Bomber Z1 BAM (130mm) - How to Repair the Top Head Unit of the Cartridge??

<Sorry – still in progress now! Pictures following!>

During the last weeks I built a bike around an old but famous Verlicchi/Sintesi downhill ‘fully’ frame (aka ‘Bromont’) from about 1992-1995 and I can tell you : I have a lot of fun with it!

I started with a red DH3 (460 mm), that for sure is o.k. and fits 100% to year and frame, but I needed a fork with some more crown to axle length, more than the XC’s 420mm. So I first took a Bomber Z1 (1997) and now a Bomber Z1 BAM (1999) with about 505 mm crown to axle length. ‘BAM’s are a bit lighter (Bomber Aerospace Material – aluminium type).
I believe thats (the BAM) total o.k. for my needs, I want to have a fork suitable for my needs, and it has to be from this period. That’s it. Sure!

The BAM is technicaly like a standard Z1 but with this changes :

The brace had been lightened by milling it more out.
The top cap screws have been optimized (not that height like Z1).
The top unit of the cartridge (the part over the red nut, which can be disassembled) is a little bit shorter to fit the top cap screw.
The top knobs are blue anodized now and flatened on 2 sites.
Different sticker design (orange top and bottom, somehow chromed sticker in the center)

Here this the BUT! of the story.

I bought a Z1 BAM with 130mm travel from 1999 via Ebay Kleinanzeigen. The fork had the right height and was promoted as ‘.o.k.’ with no technicak errors, but unfortunately the top of the left cartridges had been broken – just the part per the knob is screwed on. I believe someone teared it off without knowledge and sensitivity. Argh!!

This is the most important part of the fork, most of the others can be replaces easily, but usualy cartridges are dead as dead and for about 21 year old parts there are no replaceables. Additional the Z1 BAM from 1999 with 130 is not that spreaded than 100mm tavel forks. There is another Z1 BAM from 1997 with 100mm, I hoped to get one, but nada. The fork was so far in nearly accaptable conditon, oi was nearly out, but bushings feel o.k. I do not care about oil seals, knobs, crown, screws or steerer as I have all this as replacements spares in stock.

So, what can I do? I inspected my other Z1, a 100mm travel Z1 from 1997 and I realized, that the top of the cartridges are similiar. The tops are looking the same, but there are little differences. So I had to compare in detail …

The seller agreed about paying me a little fee back because of the damage – this is extraordinary friendly and very fair. Thanks, Chris!!

20201024 updates: By searching around I met a very friendly guy in polen online who was able to sell me some cartridges for the Z1 and the Z1 BAM, some are NOS, some used but from excellent conditions. My Z1 BAM is running, but I have all spares for reparing now, including seals and bushings. 🙂
I will be able to rebuild and sell the Z1 classic (100mm, 1997) now. 👍✔

Differences 20200829 :

Thread of part no. 7 ‘Preload Adjuster’ has a different thread – compared Z1 1997 against Z1 BAM 1999 ! :
– Z1 : tread is clock wise
– Z1 BAM : thread is counter clockwise !
…

Updates 20200829 :

My springs are a little low, I ‘m not that heavy (80kg), but a very little weigth on the handlebar and the fork is compressing. I added on both sites 20mm preload springs.
I changed the crown, the one I bought was that that ugly! I had a spare one including an aluminium steerer, which fits.
Exchanged all screws
Spings are a little bit ‘noisy’ : Added about 6cm shrink tubing over the springs in the middle and on the end (shrink tubing covers the 20mm spring and ca. 30mm on to the long spring)
Added BrakeStuff canti sockets

ToDo: