Hi, I'd like to share with anyone here who would like to upgrade their rear suspension, a very good change over at very little cost. Now to start with, if you want to bolt something straight in , well this is not the way for you, it requires a bit of basic metal work and some ingenuity. This is not saying it's a hard job to do, and you do have to spend some money and lose the resale of your original shock as a complete unit, as you have to use components off your MC18 showa.
I have photos to put up, if I can upload them but first I'll describe what and how:
No way can I fund a new Ohlins, and seconds are hard to find, so I searched the net for something similar, mainly with compression and rebound adjustment, I have used a YZF R6 2010 rear shock in another NSR chassis that worked well and was reasonably easy to fit up, so I wasn't going in blind. here wasn't much in the way of modern units that came within the spec I was looking for until I cam across a SACHS , out of an MV Augusta F4 750. It had rebound and compression adj, eye to eye was within 4mm and the spring diameter's, Id & Od where the same as my NSR's. Better still the price was right, 103.5 pound.
BTW, these are the same shock as used on most high spec Ducati's as well, and there are a heap of them on offer in the US on theBay, possibly they have been replaced with Ohlins is my Guess, and again, at very reasonable prices.
So here's what the go to fit one up: Firstly remove your NSR shock and undo the lower shock eye from the from the shock rod. This requires the spring to be compressed and a spanner put on the lock nut. Another method is to grind of the anchor pins that hold on the preload adjuster sleeve and slip the adjusters and sleeve off over the top shock eye. Rules out using the shock again thou. From your original shock you will need to use the lower spring guide/retainer and the retaining plate that sits underneath the guide, and the spring. Do the same with the sachs, remove the lower spring retainer and the spring.
This is where it gets a bit tricky, from the Sachs shock, you take the top eye retaining washers out, they are machined with a step and a giude on them and you have to cut the guide of at the step( hacksaw does it) this is so you can get the NSR 12mm shock bolt through the sachs to eye, as the sach are 10mm both ends. Fortunately the sachs top shock eye bearing has an ID of12mm so its a then a straight fit, once the 10mm guides are cut off.
The bottoms a bit easier in the bolt up as it matches the 10mm NSR lower eye, but you have to make up a couple of spacer to take up the gap left by the narrower sachs unit, you will need 2 spacer with a 10mm id hole with approx a 22mm od. The spacers should be approx 6mm wide.
The next tricky bit is to linish or file the sachs lower shock eye Aluminium casting outer face "flat", as it's cast with a radius and this radius contacts the suspension "dogbone", so by removing some of the radius you gain a bit more clearance, without doing any damage to the shock, the shock need only clear the dogbone by a 1/2 mm as all the work from there by the shock is up away from the dogbone.
The next bit of work needed is to fit the NSR spring which slides straight on to the top perload adjusters then slip the NSR lower spring guide oner the bottom of the shock and into place. The NSR lower spring retainer the will need to have a slot cut into it from the outside to the centre, just slightly wider than the sachs shock rod. Then th3e lower retainer has to have the Id increase to the dimensions of the sachs lower retainer/ rebound adjuster, at the worst this can be done with a set of files or a die grinder, then once with a comfortable fit, slide the NSR lower retainer into the spring guide and over the sachs retainer and bingo, you have a working modern rear shock that fits your MC18.
Whilst we where doing this we checked the valveing of the sachs against that of the NSR and the sachs range of adjustments places the stock NSR valveing at about a a third of the way through the sachs adjustments so there is plenty to play with. Proof will be in the running, and that's a way of at present but we are confident from previous experience that it will work fine, particularly seeing we are sticking with the original spring and the bike has had a bit of weight taken out of it already.. The spring when installed has no load on it al all and is loose in the guides so it's all good. The picture are a breif look at some of the installation work, hope they explain a bit better than this post.