16" drum rear wheel

[edwin]

I'm not sure whether this is the correct place for my post. But here goes.

My sons XS250 build is tantalizing close, but as you fellow builders will know things tend to conspire against you at this stage.My latest issue is the drum of the rear wheel is out of true resulting in the brake pedal going down and the back up again under braking.
My question is. Does anyone have another wheel for sale? Or is there someone with the lathe capable of truing inside these alloy drum wheels ( I have two both distorted )?

Any help would be greatly appreciated.

Regards Edwin

 

[bcware]

Pardon my saying so, but this seems extremely unlikely. I've never heard of this happening before and you're claiming it's happened to two different rear wheels?

Either you're the unluckiest man alive or there is something wrong with your linkage! Unless you crashed the bike hard, of course.

Maybe you can take some pictures?

I would also verify all spacers are in place on the rear wheel and that the bearings are not damaged.

 

[edwin]

Thanks for the word
I was surprised also to find both wheels I have the same issue. the wheel(s) spins true on the spindle with bike on the centre stand with no play in the bearing. I bought NOS shoes from Granby's fitted those with the better of the two wheels. When the wheel is spun with your left hand and slight pressure applied to the brake peddle it gives you the impression of having a high spot that catches on every revolution.
As to the previous lives of these wheels I can't say,both came to me from non runners.
I've also changed the brake plate that carries the shoes to no avail.
I will post photo's when I return home tomorrow.

Regarding the luck I am or not having with this build there isn't the room or the inclination to go into that. " If you know what I mean "

Thanks again for the input.

Edwin

 

[bcware]

Perhaps there is still some chance it might not be the wheel, but it seems that you are likely correct and I have learned something today.

Keep me apprised. Perhaps Drewpy will chime in and provide a suggestion; he dwells on the same island and seems to know how to get things done!

 

[edwin]

As soon as I make progress I will let you know

 

[lemonhead]

I talked to an older gent once who told me he would fix his warped disc brakes on his car by gluing sandpaper to his brake pads. He said he would run them around a parking lot like this until the wobble went away, then he would hit the brakes hard and the sandpaper and glue would wear right off the pads.

Not sure if this is true, or if he was yanking my chain, but it might be a cost effective way to round out your wheels.

 

[bcware]

The theory is sound. Truly warped discs are a myth for the most part. Shudders and vibrations from discs are almost always due to uneven deposits on the surface of the rotor. The sandpaper theoretically would remove those deposits. It sounds like a lot of work and potentially dangerous, but it might work.

As far as the rear drum goes I am afraid, since it is an alloy wheel, that there is more significant damage that can not simply be fixed by cleaning the surface. It might be worth a try, however, if the variance is very small.

 

[edwin]

Funnily enough I have tried something similar. Using an old pair of shoes and valve grinding paste this identified the high spots but removing them with a dremel type device with a snake drive wasn't accurate enough as the problem persisted.
Don't you just love these old boy engineers.
Something has just occurred to me, the wheels i have are without a steel insert for the shoes to work against. Do all of these wheels leave the factory like this or are these early ones and the design improved later?

 

[bcware]

Mine is an earlier model from 1978, but I believe the wheels are pure aluminium. No steel that I noticed anyway. If you mean lining the drum that is!

 

[edwin]

yeah that was my thought

 

[bcware]

These bikes are very light, so heat isn't a huge issue unless they are being raced, but it is entirely plausible that a fat man with an inclination to drag the brakes a lot could cause some distortion.

 

[Gra900]

My 83 4G5 just failed it’s MOT due to oval rear drum. The brake test machine showed braking force oscillating from 100 to 150 which is too match, apparently. ive been advised to take it down to a machine shop and get the inside tried up.