Oscillation trepidation !

[robert regan]

yes John I do still have the mk1 cabriolet its a great car to drive off road for this year it ran a big end and a replacement engine with a block rebore and new pistons started to smoke after only about 700 miles and got worseT and worseT after inspecting that engine I could see no obvious reason why, its original engine is now going back in and will be back on the road next year best Regards to all Rob.

[Ivor Hawkins]

Hi Rob

Just to let you know that your old Pearl CLO293 (Now TSK490) is still going strong after 22 years in my ownership !

Do you still have the Mk 1 you bought a few years ago ?

Great hear the Pearl is still going strong, what a shame its original registration has been lost, it’s like a part of its history has gone.

[John Cornforth]

Apologies for thread drift. A few years ago (before all that GDPR malarkey) I applied to DVLA for a copy of all they had on file for CLO293 / TSK490 and paid the £5. I was pleasantly surprised a few weeks later to get a wodge of photocopied microfilm records which covered owners going back to the mid 1970s. Someone must have spent a long time going through their records. This revealed that someone had kept the car for only a few months, long enough to pinch the original reg for their Porsche. An "A" suffix plate was allocated, which later on a dealer later changed to an "Age Related" plate which was a step in the right direction. All water under the bridge now !

[Duncan Grimmond]

Pedantry rules, OK? Or I that peasantry rool's ok? Okay?

[Ivor Hawkins]

Thanks John, at least you have been able to trace the history!

[andrew34ruby]

Back to the start of this thread. Alarming steering thrashing left right left right, shimmy with avengeance at about 18 mph, starting with a bit of wavy tarmac. It thrashed the steering wheel about and the only thing was to slow down to a stop, or maybe 2 mph.

Again a huge thanks to everyone on here for advice and also thanks to Ruaridh for advice too.

It now seems to be fixed, though time will tell!

Various things were suggested as a cause but in total I think seven people suggested it was all to do with the steering drag link, free play, and the little coil springs inside each end.

I checked everything for free-play and could only find a tiny bit of sideways movement in the king-pin top bushes, and a fair bit of play in the steering box.

After the mentions of the drag link end I tried them again and yes there was a tiny bit of play in the front joint of the drag link.

My first experiment was to see if it would still shimmy, at that time it had only done it twice, on the same evening. So without fixing anything I drove it in town at about 20 mph and aimed for every bit of undulating road repair. It did the shimmy. I went round the block and yes, I could make it shimmy whenever I wanted.

Next was to adjust out most of the little bit of play using shims with no spring fitted (maybe I should have driven it like this, but didn't) I then fitted a new spring inside the front joint. A test drive did not create shimmy. Three times over the same wavy tarmac and no shimmy.

As yet I have done nothing with the back end of the drag link, it still has a tiny bit of play, and a very old spring.

New and old springs were very different. Old were shorter and weaker.

Just how such a small amount of play and weak spring can allow this alarming shimmy, we don't know, but for now I'm back to enjoying it.
Thanks again for advice, thanks to Jamie for selling the springs, and thanks to David Cockrane and Ilke for bothering to stock exactly the right bolts that go through the drag link.

[Ruairidh Dunford]

Glad to hear it worked, I hope it continues to.

[Malcolm Parker]

The small springs in the drag link joints are obviously there for a purpose.  When I first got an Austin 7 back in the mid 1970's I had a great deal of difficulty convincing the MOT inspector that there was a spring in the drag link joint, he insisted that it should be rock solid.   I have since come to believe that the springs cushion the steering arm from the worst road shocks and reduce the likelihood of it failing.