Jubilee Seat Pan Repair

Thought I'd start  by looking at this collapsing saggy, saddle...

Seat badly fitted and sagging

The seat fitted to this bike was poorly fitted, this became clearer on removal...

Seat cover was attached by extensive pop-rivets
through perforations in the seat pan sides.

Seat cover peels back loosely, note non-std and
now disconnected switch fitted beneath-
hints at previous security step as the bike has no ign key.

Seat foam deteriorated and collapsed

Cover removed to reveal seat foam

The seat pan itself was very rusty and extensively cracked. There were signs that its been patched up before.

Cracks to rear of seat, strengthening pieces added in past

Cracks at mid point of side. Only one rubber button present on this seat-
there should be one in the same position on the other side.

Seat pan front: Note damage to left side and destruction of rubber holder.

The seat is attached to the bike by two vertical stays at the rear that fit over the suspension upper mounting studs and two rubber bushes at the front that fit into metal holders beneath the seat  and accept two protruding studs on top of the frame side tubes. Note that in this seat only the right bush (as shown in this picture) is present, the left hand bush holder has been destroyed although the bush itself was still on the bike. There is also quite a bit of damage to the front of the seat, and in fact the metal here had been thinned by corrosion.

Overall this pan was in bad condition, really I would fit a new one if one were available. Of course anything made by man can be reproduced but the cost of having a custom made seat pan is expensive. As this pan has been repaired once and is already on the verge of viability, there was nothing to be lost by my attempting to repair it. 

My fabricating skills are not extensive, this pan really demands new parts be made and welded in but this isnt going to be practical at my skill level. Instead I will try to reinforce where possible by welding strengthening plates  over the stress points. The front of the seat has worn too thin and is too badly corroded so I was forced to cut that out and replace with a new piece of metal.

New metal welded in to the seat front

 The rubber retainers needed to be replaced and I found that bending sheet metal around a 20mm steel electrical conduit was just about perfect.

Metal sheet folded around 20 mm conduit

This was sliced to create bush holders

The bush holders made above were then trimmed with metal snips before welding them into place beneath the seat pan on the new metal I had installed. This is quite tricky as they need to be positioned very close to the side of the seat. It took several attempts and even now I'm not sure that the bushes will be in exactly the right position (!), but hopefully good enough for a positive and secure mount.

Completed pan (underside) with new bush holders fitted

Seat pan upper side

The welds on this pan are clearly not pretty, but they will be invisible and mostly covered with foam and fabric. The pan is at least solid now even though its a patchwork of reinforcing plates. The cross seat strengthening strip was also installed by a previous owner and seemed a good idea, so in a belt-and-braces approach I reinstalled it onto welded studs.

I gave the pan two coats with Jenolite rust converter. I like this stuff because its water based and seeps everywhere water has penetrated and so treats rust in inaccessible places. I let this dry over 15 mins and then rinsed off any excess with methylated spirit. This degreased the pan and also penetrated into all the crevices removing water and replacing it with the more volatile alcohol. The meths can be removed easily with a hot-air gun- or as this happened on a rare sunny day in Surrey, an hour in full sun!

The original pan was painted blue, so I gave it two coats of smooth Hammerite, This is a lighter colour than the original blue, but all bar the underside will be invisible anyway. The blue on this bike is probably a hard to get cellulose paint but fortunately the modern Vauxhall colour Polar Sea Blue (pearlescent) is a pretty good match so I gave the underside of the seat a coat of that before fitting the foam.

Underside painted with vauxhall polar sea blue

... topside left in hammerite blue.

Here is the finished pan- I am aware it doesn't look great but its solid and the rust has been controlled.

I sourced a new foam through the owners club and a new seat cover from Ebay. There were surprises with both when they arrived; the seat foam being rather too large and the cover having an unusual inner fillet, so both will need further investigation before I can get on with the fitting.
I since found out that the inner fillet is normal for this pattern of seat cover. The outer layer hangs free at the seam to give a neat edge to the saddle whilst the inner fillet is clipped and glued to the seat pan edges.  Unfortunately the seat cover I received was simply too small. Its quality was great and although it fitted the length and width of the foam, its depth was simply too little - it covered the foam but not the seat pan and there was no way it could be pulled down to attach to the seat. In fact it would fit perfectly only if you left the foam out entirely! For reference the distance from beading to beading (ie that around the saddle and around the base) was only 4 inches, and the inner fillet only 1 3/4 at its widest. These are both way smaller than the torn cover I removed so it will have to go back.

Cover depth from beading to beading at the rear of the saddle- 4"

Inner flap depth 1 3/4"

I will order a replacement from the owners club- this presumably will fit the foam they supplied.