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Rusty Disks

2K views 11 replies 10 participants last post by  cah197 
#1 ·
#2 ·
May be a good idea in some circumstances but I have never had disc problems caused by rust. Run out on discs due to overheating and warping - yes. In that case it was necessary to replace the dics as machining would have thinned them too much. I also had some new front wheel bearings that had been badly fitted and this caused brake judder.
 
#4 ·
A lot depends on how badly your discs are rusted! My Ampera rears had rusted, so I took them off and skimmed them; originally 12mm thick, they ended up 10mm thick after I'd faced off both sides - and this is the min thickness allowed! Any more rust and they'd have been junk.

Before:
133539


After:
133540
 
#8 ·
The reason they needed skimming was precisely because they'd had virtually zero wear in 60k miles of motoring! I will continue to monitor their thickness, but frankly they're cosmetic items unless I really have to hit the brakes hard, which I seldom do.
Cost to me was £0 as I have my own lathe. But it was an extremely messy process, and took about 1/2 a day of my time to do the actual turning, as there was a lot of rust-dust coming off which I wanted to fall into the swarf-tray, rather than fly around in the air. So I turned them at a very slow speed, compared to what a piece-work turned would use!
Was it worth the £100 saving? For a total of around 1 days work? To me, yes, just.

I've skimmed disks before, which were getting tapered due to normal wear, and those are easy as there's negligible rust. I don't think I'll be doing any more Ampera rears in a hurry! Easier to simply fit new ones!!
 
#10 ·
Last time I changed my discs on the Ampera I took the old ones to be skimmed. They managed to do the fronts but the back ones were too far gone to be skimmed. The cost for doing the fronts was not much less than new discs so in future it will be new discs for me and cash in the old ones to the scrap merchant along with the old batteries that I seem to be accumulating.

Edited to add that I checked the link in the first post for my nearest place and it is the place that I take my cars to for servicing/MOTs/tyres and one pair of discs skimmed anyway. Last set of rear discs from them, fitted for the MOT was £86 + whatever labour at £50 per hour.
 
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