Hi, folks.
Sometimes there is an audible, low-frequency thumping/knocking "non-metallic, train-like ka-dunk" sound from the rear of my 1964 Mk2 (3.4 man/OD, non-PS). The sound is accompanied by the corresponding "ka-dunk", muted vibration inside the car, it kind of feels like the car is "dragging and pulling" a bit. It ONLY occurs when driving steady just over 80km/h, and speeding up or down 2 or 3 km/h the noise and vibration all disappear.
Seems like some components of the rear axle or suspension are "oscillating" @ +80Km/h; does this make any sense to you? Any obvious candidates regarding worn parts or malfunctions to check out?
BTW; my car has 72 spoke wire wheels from 1989 with quite old (mid 90s?) but not worn Avon Radial Steel Tubeless 185 R15 93H.

 

Obviously check you rims and wheels, as well as the splines and knock-off nut that hold the wheel(s) in place.
Also check the drive shaft for loose bolts and bad UV joints.
Can't remember if there is a "steady" bearing in there or not, if there is, inspect that as well.


Just from your description though it sounds like a bad UV joint and you should inspect this before driving it any further.

 

Thanks a lot, Jeff.
I may change the tyres this winter, so I will get to checking the splines etc.
Regarding the UV-joints; I guess they should both be dead tight, i.e. no slack/drift whatsoever? Is fitting these new joints a job for a competent and experienced allround car mechanic, or do I have to use my $150 hour Jaguar specialist garage?

 

You can do it!
Lin

 

Here's not a bad video.




It's just a standard U joint, if you don't feel comfortable doing it, any competent garage will do it for you.


You can save some money by removing the entire drive shaft and taking it to the garage.


Also note the condition of the bolts where it mates on either end, if the bolts are rusty or if someone replaced them with low grade bolts and used lock washers, then you need to get some new ones. The new bolts should be very high grade with interference fine thread nuts.
Hardware store bolts must not be used, for the most part they're just cheap garbage for the handy-man.
And speaking of interference fit nuts and bolts, they can only be used once, so you will probably have to replace them anyway.
Take a sample to you local auto parts store, tell them what it's for and they'll help you out.


Yes the joints should be tight _ no discernible movement with your hands.


The car should be on a level surface, out of gear and the park break on so the drive shaft can be moved enough to check the joints.
You may even want to block the wheels just for safety reasons.
You also have to be quite thin to crawl underneath to check the shaft, otherwise the car will have to be raised up.

 

I didn`t get to sort this issue before winter-hibernating since mid October...
Anyway I will start the spring season with a set of fresh tires + tubes, and at the same time get a proper balancing of the 72-spoke wire wheels.
I guess it is a good idea to check the splines, too.
BTW: these budget Taiwan Nankang tires sure look OK to me; is there any reason to expect they will not handle decent for "normal driving"?
http://www.eiretyres.com/cgi-bin/rshop.pl?Marke=Nankang&X-Profil=Classic%20001&X-Name=185%2F80%20R15%2093V%20BSW&dsco=124&details=O rdern&typ=R-262531&ranzahl=4&rsmFahrzeugart=PKW&sowigan=So&Bre ite=185&Quer=80&Felge=15&Speed=V

If all this won`t make any improvement I will have my garage to check/swap both(?) UJs.
The whole summer I have been modestly plagued by oil leaking from the rear differential, and there is still some dripping, even with new diff-gasket, drain plug and rear propshaft Z-ring /sim-ring.
Maybe there is a connection between the slight wobbling/sound and the oil leak IF it indeed turns out to be some UJ(s)-issues?

 

Are your spring hanger rubbers in good order ? Also the Panhard rod rubbers ? And maybe the top shock mounts ? All these wear over time and cause thumping noises.

Edit
Forgot the parallel arms ! These, too, have rubber bushes at each end