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Although my Azusa brakes fitted with the Sonex drum work ok, I do not like the "shudder" when applying them, which I understand is common.
Ca anyone say with certainty that the fitting of Sonex disc brakes cures this problem??.
Thanks

Hi Phil, I bet this one has been around a few times before. The problem with mine was that the wheels, and consequently the brake drums, didn't run true on the bearings. I have read that the bearings are sometimes not pressed fully home, but I don't see that as the problem. The bearings are still in the same hole. I got away with it for a while because I was running the bearings a bit loose, so the drum sort of self-centred when I applied the brakes. I run a spacer between the bearings so that the axle nut can be fully tightened. Eventually I corrected the spacer length to take up the slop in the bearings but the brake shudder showed up because the drums couldn't self-centre any more. I fixed it for good by re-machining the wheels and fitting sealed ball bearings. Now my wheels run true, the brake drums run true, the brakes work well and I don't have to clean and regrease the bearings.

Peter
Sonex 894

Jim Hicke had a nice writeup in the latest association newsletter about switching from drums to the Sonex hydraulic brakes. His answer- yes it fixes it.

What's bugging me a little on these brakes Peter is the fact I had almost the same set up on my Corby except that had "pressed" drums and toe brakes. That never had "shudder" from the undercarriage. The pressed drums were perhaps easier to get square on the wheels then the machined drums as there was more clearance. I also wonder if part of the problem is the fact that both brakes are linked together so any pulsating in one carries over to the opposite one. I will talk to a friend who has a lathe I think as a first option.

I have the stamped brakes and don't notice much shudder. They do seem to brake a little smoother if I apply more pressure and I've hypothesized that maybe the stamped drums change shape a little to compensate for any out-of-round or slight offset. They do seem prone to squeaking--if I could fix this I'd be almost completely satisfied with them. It seems like they squeak less when I fly more often or after I've warmed them up with heavy braking.

The braking action is very smooth from ~40mph down to ~5. I do notice a little bit of shutter right before stopping. This is all pretty subjective, though, since I might compensate for it by modulating the brake pressure just right.

I'm curious how many people have similar good luck with the stamped drums. When the disc brakes came out, I didn't want to spend extra on the machined drums that I might end up replacing. I've been mostly happy with the stock drum and never upgraded them.

Phil, you might be right about the linked brakes compounding the effect. The brakes on my Sonex are independent. I have two levers that I operate with two fingers. Like Chris, I have the pressed steel drums too. Are your wheels running true?

Peter
Sonex 894

They are not great Peter but they are as good as I can get them without a lathe. (Lucky they are not larger diameter).