Panhard Groups
brakes - Printable Version

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brakes - geoff - 09-05-2023

My front wheel is dragging 50% of its rotation as I rotate it such that it resembles the drum being elliptical.

I have clocked its mounting on the driveshaft and that seems perfect.

As best as I can, I have ascertained that the drum's diameter varies by about 1mm. around its circumference - is this acceptable or should it be near perfectly round?

I ask because I took it to a mechanical workshop who said that it would cost too much to skim it due to it being so difficult to mount on a lathe.

I am wondering whether to try to obtain a new (old) one.

What are your thoughts?

cheers

geoff

RE: brakes - 24c - 09-07-2023

Geoff,

I don't think 1mm is that critical, as the drums only have one wheel cylinder, as they cam or servo onto the drum from the bottom pivot. You can clock the drum, but as it doesn't move outwards concentrically it's pointless. The shoes will bed in with time, and the dragging is more to do with sticking pistons, as my PL17 stood outside for years with silicone fluid and refurbished system is totally free running, just wish I had a crankshaft for it.

The easy way to machine the drum, is reverse it, use a 4 jaw chuck on the internal hole (if Alfin) or make an arbor to hold it.

Mike

RE: brakes - geoff - 09-09-2023

(09-07-2023, 06:22 PM)24c Wrote: Geoff,

I don't think 1mm is that critical, as the drums only have one wheel cylinder, as they cam or servo onto the drum from the bottom pivot. You can clock the drum, but as it doesn't move outwards concentrically it's pointless. The shoes will bed in with time, and the dragging is more to do with sticking pistons, as my PL17 stood outside for years with silicone fluid and refurbished system is totally free running, just wish I had a crankshaft for it.

The easy way to machine the drum, is reverse it, use a 4 jaw chuck on the internal hole (if Alfin) or make an arbor to hold it.

Mike
yes, I don't know why my man here did not propose reversing the chuck. It does seem obvious from what little I know of machining.
Anyway I have a solution now, Ted has offered me a pair of wheels he had refurbished some time ago.
Interestingly he told me that he had to make up an adaptor from an old driveshaft in order to clamp it in the lathe - so his man did not think of reversing the chuck either !

RE: brakes - 24c - 09-14-2023

Geoff

using a driveshaft hub is like making an arbor Smile I had a problem the over the last few months where I had to get professional roofers to look at a job, four different companies, five visits and all said they couldn't do it without "x, y or z". They were talking nonsense, so ended up doing it myself, and yes it was difficult, but remarkably simple to get a good result. I hope Ted's stuff works out for you and your confidence in the braking system is restored.

RE: brakes - geoff - 09-15-2023

(09-14-2023, 09:01 PM)24c Wrote: Geoff

using a driveshaft hub is like making an arbor Smile I had a problem the over the last few months where I had to get professional roofers to look at a job, four different companies, five visits and all said they couldn't do it without "x, y or z". They were talking nonsense, so ended up doing it myself, and yes it was difficult, but remarkably simple to get a good result. I hope Ted's stuff works out for you and your confidence in the braking system is restored.
yes I still don't know why my guy - or Ted's for that matter did not propose just reversing the chuck as you said.