Knocking Noise from Rear Wheel

[Mike J]

I’m hoping someone can help me diagnose a noise that is coming from the driver’s side rear wheel of my 1976 Triumph Spitfire.

Here’s some history: I recently removed the differential and had the bearings and seals replaced by a specialty shop. I personally replace all three u-joints, rear break cylinders, and stabilizer arm bushings. After putting everything back together I hear a knocking noise which seems to be coming from the vicinity of the wheel.

Here are the symptoms: The knocking noise occurs twice for every complete rotation of the tire (the faster you drive, the faster the knocking). There is no noise when the car is on stands (the weight of the car must be on the tires). The noise goes away when driving up a slight grade (additional tension on the drive components?). The noise goes away when taking a sharp right hand turn. The noise occurs when the brake drum is removed (thinking it may be brake related I removed the drum as an experiment).

My first thought was that the differential wasn’t reassembled properly or possibly had a nick on one of the gears. But unless the noise is being radiated down the final drive shaft I truly believe it is coming from the area of the wheel. I don’t have much experience with wheel bearings but it doesn’t make sense to me that they would make a noise with these symptoms. Before I fabricate the specialty tools necessary to inspect/replace the bearings I’m hoping someone can let me know if I’m headed in the right direction.
Thanks,
Mike

[growe58]

A common problem with spitfires is a little slop in the u-joints allowing them to move back and forth as the axle turns. It's more of a clicking noise than a knocking but otherwise matches your symptoms. I know that you've just replaced the u-joints but if it wasn't really difficult to get the circlips in, you probably have play. You can eliminate the play by making a shim out of some thin scrap metal (a soda can works just fine) and putting it under the circlip. You may also be able to get some thicker circlips, some j-joints come with the thin ones and some with the thicker ones.

Good luck!

[Mike J]

Thanks for the input growe58!


Previously I would have said this wasn't the problem because the u-joint went together nice and snug. But after replacing the wheel bearings and the trunnion bushings I was running out of things to try so I decided to replace the u-joint again thinking I may have screwed something up the first time. Once again everything seemed to go back together without any problems so I took it out for a test ride. Well there was no noise for the first 500 ft but after taking a left hand turn the noise came back only this time the "knocking" was more of a "clicking" and it only occurred once per revolution. This latest symptom sure seems to fall in line with your diagnoses.


Could you check out this video and tell me if the "clicking" sounds like the problem you've described.


http://www.youtube.com/watch?v=AEZvZR8CG2k


The good news is I think I can remove the rear axle in less than 10 minutes now and if this fixes the problem I'll have a fully refurbished rear wheel (and only a few hunderd more grey hairs).


Thanks!