Shock rebuild

The Cagiva era Morinis
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nr.
Posts: 24
Joined: 25 May 2021 13:42
Location: Ely, UK
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Shock rebuild

Post by nr. »

I know that the subject of shocks for the Dart has been done before, but I'm wondering if anyone has any good information on spares availability for the Marzocchi PBS series shock? I whipped mine out this evening after some rather alarming moments at Cadwell last time out, and it's definitely seen better days. What's left of the damping has long since vanished, leaving most of it smeared over the spring. The bump stop isn't there any more. (Was there meant to be one there?) Happily, the coating on the spring appears to be in excellent condition, which is a real surprise.

The engineer in me absolutely knows that rebuilding it is likely to be an exercise in futility, and a Hagon or other unit would be a far better investment. But I'm curious to at least know if it's possible to rebuild the original. So, has anyone done this in the past few years? If so, were spares readily available?

Currently got a bit of wood in there so I can wheel the thing around the garage. It feels better than the shock if I'm honest.

Ta,
morini_tom
Posts: 920
Joined: 05 May 2006 13:47
Location: Northampton

Re: Shock rebuild

Post by morini_tom »

I think the problem is they are peened over so not easily unboltable, to rebuild, however if the seals are ok and it just needs fresh oil and gas then something might be possible.

My second dart came with a shock which had been rebuilt by a previous owner- as evidenced by a schrader valve on the shock body- presumably it was drilled, tapped, drained, filled with oil and then the valve screwed in.

It felt ok on the bench however when I bolted it to the bike the schrader valve clashed with the shock linkage and broke off, which resulted in an oily mess everywhere… however the principle of the mod is ok perhaps with better positioning of the valve or more careful fitment on my part.

When I can get to it I’ll take some photos for you if that’s any help. Happy to lend it to you for copying if that helps as it’s no use to me until I repair it anyway.

On the other hand I helped Chris fit a YSS damper to his dart a few years back. It was cheap enough and seems to work well, certainly an improvement on the worn original. Could be a reasonable halfway house route if you didn’t want to go down the wilbers route like I did
nr.
Posts: 24
Joined: 25 May 2021 13:42
Location: Ely, UK
Contact:

Re: Shock rebuild

Post by nr. »

Having given it a good clean-up, there's definitely scoring on the damper rod, so whatever oil I put in there now will only end up stopping the outside from rusting, so I reckon it's time for a replacement rather than a rebuild! Shame, as other than that, it seems to be in good shape. I've done a bit of phoning around today, and MCT came up with the Wilbers option, but warned me that it would take months, so I've put that to one side for now. KTech have been great, and are rooting around to see if they can come up with anything (which I know, won't be cheap, but it will be the best handling Dart ever) which is promising. And I hadn't considered YSS, so I'll have a look there tomorrow.

I suspect a long and involved blog post will happen in the next couple of weeks :)
morini_tom
Posts: 920
Joined: 05 May 2006 13:47
Location: Northampton

Re: Shock rebuild

Post by morini_tom »

The YSS which Chris fitted was I think around £150 and was available reasonably quickly from Uk stock. Model number yss me302-320T-09-X. It will have been listed as for a cagiva freccia, which of course shares the same chassis.

Freccia and dart both had the PBS damper but spring rate and preload was different. Dart damper bodies tend to have more threads on them, presumably because they have more preload. But a new freccia damper will work just fine out the box, certainly compared to a worn 30 year old PBS.

I spent a lot of time deciding what I wanted for my dart, partly because I’m pushing a fair amount more power, partly because my Mito front end just didn’t work perfectly with the saggy original damper and partly because I needed a narrower spring to clear my underseat pipes (I have 2 pipes coming up past the shock). The wilburs was absolutely the right choice for me, but at a cost and not for everyone. I won’t go into my route here, you’ll have seen it on the other dart shock thread on this forum, but if you need any more info just ask.

Cheers,
Tom
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72degrees
Posts: 1549
Joined: 31 Aug 2007 21:24
Location: West Midlands

Re: Shock rebuild

Post by 72degrees »

The Wilbers shock I put on my Kawasaki ER6n transformed it. The Ktech fork cartridge emulators possibly more so, to be fair.
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