I thought I might share this one with you.
After years of trying to track down vibes after lifting the Syncro, I seem to have eliminated it. Tyres out of round both on the same side.
By simply doing a tyre swap it's knocked out the last 15% of what was a very annoying vibration. Cost was about 20 mins of my time.
That was after cv's, prop shaft balance and realignment, etc etc.
Why didn't I think of that in the first place. Because I assumed tyre shops would pick it up . Wrong.
Mark, I've been working on a thesis about tyre vibrations while commuting on the Hume Highway between Goulburn and Yass.
When I join the highway and wind up to 110 the van rattles and hums like the tailshaft has the heebie-jeebies, I can hardly hear the radio, and the van struggles to maintain cruising speed.
After 20 kilometres everything has smoothed out nicely and we're humming along easily.
By 40 k's I'm bopping to the music with one eye on the speedo so she won't bust 120.
By 60 k's it's so smooth and quiet that I could be in a space shuttle on the dark side of the moon, with the speedo hovering at warp speed.
I'd like to be able to tell you that I have to pull up the handbrake a couple of notches by the time I get to Yass, but I'm hampered by the truth.
I think if I carried on to Melbourne I'd probably lose my license or wear out the brakes.
So here's the theory ...
All-terrain light truck tyres develop 'flat spots' when parked overnight, and take a while to regain perfect roundness. The heavier-duty the carcass, the more obvious it becomes.
An aggressive tread pattern with uneven wear further aggravates the problem.
When Uniroyal brought out the first steel-belted radial tyre, the "Steel Cat", back in the 1970's, they spent a lot of time and money explaining this phenomena to disgruntled customers. I was one of them.
Not long ago I had to toss out my well-loved BFG's when one of them went 'out of round' after several years.
I jacked up the car and spun the wheels, caressing the rubber. It brought a lump to my throat when I felt the tell-tale growth. A terminal case, requiring the painful excision of a large swelling from the wallet.
Try a set of light duty highway pattern tyres and feel the difference - like swapping a sumo wrestler for a ballet dancer!
Cheers, Roger [Beetle] Bayley.
Your right, Scott.
Michelin and Pirelli were selling radial tyres for years before Uniroyal. The context of the comment was that the Uniroyals were the first to become infamous for "flat spotting" when parked, causing vibration issues.