Author Topic: 1929 B29 brakes  (Read 5142 times)

0 Members and 1 Guest are viewing this topic.

Offline Alan

  • Full Member
  • **
  • Join Date: Apr 2004
  • Posts: 114
  • Location: Australia
1929 B29 brakes
« on: 26 Sep 2005 at 05:59 »
Can anyone help me to get the front brake on my B29 working better than its current dismal performance..the B29 has the brake rod that runs in front of the girder forks on the LHS,not behind as I believe the EW's had. I have had the old lining replaced with new woven material, the drum is as circular as I can get it and the size of the drum for the period should in theory give better performance than the average for that time.
My first few rides have been extremely tense to say the least (especially as the back isn't much better) and all help greatly appreciated.

Offline Dave

  • Administrator
  • ****
  • Join Date: Mar 2004
  • Posts: 3272
  • Location: Australia
Re: 1929 B29 brakes
« Reply #1 on: 26 Sep 2005 at 08:46 »
So what actually happens Alan? Is it just not slowing you down or is there some shuddering or noise of any description? Do you have any photos of the setup?

Offline Alan

  • Full Member
  • **
  • Join Date: Apr 2004
  • Posts: 114
  • Location: Australia
Re: 1929 B29 brakes
« Reply #2 on: 27 Sep 2005 at 02:55 »
Dave: The new lining didn't give me much clearance and I tried to set up the outside of the lining via the adjusters so that the outer circumference of the lining was the same as the backing plate..the chap in the brake shop who does a fair bit of old machine work said to use woven lining as this would be better than the usual material. The lever on the plate is on the top,located through the girder forks locating hole,  pointing forwards and pulls upwards. There is no noticeable noise or shuddering when I pull on the brakes, just a serious lack of "retarding forward movement".

Alan.............................
 

Offline Doug

  • Global Moderator
  • ****
  • Join Date: Mar 2004
  • Posts: 3559
  • Location: Pennsylvania, USA
Re: 1929 B29 brakes
« Reply #3 on: 27 Sep 2005 at 04:20 »
Alan,

Part way through EW production Douglas reversed the brake lever from pointing rearward to pointing forward to defeat the servo-action.  Speculation is the front brake was prone to grabbing and possibly causing the dreaded front wheel skid.  For whatever reason, they left it anti-servo from then on.  Some rear brakes were still servo, unless the lever points down, then it too is anti-servo. 

There seems to be no rhyme or reason to brake performance.  Folks that have put far more milage on many more Douglases models than I say they have had decrepitly maintained brakes that were excellent and totally refurbished ones that were dismal, and every combination and shade of performance in between. 

Woven or molded lining actually has little to do with it, a soft high coefficient of friction is more important.  Some woven linings can be quite hard. 

Having the lining perfectly circular just clear of the drum helps eliminate sponginess and maximize efficiency.  There are several way to achieve this.  The best is to have the lining glued to the band, but it is imperative it be expanded into the brake drum while the glue sets.  Like a wood laminate glue-up, it tends to keep the shape it was in when the glue set.  Then you can rivet the linings for extra security after the glue sets.  If you just rivet the linings on, it is difficult to get the band to stay truly circular (they never really are.)  So mount the band on the backing plate and advance the adjusters slightly.  Lock in place and cut or grind the linings circular to the drum diameter.  Back off each adjuster an equal amount to achieve the minimal running clearance. 

Having a soft compound and ensuring all the lining surface comes into play is about all you can do.  From about 1930 on, Douglas started to use cast iron drums which are stiffer than the pressed steel ones. 

-Doug


[fix typo. 22Aug19 -Doug]
« Last Edit: 22 Aug 2019 at 17:48 by Doug »