Thursday, March 13, 2014

Fixed: Scrubbing Noise

Yesterday I had a bit of an epiphany. I realised that taking video while driving is a very, very handy diagnosis assistant, especially for steering/suspension noises; it's a video data-log of steering angle!

So I watched the video and noticed I was getting the noise only when the steering was rotated to the right part of a turn (bottom of the wheel at 9 o'clock position) - this is what I found when I turned to this with the car sitting static. A quick bounce on the fender showed tyre to guard contact.

A few minutes later with some bars, a big lever, some hammers and some multigrips and I've got clearance both at the top of the tyre (to the detriment of the guard finish!) and at the front where it was most often scrubbing.

Here's a better shot of the punished guard. I've got a bunch of rust on this car to fix so will give this a light skim of bog and re-paint at the same time. It was never going to be a show car (otherwise I'd have never taken on this conversion with this base!)

The inside of the arch has been folded over and hammered back flat to the guard, or as flat as practicable.

Took it for another drive (no video this time!) and it's quite a sensible, comfortable drive. Did a few weaves and low speed transitions and it seems to handle OK, although may still be a bit soft despite the increased spring rate due to shortening of the springs.

The right hand side tyre seems to scrub on the footwell slightly at lock too (heard when performing a u-turn - I can see scrub marks. Nothing a bit of hammer-clearancing can't fix.

I am going to guess that the main reason for the scrubbing is the offset of the wheels; the further out from the hub they sit (positive offset) the wider of an arc they scribe, and so their travel fore and aft is amplified from a lower offset wheel. It wouldn't be a problem at standard height unless hitting a HUGE bump mid corner, but is obviously more noticable in a lowered vehicle on small bumps (or in an excessively lowered vehicle on flat roads!)

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