20 replies to this topic

[Kebab897]

I'm wondering if the 900's rear shock top mounting point can be lowered or (despite the threaded stem) does it only sit at the one height?  Asking as I'm aware of an alternative rear shock that should fit the 900, but is only 315mm long from centre of top mount to centre of bottom mount.  I thought if the clevis could be lowered 10mm then there'd be no need to mess around with much longer dogbones, assuming that they would still fit in there...

 

Also...getting to the top mount clevis?! Do you have to basically remove the back half of the bike to get in under the seat undertray or is there another way to access it?

Edited by Kebab897, 21 March 2023 - 06:29 pm.

[fixitsan]

MT-09 shocks fit. Just put the TDM spring on it

[Kebab897]

MT-09 shocks fit. Just put the TDM spring on it

I know, I've read about some of your sterling research already But thinking of another shock (sitting in front of me), which was removed from my previous bike.  Suppose I can sell the shock on if it can't be adapted to fit, but having had it serviced & rebuilt a couple of months ago, it felt great & I'm reluctant to part with it   

[fixitsan]

I know, I've read about some of your sterling research already But thinking of another shock (sitting in front of me), which was removed from my previous bike.  Suppose I can sell the shock on if it can't be adapted to fit, but having had it serviced & rebuilt a couple of months ago, it felt great & I'm reluctant to part with it 

If it's a common make then things like the end clevis can be exchanged for a longer/shorter one. If it's Ohlins, YSS, Niton or so on, then they manufacture a single shock body and just fit different end eyes/clevises to the body and strut to suit different bikes . I would check the shock manufacturers catalogue, there might be a bolt on solution

[Kebab897]

If it's a common make then things like the end clevis can be exchanged for a longer/shorter one. If it's Ohlins, YSS, Niton or so on, then they manufacture a single shock body and just fit different end eyes/clevises to the body and strut to suit different bikes . I would check the shock manufacturers catalogue, there might be a bolt on solution

Sorry, perhaps I've used the wrong terminology here. I was asking about the TDM part (that sits under the battery area) that connects to the 900's frame and the top of the shock inserts up into, such as current ebay item # 263967942765. I was wondering if that part could be wound further downwards as it's threaded, or can it only sit in one position?

[fixitsan]

Sorry, perhaps I've used the wrong terminology here. I was asking about the TDM part (that sits under the battery area) that connects to the 900's frame and the top of the shock inserts up into, such as current ebay item # 263967942765. I was wondering if that part could be wound further downwards as it's threaded, or can it only sit in one position?

I've got it now, I had it in my head that the top mount was a part of the cast frame and not an additional component.

 

I was just thinking about modding the shock because Ohlins end eyes just unscrew and you screw a different one in (more or less) , Same sort of idea,

 

I imagine you could get something made up for the top mount, maybe out of stainless in fact

 

Something like this, sized to suit  ? https://www.ebay.co....tm/134130445764

I don't think the thrust direction would change very much so all the load is still linear through the top mount central axis the same as it is when standard.

 

Saves getting a new shock at all if you have one already

 

If there's enough thread on the existing  bracket then using a nut to fill the gap probably would be fine

Edited by fixitsan, 07 June 2022 - 08:42 am.

[Kebab897]

Thanks. Rather than strip the bike down, I might order one of those spare TDM mounting brackets and compare it's dimensions to a few spares i've collected over the years - I have a 2006 onwards R6 version and a mid-1990s YZF750 version lying around somewhere. If they're the same dimensions as the TDM version then I'll probably have to go down the bespoke part route.

 

Oh, and I'm not into secret squirrel stuff - the shock I'm trying to fit is a Sachs shock from the 2010-2014 BMW S1000RR (pre ESA nonsense), which was coveted by Fazer 1000 owners as an alternative shock to Yamaha's own R6 shock. A current UK example here: https://www.ebay.co....soAAOSwRj1imdAE  but it's overpriced: probably cheaper to buy one from the States & get it shipped over!

[fixitsan]

That would be

 

Thanks. Rather than strip the bike down, I might order one of those spare TDM mounting brackets and compare it's dimensions to a few spares i've collected over the years - I have a 2006 onwards R6 version and a mid-1990s YZF750 version lying around somewhere. If they're the same dimensions as the TDM version then I'll probably have to go down the bespoke part route.

 

Oh, and I'm not into secret squirrel stuff - the shock I'm trying to fit is a Sachs shock from the 2010-2014 BMW S1000RR (pre ESA nonsense), which was coveted by Fazer 1000 owners as an alternative shock to Yamaha's own R6 shock. A current UK example here: https://www.ebay.co....soAAOSwRj1imdAE  but it's overpriced: probably cheaper to buy one from the States & get it shipped over!

 a nice option if you can make it fit.

R6 has more thread on it's top mount, an R1 has a thick boss which offsets the bolt downwards, but the ZX6R clevis is very long in the thread, although no idea if it's wide enough to take the eye of the shock, you'ld need to check on the parts lists. The thread seems larger than the Yam one too https://www.ebay.co....tm/175150238704

 

ZX10R looks longer too https://www.ebay.co....tm/304172302594

Edited by fixitsan, 08 June 2022 - 07:06 am.

[Kebab897]

So, I've bought a standard TDM mount and here it is (hopefully?) shown beside the longer, silver R6 shock mount.

 

https://kebab897.imgbb.com/

 

Dimensions of thread etc are exactly the same as the TDM's so it'd be a straight swap.  I estimate it'll allow me lower a shock between 6 and 8mm, which is good but not quite enough - would still need significantly different dogbones. Going to order a longer Kawasaki top shock mount soon as they seem to be longer again.

[Kebab897]

So...I researched this further and came up with a design which allows me to graft rear shocks from several other bikes onto the TDM 900.

 

The standard shock is about 330mm from centre of top eyelet to centre of the bottom eyelet. Fitting a slightly shorter shock using different length dogbones works to a certain point, but I've found from previous experiences with other bikes that fitting shocks 10mm shorter / longer tend to affect the unit's damping in slightly unpredictable ways.

 

As the TDM's top shock mounts attaches to the frame using a clevis, I reasoned that a clevis from another bike might fit and could be altered to offer more adjustability re shock length. Although I bought several off second-hand shock mounts off ebay, most did not have the dimensions needed for a straight transplant.

 

Enter Mr Henty, who was able to decipher my diagrams and alter a Kawasaki shock mount as per my requirements.  I now have a clevis which can accomodate shocks ranging from 290 - 330mm in length, using several spacer blocks to shorten the space where the shock sits. Although originally intending to fit my BMW S1000RR shock to the bike, I've started by fitting a 2008-2016 Yamaha R6 shock as it's the shortest one I have, at 293mm from eyelet-to-eyelet. Surprisingly it is also one of the best: despite being just another standard Yamaha shock, the valving / damping characteristics are on another level compared to the TDM's standard unit. My initial pilot run yesterday confirmed that it works better than the standard rear shock & that's before any fine-tuning.  

 

Pics etc.of shock mount to follow.  This is however not a simple swap - for the TDM's shock clevis to come off, you need to remove the side panels & the tank to access it, so that should deter about 98% of forum members from considering this mod    I'm also not sure if Lee ever wants to make another one, although he now has all the dimensions at hand.

So, I can think of shocks from 5 other bikes that can now fit the TDM900 and potentially even more, meaning a lot more choice out there for cheap-ish rear shock replacements...

[fixitsan]

The R6 spring is rated at 9.8kg/mm, or 98NM

The TDM spring is rated around 130NM

 

Have you swapped the spring of the R6 shock ? If not, I suspect you're enjoying a plush well damped ride.

 

Usually, a softer spring indicates there's less of a force multiplying effect at the shock linkage, and increased travel in the range of movement of the shock. The increased travel translates to faster piston movement, and the shock may be shimmed less aggressively to accommodate it.

 

The MT-09 Ohlins shock which I fitted had similar characteristics to the R6 in that regard, but, it didn't feel bad at all. I had to upgrade the spring for my 110kg weight anyway, so went a couple of spring rates higher than expected for my weight and it felt very good, any difference in the shimming was easy to compensate for with the adjuster. It's certainly in the ballpark.

 

I then fitted the ' usual' TDM900 Ohlins, which only feels different when riding on very gentle rollers where it feels more relaxed, but tightens up as soon as the piston starts having to move rapidly, like when going over harder bumps.

Edited by fixitsan, 22 March 2023 - 09:42 am.

[leehenty]

Glad its all worked out. One of the more unusual requests Ive had.

Edited by leehenty, 22 March 2023 - 03:40 pm.

[Kebab897]

Piccies.

 

1. Spare OEM mount and modded Kawasaki shock mount with spacers:

 

2. Removal of TDM Shock Mount:

 

3. View from underneath once mount was removed:

 

4. TDM900 shock, BMW S1000RR and Yamaha R6 Shocks:

 

5. Kawasaki mount fitted along with R6 Shock:

 

6. New home for R6 shock:

[Kebab897]

The R6 spring is rated at 9.8kg/mm, or 98NM

The TDM spring is rated around 130NM

 

Have you swapped the spring of the R6 shock ? If not, I suspect you're enjoying a plush well damped ride.

 

Usually, a softer spring indicates there's less of a force multiplying effect at the shock linkage, and increased travel in the range of movement of the shock. The increased travel translates to faster piston movement, and the shock may be shimmed less aggressively to accommodate it.

 

The MT-09 Ohlins shock which I fitted had similar characteristics to the R6 in that regard, but, it didn't feel bad at all. I had to upgrade the spring for my 110kg weight anyway, so went a couple of spring rates higher than expected for my weight and it felt very good, any difference in the shimming was easy to compensate for with the adjuster. It's certainly in the ballpark.

 

I then fitted the ' usual' TDM900 Ohlins, which only feels different when riding on very gentle rollers where it feels more relaxed, but tightens up as soon as the piston starts having to move rapidly, like when going over harder bumps.

Standard spring still in place for now.  Yes, I was aware that it had a 550lbs spring whereas the TDM9 was around 700lbs.  So I cranked the preload up to the maximum, expecting her to bounce a lot & also drag the undercarriage. There was too much traffic around for a proper test, but had her up to around 60mph including through corners and no sign of bottoming out or wobbling.

 

Further tests needed, but yes she'll probably need a replacement spring as you say. Unfortunately I can't transplant the TDM9 spring as it's too long, will have to go for a 6.0" or 6.5" inch spring setup. I think I have an old 6" Faulkners 650lbs spring from my time fitting these shocks to Fazer 600's buried away somewhere. I'll dig it out and see what improvement that makes.

[leehenty]

For anyone else considering doing this, the thread holding the clevis is M14 x 1.5. The Kawasaki part used is M16 but cannot be turned down to M14 as the pin is hollow, so its mill off the weld, knock it out, and make threaded stepped steel part to fit the hole securing with two welds. I would advise that the pin be made of EN16 or better. I still have about 300 mm of 3/4 EN16 steel bar in stock, so it is possible to make another.

Edited by leehenty, 24 March 2023 - 01:49 pm.

[fixitsan]

Standard spring still in place for now.  Yes, I was aware that it had a 550lbs spring whereas the TDM9 was around 700lbs.  So I cranked the preload up to the maximum, expecting her to bounce a lot & also drag the undercarriage. There was too much traffic around for a proper test, but had her up to around 60mph including through corners and no sign of bottoming out or wobbling.

 

Further tests needed, but yes she'll probably need a replacement spring as you say. Unfortunately I can't transplant the TDM9 spring as it's too long, will have to go for a 6.0" or 6.5" inch spring setup. I think I have an old 6" Faulkners 650lbs spring from my time fitting these shocks to Fazer 600's buried away somewhere. I'll dig it out and see what improvement that makes.

 

Sounds like what you'ld expect. there shouldn't be much bouncing if the damping is in good order.

 

Having the correct spring with knackered damping would probably be worse than what you're using, you'ld be launched out of the seat every time the rebound of the spring kicks in after compressing it in a dip in the road !

Edited by fixitsan, 24 March 2023 - 06:23 pm.

[leehenty]

So we came up with these spacers to fit different springs.

Attached Files

•  0F8A8A20-5DAA-47E5-8F4C-0686BEEE6FB9.jpeg   94.64KB   1 downloads

[fixitsan]

So we came up with these spacers to fit different springs.

 

Henty Skunkworks

[leehenty]

The gentleman above specified the sizes, I just made it happen 😎

[Kebab897]

Aftermarket shock springs seem to come in various lengths, none of them apparently being a direct replacement for the outgoing 165mm long 550lb R6 spring.  K-tech do springs 150mm, 155mm, 160mm and 175mm long.  Faulkner's shock springs are half the price of K-Tech but aren't as good a fit and only come in black. Their nearest spring length is 152mm. Ohlins appear to have their own mysterious codes for shock springs which I have yet to learn about...but they're waay overpriced, anyway.

So I asked Lee to make spacers 5mm, 10mm and 13mm thick to cover the preload slack from most of the aftermarket spring lengths.

 

Picture is of shock with a Faulkners 6 inch / 625lb spring fitted and a 10mm thick preload spacer on top. After fitting it, I had second thoughts and decided to go with a heavier Faulkners 6 inch / 650lb spring and the 13mm thick spacer to give slightly more preload. Yet to get out for proper testing, but thinking it's got to be close to desired range now.  Then just to fine-tune the Rebound, High-speed compression settings and Low-speed compression settings...so many more ways to set it up wrong

 

Edited by Kebab897, 04 April 2023 - 06:42 pm.