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Missouri_CJ 07-19-2018 01:48 PM

Pinion Angle
 
Hi, I am building a CJ5. The previous owner put a 2-3in lift on the Jeep. This has made the pinion angle wrong. I was wondering what the best solution is to fix this. I doubt anyone is close enough to Mid-Missouri to come take a look, so I am reaching out to the forum. I bought 8* shims and were going to put those on tonight to see if that does the trick. I always thought the drive shaft had to be completely flat. If it is not pulling out of the slip yoke in the middle is it fine? Sorry for so many questions. Thank you for the help in advance! Pictures are always appreciated!

NashvilleTJ 07-19-2018 05:33 PM

Why do you believe the pinion angle is wrong? If it is a CJ5, you are running leaf springs and single u-joint shafts, correct?

Jeff


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BagusJeep 07-20-2018 12:33 AM

On a CJ5 the rear driveshaft is very short so you will have to solve this issue.

as stock the single joint sin each end required the axle pinion and transfer case output be parallel, not pointing at each other.

The change in angular velocity of each joint on each rotation was matched by the other joint, by phasing them opposite to each other they cancelled out and there was a smooth velocity.

If one of those joints is moving through a greater angle than the other, you have an overall change in angular velocity on each rotation, so the rear wheels start to bunny hop.

So the guide is to keep the pinion and output parallel within a few degrees. Putting on 8 degree shims with a stock shaft will make it worse.

This means the driveshaft has to angle down and that is a problem when you start to lift. The joints will not last long at 7 degrees angle or more and will bind around 12 degrees.

The solution is a CV joint that allows the pinion angle to be changed, so it can point at the transfer case output. This reduces the angles.

For a better explanation try Tom Woods driveshafts website.

Turbos10 07-20-2018 06:17 AM

Completely agree with the CV shaft. You will then point the pinion at the rear of the transmission and have zero angle at the axle joint. Mine had an axle swap by the PO who did not understand angles and mounted it as if it was a single joint shaft. It vibrated like crazy. To fix it I cut the spring perches loose from the axle, rotated the axle to where I wanted it, and welded them back down. Smooth as silk at 70mph now.

jp360cj 07-20-2018 06:40 AM

As said, with a single cardan driveshaft (1 U joint at each end) you want the tcase output and pinion to be parallel. Get an angle finder, and measure the tcase output angle, pinion angle, and driveshaft angle. We can help you dial it in from there. Tom Woods website has good instructions and info too (www.4xshaft.com).

I use an angle finder like this one:

https://mobileimages.lowes.com/produ...8987110061.jpg

Missouri_CJ 07-20-2018 07:23 AM

Yes, Jeff I am. However, the angle is about 35* I believe and when the chassis rolls the slip yoke starts to come out.

Missouri_CJ 07-20-2018 07:27 AM

Turbos10 Do you have any pictures of your set up?

Missouri_CJ 07-20-2018 07:29 AM

I dropped the t-case about half an inch and put the shim in. It looks a lot smoother and when we rolled the chassis around the yoke did not slip. I will get an angle gauge and be able to put the exact degrees. It sounds like you want the two angles to be close to one another, however I do not understand how you can get the drive shaft parallel?

jp360cj 07-20-2018 07:55 AM

Quote:

Originally Posted by Missouri_CJ (Post 40286927)
Yes, Jeff I am. However, the angle is about 35* I believe and when the chassis rolls the slip yoke starts to come out.

What angle is 35*? The driveshaft itself? Seems high for only 2-3" of lift, but it's only relevant when compared to the pinion and transfer case output angles. What transmission are you running?

When you say the slip yoke starts to come out, do you mean the driveshaft is about to come apart, or just that the slip yoke moved in and out? If it's close to coming apart, then the driveshaft is too short. If it's just moving, then that's what it's supposed to do. Although, it should be related to to the suspension cycling, not just rolling forward/backward.

Quote:

Originally Posted by Missouri_CJ (Post 40286935)
I dropped the t-case about half an inch and put the shim in. It looks a lot smoother and when we rolled the chassis around the yoke did not slip. I will get an angle gauge and be able to put the exact degrees. It sounds like you want the two angles to be close to one another, however I do not understand how you can get the drive shaft parallel?

What do you mean by it "looks a lot smoother"? The ultimate goal with a single cardan shaft is to have the operating angles of the u joints the same, and less than 15*. According to Tom Woods, 15* is a pushed limit, so you may have vibration before then. The driveshaft itself doesn't need to be parallel to anything. It's the output shaft of the transfer case and the pinion on the rear axle that need to be parallel. This will put the U joint operating angles the same. **THIS IS ASSUMING YOU HAVE A STOCK STYLE SINGLE CARDAN DRIVESHAFT. IF YOU HAVE A DOUBLE CARDAN (CV) SHAFT, YOUR MEASUREMENTS WILL NEED TO BE DIFFERENT**

Also, it sounds like this CJ is in the process of being built...Is it sitting at final ride height with the weight of the drivetrain, body, etc sitting on it? If not, then you'll want to get some weight on it before finalizing the pinion angle.

NashvilleTJ 07-20-2018 09:02 AM

Are you able to drive the rig and if so, are you getting vibration from the rear end? Thatís the key indicator if there is a problem with the relative angles of the u-joints. As was noted earlier, pictures of the setup would help.

Turbos10 07-20-2018 11:34 AM

1 Attachment(s)
Quote:

Originally Posted by Missouri_CJ (Post 40286931)
Turbos10 Do you have any pictures of your set up?

Here you go

80cj 07-20-2018 12:30 PM

Posting a picture would really help clarify things. For one thing you don't state what year CJ and drive train you have. An earlier CJ-5 with 3 speed would have a decent length drive shaft that may be able to tolerate the lift you describe but only needs to be shimmed to achieve proper angles. Later CJ-5s with 4 speeds will have shorter drive shafts which become more problematic with lifts and often require a new drive shaft with a double cardan constant velocity joint. If your drive shaft is pulling apart then you probably require a new longer one but still, drive shaft angles may be too severe thus affecting the length.

NashvilleTJ 07-20-2018 05:24 PM

Looks like a double cardan joint at the case after all. If that is true, hard to tell from the picture but it looks like the setup is close to correct. The angle between the drive shaft and the pinion shaft should be close to 0 - or perhaps 1 degree low given the leaf springs (the CJ guys can give better advice there). If you are worried about the length of the drive shaft being too short, you do need to pull the it and see how much spline engagement you have. You should have at least a couple of inches at full droop. Since the shaft is not stock (double-cardan), and looks at least from the picture that it may be set up correctly, perhaps the PO did it right, and maybe did know what he was doing. If that's the case, my guess is that the length is probably fine as well.

jp360cj 07-20-2018 09:10 PM

I don't think the pic in post #9 is the OP's jeep. But it did look set up correctly and might can provide some visual aid to the OP.


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CSP 07-20-2018 10:12 PM

Quote:

Originally Posted by NashvilleTJ (Post 40287607)
Looks like a double cardan joint at the case after all. If that is true, hard to tell from the picture but it looks like the setup is close to correct.

Not the driveshaft in question. It's an example of what one should look like with a double cardan joint.


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