Drive shaft angles for double cardin

[xjdavid1]

I have always thought that for a double cardin driveshaft that I need 0 degrees on the bottom uni that is the diff pinion pointing at the transfercase. Now have a look at this http://home.att.net/~benmlee/driveline/U-JOINT2.htm
I have a 4.5"RE kit and have 12 degrees on the double cardin. I havent measured the individual angles on the double cardin yet but from the above website I should have about 1 degree phase error from the double cardin. Using the spreed sheet on the above website I should have about 3 degrees on the uni on the diff. That is 3 degrees between the pinion angle and the driveshaft. I do have vibrations at the moment and am running allterains so car is fairly quiet and I can hear and feel the Rear drive shaft noises and vibrations. Is anybody else using the above information the set their pinion angle. I currently have about 0 degrees on the uni on the diff.

 

[5-90]

As I recall, that's essentially correct.

Driveshaft phasing with two single Cardan joints is to have the axes of the output shaft and the pinion shaft parallel to each other and to the static ground plane. This causes a negation of vibration - when one joint is "speeding up," the other is "slowing down" - and vice versa. This should work up until the included angle between the driveshaft and the output axis/pinion axis reaches something like 75% of the rated operating angle of the Cardan joint.

When you have a double Cardan (or "constant velocity") joint at one end of the driveshaft, then it's a little different. Since the double Cardan can operate at a greater angle than the single Cardan, you can get away with some more, but you still have to watch what you're doing. In this case, you should have the output axis (typically the end on which the double Cardan is fixed) at or near horizontal with the static ground plane, and you want the single Cardan (usually the pinion end) pointed at the centre of the double Cardan assembly - IOW, ZERO degrees at the pinion axis WRT the driveshaft axis.

This assumes "at rest" or "road operating" conditions - where you are likely to see high-speed driveshaft operation. Major suspension articulation under power typically takes place at very low speeds, and relatively low driveshaft operating speeds, and vibrations are not as noticeable.

Degree ("wedge") shims are acceptable for use in correcting driveline angles, but the idea would be to grind the spring pad welds and remount the spring pads, or just mount new ones (you'll probably have to remove the old ones anyhow.)

5-90

IOW - In Other Words
WRT - With Respect To

 

[xjdavid1]

But the website is saying that the angle on the uni on the diff should not be zero but should in my case be about 3 degrees. That is the angle between the diff pinion and the driveshaft.

 

[5-90]

I saw the site. Let me make a couple assumptions here...

1) They're talking about production parts, for a production vehicle. Therefore, the standards are likely to be just a little lower for those parts - they're making them in job lots of 5,000 or so, rather than a couple at a time.

2) Since you're looking at 4.5" of lift, you're probably going to be replacing your driveshaft anyhow. While the maker's instructions can and should pre-empt mine, the fact of the matter is that an aftermarket shaft for the 4WD world is going to be made rather better - and checked rather more stringently - than a production part. Rather than making them by 5,000's, they're making them by "eaches."

3) You're not talking about a production part anyhow - I'm thinking you're either looking to replace the driveshaft now that you've lifted, or that you're looking to get a driveshaft to put on while you are doing your lift. Either way, that's going to invalidate some information - again, that's information mainly for production vehicles with production parts (yes, I read the website. OK, "scanned" and bookmarked for later reference. There is some interesting information there, and I'd like to crunch a few numbers to verify things myself...)

Does this make sense so far? Please correct my assumptions, if needed, and I'll revisit the subject (or perhaps someone who knows rather more than I might chime in, and we may both learn something!)

5-90

 

[Steve F]

3 degrees allows the diff to rotate slightly under load and the pinion to move upwards which will reduce the angle closer to 0 degrees. 3 degree is the typical static setting between pinion and driveshaft.

Cheers
Steve

 

[xjdavid1]

No from the website the 3 degrees is calculated from the spreed sheet formula after inputting 1 degree phase error which is what I should have looking at the graph on the website. I take it I would need the turn the diff down further to make up for the axil wrap. I currently have replaced my factory driveshaft with a double cardin driveshaft but still have vibrations even though I have set the angle on the diff uni to zero or a bit below to makeup for axit wrap. From what I can gather from the websit I need to turn the diff down a further 3 degrees.

 

[xjdavid1]

I just measured the angles and found that the angle on the top uni in the double cardin was 5.2 and the angle on the lower uni in the double cardin was 3.4 so I pulled the bottom spline out and rotated the uni on the diff end 90 degrees as in the the picture in the above website. From the website spreed sheet by entering in the angles on the uni's in the double cardin that is 5.4 and 3.4 the formula told me I needed to have the uni on the diff at 3.4 degrees. Is this what everybody else is doing and are you all getting good results. This has helped mine so far although my diff uni is still only 1.7 degrees down because I have to take out the 3 degrees wedge and put in a 5 which I still have to buy. I suspect that the front DS is contributing to my remaining hum and vibrations in the car. I have never heard anybody use this method and am keen to hear what everybody else is doing.

 

[Gojeep]

I have always setup SYE's with the pinion 3* down from the driveshaft angle so that it is a the same as the driveshaft angle when under load. I never get any vibration from that setup and told you this months ago now when you first installed the SYE?
I once did have a XJ in here that still had some after I corrected it as above but it turned out to be the front shaft was crook as they vibes went away the moment I took it out. Make sure you dont have the same problem.

 

[xjdavid1]

I think you maybe missing what the website is saying. It is saying that the diff uni is set to in my case 3.4 degree plus some to makeup for axil wrap under acceleration. This is to cancell out the phase error from the 2 uni's in the double cardin that are not the same being 5.4 and 3.7. This raises the question is the angle on the top uni in the double cardin greater than the bottom uni in the double cardin in the front DS. If so I should turn the diff uni on the spline 90 degrees also. This raises the question has the double cardin been installed the right way around. I suspect I am getting more hum and vibs because the rear is at 6" and the front 5.5" which is fairly high. I am also running allterains so I have no tyre noise to drown other noises out.

GoJeep do you rotate the diff uni on the spline so the top ears lineup with the bottom ears when the angle on the bottom uni in the double cardin is greater than the top and have themn at 90 degrees when the angle on the top uni in the double cardin is the greater as per the drawing in the website. I have never heard anybody talk about this before.

 

[xjdavid1]

Now I am a bit confused about this spread sheet http://home.att.net/~benmlee/driveline/ujointstudy.xls
and what he means by pinion angle. Is this in relation the the DS or horizontal. I would have thought uni angle would have been more meaningfull.

 

[Goatman]

Looks to me like you can either take the advice that you're comng here to get, or keep confusing yourself with a silly spreadsheet. Really, this is pretty simple. I don't have the time and don't care to read your spread sheet. Basically the two u-joints in the double carden joint cancel each other out, so the third u-joint at the pinion needs to be at or very near 0*. It is normal to set it slightly down to account for a slight rotating of the pinion up under power, but how much down depends on how much your springs flex. I'm not talking about the angle to the ground, I'm referring to the operating angle of the joint itself.

 

[xjdavid1]

I have no vibs at the moment but have some cabin hamonic resonance at 60mph. It is not there when I backoff so it must be in the rear DS. A DS shop sugested I fill the DS with foam. Has anybody ever tried this.

 

[XJCreeper]

If you've got yourself a quality custom built high angle driveshaft and set your pinion angle to 2-3 degrees you should have no vibes. Forget about wasting time with the spreadsheet and go get some leaf shims. With a little investment in time under you XJ you will find the ideal combination as the folks here are telling you and eliminate the vibes.

 

[MTY Mouse]

I am doing a 6.5" rough country and have a tom woods , it sounds like 2-3 degree leaf shims will do it??? please help, hoping that someone has the same set up that has been through this already.

 

[outlander]

I am doing a 6.5" rough country and have a tom woods , it sounds like 2-3 degree leaf shims will do it??? please help, hoping that someone has the same set up that has been through this already.

Get your lift on there and go find one of these

its the only way to know for sure.Problem is when installing a new lift they are usually taller tham the advertised height to account for sag.Put about four 50lb bags of sand in the back and let it set for a few weeks before trying to set your pinion angle.(take the bags out before measuring angles)

as long as you have a sye you can still drive it around with the bags of sand in there with the rear driveshaft removed.