Series 3 Poor pick up, rear wheel spins and locks

Yes running rich, check the air mixture screw is set correctly, at least the plugs are dry, that's better than black and oily.

Col

Any tips as to how to remove recalcitrant screw holding on front drum? Have tried WD40, large screwdriver, impact driver. No success. Yet!

Is the screw head still intact, keep bashing with impact driver
PB Blaster is good for releasing rusty screws particularly if left to soak overnight

Get some Plus gas or RP 90 which are a releasing fluid. WD40 is mostly a water dispersant hence the name. Impact driver should shift it if it can grip the screw. Otherwise drill off the head. A blast with a blowlamp can help start it moving.

I've often wondered why those screws are fitted, the wheel nuts do a good job of holding the drums on.

Col

I think with them fitted [ 3 on a series 2 hub ] it made it possible to adjust brakes without wheel on. Just my thought.

Change you impact wrench to tighten for a couple of goes then change back to slacken.

I swapped the drum screws for countersunk zinc plated allen key head bolts. As far as I remember, 3/8" - 16 TPI Whitworth is the correct thread size.

3/8 - 16 UNC will work in this case, as not many places stock Whitworth bolts nowadays.

With copperslip on the threads, I have never had problems with them sticking since. With the older drums, the jacking hole was also the same thread size, so you could immediately use the bolt you had just removed to remove the drum.

They seem to have changed the jacking threads to M8x1.25 on the newer drums, which can be a minor pain as it means going to find another bolt to remove the drum.

Biggest issue with drum screws is getting correct angle on the countersink.
Blanchards have genuine at 30p @
https://pablanchard.co.uk/Brake-Drum-Screw-Genuine-1510-G

Now you mention it, I also used a matching countersink bit to cut the hole to the correct angle.

I shot blasted and spray painted the original drums to the point where they looked almost as new. The friction surfaces were not too badly worn, the outsides were just covered with flaky rust as can happen to cast iron.

Ok. So i have replaced all the wheel brake cylinders and am now trying to bleed the brakes so they don’t need pumping. This is proving difficult. But...more worrying the engine is a challenge. A chum came round to fix the stalling. He loosened the distributor and rotated it (quite a lot - advancing the spark) and made the engine runner much smoother. That’s the good bit. I then drove it a mile and what sounded like pinking under load got much louder. It may have been more than pinking. A sort of clacking that got louder the more load it was under. I then started it today and it appears to only be firing on 3 cylinders. Number 4 (nearest the bulkhead) doesn't seem to be firing. The spark plug has what looks like rust on it. The other 3 are clear.

Any ideas?

Can you swap the plugs around and put one of the others on 4 and see if it sparks and or plug lead
Light brown on the plug insulator bit seems normal
For bleeding I use one of those cheapie easi bleed things from Halfords
Just put it on open nipple and press down gently a few times , one man operation
Have you a pedal nearly hard or nowhere near , the other trick as in manual is to Clamp the flexis to pinpoint where the air is ,

I got one of these for bleeding the brakes: https://www.ebay.co.uk/itm/282461470709

Really useful and a lot easier and more effective than the other solutions I've tried before (such as those that run from a compressor or spare tyre). I'd definitely recommend a proper vacuum pump for this.

I had problems with air in my 109 brakes when I first got it, the final thing I did to solve the problem was jam the brake pedal down with a hammer and left it like that for 24 hours. No more pumping after that.

Col

If the spark plug to number 4 is rusty, that suggests to me that no fuel is getting to it, check the inlet valve clearance for that cylinder.

Col

Thanks. Will try the jam-down-brake-pedal solution. As for the misbehaving piston could the extremely advanced spark have caused the valves to collide with the piston? The ‘pinking’ - if it was that - was very loud.

Willybuck said:

Thanks. Will try the jam-down-brake-pedal solution. As for the misbehaving piston could the extremely advanced spark have caused the valves to collide with the piston? The ‘pinking’ - if it was that - was very loud.

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No, advancing the ignition would not cause the piston to hit a valve. The pinking is pre-ignition, in other words the spark is happening to early and the resulting bang is trying to push the piston down too early.

Col

Colthebrummie said:

had problems with air in my 109 brakes when I first got it, the final thing I did to solve the problem was jam the brake pedal down with a hammer and left it like that for 24 hours. No more pumping after that.

Click to expand...

Never tried that, where do you think the trapped air goes

steve2286w said:

Never tried that, where do you think the trapped air goes

Click to expand...

I think the pressure caused by the pedal being jammed down for hours causes small air bubbles to find their way into the master cylinder reservoir.

Col