Front Driveshaft angularity - Maximum U-joint Angle??

[Greg72]

Doing some calculations for the "Might As Well" build.

With the driveline in place, the front driveshaft is a total of 42" long. YES, that's right....it's about 6" longer than the rear driveshaft!!!

I'm not running much lift (maybe 7" total) and by my calculations, the current u-joint angle at the D60 yoke is 22.39 degrees. That does not account for the fact that the pinion is turned up slightly toward the xfercase (10 degrees)...so my effective operating angle should subract that out.... for a total operating u-joint angle of 12.39 degrees.

Sounds good....except that I'll end up with a miserably long front driveshaft that is going to be a rock-magnet because it's sticking out across almost half of the underside of the truck!!

My thought is to build a 2-piece front driveshaft with a carrier bearing at the pivot. This will allow me to run a straight section of driveline parallel to the frame (up out of harms way) and then drop a much shorter front driveshaft more directly to the yoke of the D60. I've been playing around with a few numbers, and effective u-joint angles.

10" straight section / 32.9" driveshaft = 19.03 degrees @ u-joint
12" straight section / 31.2" driveshaft = 20.81 degrees @ u-joint
16" straight section / 27.8" driveshaft = 25.02 degrees @ u-joint

Remember, those angles already account for the 10 degrees of angle that are in the D60 pinion, which make the angles look better than if the yoke was 100% parallel to the ground.

I haven't run the calcs yet for when the suspension cycles (up or down) either way is going to make those operating angles worse... the question is by how much. I'll figure that out later tonight or tomorrow.

Ultimately, what I want to know now is:

What is the maximum safe operating angle for a front u-joint? I am assuming that the D60 is a 1350 style yoke, since I haven't swapped out whatever it came with stock. I realize that unlike a rear u-joint, it will not see 100% duty cycle, but I also don't want to be spitting out joints left-and-right on the trails because I am running too steep of a driveline angle.

Any input???

 

[4X4HIGH]

If you look at just about any driveline related shop info you'll see that 3* working angle is the max you should run, obviously that isn't going to happen in a 4x4 rig. Your best bet is to figure out how much droop and stuff you'll have and then determine if the u-joint is going to bind anywhere. As long as the joint isn't binding you should be ok.

 

[sloth]

Is your short transfercase-side shaft parallel to the ground? If so, see if you have enough room to angle it down towards the front pinion; you may have to be a little creative in how you mount the carrier bearing. I did this on a heavily modded CJ7 that had the t-case rotated up for clearance and it really helped to reduce the angles while still keeping the carrier bearing/center joint above the bottom of the frame. I ran a CV at the t-case since the joint angles on that shaft were not supplementary. Don't know if it will work with your setup, just an idea.

-Mike

 

[DPI]

This is a handy little chart. I would skip the 1350 joint and go with the 1410. I tried a 1350 CV and it busted the first trip out with my Atlas, before the 241 doubler. Then went with the Tom Woods offset trunion and experienced terrible vibration. I then added the doubler and the 1410 joint at the case and have had zero issues with that. My final front shaft length is 38" IIRC with 6" of BDS springs up front.

 

[Greg72]

What is the standard yoke on a D60? Is it a 1350?

I just yanked off two yokes from the Atlas-4 and replaced them with H.A.D. flanges (I already have a CV-style rear driveshaft I'm reusing, and I thought I'd do one up front too)

I guess there's a chance I might already have 1410 yoke "spares", so it would be easy enough to swap one onto the D60.

Interesting idea about using the carrier bearing to reduce the overall angularity... On a 2-piece driveshaft, where does the CV go? I'm assuming that the straight section is regular yokes on both ends, and the CV-flange comes off the carrier bearing before heading down to the front axle???

 

[MTBLAZER89]

Greg,

1310 is stock on a Dana 60.

Maybe Chaddy will pop in here. he runs a carrier bearing on a two piece front shaft with his case locked above the frame rails. This was the solution for him to the angles with a clocked case.

I have a similar lift 6-7" and a shorter shaft and my angles look ok to me and I havent done anything with my 60 pinion as far as shimming it up.

 

[bp71k5]

Have you thought about REALLY rotating the pinion up like the second illustration?

 

[Hogback Fabrication]

Have you thought about REALLY rotating the pinion up like the second illustration?

Its the best for pinion yoke and driveshaft clearance but the pinion bearings will starve for oil (unless its a trailed trail only rig and the diff is overfilled). IIRC 10 or 15 degrees is the absolute max to tilt the pinion.

 

[throttleissues]

Have you thought about REALLY rotating the pinion up like the second illustration?

When susp travels up, it would break the u-joint at the pinion from putting it in an extreme angle. That looks great stationary, but doesn't work with susp movement.This whole thread is an interesting idea, and I'd like to see what comes of it. I think you could put a CV at the xfer case and single cardans at the carrier and pinion. That should allow you to angle the stationary section without any problems.

 

[Hogback Fabrication]

When susp travels up, it would break the u-joint at the pinion from putting it in an extreme angle. That looks great stationary, but doesn't work with susp movement.

That's not true at all, it depends on the operating angle and max operating angle of the joint.

If what you are saying is inherently true, the more conventional setup (the first picture) would cause binding when the suspension travels down.

My rear driveshaft is setup like the second picture and works very well.

This whole thread is an interesting idea, and I'd like to see what comes of it. I think you could put a CV at the xfer case and single cardans at the carrier and pinion. That should allow you to angle the stationary section without any problems.

Why put a cv at the t-case? The section of driveshaft up to the carrier bearing will have ~0 degrees of operating angle.

 

[throttleissues]

OK, 383, I'd really like to see pics of that. If yours is set up this way, it must be with VERY shallow angles, not like the pic. The problem would be that one angle gets more obtuse as the other becomes more acute. This means your driveshaft would only be at proper angles at ride height.
The second part of your post shows that you didn't read my WHOLE post. I was referring to angling the first section slightly to help the angles on the active shaft, that's why I made reference to being able to angle the stationary section without vibration problems. Fock, that's what I get for trying to help out.

 

[Hogback Fabrication]

Fock, that's what I get for trying to help out.

First, don't take any of my posts as confrontational. I don't mean them that way, just trying to keep facts out there

OK, 383, I'd really like to see pics of that. If yours is set up this way, it must be with VERY shallow angles, not like the pic. The problem would be that one angle gets more obtuse as the other becomes more acute. This means your driveshaft would only be at proper angles at ride height.

Explain this to me:

How does this setup bind in uptravel:

But this setup does not bind in downtravel?

Neither setup inherently binds. Both could bind based on the operating angles involved and the joints used. Neither one binds easier than the other. Don't forget that the drawings are greatly exaggerated.

The second part of your post shows that you didn't read my WHOLE post. I was referring to angling the first section slightly to help the angles on the active shaft, that's why I made reference to being able to angle the stationary section without vibration problems.

Yep, I missed that part. The cv still isn't necessary though because if you setup the pillow block correctly the two u-joint angles will be the same and you shouldn't get any vibration from that part of the shaft.

 

[MTBLAZER89]

Something else I learned the other day while setting up the angles for my new perches. The pinion angle to driveshaft angle really doesn't change as much as i though it would through travel. Maybe a few degrees.

I set my pinion up with my drive shaft at 0* difference at full droop. When i got it to ride height I only had to bring the pinion up a few degrees to get it back to 0.

The pinion does move in an arc as the shacle angle changes but the angle of the driveshaft also goes up or down so the difference is minimal.

I think if your angles are ok at ride height then they will be ok at either end of travel. The CV is usally what people have issues with binding not the actual joint at the pinion.

Front axle is a little different I am sure because you can get the one side way down where as having the whole axle droooped isn't real common.

Just some info I discovered while measuring angles and cycling my suspension the other day

 

[bp71k5]

Greg,

You might also consider a bigger CV driveshaft instead of a standard shaft. The 1350 I just had built is much bigger in the CV section than my old one. This effectively moves the transfer case side ujoint forward before is starts dropping toward the axle. I'd estimate the length of the CV section is at least 6". I'd have to guess a 1410 is even longer and might be close to your straight section length of 8"-10".

 

[Greg72]

This is all great information and disussion folks, please keep the ideas coming!

Keep in mind that we are talking about the setup for a FRONT D60 axle....so rotating the pumpkin up is not going to happen. This will mess up the caster numbers horribly, and I'm not willing to cut-and-turn the C's (and machine the passenger side spring pad!) to maintain the proper caster settings.

This will be a street & trail truck, so the solution will be required to operate smoothly in both environments.



After reading some of these ideas, I wonder if there is merit to installing the "straight" section with a few degrees of offset in it to lower the height of it before it gets to the carrier bearing...??

THE CALCS:

If I installed a 12" straight section and set it up to drop 4" lower than the front output....I'd be running the u-joints at both ends at the same 8.4 degrees. That would mean that instead of dropping a total of 16 inches (from carrier bearing to D60 yoke), the total distance I'd be dropping down would only be 12"....and the resulting efffective u-joint angle at the pinion would only be 14.1 degrees!!! Quite good. If I set up that 12" section correctly, the u-joints would both be at 8.4 degrees at both ends...so there shouldn't be any vibration or phasing issues.

I need to sip a bit more coffee and re-read all the replies again. Good stuff!

 

[throttleissues]

But this setup does not bind in downtravel?

Neither setup inherently binds. Both could bind based on the operating angles involved and the joints used. Neither one binds easier than the other. Don't forget that the drawings are greatly exaggerated.




Yep, I missed that part. The cv still isn't necessary though because if you setup the pillow block correctly the two u-joint angles will be the same and you shouldn't get any vibration from that part of the shaft.

Granted that neither inherently binds , but you have to admit my point about the angles moving aaway from balance with any movement in the pinion-up pic. Anyway, yes, this one would bind in downtravel, but it also looks like the d-shaft in most of the Wranglers I've seen.The CV is necessary to balance the angles IF the pinion is tilted up to a different angle than xfer case output AND first section of d-shaft (from xfer case) is tilted down (rather than run parallel to output shaft), because overall angle between xfer case and pinion wouldn't match. On the other hand, it's a front shaft and he may not care about a little vibration.Just have to keep in mind that 2 single-cardans will only balance out an angle consistently if the output and pinion are parallel(exept for the couple degrees down for torque-up).

 

[Greg72]

What's someone in Palmdale, CA doing awake this early in the morning??

The west coast guys usually don't check in around here until noon (EST)

 

[1979jimmy350]

if your going to use a 2 peice shaft on the rear portion of it, you need some down angle, a flat shaft with no angle is just as bad as to much angle. Plus if you slope the first part to the carrier bearign down you get better angle on your front portion. What you could do is run a single ujoint at the transfer case run that to a carrier bearing, then on the spline shaft that comes out of the carrier bearing you can use a double cardian that has a slip built into one end then runt the shaft to the diff, this should provide you with a lot of angulation.

 

[Chaddy]

Here is my 2 piece drive line.

 

[muddybuddy]

i was just gona say chaddy has a 2piece setup up front