Brake drums

[Stesaw]

Update.  Did the offside brake drum today, several hours of fiddling about.  Brake drum bolts put up a bit of resistance but managed to get them off without rounding them.  Brake drum removed quite easily with gentle taps from a rubber hammer.  Slave cylinder was leaking (rubber dust cover full of fluid) no external visibility of this outside the drum so glad I took them off for a check.  Been losing fluid for a while so suspected this area as a possibility.  Ordered two slave cylinders from GSF and collected within an hour, bought two in case other side needs changing.  Lot of fiddling about to get cylinder swopped but eventually on.  Hopefully blead ok as tube popped off blead nipple and sprayed the area.  Few questions.

1.  Found it difficult to adjust the brake via the nurled wheel nob aperture at the back, any recommended tool for this, short screw driver tried but unsure if it was making contact with the wheel adjuster.  So took drum off again and tightened the wheel adjuster this way.  Drum back on and slight rubbing noise.  Handbrake on and drum/wheel would not move so ok there.  Tried footbrake but as working by myself difficulty to test even with a stick against the pedal, drum still rotated. I would have thought that this would prevent the wheel/drum from turning.

Any tips/observations welcome.

As I understand it the majority of the braking force from the pedal is on the front discs. Adjusting the rears from that hole in the back of the plate is a pain in the a***.

[TONYT25T25]

Thanks I am wondering if I did not allow the new cylinder to fill up before bleading it.

[maxstu]

The servo will produce the necessary pressure. Get a pal to start engine (in neutral ) and depress brake pedal. Then try rotating wheel again.

[TONYT25T25]

Thanks, when I bled it I don't think I allowed the cylinder to fill first, ie opened up the bleed nipple then depressed the brake pedal, will have another go tomorrow along with your tips. 

[ash1293]

Quick side note, since t25 wheels are lug centric rather than hub centric it is possible to create a slight pulse under braking if wheel not perfectly centred.

Yes, I know this sounds ridiculous as in theory when doing up the nuts/bolts it should in theory pull the wheel true but I have both heard and experienced this myself.

[TONYT25T25]

Lost me on that one Ash. 

[ash1293]

Lost me on that one Ash. 

Think about the rear, if wheel is put onto studs and nuts not torqued up correctly in opposing positions, it is possible for wheel to be slightly off centre. It’s the nuts that are centering wheel in this case. It would only be slightly off but can induce a slight pulse..

[TONYT25T25]

Got you, but surely that's why you tighten opposite bolts/nuts.  What I do is tighten opposites by hand then do the same on a gradual tightening basis with a wrench.

[ash1293]

Exactly - just making the point pulsing brakes is not always down to warped discs or oval drums.

[TONYT25T25]

Update, just finished other side and did it in about half the time than it took me on the other side.  I thought I got away with not having to change the cylinder but on closer inspection and pulling the dust cover away that also was full of brake fluid so had to change it.  Same method of adjusting as per previous post and all looks good.  Hopefully all tightened up ok but will keep an eye on reservoir as well as vicinity of repairs.  How long should these last, I think I last did mine prior to these about 7 years ago. 

[TONYT25T25]

Just a thought and looking for some feedback, if rear drum brake pads wear down excessively therefore allowing the slave cylinder pistons to extend and open more would this allow brake fluid past the internal seal and flow into the rubber dust covers.  Going to have a look tomorrow at the ones I removed to see what state the seals are in and how much distance is allowed before they leak.     I thought the leaks were due to perished seals but just wondering.

[maxstu]

I would suggest there is plenty off piston in reserve. Take a disc brake set up for example. A pistons' depth is far in excess of pad thickness. Hopefully the same applies to the drum set up.

[TONYT25T25]

Agreed, took the cylinders apart and plenty of room before pistons pop out past the internal seals, both of mine were contaminated with rust by the look of the colour and also quite pitted, not sure of state of seals as they were intact.  Easy to repair with a seal kit but not sure worth it when you can buy new ones relatively cheaply.

[maxstu]

[TONYT25T25]

Also looking at the ones I removed it looks as if the piston on one side of the cylinder unit had seized, so I suspect only one side of the brake drum shoes were being activated.