theduck
|
| posted on 6/10/12 at 03:23 PM |
|
|
Brake bleeding...
Probably a stupid question but one I want to make sure I have right.
If I have the rear drums off, would this make the brake pedal light/hit the pedal stop?
I have an issue with the rear setup but have bled all the brakes and although the fronts work the pedal is very long and soft, which I assume is
because of the rear drums being off.
|
|
|
|
|
daviep
|
| posted on 6/10/12 at 03:42 PM |
|
|
quote:
Originally posted by theduck
Probably a stupid question but one I want to make sure I have right.
If I have the rear drums off, would this make the brake pedal light/hit the pedal stop?
I have an issue with the rear setup but have bled all the brakes and although the fronts work the pedal is very long and soft, which I assume is
because of the rear drums being off.
Yes it will, there is nothing to stop the wheel cylinders expanding. Be careful if you pump the pedal too much the wheel cylinder pistons will pop out
You probably won't be able to get the drums back on now as the auto adjusters will have clicked up.
Cheers
Davie
“A truly great library contains something in it to offend everyone.”
|
|
|
SCAR
|
| posted on 6/10/12 at 03:48 PM |
|
|
Not sure if I am reading your post correct but dont press the brake pedal with the rear drums off as there will be nothing for the brake shoes to
push against. You will probably just pop the pistons out of the brake slave cylinders. I dont think you can bleed the system (pedal method) without
the drums attatched as you wont get any system pressure. You would only be pushing against the brake shoe return springs.
Daviep post beat me to it
[Edited on 6/10/12 by SCAR]
|
|
|
theduck
|
| posted on 6/10/12 at 03:50 PM |
|
|
Thanks daviep for confirming that.
Problem I have with the rear drums is that they are binding against the back plate, I had tried spacing them Out 3mm to see if that cures the problem,
but it didn't, even 6mm didn't cure it completely(!) though I realise this wouldn't be safe anyway. I'm not sure if something
is misaligned or something is bent, but whatever it is, it's the or thing stopping it from entering the 'finishing off' stages.
Edit SCAR I was using an eezibleed. Also the rear cylinders are ok, just need to reset the auto adjusters, but looking like the whole rear brake setup
needs stripping down anyway.
[Edited on 6/10/12 by theduck]
|
|
|
vyperstrype
|
| posted on 6/10/12 at 04:00 PM |
|
|
I know it's a silly question but are you sure that the Brake Shoes are the right way round, as this can cause Brake Bind. The leading edges on
the shoes are different. The Brake Lining is bonded usually 1cm from one end from the Brake Shoe and the other end is normally about 3 or 4mm from the
other end. If you get them the wrong way round they will not locate central in the Drums.
I hope this helps.
Regards Eric.
Where there's a will, there's a death!!
|
|
|
rusty nuts
|
| posted on 6/10/12 at 05:14 PM |
|
|
Are you sure the drums are binding on the backplates rather than the shoes? If the drums are binding on the backplates then either the drums,
backplates or possibly the drive shafts/flanges are at fault. Likely suspects are incorrect drums fitted? Incorrectly fitted shoes will not cause the
drums to bind on the backplates but may cause the drum to bind on the shoes
|
|
|
theduck
|
| posted on 6/10/12 at 06:03 PM |
|
|
Can't say definitely binding on back plate but that's my suspision as drum doesn't seem to be parallel to the back plate.
|
|
|
rusty nuts
|
| posted on 6/10/12 at 07:45 PM |
|
|
More likely to be backplate not parallel with the drum unless the drive shaft is bent? Try releasing the auto adjuster backing off the brake shoes ,
then refit the drum and check for binding. If drum then rotates without binding the problem is down to the shoes, if not then the drum. Is the drum
worn leaving a ridge on the inner or outer edge?
|
|
|
theduck
|
| posted on 7/10/12 at 09:50 AM |
|
|
Ok so I have removed the shoes and refitted the drum and with the wheel bolts done up finger right it still binds so it's got to be the back
plate. Help?
|
|
|
theduck
|
| posted on 7/10/12 at 10:23 AM |
|
|
Can see in this photo where drum is rubbing against the backplate.
[Edited on 7/10/12 by theduck]
|
|
|
rusty nuts
|
| posted on 7/10/12 at 10:56 AM |
|
|
Has the backplate got signs like that all the way round? Has the inside edge of the drum worn all around or in just one place? If it is one place then
it may be a bent halfshaft? Check the runout of the drive flange, if it's OK then it may be possible to "relieve" the brake drum at
the high spot.
|
|
|
theduck
|
| posted on 7/10/12 at 11:01 AM |
|
|
It's all the way round.
|
|
|
theduck
|
| posted on 7/10/12 at 01:13 PM |
|
|
Ok so I've had the father in law round as we have looked at this together and determined something's definitely wrong. The drum seems to
be too wide for the hub/backplate distance by about a cm when measuring the distance from hub face to back plate and from inside drum to outside edge.
Now as far as I am aware all these parts are off the same sierra, so what could be wrong/missing that would cause this? Or have I just got
mismatched parts?
|
|
|
rusty nuts
|
| posted on 7/10/12 at 04:12 PM |
|
|
Like I said in one of my earlier posts the most likely cause is incorrect drums. Measure the diameter and the width along with the stud spacings and
have a word with your local motor factor , they should have a catalogue with sizes etc to work from even if your not sure what you want
|
|
|
theduck
|
| posted on 7/10/12 at 07:31 PM |
|
|
Thanks rusty nuts. I will look into getting some other drums that have a slightly shorter internal height.
|
|
|
AdrianH
|
| posted on 8/10/12 at 09:46 PM |
|
|
Just picked up this post.
And OK I may be stupid here but if that is meant to be anything like the sierra rear drums you have the backplate fitted wrong!
The plate should go between the hub and the upright.
Your picture shows it as though you have upright, hub then backplate, therefore your backplate will be approx 8 to 10 mm into the shoe area then it
should.
Not sure if all that makes sense.
I will go away and check your archive for any more clues.
Adrian
No photo archive.
[Edited on 8-10-12 by AdrianH]
Why do I have to make the tools to finish the job? More time then money.
|
|
|
theduck
|
| posted on 9/10/12 at 06:26 AM |
|
|
Thanks Adrian, I think I know what you mean. Just to clarify though that in the picture below, where I have the back plate in between those two bits,
it should go on before.
Edit picture would help, note its a library image.
[Edited on 9/10/12 by theduck]
[Edited on 9/10/12 by theduck]
|
|
|
AdrianH
|
| posted on 9/10/12 at 06:42 AM |
|
|
That looks like a rear hub for a brake calliper with disks, but, yes in effect.
If you have a Sierra Manual mine is 82 to 93 and there is a picture 6.14 Strut and spring fitted to top of trailing shoe 1.6 model.
It shows that the bearing hub is on the outside of the backplate.
In effect the backplate is sandwiched between the bearing hub and backplate.
I would say that would give an extra 8 to 10 mm from the hub face where the brake drum fastens to the backplate. The shoes will all be the same as
they bolt to the backplate.
Adrian
Why do I have to make the tools to finish the job? More time then money.
|
|
|
theduck
|
| posted on 9/10/12 at 07:01 AM |
|
|
Thank you! That is it, I had it off at the weekend and it will buy enough space.
|
|
|
rusty nuts
|
| posted on 9/10/12 at 06:54 PM |
|
|
Well spotted, obvious when I looked again
|
|
|
theduck
|
| posted on 10/10/12 at 07:25 PM |
|
|
Big to Adrian! Done the one side tonight and it's fixed the problem, just the other side to do now :-)
|
|
|
.jpg)
