" steel where I've made my mounts (the LR frame is shockingly thin). Every bracket is 1/4" plate. Although I've doubled the horsepower and torque of this rig, I'm not the least bit concerned about the strength of the suspension. This is not a rock bouncer or KOH rig. It's more than I need for what I plan to do with it.

Right now I'm only concerned about setting up the drivelines properly, and we're way, way off topic. Not that I'm surprised. You ask a question here and every other part of your build get's criticized in the process. Total waste of time
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Old 08-01-2015, 04:43 AM   #17 (permalink)
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Did not one person click the fucking link in my first post?

My driveline is setup as shown in your second pic, but the diff is pointed down from the TC just slightly over 1 deg... ah fuck it. This is clearly a waste of time.
You'll be fine, If anything I would aim for closer to 2'. I have more than 2' difference on mine and have not noticed any issues. For reasons stated before obviously you don't want to go with 0'.
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Old 08-01-2015, 07:56 AM   #18 (permalink)
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I disagree completely. The discovery suspension is actually very good compared to jeeps or any other factory off road suspension with short stamped steel links. The suspension is an area I have to give LR some credit. I'm only running 10" travel shocks, which keeps the geometry well within the working range of a 1350 DC joint. I could have gone though the trouble to build a link suspension (4 or radius), but I quickly realized that would be a waste of time with such short travel shocks and my intended uses. I don't drive over the terrain that Buck does. This is an overland/trail rig. If I wanted to climb rocks I wouldn't waste my time with any full bodied vehicle, I'd build a buggy from scratch.

I've got a 1.5" .250 wall panhard in front, but yes, the factory Watts out back attached to a truss over the rear diff. I set up the watts to have more travel than my shocks will allow by far. I'm never going to punch holes in the body for longer shocks, so the watts is perfect.

The frame has been plated with 1/4" steel where I've made my mounts (the LR frame is shockingly thin). Every bracket is 1/4" plate. Although I've doubled the horsepower and torque of this rig, I'm not the least bit concerned about the strength of the suspension. This is not a rock bouncer or KOH rig. It's more than I need for what I plan to do with it.

Right now I'm only concerned about setting up the drivelines properly, and we're way, way off topic. Not that I'm surprised. You ask a question here and every other part of your build get's criticized in the process. Total waste of time
Because it all it related and not a simple question, set it up for the 2* or leave it alone. I asked because you need to factor in suspension travel and with the way you've described your setup, that won't be a problem because there'll be little, if any...
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Old 08-01-2015, 11:17 AM   #19 (permalink)
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You'll be fine, If anything I would aim for closer to 2'. I have more than 2' difference on mine and have not noticed any issues. For reasons stated before obviously you don't want to go with 0'.
Thanks.
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Old 08-01-2015, 04:27 PM   #20 (permalink)
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I understand fully. The pinion needs to be pointed directly at the TC output to run a DC driveline, within a few degrees.

The point of this thread is to determine if the diagram on the high angle drivelines website only applies to a leaf sprung vehicle (leaf springs twist under load, altering the pinion angle), or if I should consider it on a vehicle with radius arms as well. Click the link and look at the diagram. My setup is almost exactly as drawn.
Going by statements/questions in you posts (this thread), you don't fully understand.

If you go back to post #2, I told you why the U-joint at the diff should be aligned to operate at an angle between 1 and 3 degrees. It has nothing to do with whether the suspension has leaf springs or radius arms.

If you fully understand then WTF would you say, in response to my earlier post,
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I'd be a bit nervous about pointing the diff up past zero, unless I put another DC joint at the pinion.
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Old 08-01-2015, 07:41 PM   #21 (permalink)
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Going by statements/questions in you posts (this thread), you don't fully understand.

If you go back to post #2, I told you why the U-joint at the diff should be aligned to operate at an angle between 1 and 3 degrees. It has nothing to do with whether the suspension has leaf springs or radius arms.

If you fully understand then WTF would you say, in response to my earlier post,
Jesus Christ you fuck tards just like to argue. No wonder nobody posts anything interesting here.

It has everything to do with the type of suspension. Leaf springs wrap, allowing the axle to twist more than it would with bushing/link suspension. The question all along was to how much, but you idiots can't get your head around that question.

First, never point the diff up beyond 0 (or directly in line with the TC) because you will have vibrations. It should always be 0, or 1-2 deg BELOW for better u-joint life.

Read the fucking BillaVista driveshaft bible. Here, I'll do you a favor and provide the exact excerpt with the relevant information:

"The second operating angle should be within 0.5° (1/2)° of the first AT CRUISE THROTTLE. This is a critical point. virtually every axle (to a greater or lesser degree, depending on power and suspension) will experience some "axle wrap" or pinion rotation ( pinion rotates up in rear axle, and down in front axle) depending on acceleration and to some extent braking torque. This will of course alter the geometry of the pinion, and therefore the whole driveshaft! Since the driveshaft will presumably spend most of it's time (and therefore the effects of it's vibrations will be most annoying and damaging) in a cruise throttle condition, it is standard practice to set driveshaft geometry for this state (If you have a highly specialized vehicle, like a drag car, this may not apply - and you will want to discuss your needs with an expert like Jess at High Angle Driveline). Generally, for most truck rear axles, at cruise, the pinion will rotate up 1-2° from its static position. As such, it is common practice to shim the axle or adjust the links, rotating the pinion and changing the pinion slope at rests, such that the pinion slope is 2° lower than that required to achieve equal operating angles at rest. Read that bit again, carefully! It's a bit of a juggle, because as you adjust the pinion slope itself, so you also actually alter the driveshafts slope, and therefore the transfer case operating angle as well. Once you get close though, you will easily end up at the correct balance point. the point I'm making is, don't just make a whopping 20° change to the pinion angle, then weld those spring perches on and call it done. That big of a change will have effected things, so you'd have to measure and re-calc all the slopes and operating angles again, as you hone in on the final setting"

Don't jump all over me when it is you that don't have a fucking clue what you're talking about.
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Old 08-01-2015, 07:55 PM   #22 (permalink)
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I really think you are a retard…
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Old 08-01-2015, 09:41 PM   #23 (permalink)
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I really think you are a retard…
Was just thinking the same thing about a couple of you...
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Old 08-03-2015, 11:00 AM   #24 (permalink)
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Was just thinking the same thing about a couple of you...
It's not as though there aren't a handful of engineers on this board or anything.

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Old 08-03-2015, 11:15 AM   #25 (permalink)
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It's not as though there aren't a handful of engineers on this board or anything.

Clearly none of them are posting in this thread.
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