HondaVTRSP.com

So after promising a shock rebuild post after Introductions I thought I'd better get on with it. Many SP owners quite wisely follow sage advice, bin their original shock and put on an aftermarket item, as it's generally recognised it's not that great. But as I rather like originality and performance I thought a decent half-way house could be achieved by tweaking the original shock, especially the SP-2 version that was deemed an improvement or the original. Honda's official press release stated that it provided "a wider range of damping settings for more precise tuning..."

Thinking that the front forks could also do with a full service I booked onto two of Reactive Suspension's Suspension School Courses covering shock and fork servicing.

http://www.reactivesuspension.com/suspensionschool.php

In a nutshell it was a great two days spent learning the theory and practice of how these items work (or don't in some cases) and then getting fully hands on servicing either your own items or items supplied by the school. I can highly recommend it. Classes are small - usually 4-6 students and Gareth is a great teacher. Questions are welcome and I asked several SP related questions which I'll go into later. Gareth also worked with Shane Byrne when he was riding the Honda SP-1 in British Superbikes.

Let's jump straight into removal of the shock onwards and note this isn't a 100% step by step guide, more a general review of the shock service I undertook.



Here we have the shock off the bike, spring and lower collar removed. First useful part of the course is that if you decide you don't want to do lots of suspension servicing you can use the schools specialist tools. The first you'll need is a spring compressor to get the spring off the shock. Next we release the pressure from the reservoir body via the Schrader valve. To access this you'll need to remove, with a fine point drift or sharp instrument, the reservoir cover. Once done you expose the valve but the process destroys the cover which has no way of re-attaching later on. The SP manual pretty much describes the shock unit as unserviceable and should be replaced if you have problems (not so) and this is just one of several 'features' to stop you servicing it.



Here we can see the notch in the Seal Head Cap that needs to come off to access the internals. The seal head is removed by using a drift placed in the notch and carefully prising the seal head up. Once the cap is off we can push the seal head down thereby exposing the retaining ring that needs to come off using another fine pointed instrument but with the ends smoothed off so we don't score the internal shock body.



With the ring removed we carefully remove the Shock Shaft. Careful extraction prevents the inevitable bath of oil one gets if you rush this stage!



Here's the shaft completely removed with the rubber bump stop, pistons and shim stacks revealed. Note the removed Schrader valve at top left when we released the pressure from the reservoir.

We then need to get at those pistons and shim stacks to 'blueprint' them over and above OEM to try and improve the standard shock. This together with refilling with really high quality oil are the only sensible things we can do to improve the stock shock. To remove the nut securing these assemblies together is another 'do not tamper' style affair. The nut is held in place by peening the edges of the threads at the top of the shaft so the nut can't be removed. Normally not a big problem as we can carefully remove the peening with a grinder or file but in this case the Showa unit incorporates a small disc that works as part of the damping system inside the shaft threads. Remove too much material and the disc can fall out so shock is useless. I bailed and gave it to Gareth to remove with his years of experience and skill. Removing the nut allows the stripping of the shims and piston assembly. On the course this is done the lengthy but correct way; noting each and every shim size with a micrometer and writing down their exact order so there's no chance of reassembling the unit incorrectly. You'll see from the number of shims that this isn't a two minute job.



The parts are all throughly cleaned with brake cleaner and the piston itself is blueprinted for the best possible mating surface by rubbing down on an engineering plate and then cleaning again.

I noted that the rebound adjuster (at the bottom of the shock) turned ineffectively on my SP-1 and Gareth explained why. The adjuster has a very finely turned step in the middle so the rebound adjustment basically moves a needle along an angled surface to increase or decrease the flow of oil through the damping. The problem is that this makes the lowest setting of the adjuster very thin indeed with the inevitable result the adjuster can break off at that point. It might be worth checking your adjuster to see if it has some resistance, or if it just turns uselessly round and around like mine did .

After reassembly and stripping the compression adjuster in the same fashion, we refill the shock with oil and then can either bleed it manually or use a special vacuum refilling system that really does bled all the unwanted air out of the system. I opted for the latter, once again leaving Gareth to refill with top spec Silkolene shock oil (normally 2.5 to 5w).



That's a really quick review of a whole day of shock servicing and pages of theory learnt and hopefully will give an insight as to what goes on inside a Showa SP-2 shock. The bearings and linkages holding the suspension together also got a full overhaul, so when my new brake lines arrive and I bleed the brakes I'll be able to give an on-road report of what the riding results are. I might even do the fork service write up

Excellent post
Would like to read about the fork service one as well

Great post and waiting for the next one

Good post. Keep them coming.

Looks like a great course Very interesting

Adrian wrote:the reservoir cover. Once done you expose the valve but the process destroys the cover which has no way of re-attaching later on.

Does this mean its left exposed from now on? and if so, will it shorten the service interval of the shock as dirt and wet can get in?

Pete

Thanks guys, I just need to get the brake service complete then I can get out and test it all. Here's some extra images. Pete, on the reservoir cover plate being removed situation, the second internal cover is totally sealed as it's holding the gas/oil mix and reservoir "bladder" in place so if that leaked the shock would fail anyway. Here's how it looks:

You could say a layer of defence has been removed but I think its there to complete the "we don't want you messing with our shock" mantra of the manufacturer rather than to keep elements out. Many aftermarket shocks feature this outer cover and make it serviceable so they use a threaded cover that can come off as many times as you want. Another reason SP owners often go for aftermarket shocks.

I found a picture of the rebound adjuster that I mentioned is known to break due to the stepped nature of the adjustment. Here you can clearly see why that could happen:

And that other problem area mentioned in the post above is the disc that serves as part of the damping system, which is held in place at the top of the damper shaft by peening the edge of the thread. You can see here that if you remove too much metal the disc will no longer be held in place.

Here's another image showing the rebound damping system after removing the bottom link/clevis pin assembly that contains the aforementioned pesky little rebound adjuster. Hopefully you can see that the needle moves up and down through the centre of the shaft oilway as the adjuster is turned in and out with the adjuster moving up or down on the "ramp" of the adjuster. Well, until it breaks anyway.

And finally for now, servicing the bottom link: remove outer seal and metal centre spacer, use correct Moly grease for the needle bearings and re-assemble x 3!

Thanks Adrian.
I've got a much better idea of which cover you meant now. A picture might paint a thousand words but if you are a numskull like me and look at the wrong picture it's easy to get yourself muddled up I can see now there is very little likelihood of any problem whatsoever without the reservoir cover.
On a different note:
I keep thinking I should pull my bottom link and check the roller bearings. What sort of mileage has your bike covered and what was the condition of the bearings like when you got the dust covers off? The piccie looks like it's been pretty well looked after and not seen much weather.

Pete

Oh, suspension was the one remaining mystery area (well maybe plus electrics a bit) for me even after plenty of research, which is why the course was so good for me; I understand its quite hard to visualise these things sometimes. On the shock link, that's an 'after' picture of the link. Here's the 'before' when it came off the bike at about 8,000 miles.

There was nothing to suggest any wear but it seemed daft to do a suspension service and not take care of everything whilst the bike was on the ramp. There seemed to be a very slight bit of wear on the swingarm pivots holding the link, almost as if it didn't quite line up perfectly but I just smoothed it off with some fine grit paper and made sure some regular grease went in between link and support posts before re-assembly. The bearings were fine, ditto the seals as I'd expect after such low mileage and pampering under a garage. Everything got completely cleaned and re-lubed and torqued back up. Here's the parts after servicing.

WSB and MotoGP and sunny weather this weekend. Fork service post will definitely be delayed

Wow!
They look like new! I've just finished replacing the front wheel bearings this evening and then stripping and cleaning the rear brake caliper (some new pads too). I gave the linkage a good looking at whilst I was down there and even though it still all looks pretty good after 32K miles and now ten years old, I keep thinking I've got to stop guessing and just get on and do it

I'll look forward to your front end write up. Best mod I ever did to mine in my opinion. The std Honda set up is fine if you are a 7.5 stone waif but, unfortunately, I needed something a little more beefy