Progress update on the RTS build. Bought a cheap 97 Bomber Z1 with issues to replace the blue Z4. So also a Z3 QR20 Bomber as a donor fork, for the bushings and other unobtainable spares. Including a crown with alloy steerer. Used the nicer but slightly newer brace, with the additional CNC-ing work. Also added the additional top out springs from the z3, which lowered the fork to around 85-90 mm travel. I was concerned 100mm fork would push the geometry too far. I've had experience with this from my other GT (91 Karakoram Elite). I originally ran this at 100mm but the front would get too light on climbs. Lowered that to 80mm and it worked wonderfully.
The weld has had over 6 weeks to age harden now and is looking solid, the dull finish around the weld has naturally evened out, looking shiny now. Magic.
The final piece was the shock, which I worked out was toast. I had the options of sending it off to Noleen in the USA (too expensive), ordering a seal kit from Noleen and attempting to rebuild myself (risky and no way to inject the nitrogen myself to 200 psi). So went for the safe option and sent it off to an expert in the UK. Found RSF (Plymouth), they have worked on these shocks before. Had a chat with Dave, he was confident he could rebuild it, using seals he has custom made. Long story short it took longer than expect due to a number of issues. Dave was honest and upfront and I would recommend him for this work. Can really feeling the damping working when you compress it with the spring removed. Its ridable again! Dave found the shaft seal had melted and left the oil in the 90's...
Shock was reunited with the frame and bike was ready for a ride! Did a 16 mile XC loop from one end of the Malvern Hills and back stopping at the Obelisk at Eastnor, which will be familiar to anyone who attends the Mavens Classic. Bike performed well, with a few issues, was a pretty tough ride for a shakedown! The rear suspension is fairly subtle but effective, definitely takes the edge of rocky trails, reducing fatigue. Welded BB shell is still good.
The main annoyance was play in the bushings. I isolated this down to the shock rod end. Causing a constant knocking. I like my bikes to be right and although I doubt its a huge issue it is niggling me! Anyone have any experience with what can cause this? I can see the top hat spacers fit well but not tight into the eyelet on the shock. Can these be sourced anywhere? I also noted the original bolts are threaded all the way, I expected these only to be partially threaded. Would a shoulder bolt be better? Or am I just expecting too much from an old system?