From: Marit & Bjornung (bjjen13b@telepost.no)
Subject: Range Rover front propshaft
Date: Sun, 26 Nov 1995 21:50:51 +-100
To: Land-Rover-Owner@uk.stratus.com


Item 527

RR 86 MY


51/54 VIBRATION DIAGNOSIS

The following is intended as an aid for the diagnosis and solution of vibration problems on 1986 model year Range Rovers.

When investigating complaints of vibration in the vehicle, it is important that the vehicle is assessed in a logical manner, so that, by a process of elimination, it is possible to determine the exact source of the problem. Therefore the first part of this bulletin gives a step by step sequence for the diagnosis of vibration sources and their elimination. Before initiating any investigation, however, check the vehicle to ensure that the cause is not due to an obviously simple fault. For example: check that all engine and gearbox mountings are of the correct specification and are correctly fitted; check that all exhaust mountings are correctly fitted, in particular check that there is no metal to metal contact between the mountings and the body; check the torque of the propshaft drive flange bolts, the universal joints for excessive play and transfer box and differential bearings for excessive wear.

If your initial investigations do not identify a problem it will be necessary to carry out the following procedure, which will involve some testing of the vehicle.

NOTE

Should it be found at the outset that several vibrations are evident at different road or engine speeds, each must be treated individually. It is highly unlikely that the vibrations will be due to the same problem and therefore each will require a separate cure.

Similarly, if a vehicle is found to be suffering from a particularly harsh vibration, it may not be possible to detect other, less noticeable vibra tions which may exist. However, once the primary vibration has been eliminated, the secondary vibration, which again will only be evident at different road or engine speeds, will then become prominent. Again each vibration must be treated separately, allowing the causes to be isolated and the necessary remedial action taken.

RANGE ROVER VIBRATION DIAGNOSIS PROCEDURE
1. Road test the vehicle. Does the problem always occur at the same road speed irrespective of the gear selected? (SEE NOTE A).

YES: CHECK 2.
NO: Confirm that the problem occurs at the same engine RPM in all gears. CHECK 21.

2. Does the problem occur at 30-50 mph (48-80 km/hr) in all the available gears?

YES: Check that the front propshaft is correctly phased. The rear yoke must lead the front yoke by two splines. Fit correctly if necessary and re-test. If problem persists CHECK 3.
NO: CHECK 9.

3. Mark the drive flange and remove the front propshaft, engage the diff lock and re-test. Has the vibration been eliminated?

YES: CHECK 4.
NO: Check balance of front and rear wheel and tyre assemblies, using ON-CAR balancing equipment. Check that tyres have even wear characteristics with no evidence of flat spots. If wheels and tyres OK Check 19.

4. Check drive flanges (front output drive flange and front differential pinion flange) for eccentricity and run-out. (SEE NOTE B). Do the flanges conform to the tolerances?

YES: CHECK 7.
NO: CHECK 5.

5. Replace the flange(s). Recheck the eccentricity and run-out. Does the flange(s) conform to tolerances?

YES: CHECK 6.
NO: Fit 2nd replacement flange. Recheck eccentricity and run-out. If tolerances are still incorrect, the differential unit (or alternatively the transfer box) is suspect and should be checked separately. If tolerances correct CHECK 6.

6. Re-test the vehicle with the front propshaft fitted. Is problem still evident?

YES: CHECK 7.
NO: ------.

7. Substitute a replacement propshaft from a donor vehicle and Re-test. Is the problem still evident?

YES: CHECK 8.
NO: Replace propshaft with new unit (or leave on donor unit).

8. Fit the vibration damper assembly to the front axle, (see Attachment 1). (The attachment contains some figures. For further information, please contact Internet E-mail address: bjjen13b@telepost.no).Refit the front propshaft and road test. Is the problem still evident?

YES: Repeat diagnosis.
NO: ------.

9. Does the problem occur at 80-80 mph (112-129 kph) in ALL the available gears?

YES: Check that the rear propshaft is correctly fitted. The front and rear yokes must be IN LINE. There should be no phase difference. Realign if necessary and re-test. If problem persists, check ALL wheel and tyre assemblies for balance. If problem still evident CHECK 10.
NO: CHECK 19.

10. Mark the drive flanges and remove the rear propshaft. Secure the transmission brake drum with the propshaft flange nuts. With the differential lock engaged, re-test the vehicle. Is the problem still evident?

YES: CHECK 11.
NO: CHECK 15.

11. Remove the transmission brake drum and re-test. Is the problem still evident?

YES: Cause of problem is unknown. Re-check diagnostic procedure.
NO: CHECK 12.

12. Check the rear output flange on the transfer box, where the DRUM SITS, for eccentricity and run-out (See NOTE B). Does the flange conform to the tolerances?

YES: The handbrake drum is suspect and must be replaced with a known good component. Then CHECK 15.
NO: CHECK 13.

13. Replace the output flange and recheck the eccentricity and run-out. Does the flange conform to the tolerances?

YES: CHECK 14.
NO: Fit 2nd replacement output flange. Recheck eccentricity and run-out. If tolerances still incorrect, transfer box is suspect, and should be checked separately. If tolerances correct CHECK 14.

14. Refit the original handbrake drum and secure to flange with propshaft nuts. Re-test the vehicle without the propshaft fitted. Is problem still evident?

YES: The handbrake drum is suspect and must be replaced with a known good component. Then CHECK 15.
NO: CHECK 15.

15. Check the rear differential pinion flange for eccentricity and run-out. (See NOTE B). Does the flange conform to the tolerances?

YES: CHECK 17.
NO: CHECK 16.

16. Replace the flange. Recheck the eccentricity and run-out. Does the flange conform to the tolerances?

YES: CHECK 17.
NO: Fit 2nd replacement flange. Recheck eccentricity and run-out. If tolerances are still incorrect, the differential unit is suspect, and should be checked separately. If tolerances correct CHECK 17.

17. Re-test vehicle with rear propshaft fitted. Is problem still evident?

YES: CHECK 18.
NO: ------.

18. Substitute a replacement propshaft from donor vehicle and re-test. Is the problem still evident?

YES: CHECK 20.
NO: Cause of problem is unknown. Recheck fault diagnosis procedure.

19. If the vehicle has a manual gearbox, does the problem occur at 30-50 mph (48-80 kph) in all the available gears except 4th gear.

YES: CHECK 20.
NO: Cause of problem is unknown. Recheck fault diagnosis procedure.

20. Disconnect the front propshaft. Re-test with the differential lock engaged. Is the vibration still evident or is it worse?

YES: If this is confirmed, main gearbox is suspect, and should be investigated separately.
NO: RE-CHECK 2.

21. Are the correct engine mountings fitted? Current production usage:- Part no 566222 (colour coded yellow spot) for front engine mountings. Part No NRC 9154 (colour coded white spot) for rear engine mountings. (See also Service Bulletin 11A/85, Item 1).

YES: CHECK 22.
NO: Fit new engine mountings and re-test. If problem persists CHECK 22.

22. Remove the water pump drive belt. Test the vehicle statically by revving the engine in neutral. In order to avoid any overheating of the engine, DO NOT prolong the test. Does the problem remain?

YES: CHECK 24.
NO: CHECK 23.

23. Replace the fan and viscous drive unit, by substitution with known components from a donor vehicle. Refit the drive belt. Re-test the vehicle statically. Is the problem still evident?

YES: Replace water pump.
NO: ------.

24. Replace the electronic control unit by substitution with a known unit from a donor vehicle. Does the problem still exist?

YES: Cause of problem is unknown. Recheck fault diagnosis. If the vehicle is an automatic, check torque converter balance (see Attachment 2). (The attachment contains some figures.)
NO: ------.

Bjornung Jensen, bjjen13b@telepost.no