Board index Flathead Power-Technical Questions, Answers, and Suggestions Big Twin Flatties Eccentric Brake Drum???

Eccentric Brake Drum???

Moderators: Curt!, Pa

Post Sun Apr 29, 2007 7:48 am

Posts: 1642
Location: Interlaken, NY USA

Here's a problem I'm having on the BTSV and the Knuckle. The rear sprocket appears to be eccentric. adjust the chain at the tightest point to just enough slack, and it drags the brake rod at the loosest point. Doesn't make for the smoothest ride.
First, I replaced the worn rear sprocket, and , no change. Then, figuring I didn't get the sprocket riveted properly, I bought a new drum/sprocket ass'y from Ted's, same problem. Now, I didn't change the front sprocket as I'd done that a year ago, and it appeared to be in good shape. Anyway, the eccentricity appears to follow the rear sprocket, not the front. Also, a sprocket being a sprocket, I haven't figured how to put the dial indicator on it while the wheel ass'y is in the truing stand to get a better idea as to what gives. Anybody have any suggestions, or has seen this before? I figure it's something simple I'm just not seeing. All suggestions appreciated.
Dr. Dumbfounded Dick

Post Sun Apr 29, 2007 10:14 am

Posts: 3011
Location: Central Illinois, USA
I gotta ask:

Your hubs haven't been updated to timkens, have they?


Post Sun Apr 29, 2007 12:12 pm

Posts: 766
Location: CA USA
Put your wheel in the truing stand and lay a flat bar against the sprocket with the bottom fixed to the bench with hinge. Set up indicator to read off the outboard side of bar. Slowly rotate wheel with sprocket riding on bar, keeping light pressure on top of bar with other hand and take reading as bar moves.

Post Sun Apr 29, 2007 1:16 pm

Posts: 377
Location: madison wisconsin usa

i have the same problem and a timken hub, please tell!


Post Sun Apr 29, 2007 2:39 pm

Posts: 923
Location: South Provence of FRANCE

:? Hi Guys !!!
exactly the SAAAAME problems here in France , with Tedd's stuff......
IMHO : if all the rivets have not been punched with exactly the same power : the drum becomes exentric .
...we are not out of problems with this ....

Post Sun Apr 29, 2007 3:29 pm

Posts: 1642
Location: Interlaken, NY USA

Thanks for the replies.
Cotten, I still am running original bearing setup.
Beachdog, thanks for the tip on how to build a jig. That should help narrow down the problem, cause Fran-6 has probably nailed it. I didn't get a uniform rivet job with my homemade rivet set (modified tappet adjustment screw, using the hollow to get that nice half round peen). Then, expecting something from Ted to be true is asking too much. I'll setup the jig and see what that shows me.

Post Sun Apr 29, 2007 4:47 pm

Posts: 3011
Location: Central Illinois, USA
Dr. Dick!
A modified tappet screw for a presstool: great idea!
(Now I know what I can use those '70s fitz-none Dixie adjustors for.)

Re: all "Timken updates"
You are all at the mercy of your machinist's skill and fore-thought.
A little forethought should bring most of you to the conclusion that such a repair should be reserved for the most tortured of rare stepped hubs only.

From the replies it is obvious that we have more than one probable cause for this malady.
Only carefull observation and measuring will sort each one out.

I still have one wheel where I honed the star-end for an early '80s sidecar needle bearing. (Retaining the star assembly for endplay adjustment.)
But then I have a sidecar to run it on.

Good luck everybody.


Post Sun Apr 29, 2007 7:00 pm

Posts: 2677
Location: Los Angeles, CA
It takes both OD and ID grinding to do the hub fix. I hve the hubs ID ground and OD grind the new races to be installed. What are these races??? One 45" and one Sportster Male rod races will do the trick

Post Sun Apr 29, 2007 7:16 pm

Posts: 3011
Location: Central Illinois, USA
That's gotta be helluvalot better than a timken conversion.

Timkens are a great design for a bearing, but who wants the grief of custom cutting internal spacers that fall down every time you want to put the wheel back on? Especially if your under a bridge abuttment in the rain...

Star hub design was extraordinarily durable.


Post Sun Apr 29, 2007 11:39 pm

Posts: 630
Location: belgium
The Vtwin drums are the worst.
I prefer an old drum with a new sprocket.
The INA torrington-style conversion keeps the original line-up off the hubs!
When mounting the drum on the hub there are 5 positions to choose from, find the best and mark for the futur!

Post Tue May 01, 2007 6:37 am

Posts: 636
Location: Wisconsin, USA
There is a guy in the AMCA that has a method to rebuild the race surface and grind back to factory spec. He uses a method similar to electro plating but it is done with a wick, it applies the new metal to the race surface only. He does very nice work, the cost is less than the price of a new hub.

Post Sat May 05, 2007 6:57 am

Posts: 65
Location: Aberdeen, SD

Lee Armitage is the guy that repairs the hubs. He has done some step hubs for me and they turned out fantastic. When I need a replacement drum I order one from Paugco, it comes already powder coated with a new sprocket riveted on. American made quality at it's best. Paugco also makes other quality parts that I special order in raw finish and do my own parkerizing on. It is refreshing to use parts that fit and talk to a customer service person that cares and knows what you are talking about.

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