Hi All from South Africa,

I have been reading the posts on this excellent website for some time and have learned an awful lot and now I am confronted with a problem on my 2000 Pajero LWB that has me completely beat. My car is a Generation 2.5 (Blister Fender) with an automatic transmission and the 3.5 DOHC motor (The DOHC was available in South Africa until 2000).

I have searched the posts database, but have not found anything exactly like this, so here goes (I hope I get all the terminology right):

I have an infuriating vibration on my Pajero that manifests itself as a powerful drone at certain road speeds. It is related to road speed only and not engine speed and is most pronounced at around 50 mph and 60 mph. I bought the car in about August of 2004 and became aware of the vibration soon afterwards (when I had sorted some other things out and had learned the car's sounds to a certain extent).

The vibration can be replicated by lifting the rear wheels off the ground, engaging drive (2H on the transfer case, off course) and spinning the rear wheels up to road speed. The vibration occurs at exactly the same speeds (on the speedometer) as on the road.

I have done the following to try to locate root cause of the problem:

1. Had propshaft balanced (No real improvement)
2. Renewed universal joints (No real improvement)
3. Swapped wheels with my mates Pajero (No difference)
4. Had rear diff reconditioned (Cured whine, not vibration)
5. Fitted propshaft from another Pajero ( Vibration cured!! )
6. Had my propshaft rebalanced 4 times! (Vibe still there)
7. Had propshaft retubed (Vibe still there)

The somewhat haphazard process that I followed seems to indicate clearly that the propshaft is the culprit. As I see it the propshaft can generate the vibration due to bad universals or being off balance. The universals are brand new and are dead smooth and free, which made me assume that the propshaft was not balanced properly. This made me take the car back again and again to the propshaft service centre that did the balancing originally (I live in a somewhat remote little town in the part of South Africa known as Zululand and these guys are the only ones that I know of that can do high speed propshaft balancing).

The second to last time the shaft was balanced, I had the propshaft re-tubed to try to eliminate possible out-of-of-center positioning of the universal yokes.

The last time I witnessed every step of the balancing process and insisted on the balancing machine's adapter flange being trued up and the balancing being done at approximately 2500 rpm and double checked at 1500 rpm.

I will welcome any and all suggestions of possible cures or causes...

Kind regards

Gerrit

Hi Gerrit,

Welcome! It's been a while, but I used to visit Cape Town, Jo-burg and (mostly) Port Elizabeth a couple of times a year on business. I miss the country, the food and the people.

I'm fighting a similar, but different problem. I think I've figured mine out, but haven't tested the theory yet. Some of the opportunities for vibration that I've considered may be helpful to you:

1) How many miles or kms on your rig? Does the rear driveline have a slip-yoke into the t-case like our older Pajeros? If so, is it possible that you have wear on the yoke splines that was corrected by the swap to the other prop shaft?
2) Have you cranked the torsion bars? Drive line geometry is affected by changes in both front and rear frame height. The higher the truck's frame height above the axle (in either front or rear) the more pinion angle to t-case angle is aggravated. Have you checked the drive angle relationship? The fact that the vibration dissapeared after swapping propshafts would lessen the possibility that drive angles are the problem, but there could be a slight difference in the U-joints abilitiy to handle the angles.
3) Several owners here have had bad luck with inexpensive U-joints. I suspect it's because of the normal driveline angles on the factory setup.

I can't say any of this will be the problem, but offered as food for thought.

Good luck,
Frank

first off welcome to the wire <img src="/forums/images/graemlins/cheers.gif" alt="" />... i think this brings us one step closer to wheelin' along the skeleton coast <img src="/forums/images/graemlins/lol.gif" alt="" />! it would seem that all three of us have similar rear propshaft problems... although i found mine, u-joints, and frank is still searching i would concur with him about the slip yoke. that is if you have one <img src="/forums/images/graemlins/drunk.gif" alt="" />... how does your propshaft perform when being tested? i would assume that allsgood on the machine given all the work that youve put into it. just by process of elimination, it would sound like thats all thats left... besides just replacing it.

Slip joint.

The average balancing place just chucks up the OD of the joint, spins it, and pronounces it fit for duty.

If the slip joint's worn inside, it will vibrate this- hopefully, the ouput shaft is still ok. The borrowed driveshaft solution seems to indicate that it's just the joint.

hth,

Toby

Hi guys and many thanks for your responses and the warm welcome.

FrankR, my car has relatively low mileage (currently about 57000 miles/ 91000 km on the odometer and has a full service history with the agents (this may be the root cause of all that is wrong with the car <img src="/forums/images/graemlins/angry.gif" alt="" />). The suspension is not lifted. In fact the car is pretty much stock standard at the moment (it is my wife's daily driver and I am not currently allowed to modify it <img src="/forums/images/graemlins/rolleyes.gif" alt="" />, but I am keen to get rid of the standard running boards and mud flaps for a start). The rear propshaft does have a splined slip joint at the transfer case end.

grass13, you are correct, the propshaft seems to be well balanced on the balancing machine.

FrankR, grass13 and TobyB, I will definitely look into the slip joint wear issue and report back.

Many thanks

Gerrit