• Brakes
  • Rear Brakes Binding - Self Adjusters Actually Working!

2011/12/18 19:29:07
na.charrett
OK - So I normally answer questions and not ask them, but his one has me stumped...
 
I have a Mk2 Escort that the drum brake self adjusters are working so well that they keep adjusting the rear brakes up to the point that they are distinctly binding... (I have temporarily ground off the teeth of the adjuster to solve this in the short term - but want to know if there is something else I should be looking at...)
 
Background - This car is an Autocross/Motorkhana car that has had a hydraulic handbrake for over ten years... I recently (just before the rear brake issues started) changes it froma 0.7 or 0.75 cyl to a 0.625" cyl to make it work much better (which it does).  Now the hydraulic slave cyl in in the rear line and adjusted so that it does not carry any residual pressure (First thing I checked).  I have checked the handbrake mechanism to see if ut was holding back the shoes, but I can dissconnect the handbrake linkage and it still binds.  The first to happen was the drivers side rear that did itself tight about 10 times in about 2-3 motorkhanas before I took to the adjuster with the grinder.  I then did 3 autocrosses before the passenger side has now done the same (twice) to the extent that I bent the shoes and ripped off the holding pin holders when removing the drums...
 
I am running the standard (early 2 pipe) Escort Master with 9" drums and P11034 20.64mm rear cyls for a rear brake bias setup.... Rear cyls are new (not leaking), linings are not contaminated with oil and in GC.  On the right rear I triend different springs (and even did one motorkhana test without one of the springs to see if it was them - since replaced)
 
I do not want to have to resort to a disc brake rear again (I experimented a few years ago) as I wold need to do a pedal box too... but i cannot afford to have to dismantle the rear brakes after every run.....
 
Has ANYONE ever struc this with a drum brake / hydraulic handbrake setup...
2011/12/18 23:00:00
harrier
Don't use the handbrake ???? It'll give me fighting chance in the motorkhanas again you  
2011/12/19 11:09:42
ronsmallford
I dont have hands on experience here but could this be caused by axle flex?
2011/12/19 21:30:10
jimmyd
Initial thoughts are you are overstroking the rears - ie with increased line pressure the brake shoes are traveling/flexing further than they would in usual braking forces, thereby engaging the self adjusters 
2012/01/01 19:24:23
RS 2000
agree with what jimmyd said, caused by drums that are too big in diameter for the shoes . The problem got apparent as you have increased the pressure to the rears by using smaller master cyl which flexed the shoes enough to engage the adjuster. I have seen similar problems even though drums were still within spec. Check that out and it may be time for some new drums and/or matched shoe set.
 
Cheers
2012/01/08 11:28:00
na.charrett
I cannot see how the new smaller handbrake cyl has changed it, as they now adjust up even when I do not touch the handbrake (ie the fluid just goes straight through the handbrake cyl....) with "normal" (evn light pressure) use of the foot brake.
 
Oh well
Sounds like I may need to get some new rear shoes and matched to the specific drum size too... (And I may be chasing the problem for a while..... I was afraid off that)
2012/01/25 03:01:22
boXXer
Hi guys! I'm from the UK and have been trawling through the internet for DAYS to see if anyone had a similar problem to me, then at last this thread popped up after trying different words etc in google!
 
ANYWAY, I do a lot of drifting (www.youtube.com/boxxercos if you wanna see some vids) and have EXACTLY the same problem as you with regards to the self adjusters over-compensating the pads whenever the hydro handbrake is used in anger.
 
I initially had the 8" setup with self adjusters, which used to jam on until you took the drums off and knocked back the adjusters, so i changed to a Capri 9" setup (wider than mk2 escort) which uses 57mm wide pads, and it does exactly the same thing, GRRRRRR.
 
Did you ever come up with a fix for this? im thinking the extra pressure from the Hydro Handbrake (i have 0.626 M/C also), is bending something somewhere and allowing the toothed cam to swing around.
 
What if you were to tack weld the adjuster shut? would the slave cylinders compensate for wear like the pistons do on a front caliper?
 
cheers for any help in advance

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