78 B210 5spd hatch, 59,000 orig miles. At about 40 it starts and about 55 it gets loud. I can feel it in the seat and hear (harmonic sound) it. There is no vibration in the steering wheel and it does not pull either way. Brakes are in great shape. I reached under and tried twisting the drive line, it is tight. New tires. Could it be the u-joints are dry? or maybee the exhaust is causing this some how? Any ideas?

tire balance. This is common when you get new tires. They are so small and light, they need extra care in balancing compare to average cars.

DD is on the money but there are other factors to look at if it's not as simple as that. I'd check all sorts of stuff (well no I wouldn't I just put up with it till it really annoys me then I fix it) like the idler arm bushes or the tie rods or mabey even the engine mounts? they can cause speed related vibrations as they're starting to load up at 2500rpm

Where does it sound like it's coming from? If front wheel balance you will feel it in the front wheels as it will vibrate the steering.
Otherwise rear wheel balance, rear wheel bearings, driveshaft UJ's, diff pinion bearing, even possibly gearbox output shaft bearing.

I take it is road speed related not engine rev related?

Have you tried to go faster to see if it stops? Wheels are usually worse at ~50-60km/hr depending on their size (interestingly this corresponds with road corregations). I had a tail shaft on an old holden start vibrating once and that was very specifically around 95kms/hr.

If it just gets worse with speed and doesn't get better then you've got a large out of balance force, i.e. perhaps a damaged gear or an out of round drum brake or something. I've had worn suspension components and never noticed vibration but where I lived then the roads were pretty rough (and still are).

[Edit: another point if it is speed related you can try the same speed and a different gear (if safe) to see what half of the drive line it is.]

had similar problem not long ago id put money on front unis,put some stands under the rear and drive it to that speed and track down the source.

I can't put a finger on just where the sound is coming from, it is alnost all around me. It is not related to RPM, the problem only rears its ugly head at speed. I don't have any abnormal feel in the steering wheel. It is felt more in the seat of the pants and is quite "loud", it is actually hard on the ears at about 57 mph. It is not any sort of metal sound. I have had many a car with out of balance wheels, it just doesn't feel like that and I have not heard a harmonic sound with that problem before, but of course i could be wrong. I will have all 4 wheels rebalanced. I like the idea of getting the rear wheels up and testing but safety feels like an issue. On the commment of unis, what are you reffering to?

unis = U-joints. Of course there is only one one the front of the driveshaft.


Your symptoms are exactly what my 1200 does. It is from 45-55mph, and smooths out at 65. It is the wheel balance.

Oh, and the steering wheel doesn't shake -- not much anywho.

Does yours make a loud whooshing sound almost like a wild exhaust note?

Yas it is low pitched, like a loud rumbling.

If you didn't have this problem until the new tires were fitted, why do think it is something other than the tires?