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Author Topic: 5 Minute Fix for the older rear brake setup on the ACE  (Read 2396 times)

Offline sprocket2cog

  • Posts: 470
5 MINUTE FIX
talking about the back brakes got me thinking again how to make the back drum better on the older aces with out too much fuss.
so with that in mind i applied some high school physics to the problem and have come up with a 5 min fix for the stock brakes on the early ace.
You will need two pairs of small pliers and a split pin to replace the one you need to take out.
step one- remove the nut on the brake end of the main linkage
step two - remove the split pin from the back of the horn at the lever end of the main linkage its on the back behind the rear wheel and remove the main pivot pin and washer
step three - rotate the rear linkage so the horn is now facing up instead of down. reinsert the main pin and washer then replace the split pin retainer making sure to fold the legs around the pivot pin the same as the old one was
step four -put the linage back in the rear drum arm and replace and adjust nut until it is not dragging the shoes in the drum.
step five- look at the spring in the photo , you want to bend the spring straight and then make a small little hook on it.
if you look inside the horn where the spring was attached you will see a small protrusion where the rod comes in , just hook the spring under that.
adjust the play on the brake switch to get the lights working correctly wiggle the linage up and down etc to set it as vibrations can set off the light if the spring is too tight.


the reason it works, by moving the pivot of the likage closer to the fulcrum you decrease the effort needed to apply the brakes but increase the amount of travel needed, so its easier to get the same amount of force as before which means  more brakeing power for a given weight on the pedal
« Last Edit: Jan 06, 2016, 02:54:56 by sprocket2cog »
its all about the cornering

My Ace
http://www.dotheton.com/forum/index.php?topic=45949

Offline sprocket2cog

  • Posts: 470
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #1 on: Jan 07, 2016, 01:59:48 »
today i had a look at the rear actuater arm on the drum and noticed it wasnt really a the right angle to utilise the force of the main linkage to the front well.
a percentage of the force goes into pulling the arm inwards towards the drum pivot instead of rotaing around it.
you can see in the drawing that rotating it up a little gets a better angle on the arm so more force goes into rotating the brake cam inside the drum.
its pretty easy to do, just rotate the arm one tooth towards the front of the bike so its just before vertical.
you will need to cut 2 or 3 turns off the spring (i used a dremal cutting disc) as the rod will stick though the lever arm more now leaving less room to compress the locking sring on the linkage

with the two mods to the rear brakes i was able to lock the back wheel up from 40kph using the stock brake pads
i couldnt lock up the back wheel before due to the effort needed on the pedal.
its all about the cornering

My Ace
http://www.dotheton.com/forum/index.php?topic=45949

Offline Hibby Jr

  • Posts: 31
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #2 on: Jan 07, 2016, 21:57:11 »
UH... I think the problem is it's upside down ;D

Offline Tune-A-Fishİ

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  • Posts: 6844
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Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #3 on: Jan 07, 2016, 22:51:09 »
UH... I think the problem is it's upside down ;D

Thank the software. Click the image and wha la it's right side up  :o
"I didn't come here and I ain't leavin"  Willie Nelson

"love hard, live fast, die fun" Kacey Musgraves

"Like a Wreckin Ball!" Eric Church

Offline Tad

  • Posts: 178
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #4 on: Jan 08, 2016, 03:15:13 »
Hi Sprocket, thanks for sharing your work on rear brake. when the weather gets a bit warmer and drier over here in UK I will be in the garage to improve mine.
Also nice to see photos from your magic lantern.

Offline sprocket2cog

  • Posts: 470
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #5 on: Jan 08, 2016, 03:30:13 »
Hi Sprocket, thanks for sharing your work on rear brake. when the weather gets a bit warmer and drier over here in UK I will be in the garage to improve mine.
Also nice to see photos from your magic lantern.
no worries, mate, it waas a surprise to how much it changed the brakes, they actually work now !
they havve a little more travel but easier to apply  for the same amount of braking force.
its all about the cornering

My Ace
http://www.dotheton.com/forum/index.php?topic=45949

Offline xb33bsa

  • Posts: 7726
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #6 on: Jan 08, 2016, 07:05:53 »
great work guys there also is a modifaction to the cam in a single leading shoe brake that could be applied to your aces front and back,to improve braking, mildy
i posted some detail about it over on the sr250 thread
the mod comes from me copying an actual production use that yamaha implemented on some mx bikes the year before they went to tls

Offline sprocket2cog

  • Posts: 470
Re: 5 Minute Fix for the older rear brake setup on the ACE
« Reply #7 on: Jan 08, 2016, 14:31:41 »
cool, have you got a link to the thread page its on would love to have a look its not too bad the ace has a single disc front end and a drum rear , the front is an easy fix , better brake pads and fluid as well as a braided line etc
 
its all about the cornering

My Ace
http://www.dotheton.com/forum/index.php?topic=45949