Some years ago on another forum a local biker changed his XZ400 rear monoshock for those off a Ducati. He ran into carburation problems and never really got the bike on the road so never reported how the handling changed.
Older Ducati (Sachs) shocks are about 330mm eye centre to eye center with 10mm bushes.
XZ shocks are 345mm long and have 12mm bushes.
Apart from fiddling with the bushes and spacers, how would a short shock affect the geometry/handling?
Are there other alternative older shocks are out there which would be a good substitute for our bikes - and not cost a weeks wages.? Thanks.
You can sort through some of the older threads searching for "shock" or "rear shock". I found two 'reasonable' suggestions: Triumph TT600 shock, and Yamaha R1 rear shock. Both need a bit of fitting.
Ah! Many thanks. I wasn't searching the whole forum. Looks like most of the blokes changing out their rear shocks were in my own back yard all along. All good.
There is very little feedback from projects that are on the road with different rear shockers fitted so it is hard to know if any are effective. I had a very pleasant evening reading through part of POD's long running thread, "Going Racing" He came to the conclusion that the R1 shocker was too light for the geometry of the XZ's frame and was too soft. He rebuilt his '82 shocker in the end - even if we are not supposed to be able to.
Thanks again
The bushes should not be a huge issue, bushes are easly available in multiple sizes and they press in an out with a hydraulic press, or as I did, with a bench mounted vice and a bit of anglo saxon. I used an appropriately sized socket which does work, but no substitute for a correctly dimensioned drift.
5 or 10mm shorter in the rear can be compensated by dropping the forks through a somewhat lesser amount to keep the same stance.
Even if the springing had been ok on the R1, the shorter shock would have meant the real wheel hitting the seat on big bumps.
The Triumph 600 shock was a better fit than the R1, but did need some work with a grinder because of the shape of the eyes. I've passed this on to Iain for his race bike.
Glyn also had a TT600 shocker fitted on his bike and I read somewhere that he offered to share his fitting diagram with others. He said he was able to leave the frame and swing arm unaltered. I'll drop him a line and see what he did.
POD, I suspect that rebuilding an original shocker (which you have done, but the rest of us have been told by others can't be done) is a job best suited for the advanced engineers among us.
Glyn's adapter.
Glyn Pickering doesn't haunt this forum too often at the moment. However, he has invited me to post a pic of his final setup so you can get an idea how his adapter plate worked (thanks POD) and where he fitted the reservoir bottle.
Glyns solution neatly avoids having to alter the original frame so that the change can be reversible to stock at a later date if need be. It also avoids having to grind into the TT600 's eye to get frame clearance as POD experienced.
On the strength of this I sourced a low mileage 02 Triumph TT600 shocker for the princely sum of AU$49.50 plus postage on Australian e-bay. Looking forward to doing this project.
Thanks for the info Glyn and POD
Today the TT600 shocker arrived and I got it side by side on the bench with the XZ400 shocker.
Both are 315mm from eye centre to eye centre.
The bottom eye of the TT600 has a roller bearing with a bush that has a 10mm ID and a 17mm OD
Glyns plans calls for a bush that is 12mmID x 17mmOD and 45mm long to secure it in the original swing arm with the original fixings.
Today I looked at bushes that are available locally. Nothing is 45mm long. However an IRT-1220-2 is available which has the required ID and OD and is 20.5mm long. 2 of these side by side would make up the required bushing length with the roller bearing in the middle. Sound like a plan? https://www.123bearing.com/section-accessory-bearing-inner-race.php
Alternatively I could get one bush to cover the roller bearing section and have two other shorter bushes ground down to 10.25mm to fit either side in the securing pin and make up the 45mm. Any preferences?. Advice appreciated.
I didn't like Glyns plan as I thought the shock might wander on the bearing inner and then who knows what.
Before I gave my shock to Iain I took it to a suspension guyhe found an entire eurethane bushing to fit with a 12mm id almost identical to the XZ. Are they the same eye size? If so you could press the bearing out of the xz shock and into the TT one.
That's a good point. I had been concerned about about how I would stop movement along the inner race bushing. I have been thinking of a couple of suitably sized thrust washers to lie between the bearing housing and the swing arm sides to keep the shocker snug and centred.
After hunting around, M16 stainless steel washers will do the job perfectly. They have an ID of 17mm (the ones I measured up were 17.1mm) x 3mm thick). If needed, I can get these skimmed off on a grinder to the exact packing size.
The sizes of the lower eyes are different. The XZ is quite a bit smaller.
I suggest you search eBay for a NA6901UU bearing. Listed as 12X24X23mm, and some come with a very hard and long inner race. Check out the images if you search on Google and pick the one that looks most suitable. I got one for $12.usd.
I'm trying to remember what I had to do to make it fit the TT600 shock, I think I had to grind the end of the inner race a bit.
Thanks Fret Not. I will have a search for these.
Can you give a description of the ride difference between the XZ and the TT600 shockers? Was it worth the time, trouble and cost?
HAH!! Mine is not running at this time, so I have not been able to compare the shocks, but from many previous comments just about anything should be an improvement over the original shock/spring holder.