Out of balance brake drum?

[Gixxer-18]

Hi, I've got a CB250RS, SOHC single, and a pulsing feeling in the back wheel under braking. I'm pretty certain that's an oval drum. To rectify this do I need to strip the rim, tyre and spokes from the hub, and then get the ovality in the drum turned true, or keep the rim and drum under tension with the spokes as the drum is trued? What's the preferred method? And would a specialist wheel builder be able to do this, or is the drum a scrapper and I need a new hub, it's a shame as the wheels were rebuilt by the previous owner with stainless spokes and new rims!
Thanks
Nigel.

[MICK CLARKE]

You need to have the drum skimmed back to true as part of the complete wheel,so leave it as it is,any of the wheel building companys should be able to do it for you,but a small engineering company with a lathe with a big enough throw can also do it and probably a lot cheaper.
I think a company called Central Wheels,If memory serves is one such place that offers this service.

[Gixxer-18]

No, Oddjob, I haven't specifically checked the bearings, but I have experienced a crumbled rear wheel bearing on a 400/4 which I had to ride through France from the Italian border back to the UK in the early 80's and it doesn't  feel like that did at all. I'm pretty certain it's an oval brake drum, the same pulsing happened on my Triumph Tiger 100 only when depressing the brake lever. Unbolting the brake drum, rotating the drum and realigning the bolts helped a bit, but fitting a new drum which is also the rear sprocket on the Triumph bike cured the problem.
I can't change the drum without replacing the hub on the Honda, and the PO had the hub powder coated black when he fitted a new rim and stainless spokes, I think either the spoke tension has pulled the drum out of true, or the heat from the Powder Coating has distorted it but don't know what the preferred method of truing the drum is, hence this thread?
Thanks Mick, for your reply which came in as I was typing this reply.... Glad to hear your thoughts! I had thought that if the hub was stripped of the spokes and trued up it might distort again as the rebuilt rim was pulled up tight. I'll talk to Central Wheels tomorrow for advice.
Nigel.

[matthewmosse]

On my 500/4 a pulsing drum signalled a craked liner, a big enough lathe should be able to skim it or re line it as a complete wheel. Search cb500 brake drum re lining / paul Jackson huddersfield- his number has been posted up a few times here, on this forum, he can re line them or just skim. I have done my own and frankly the price he will do it for I won't try to compete.

[Bryanj]

Plus 1 for Paul, as long as he can find a piece of cast iron pipe the right size the turnround time is quick to

[matthewmosse]

It isn't an inpossible job for a diy'er with a lathe and oven plus freezer, the few I did were on a small chineese made hobbists lathe that required the hub to be bare, my more recently aquired lathe will accomodate the whole wheel, tyre and all, but not quite setup right just yet. I did mine before the late Rod Gibson published Pauls details in Ccm along with details of what he does. On the 550 at least the drum liner itself is lightly castleated once you get to machine it out. The hardest part can be just finding a suitable bit of cast iron to insert in place of the old liner.

[Gixxer-18]

 Thanks for the help guys; I'm going with the professional wheel builder route, I don't have access to a Lathe or know anybody with that sort of experience so I will go to the professionals.
Thanks for all your help.
Regards;
Nigel.

[Lynx]

I had this when I first put the 400 back on the road. Strangly enough after about 200 miles it was fine. I can't explain it. I had fitted new brake shoes. I ndon't know if it was related to that.

[matthewmosse]

First step, take the wheel out and inspect, check shoes too, outside chance of issues with the shoes not seating, perhaps if the linings are comming unstuck, had this with a rebel 125 and 250 nighthawk.
Hopefully it is something easier than a cracked liner or warped drum. Thinking about it the nighthawk had a tendancy to wear the drum into groves, and then the shoes were a swine to bed in, had 3 wheels all do this, might give rise to pulsing, also be sure to follow the step of applying the rear brake when re assembing to re centre things before tightening.