Aprilia Cabrio - here we go again

[simonandjuliet]

More on Houdaille shocks and thank you Sebastien for some of the pointers.

It appears that there is no-one in Europe who is rebuilding these at the moment, the Swiss company appears to have shut up shop. I have been reading comments on Panhard/Citroen fora, there is a (possibly 2) company in the USA who can rebuild them but they are quite expensive , approx $500 each, plus postage etc

So, I am going to flush and refill mine. There is some info on the document Sebastien referenced plus I have come across a pre-war doc from Citroen that also talks about regulating the shocks, it is in French but the diagrams are easy to follow, and the French pretty straight forward.

I think that "castor oil" - which incidently gave its name to "Castrol" - is the same as glycerine and is available as "huile de ricin" in France, but if anyone can confirm this I would appreciate it. It does sound a bit like a nerve-agent though !!

Plus I need to find the solvent for glycerine - I think it's alcohol, but again need to check

Attached are photos of the Citroen document

[nistri]

Simon
Thank you for the very helpful instructions. My 1947 Ardea appears to have the same Houdaille shock absorbers as your Aprilia. Difficult to say how much glycerine one would use. However, after a bit of cross referencing it seemed that the huile de ricin (olio di ricino) as mineral oil is no longer made and is replaced by the Castrol oil shown in the picture. I have used it in my 1947 Ardea with good results for the past 10 years, Andrea

[lancialulu]

I had this challenge when I had my Aprilia 2nd series with Houdaille rear shock absorbers. One appeared at level and the other was a bit low. I decided to do the taste test albeit the stuff was 60 years old I suspected. Anyway from my youth (don't ask) I know what glycerin tastes like (no I wasn't make nitro glycerin) so I dipped the full shock absorber and it was definitely tasting like glycerin so I ordered 250ml clinical quality glycerin and topped the low one up after confirming it tasted the same....

[simonandjuliet]

Don't your parents make you drink castor oil when you are naughty ??

Just ordered "huile de ricin" from the chap in Pinet (as in Picpoul de Pinet) who supplies old fashioned oils. He used to supply Penrite , but they shut down their European operation 2 weeks after Brexit , apparently !

[lancialulu]

Don't your parents make you drink castor oil when you are naughty ??

Luckily I had liberal parents. I case folk were wondering two innocent substances potassium permanganate and glycerin are hugely exothermic....

[Sebastien]

A small word of caution, if I may.

Castor oil is not the same as glycerin / Glycerol !

https://en.wikipedia.org/wiki/Glycerol
https://en.wikipedia.org/wiki/Castor_oil

Glycerin should be easily available at a pharmacist, even now!

[nistri]

Yes, I fully agree: in fact, castor oil ("olio di ricino") is what Lancia indicated for the shocks, Andrea

[simonandjuliet]

I must admit that I am getting confused ..... I have seen references to both glycerine and castor oil for Houdaille shocks and had begun to wonder if the products are interchangeable.
Sebastien I agree that they are different compounds , but have they been used along side (mixed ??) each other over the years ? Do they interact/have different properties ? I don't know .... yet. I am going to get hold of both compounds and add them together and see what happens - not too exothermic I hope

Tim, we mixed fertilizer and sugar as kids .... that was interesting

As Andrea says, Castor oil #1 was recommended - I just came across this again in the "Instructions for use and maintenance of the Aprilia"

But thank you all for your input, it is appreciated

[frankxhv773t]

It was weed killer and sugar in my childhood. Sodium chlorate and sugar, mixed in a solution then soaked into cotton wool and dried out was a reasonable DIY version of gun cotton. Oh the fun we had! We didn't burn the school down but it was a close run thing on a couple of occasions!

[simonandjuliet]

Today's bit of over-engineered Aprilia mechanicals are the rear spring hangers. For those who don't know, most Aprilias have independant rear suspension using a system of trailing arms that have a torsion bar at the axis and a transverse spring , slung underneath. The two systems working in opposition - the torsion bars twisting the trailing arms up and the spring holding them down

The spring is connected to the trailing arms via a wire loop-hanger that has pivots at both ends. These should be lubricated every 5,000 miles with a slide-on grease gun, but often they are overlooked and wear badly (see below !), plus if the wire hangers are not inspected regularly, they fail with dramatic results ! Harry told a story about an Aprilia crossing Tower Bridge when a wire broke and it flipped the car onto its side ..

I took the spring and hangers to bits and discovered some horrors, fortunately I have all the new bits to replace them , but here's what to look for

Both sides had broken and oval-ed pivots at both ends of the wire and the wire had started to fray. The rollers were flat and the bearing surfaces looked like threepenny bits, the axles were deeply gouged as well.

It is theoretically possible to rebuild these units (one photo shows all the pieces necessary), but in order to open up the old bits, you have to grind off the peened flanges. Mine were so bad it wasn't worth saving the bits , and I have new ones. I am wondering if it is possible to strip these units and replace with modern sealed bearings - I am looking into this ....

Final pictures show the replacement bits and the re-greased bits - they haven't been greased for 75 years !


 

[lancialulu]

Should be nice and compliant when you get it on the road.....whats the timeline??

[simonandjuliet]

How long is that piece of string ?

[simonandjuliet]

One of my least favourite jobs - stripping Aprilia springs. They are just so messy, so I found a corner of the garden and set to !

Anyway, stripped, degreased , cleaned, rubbed down and painted. A combination of scraper, solvent, karcher, petrol , degreaser and stripping disks .... hopefully I can put it back together tomorrow

[Dikappa]

A man's got to do what a man's got to do!  The man who did the Lambda springs for me specifically said not to blast the springs, he said it would damage some special layer.  Now they where so rusted out I 'm still in doubt if that layer is still present...

I bought OKS 510 paint, which is supposed to be a dry lubricant after being applied

 

[simonandjuliet]

Thanks Koen
I have given them a coat of rust converter/primer and then a light coat of black because it is all going to get greased - copparslip probably. I think David W then wraps them up in leather or similar. I must admit that I'm not going to do that, I prefer to keep an eye on them as they do break leaves from time to time

Having said that, I do have a very nice set of leather, lace-up cuffs for the outer UJ's