Thread: Drive Line Vibrations 2" Lift

Originally Posted by Hitower

Slunnie

Why would there be the possibility of a drive line vibration in a D2 with a 2" lift and a non-rotoflex coupling?

A bit of back ground on this query - I exchanged the tail shaft in my D2 TD5 for an earlier model universal only shaft so as not to have the issue a friend was having with his 2" lifted TDI flogging out the rotoflex coupling. I am getting a growly noise from under the car when I back off the power from any where over 110km/hr. I hadn't thought of this possibly being the issue.

PM me or you can call 0406-181-810 so I can query you a little further on this.

Thanks
Tony (Hitower)

Hi Tony,

I can't really say exactly what the problem is with your Disco. The reason for the rotoflex however is to absorb driveline vibrations. The rubber coupling will flex and absorb vibrations in the driveline that are caused by Uni joint which are operating on an angle. When the uni is on an angle, through its cycle the shaft is forced to slightly speed up and slow down, where the rotoflex doesn't do this, and the give in the rubber will absorb the vibrations from that which is happening in the rest of the driveline. As soon as you replace this with the regular uni joint there is no longer any give in the system and so you will feel the vibrations. The more you increase the propshaft angles, then the more you will feel the vibrations. The advantage in this conversion is that the uni to uni tailshaft is a lot stronger than the uni to rotoflex tailshaft.

The big difference between the Disco1 and the Disco2 is in the rear suspension. As you lift a Disco1 it causes the rear pinion to point further down as you lift it more. This then forces the rotoflex to work at an angle and the severity depends on how much lift you run. The rotoflex isn't fond of running on an angle and they will eventually flog out.

The D2 on the other hand has rear suspension that pretty much always keeps the pinion pointing towards the output flange on the back of the transfer case. This means that as you lift it 2", 3", 4" etc the angle that the rotoflex makes still remains very similar to standard

This all means that a lifted Disco1 will increase wear on the Rotoflex, a lifted D2 makes very little difference to the Rotoflex. If you are not breaking rotoflexs then I would swap the old shaftback in with a new rotoflex back into the Disco2 as the uni-uni shaft that you are running will provide no benefits for you. If you do heavy 4WDing that breaks the rotoflex then a uni-uni shaft will have strength benefits.

Hi Tony,
I have a D2a with a 2" lift. I changed over the rotoflex to a normal cardan joint a few months back having flogged out 3 of the rubber couplings (one original and 2 replacements). I have not noticed any new vibration coming from the drive line. If you are regularly going off road with a full load I'd recommend getting rid of the rotoflex. Cost me about $530 fitted.

cheers
Mundy