Lancia Motor Club

It might appear that I have little else to do (true) apart from writing at length about Aurelia brake drums but having trawled through the data I have here, I believe the following is tryue.
Last night I had a good look at some Aurelia Technical documents regarding front brake drums.
 
It appears that 2nd, 3rd and 4th Series B20 and B12 and B24 Spider all had single leading shoe and the drums were 300mm o/d x 70mm. The drums were either steel or aluminium casting with cast iron inserts. ( The I/d of the wheel cylinders varied and 4th series seem to often  have stepped cylinders)
 
B20 5th series and B24S Convertibles had  twin leading shoe brakes with 300mm o/d drums and the linings were  206mm long x 65 mm wide. The drums were aluminium casting with cast iron inserts.
 
B20 6th Series (and some late B24S Convertibles ?) had twin leading shoe brakes with 300mm o/d drums and the linings were 236 or 314 mm long x 70mm wide. The drums were aluminium casting with cast iron inserts. I assume the shoes are wider and longer than 5th series to reduce brake judder.
 
There are detail design and manufacturing differences between the various aluminium drum with cast iron inserts but dimensionally all the drums have the same inner dimensions and in principle all the drums are interchangeable.

As to what drums and shoes I have for sale here is a summary:

I have one axle set of 4 shoes for front brakes on B20 5th series/B24S Convertible The shoes have linings 206mm long x 65 mm wide. and they are asbestos based and hardly worn .

Cast iron brake drums:
2 x 300.4mm I/d. No scoring or corrosion.
2 x 302mm I/d These have been skimmed and are smooth with not scoring or corrosion.

Aluminium with cast iron insert, all of which have a good inner surface.
1 x 300.2mm I/d
1 x 301.2mm I/d
1 x 301.3mm I/d
I have another pair  these in Italy but I don't have its I/d to hand.

And as mentioned in an earlier post, I have 4 sets of complete single leading shoes front brake assemblies including shoes, back plates etc. All in good condition although they will need rebuilding with new seals.
And then I have plenty of rear brake drums etc and also smaller drums for the earlier Aurelia models.
I am not aware if new brake drums are available but if they are they will not be cheap.
Also I don't have the factory limit for the I/d of these front brake drums.

Apologies for the length of this but as with many  things Lancia, the progression not totally straightforward or logical.
Chris

Here are the 5th series brake shoes with new 3.5mm asbestos type linings fitted referred to above.
Also one of the available single leading shoe brake assemblies is shown.
Chris

I have often been puzzled by the brake shoes on the front brakes. One steel and one aluminium as shown on your photo. Neither Paul Mayo's manual nor the parts book shows this. Is it like this on all B20s or only on the early ones? Mine is a 3rd series. And, which is the front shoe and which is the rear shoe?

Are the different metals to do with differing air flow around each of the shoes?

Is it my imagination or have I seen lead weights bolted to shoes?  The STORY I've heard is that the judder was so horrible they tried any and everything they could think of to kill resonances.  Have also heard that they were all 100pct fine when new and don't HAVE to be like that if set up properly and looked after.

Something I've never really liked with Aurelia axles is the I-beam which isn't as stiff in torsion as the (to my eye) gorgous Augusta front axles which are tubes.  "Maybe" some racers "might" have plated the outboard sections of their front axles to make a box section with the orginal I becoming an interior web which will be masses stiffer.

As an aside when I had the Jason/Louise car it used to bob about and move left and right needing quite a bit of margin to clipping points or gutters etc etc.  It was also really sensitive to toe in.  Since the negative camber was taken off (it had a lot when I had it) that problem has gone away.  Having the pillars narrow at the top and wide at the base and a fixed length between the steering arms will obviously toe in and out with bump, and if that's not even or the grip or weight isn't even then it will steer...  Someone who followed me round Goodwood at a track day thought it looked like it was about to have an accident for most of the lap.  I didn't mind having learnt to drive in a Volvo 245 Estate which needed quite a bit of space round it and acceptance that instructions took a while to reach the tyres and patience was needed to get a response before sending further instructions.  Mostly it was hold a line and leave it do its thing...sort of like delegating at work not micro managing.

Something else "they all do" is a little shimmy back through the wheel when loaded up.  Is that true at all or a general sliding pillar thing on the limit?  Maybe its only loaded up to the extent possible on inappropriate tyres or something that happens on the wrong size or offset wheels.

Back to the judder - no issue on the road but it would sometimes (end of the Manx TT pit straight) have a high frequency eye ball rattling judder that spectators could notice.  I think its now on the twin leading setup and they had new drums made by "Type Cast" I think.

Those Augusta axles aren't immune to judder.  There's a single seat special I think with an MG engine that was raced hard a while back and they had judder.  I passed on the story that old ali/iron drums might skim true when cold but go funny shapes when warm, and to perhaps try getting some new made might help.

John Savage told me when racing his Aurelia it juddered cold but fine when pushing on. Perhaps his drums had worn true under racing conditions.  I don't think he ever measured it cold to understand why.  Others said that leaving the hand brake on when the brakes were hot was a bad idea as when the drums cooled and shrunk that could distort the drums.

A little wander down memory lane...

Getting a long way off topic - sorry - but not this one!

https://www.lancia.myzen.co.uk/forum/index.php?topic=7016.0

Am racking my brain for the name of the MG special two seat sports racer that also has an Augusta front axle.  I saw it at Crystal Palace and wrote an article for an MG club about it.  It was like a 2/3 scale C-Type Jag.

Back to the topic. I still hope that someone can answer my question about the different brake shoes.

We all hope you were going to give the answer to that Niels, I find it weird to!

On the Appia commercials (Aurelia brakes) both the front and rear brakes use the iron shoes as the leading shoe, (and the aluminium shoe at the rear) - to my mind this is the one that does "more" work and gets hotter - so is it something to do with heat dissipation/absorption ??

So more airflow = more heat dissipation?

It is embarrassing, but when I first took the brakes apart I forgot to note which shoe was in front. I tried to think what appeared most logical and concluded that having the iron shoe as the leading one made most sense. It is much heavier than the aluminium one, so I thought that it made most sense to press the heaviest shoe forward when braking and let the lighter shoe work against the inertia. I am glad to see that this may be right - even if for a different reason.

I like this reason. Iron shoe more inertia to resist brake judder.....??

Wondering about judder - seems like three possible sources:

- the shoe pressing in the drum
- a worn pivot point allowing wobble
- resonance with the front axle

Any others?

Lancia beefed up the axle over the Aurelia's lifespan, suggesting resonance. People have also noted the wear on the pivot point. And then the shoe in the drum - difference of alum vs iron? Hard to say. Anyone got some more thoughts on this?

The s.2 has pretty significant judder although oddly not alwyas. Also, sometimes you can "push through it".... its less after the brakes have been set tight, so there's likely something about the shoes:drum that's a factor here.

I have honestly never experienced front brake judder on an Aurelia in > 40 years of continuous ownership of more than 10 cars from S1 to S5 incl B24S Convertible using both old asbestos linings and new non asbestos ones.
If I could tell you exactly why, I would do. All I do is ensure the drums are round and not grooved and that the linings have plenty of life left in them. I carefully re-adjust the linings after they have bedded in and always ensure they lining pivots are not worn.
I have had a problem with hot OE drums being too tight in a 15" wheel ( made with Aurelia centres and Flavia rims) but this was cured by taking a small amount off the drum cooling fins.
Chris

Chris - congratulations !!!  Myth busted...   

Everyone else - could try harder.

Just to follow up on a couple of Forum Member comments, here is a set of 4 steel plates I had cut with a view to welding them on the outer ends of my 3rd series B20 - the early H section axle. This thought was not anything to do with brake judder - more to do with general flexing in that area when racing. I had a shock once when after a race at Spa, I found my wheels had been touching the sliding pillar in an area which had >6mm clearance at rest?
This is one reason why the 'stickiest' tyres I ever used were Avons whereas according the rules of that particular race series I could have used an almost slick Yokohama with a stickier rubber compound..
If someone wants to stiffen their axle in this area, these plates are available for £40 delivered UK.

OOOps! Forgot the picture.

Hi Chris -

Would they fit an s.2 axle?

Geoff

Yes Geoff, any axle up to but not including 5th Series B20/B24S.
Chris