Outer Limits 4x4 Board

Hi all,
Defender 90 200 Tdi with 2" lift and a vibration in the front about 70-80 Kmh.
therefore I fit double-cardan CV propshaft.
also the front driveshaft must be in line with the differential them,as it happens to the rear one ?
Thank you.

James

Get the easy ones rid of first . Before you start going mad
Get the front tyres checked for Balance (or buckled rim).
Then i could be UJ but they tend to make a bit of noise and shows signs of wobble when under load.
Check wheel Bearings ( just general check the front wheels)

and to add to Ali's list, loose bolt front panhard rod bracket to chassis, or panhard rod bushes, steering swivel pre-load....

check castor arm bushes, just put new suspension in last week and got similar vibration or woble in front end at 70- 80ks thought it would be suspension and need double card, turns out coincidence, loose castor arm bushes

giacomo.m wrote:Hi all,
Defender 90 200 Tdi with 2" lift and a vibration in the front about 70-80 Kmh.
therefore I fit double-cardan CV propshaft.
also the front driveshaft must be in line with the differential them,as it happens to the rear one ?
Thank you.

James

The other posts have suggested other possible causes of vibration. You probably should check these first, before spending money on double cardan propshafts.

Once these other causes are eliminated, then remove the front propshaft and drive your disco with the centre diff locked, to see if that stops the vibration. If it does, then check for any problems with the propshaft - wear etc of uni-joints and slip spline, bent or damaged shaft, etc. Maybe borrow another good propshaft.

If all these fail to fix the vibration, then buy the double cardan propshaft.

Disco II double cardan propshafts can be fitted. You will have to fit the Disco II drive flange to front output shaft (transfer case).

Note that these have non greasable uni-joints and tend to fail more often, and can do expensive damage when they fail. The uni-joints can be replaced with greasable types, but it is worthwhile investigating having a shaft made with a greasable double cardin joint, rather than using a Disco II one.

You are correct about aligning the front propshaft with the differential pinion when a double cardan CV joint is used.

However this is different to how a normal rear propshaft, with uni-joints at both ends should be set-up.

In a coil sprung rover, the engine (and gearbox/transfer case) is inclined up at the front.

To prevent vibrations from the rear propshaft, the pinion of the rear differential should be inclined up at approximately the same angle. Because the rear output shaft (transfer case) and the rear differential pinion are parallel the changes in angular velocity which occur at both uni-joints are cancel each other out, to achieve constant angular velocity between the output shaft and the differential pinion.

The front output shaft (transfer case) is not parallel with the front differential pinion. The double cardan joint accomodates the change in angle between the output shaft and the propshaft, while maintaining constant angular velocity between the output shaft and the prop shaft. Then it is necessary to have the propshaft parallel, within about 2 degrees (max 3), with the differential pinion, to avoid vibration.

The best method to correct the alignment of the differential pinion with the propshaft is to bend the radius arms. Note that this may affect the castor angle.

Bush65 wrote:

giacomo.m wrote:Hi all,
Defender 90 200 Tdi with 2" lift and a vibration in the front about 70-80 Kmh.
therefore I fit double-cardan CV propshaft.
also the front driveshaft must be in line with the differential them,as it happens to the rear one ?
Thank you.

James

The other posts have suggested other possible causes of vibration. You probably should check these first, before spending money on double cardan propshafts.

Once these other causes are eliminated, then remove the front propshaft and drive your disco with the centre diff locked, to see if that stops the vibration. If it does, then check for any problems with the propshaft - wear etc of uni-joints and slip spline, bent or damaged shaft, etc. Maybe borrow another good propshaft.

If all these fail to fix the vibration, then buy the double cardan propshaft.

Disco II double cardan propshafts can be fitted. You will have to fit the Disco II drive flange to front output shaft (transfer case).

Note that these have non greasable uni-joints and tend to fail more often, and can do expensive damage when they fail. The uni-joints can be replaced with greasable types, but it is worthwhile investigating having a shaft made with a greasable double cardin joint, rather than using a Disco II one.

You are correct about aligning the front propshaft with the differential pinion when a double cardan CV joint is used.

However this is different to how a normal rear propshaft, with uni-joints at both ends should be set-up.

In a coil sprung rover, the engine (and gearbox/transfer case) is inclined up at the front.

To prevent vibrations from the rear propshaft, the pinion of the rear differential should be inclined up at approximately the same angle. Because the rear output shaft (transfer case) and the rear differential pinion are parallel the changes in angular velocity which occur at both uni-joints are cancel each other out, to achieve constant angular velocity between the output shaft and the differential pinion.

The front output shaft (transfer case) is not parallel with the front differential pinion. The double cardan joint accomodates the change in angle between the output shaft and the propshaft, while maintaining constant angular velocity between the output shaft and the prop shaft. Then it is necessary to have the propshaft parallel, within about 2 degrees (max 3), with the differential pinion, to avoid vibration.

The best method to correct the alignment of the differential pinion with the propshaft is to bend the radius arms. Note that this may affect the castor angle.

Hi John,
sorry for the delay in the answer,but I have made some day of vacation.
in front I have the QT 3° radius arm, but the double cardan propshafts its no parallel at differential pinion. therefore I must to fit the genuine radius arm ?
Thank you

James

giacomo.m wrote:Hi John,
sorry for the delay in the answer,but I have made some day of vacation.
in front I have the QT 3° radius arm, but the double cardan propshafts its no parallel at differential pinion. therefore I must to fit the genuine radius arm ?
Thank you

James

Refit the standard radius arms and check the alignment of the double cardan propshaft.

If it is close, within about 2 degrees, it should be ok for vibration, but a test drive will soon tell.

A test drive will also reveal whether the steering caster angle is acceptable. Rangies with their longer wheelbase a often ok with 2" lift.

The problem with caster correction arms like the QT ones that you have, is propshaft/pinion alignment.

The best solution is to correct the alignment of the differential pinion with the propshaft by bending the radius arms. Then rotate the swivel balls (slot the bolt holes) to correct the castor angle.

The QT radius arms are fabricated. I would not even think about trying to bend them to fix propshaft vibration.

The original rover radius arms can be bent in a press after heating to a cherry red (in the region of the bend). Cool slowly in diatomaceous earth (kitty litter) or similar after bending.

They need to be bent in 2 places.

Make the 1st bend just in front of where the chassis bushes fit. This bend is to reduce the deflection of the rubber bush when the front wheel is at maximum droop.

Make the 2nd bend at the axle end, near where the radius arm crosses over the tie rod. This bend is to align the pinion with the propshaft.

You know the exact angles of bending ?
that of tasks of that it sells Rovertym ?
Thank you.

James

RT arms are cutted/welded not bent IIRC...

giacomo.m wrote:You know the exact angles of bending ?...
James

Sorry I can't help with angles.

My rangie is too different to your D90 (custom front axle and radius arms) and it will also depend on the amount of lift (2" spring lift's vary between different spring makers and with things like winches etc) and where the bends are made.

Thank you John,
but bending the originals radius arm,or to fit the QT 3° is not had the same result ?
I do not succeed to understand what is the difference.

James.

giacomo.m wrote:Thank you John,
but bending the originals radius arm,or to fit the QT 3° is not had the same result ?
I do not succeed to understand what is the difference.

James.

The QT arms are manufactured to return the castor angle to the stock angle.

If you bend the radius arms to the same angle as the QT arms, then they will give the same results.

I am not advising you to bend the radius arms to correct the castor angle (as QT do).

My advise was to bend the radius arms to correctly align the diff pinion angle to the propshaft (to prevent propshaft vibration). And to minimise the deflection of the chassis bushes.

Once you do this, then you need to determine how far the castor angle is out. The castor angle can then be corrected by rotating the swivel housings.

To rotate the swivel housings, you need to slot the bolt holes, or fill the holes with weld and drill new holes.

Some people don't get vibration when they use a double cardan propshaft with 2" spring lift and castor correction arms.