Overhauling early Aprilia sliding pillars

[simonandjuliet]

I'm heading into the garage later this afternoon so will check everything

[simonandjuliet]

I will try and answer your questions with a few photos .....

Measurements for the bronze bush are the same as mine, but springs are quite different - dimensions in photos. I have only one new one for each spring so I can't let them go, but I am happy to lend them for getting new ones made

I have shown the order of things in the photos as well, do you still have the felt seal (not shown on the TAV) ?

[williamcorke]

Thank you Simon,

So, inevitably your photos and measurements lead to more questions...

1. The felt oil seal(s); are there two? I think I can see one that sits below the washer that is shaped like a collar (grey-ish colour) and another below (when assebled) that is more like a washer shape and brown. Is that right?

Cavalito sells a part (photo below) that is the same shape as the first of these, but where the felt is contained in a metal carrier (doesn't state on their site if it is S1 or S2 though, I'll have to ask).

I remember reading somewhere online (I thought it was Noel's site but can't find the reference) about the use of some marine quality felt to replace the original type, which improved oil retention.

Mine had no felt seals at all. No wonder it was so thoroughly encrusted!

2. The top damper spring

The plot thickens here, as the smaller of the two spring I have has similar I/D and O/d to yours, but puts sideways pressure on the central rod when the cover is tightened, so perhaps something else is amiss, though I don't see what it could be. Any ideas?

Your drawing of the upper one that seems to be causing the problem is very useful and there are lots of people I've found online who can make them, but I guess the key missing measurement is what seems to be called load - I might call it deformability, i.e. how much will it compress when subject to a specific load.

[williamcorke]

An update on 'the other' Aprilia S1 front suspension thread here.

I managed to get hold of a new old stock upper bronze bush (previous post) from a seller in Italy for a very sensible 30 Euros. Arrived this week and fits perfectly.

The issue of the top rebound spring putting sideways pressure on the damper rod and causing binding in the vertical movement of the unit is still troubling and unsolved.

The photo below shows:
1. Damper rod - 12mm O/D
2. Top guide (lower and middle rebound springs are above and below this) - 12.85mm I/D
3. The Rod loose in the guide
4. The final photo is of a part I found online which seems to be the same as mine except for the addition of a brass bush which would presumably have a 12mm I/D and so properly locate the rod. This seems like a better solution or upgrade.

Can anyone here shed any light on whether my guides are missing the bushes, whether they were added later in production or are a later owner's mod.?

Thanks, William

[williamcorke]

While waiting for a second set of lower thrust bearings from Cavalitto (apparently the unit I'm rebuilding is what Enrico at Cavalitto calls 'First, First type' and has a smaller Augusta-sized bottom thrust bearing, not the normal 68mm O/D S1 Aprilia type. Lesson to remember to never assume, always send dimensions...) I have been sorting out the front axle brakes, bearings etc.

An 8-toothed castellated tool is needed to disassemble the bearings and after asking the usual suspects if I could borrow, rent, buy, have one made by them with no success, I have made one myself by simple but - though I modestly say so myself - ingenious modification of an immersion heater spanner.

I happened on this idea searching on eBay for large spanners that could possibly be modified, and for £13.52 bought a solid cast one that I then ground down with an angle grinder. A satisfying hours work.

[GG]

Nice!