Rear drum brake binding after front disc conversion

[xychix]

21 hours ago, Red90 said:

Good lord.  Do you have the shoes assembled correctly yet?  

Hi red90. Have a week off camping with the kids.

 

And thanks to the write-up and the video I do get how to get the leading and trailing shoes mounted in the right holes and springs on the correct side.

As I'd have to replace contaminated and broken of shoes and leaking cylinders anyhows that's a standing order already. 

 

And I'll make pictures after mounting.

 

[Snagger]

Make sure you have the right slave cylinders on each side.  The cylinder size is not likely to directly cause the binding problem, but that botch with the nail is a potential cause.  But it is critical to your safety and that of other road users that the brakes have the correct parts.  Look at what happened to Nigel Gresham and his family, and the consequences down the line - steering, suspension and brakes are systems that you never take a chance with or cut a corner or costs.  Given the skewed loadings that piston will have suffered from the nail, I strongly urge you to scrap that whole slave cylinder and, on the assumption the same botch was made on the other side, to replace that cylinder too.  It may be unnecessary, but you couldn't know without very accurate measurement of the pistons and bores and x-rays of the cylinders looking for microfractures whether they're still safe to use.  I'd err on the safe side and bin them, fitting new cylinders for the drum size, new shoes and new springs.  

As for knowingly using the wrong spring holes because assembly was tricky, that is as bad as using the nail!  Use the correct holes and I'll wager the binding will be gone.  DOn't cut corners on brakes!

[xychix]

Hi Snagger and all others concerned. 

I'm a quite risk averse person, I won't be driving on the road without braking I really trust.

The binding issue was solved after my defender 90 master cylinder was fit and my pipes and hoses where renewed.
now I have brakes at the front at first pedal and brakes at 4 wheels in 2 strokes of the pedals.

As I know the rear brakes are sh#t (nails, unknown slave cylinders that appear to leak a bit, wrong placed springs, pads that have seen a fair bit of axle oil......, and that's the known issues) I'll be replacing the rear pads / slaves and all springs.

I'll get back here after that for further diagnoses. If the Zeus disc at the front take the same amount of fluid I might have to get my another new master cylinder (109, delphi with 12mm/10mm holes which correspond to the currently placed early def90 master), but more on that later.

All the comments hints and tips for sure helped me understand how the complete braking system fits together, I might not have gotten it all right yet but once this is done I'll be quite familiar with all the quircks and frotless or a 109 braking system thanks to all of you!

[xychix]

Solid stop on 1 pedal, still have the feeling I'm compressing both circuits to a certain extend and then the discs (front) do the rest. However braking in reverse is much improved telling me the rear brakes are doing their fair share. I've put an infrared handheld thermometer in the car as that's a great way to measure any temperature issues on a quick stop.

Attached pictures showing the springs (as promised)

First is RearRight second RearLeft.

Current setup (just for future readers not having to read the complete post)
- zeus discs on front
- normal 109 drum brakes on the back
- early non abs defender 90 on front. (however I'd first give it a try with a 109 series III master, in my case I'd need to reflare OR order a more recent Delphi 109 master as the fittings have changed from 2 sized UNF to 12mm/10mm. Newer 109 Delphi masters should have 12mm/10mm as well). a 110 or 109 master with a 50/50 bias should put slightly more pressure to the back compared to the defender 90 60/40 setup.
- replaced all lines and hoses.

 

Edited August 22, 2018 by xychix

[steve b]

That all looks much better and now operating ok , time to enjoy it

have fun

Steve b

[xychix]

After also changing the left front swivel pin and bearring (and figuring out 1 bolt holding axle to stubaxle was broken) the drive is waaay better at 45-45 Mph. Still like a boat but atleast I feel like the captain now..