Overland Journal: Discovery I, 5-speed

[Viggen]

I didnt think that one style propshaft is going to effect driveline vibes. I thought the additional joints were added for driveline flexibility rather than to solve a vibration issue. If I was having vibrations, I wouldve gone straight to an out of balance shaft and then tires/ wheels.

 

[MoGas]

Why two of the same length shafts?

..........I had Tom Wood build a CV and non-CV style shaft to help track down some of the rear driveshaft vibrations......

 

[gjackson]

I didnt think that one style propshaft is going to effect driveline vibes. I thought the additional joints were added for driveline flexibility rather than to solve a vibration issue. If I was having vibrations, I wouldve gone straight to an out of balance shaft and then tires/ wheels.

Land Rovers end up with pretty severe prop shaft angles when you lift them, especially in the front. Major effect of this is a nasty vibration on the driveline when coasting. Best way to get rid of it is to replace the front prop with a double. Scott already has a double (or double double) on the front, so he's investigating still existing vibrations towards the rear.

I'm sure Scott will correct me if I'm wrong.

cheers

 

[jrose609]

Land Rovers end up with pretty severe prop shaft angles when you lift them, especially in the front. Major effect of this is a nasty vibration on the driveline when coasting. Best way to get rid of it is to replace the front prop with a double. Scott already has a double (or double double) on the front, so he's investigating still existing vibrations towards the rear.

I'm sure Scott will correct me if I'm wrong.

cheers

I put RTE rear arms on my D1. They are adjusted for suspension height. Fixed my rear end vibration. Corrected the pinion angle in the rear.

 

[R_Lefebvre]

I assume he has pulled one shaft, and then the other, test driving, to isolate which shaft is causing the problems?

One of the reasons I kept the Rotoflex. I don't see how you can change the pinion angle on the D2 to make a simple 2 U-joint shaft work. The TC output and pinion angles need to be almost the same, and they're not.

 

[revor]

UJ's travel in a elliptical rotation when they are not running straight. In a single cardon type shaft (only two UJ's) the angles between the two joints must remain within 5 degrees, otherwise the ellipse at the front joint is different enough from the ellipse at the rear joint to cause vibes.
When you lift a truck say a D2, the pinion shaft (at the diff) points up more towards the front UJ at the t case, the angle of the T Case shaft remains the same, the difference between the two shafts is now more than 5 degrees and you will get vibes and shortened UJ life. To fix this you would put a Double cardon shaft in place with the CV joint at the T Case. The CV (or double cardon) joint at the front of the driveshaft cancels the Eliptical rotation within the joint (so to speak) and since the pinion shaft is pointing at the T Case joint the rear UJ is now running straight so no vibes.
In the case of lifting a D1 or a Defender the trailing arms should be made longer so the pinion can be turned down and keep the joints within the five degrees rule.

 

[Viggen]

Yeah, I thought that the pinion angle was adjusted by arms in the rear. I have 4" of lift and have a GBR double in front and a single in the back with Rovertracks trailing arms and havent experienced any vibrations. Thats why I was asking why the vibration existed. I assume he has switched out the trailing arms to adjust the angles. Could the vibration have been caused by his running a lift, possibly stock arms (I havent checked) AND the rotoflex in the rear? I cant imagine that rubber piece was designed for higher angles.

 

[R_Lefebvre]

UJ's travel in a elliptical rotation when they are not running straight. In a single cardon type shaft (only two UJ's) the angles between the two joints must remain within 5 degrees, otherwise the ellipse at the front joint is different enough from the ellipse at the rear joint to cause vibes.
When you lift a truck say a D2, the pinion shaft (at the diff) points up more towards the front UJ at the t case, the angle of the T Case shaft remains the same, the difference between the two shafts is now more than 5 degrees and you will get vibes and shortened UJ life. To fix this you would put a Double cardon shaft in place with the CV joint at the T Case. The CV (or double cardon) joint at the front of the driveshaft cancels the Eliptical rotation within the joint (so to speak) and since the pinion shaft is pointing at the T Case joint the rear UJ is now running straight so no vibes.
In the case of lifting a D1 or a Defender the trailing arms should be made longer so the pinion can be turned down and keep the joints within the five degrees rule.

Yes, sounds right.

With a single double cardon at one end of the shaft, the joint with a single u-joint should be straight through. That's how they set up the front of the D2. The pinion joint is straight through, the pinion shaft is pointed pretty much straight at the transfer case. All the angle is made up at the DC joint at the TC case end. In the rear, the TC joint is a single UJ, which takes the angle, and the rotoflex is straight through. I imagine the rotoflex takes up the vibration coming out of the single UJ. If you get rid of the rotoflex and replace it with a single UJ, you need to change the angle of the pinion to be parallel to the TC, that way both single UJ's cancel out eachother's vibes. I don't see how you can adjust the pinion angle on a D2. An alternative would be to leave the pinion angle as it is, put a DC at the TC end, and a single UJ at the rear with no angle, just as the rotoflex was.

Courtesy of Tom Wood's:

http://www.4xshaft.com/index.html

 

[Scott Brady]

I have Keith's lower control arms which allow some fine adjustment and I also have the Inland Rovers adjustable upper linkage mount. Between the two, I have all the range necessary to adjust for vibration. I am going to work with both shafts and see which one does the better job. The CV will give better results through the suspension range (running lightly loaded or heavy) and also rotates the pinion and u-joint a little further away from trail hazards.

The front is nearly vibration-free, but the rear (with rotoflex) had some heavy vibes above 60mph or so.

This will get it dialed in, I am sure.

 

[Viggen]

I have Keith's lower control arms which allow some fine adjustment and I also have the Inland Rovers adjustable upper linkage mount. Between the two, I have all the range necessary to adjust for vibration. I am going to work with both shafts and see which one does the better job. The CV will give better results through the suspension range (running lightly loaded or heavy) and also rotates the pinion and u-joint a little further away from trail hazards.

The front is nearly vibration-free, but the rear had some heavy vibes above 60mph or so.

This will get it dialed in, I am sure.

Do you think you wouldnt have any vibrations if you had gone with parts that were set up for your lift? Like rear arms set for 3"+ lift and the stock upper arm?

 

[tdesanto]

...I don't see how you can change the pinion angle on the D2 to make a simple 2 U-joint shaft work...

...I don't see how you can adjust the pinion angle on a D2...

Isn't this thread about Scott's D1?

 

[Scott Brady]

Do you think you wouldnt have any vibrations if you had gone with parts that were set up for your lift? Like rear arms set for 3"+ lift and the stock upper arm?

The vibrations are as a result of the rotoflex IMO. I only have about 60mm of lift in the rear when lightly loaded, but that put the rotoflex at enough of an angle that the vibrations started.

I do have rear arms from Keith. The upper arm is stock, but attaches to the adjustable mount on top of the axle. Between the two, I have full adjustment of the pinion angle to help work out the vibrations.

 

[R_Lefebvre]

Isn't this thread about Scott's D1?

Sure, but we're having a broader driveshaft vibe discussion, and I'm only using the D2 to show an example, as it's what I know.

Sounds like the D1 was set up similar to the D2 except the D2 had a DC up front. Scott had to buy adjustable arms to allow pinion adjustment.

 

[Viggen]

The vibrations are as a result of the rotoflex IMO. I only have about 60mm of lift in the rear when lightly loaded, but that put the rotoflex at enough of an angle that the vibrations started.

I do have rear arms from Keith. The upper arm is stock, but attaches to the adjustable mount on top of the axle. Between the two, I have full adjustment of the pinion angle to help work out the vibrations.

So, heres my question and its coming from the point of view of having a good amount of lift with off the shelf trailing arms and stock upper a arm: Was your going for adjustable arms and upper ball joint exacerbating the problem? It seems like if you just went with off the shelf arms for your lift and a proper rear shaft, there wouldve been no vibration issues as the math wouldve already been done.

 

[Scott Brady]

The truck had rear driveshaft vibrations with the stock arms. That is why I went with the pinion angle adjuster. I would have gone with Keith's arms regardless, as their primary function is strength and clearance, and they only have a small range of pinion adjustment.

Your assumptions might well be valid with a vehicle without a rotoflex, I honestly don't know.