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propshaft vibration and pulsing

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evang:
I have a recently pruchased a 1995 300 TDI disco which has the following mods 265 tyres (mud), scorpion 2 inch lift kit, a winch c/w bumper, split batteries and steering protection. All at the front.

The disco pulse/vibratates at around 40mph to 45mph worse in fifth gear than forth. It does not happen with the front prop removed. I have had the standard prop checked and its ok.

The out put shaft of the transfere box feels ok as does the diff end.

It now really does my head in.

Having borrowered a front Double Carden disco 2 prop and flange the problem has dissappeared by 50%. But still doing my head in.

I have been told that this would solve the problem. But other people have said all you need is caster correction arms. These apparantlly will make angles for the standard prop U/J's correct. Other peolpe say with caster arms you may require a Double Carden disco 2 prop???

At the moment the diff u/j angle on the Double Carden disco 2 prop is not  say with in 3 degrees as some say is required for the prop to work correctly. Will the castor arms sort this. But what if the castor is 1.5 degrees out and i fit 3 degree arms any only ideas???

The other thing the disco sits higher at the back than the front by a bout 2.5 inches along the body line. Is this normal with a lift and a winch fitted.

Therefore not having another disco to compare suspension heights with for caster angles etc. Do I buy caster arms or new springs

Cheers Lads any help would be most gratefull.

Budgie:
I need to have a good think about this one..... :-k

The fact that the vibration goes when the front prop is removed doesn't necessarily mean that it's the prop that's at fault, this is backed up by replacing the prop with the Carden prop and the vibration is still there, although reduced.

Do you get any wobble through the steering as well as the vibration?
If so, then check the wheel bearings, swivle housing bearings and C/V joins for ware.

The caster correction radius arms will require the Carden propshaft as these arms increase the angle of the U/J on the transfer box end of the standard prop, causing it to vibrate and pulse. (Are you sure you don't already have these fitted!!  :wink: ) This is turn can wreck the transfer box output bearing if not resulved.
The main reason for putting the caster correction arms on is beacuse the vehicle is wandering all over the road, "tramlinning" and generally difficult to control as a result of lifting the suspension. The arms bring the steering back into it's standard spec.
A 2" lift will not normally create these problems, only +3" and above.  :wink:

The fact that the vehicle sits higher at the back could be because the previous owner didn't componsate for the weight of the winch when ordering the springs. You can get uprate +2" spring that allow for the extra weight of the winch & bumper, if this hasn't been done then it will sit down on the front end.  

I'm sure other will be along to assist, try also doing a search for caster correction radius arms and carden props, there are a few good threads on here about these subjects.  :D

chuggaman:
castor corrected radius arms are generally the only reason why you have to fit a double cardon prop.

if you have the standard radius arms and a 2 inch lift you should not get severe vibration through the front prop unless there is another problem(transfer box out put shaft)

are you sure it is only a 2 inch lift

check the radius arm bushes to make sure they are not offset(as you can buy these to correct the degree of castor correction)

also dont rely on the fact that your "borrowed disco 2 prop" is balanced and rhe flanges are corectly set

mike

Range Rover Blues:
I dissagree.  The pulsing will be there, I'll put money on it.  It depends on many factors as to how/if the results can be fealt, backlash, bush stiffness can all play a part in transmitting or absorbing the rumble that results.

The Cardan jointed TD5 prop is a clever peice of kit, but you need to be able to understand what is happening fully and it's difficult to explain.  ANY UJ will cause pulsing, the effect increases proportional to the sine of the angle (I think) so small angles do little, say up to 3 deg, but 6 deg causes big problems.  The trick is usually to have a pair of UJs, both at the same angle and in phase, so that one absorbs the pulses caused by the other, the propshaft tube pulses but the output and input do not, problem solved. :)

This is true for the front end of a LR, even though the diff pinion is not parallel to the gearbox output shaft, the UJ angles match and all is in phase.  Clever, as the UJ angles are reduced compared to say a series front prop.

Lift the front by 2" and the top UJ only increases by 3 deg and the steering catsor becomes zero (the axle rolls on the ends of the arms), but as the ujs are both at similar angle the pulsing is almost "cancelled out" or absorbed, not entirely but almost.  Depending on that condition of your car, you may decide to live with it.

Fit castor correction and you straighten the axle UJ out, so it can't abosrb the pulsing, plus you increase the gearbox UJ by about 1/2 degree making the pulsing worse, double whammy, you loose both ways making the car hard to live with.

This situation is ideal for the TD5 prop, the axle UJ has nothing to do and the CARDAN or double UJ joint forms a CV joint, a pair of UJs are matched, in phase, thus absorbing any pulsing internally.  The large cast ring in the middle of the joint is the only bit that pulses.  In addition the joint angle is shared between the joints so reducing the pulsing effect (6 degrees now =2 lots of 3degrees).  As a bonus a Cardan joint can drive at almost twice the angle of a UJ.

Now, if you fit a TD5/Cardan/double UJ prop to a car without castor correction, then you have the CV joint at the top end, great, but the axle UJ is still driving through about 3degrees and so puts in a whole new load of pulsing (remember it was absorbing the pulsing on a standard prop) which expalins why the Cardan prop only works with castor correction.  The 2 mods should be seen as a whole package, like the springs/dampers should.


Please say you understand now, I can't think of how to explain this any easier without visual aids.

evang:
Cheers Lads who have replied I have ordered castor arms and hopefully fit them before xmas or on xmas day if the wife will let me. Also I will be leaving on the DC prop and and hopefully this will totally cure this vib

The problem is caused by the lift and landrover build tolarances made a nightmere by the methods of repair and who tells you what to buy as in parts shops owners. Solution i thnk is can you live with the vibs?? or are you fussy like me. Then get castor arms first to reinstate the steering angles even if your steering is not vague. then still getting prop vibs or rumbles then the disco 2 DC prop.

After researching the internet some lifts seem to result all sorts of diffferent vibration problems and some lifts have none. Landrovers Hey!!

I will post my findings what ever happens

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