Driveshaft Basics: Double Cardan

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woytovich

woytovich

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Given stock Toyota FJ60 drive shafts (standard and double cardan):

1. Is it true that one can use a double cardan drive shaft in place of a "standard" driveshaft without any other modifications (Presuming lengths are correct)?

2. Is it true, in general, that a DC shaft of a given length will handle a steeper angle better than a standard Toyota OEM shaft of that same length? (Given that the angle is within the acceptable range of the particular shaft/joints)

3. Will a DC shaft handle a difference in pinion angles between the diff and the transfer case better than a standard shaft?

Thanks,
mark
 
1. No. There were two driveshaft bolt patterns for the LCs between the 40 and 80. The early 60 had the rectangular bolt pattern which is the same as the mini trucks and older LCs. The later 60 had the square bolt pattern which is shared with the 80. As a result, if you put the early 60 or mini DC shaft on a later 60, 62 or 80, you'll have to drill the older pattern into the transfer case output flanges.

As a second point, the lower u-joint in a DC shaft needs to be a degree or two lower than perpendicular to the driveshaft tube when sitting on flat ground. This typically means that the pinion needs to be turned up from stock, meaning that you need to cut off the old and weld on new spring perches for the rear and typically a C&T for the front.

2. Question doesn't make sense. What does "handle a steeper angle better" mean if you're only running the joint within its specified range? The question you should ask is "Does a DC driveshaft have a larger operating range than a regular driveshaft?". If you asked my proposed question, the answer is yes.

3. Yes. The DC joint will typically give you less vibrations than a standard shaft in SOA or high SUA lift trucks. I've run a DC joint in Moonshine since the SOA was done in 2009. No noticeable vibes at any speed up to 75mph.
 
GLTHFJ60 said:
1. No....
Click to expand...

I'm not worried about flanges - drilling a flange is not the kind of mod I was talking about.


GLTHFJ60 said:
As a second point, the lower u-joint in a DC shaft needs to be a degree or two lower than perpendicular to the driveshaft tube when sitting on flat ground. This typically means that the pinion needs to be turned up from stock, meaning that you need to cut off the old and weld on new spring perches for the rear and typically a C&T for the front.
Click to expand...

Sorry, I'm not following you 100%...

What is the "lower u-joint"? Do you mean the single end of the driveshaft?

"when sitting on flat ground" - I presume you mean the truck is sitting on flat ground at rest.

So, other than the 1-2 degrees off of perpendicular, that single end u-joint needs to be (basically) straight on (not articulated)? So if this is the case, what was the arrangement with the DC in the early FJ60s?


GLTHFJ60 said:
2. Question doesn't make sense. What does "handle a steeper angle better" mean if you're only running the joint within its specified range? The question you should ask is "Does a DC driveshaft have a larger operating range than a regular driveshaft?". If you asked my proposed question, the answer is yes.
Click to expand...

Yes... I meant what you said (I think the question is basically the same...)

Thanks Johnny...
 
woytovich said:
I'm not worried about flanges - drilling a flange is not the kind of mod I was talking about.
Click to expand...

Didn't think so, but wanted to make sure :D

woytovich said:
Sorry, I'm not following you 100%...

What is the "lower u-joint"? Do you mean the single end of the driveshaft?

"when sitting on flat ground" - I presume you mean the truck is sitting on flat ground at rest.

So, other than the 1-2 degrees off of perpendicular, that single end u-joint needs to be (basically) straight on (not articulated)? So if this is the case, what was the arrangement with the DC in the early FJ60s?
Click to expand...

Lower u-joint as in the u-joint at the differential.

"When sitting on flat ground" means yes, sitting on flat ground at rest, not moving, suspension not 'flexed out' at all. All 4 tires are at the same elevation.


Correct, the lower, or single end, u-joint needs to be close to straight on. This is because two joints operating at opposite orientations are going to cancel out vibrations. This is why in the later 60 setup, the face of the transfer case output flange is parallel to the face of the pinion flange on the diff. This makes the two single u-joints operate at the same angle, which cancels out vibes. A bunch of different SOA threads discuss this. Boots4 and Dirtgypsy come to mind first.

Because the DC joint is essentially two u-joints and a ball joint, the vibes are canceled out right there. If the lower u-joint was operating at an angle, there is no fourth joint to cancel out the vibes.


I haven't taken a close look at the pinion flange angle in relation to the transfer output on an early 60. Good question though and is worth taking a look.
 
Tancruiser said:
I put a dc joint on my fj45 and it worked out really well ,no vibrations, no binding but I did build the whole driveline my self in a lathe. /PS the dc joint I used came out of an early 80s mini truck.
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Did you point the diff at the transfer or are their flanges parallel?
 
Took a quick look... will read in detail.

So as I see there and as I had previously read, a DC shaft expects the non-DC end to be in alignment between the shaft and pinion - no significant angle.

If this is the case what is the arrangement in the early FJ60s that have a DC? Is it not true that the diff and transfer flanges are parallel?

Mark
 
GLTHFJ60 said:
I haven't taken a close look at the pinion flange angle in relation to the transfer output on an early 60. Good question though and is worth taking a look.
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From above. I can tell you from experience that if the rear driveshaft is not set up how I've described it that you will have bad driveline vibrations at speed.

This is not a new concept. Do some reading on pirate and searching in here and you'll find the same story as the one I'm telling here.
 
GLTHFJ60 said:
From above. I can tell you from experience that if the rear driveshaft is not set up how I've described it that you will have bad driveline vibrations at speed.

This is not a new concept. Do some reading on pirate and searching in here and you'll find the same story as the one I'm telling here.
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I AGREE, I AGREE, I AGREE with all of what I have read and I believe is that the diff end (non-DC end) needs to be at zero degrees.

My question is simply: what is the arrangement in a stock early FJ60 that has a Double Cardan DS? I don't THINK that is following this rule....
 
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woytovich said:
My question is simply: what is the arrangement in a stock early FJ60 that has a Double Cardan DS? I don't THINK that is following this rule....
Click to expand...

I understand now.

Will someone with an early 60 ( pre 85 ) post up a couple of pictures of their front driveshaft, pinion flange and transfer case arrangement?
 
Tancruiser said:
I put a dc joint on my fj45 and it worked out really well ,no vibrations, no binding but I did build the whole driveline my self in a lathe. /PS the dc joint I used came out of an early 80s mini truck.
Click to expand...

Did you point the diff at the transfer or are their flanges parallel?
 
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