41 replies to this topic

[JohnnyW]

The original springs are progressive.

 

I seem to recall a previous discussion about fork springs and I'm sure the original springs were described as linear and as my forks are currently dismantled, the springs certainly look to be linear rather than progressive.   

 

JohnnyW

[dandywarhol]

The originals have a tightly wound wire at the top Johnny, and are progressive. The Race Tech springs you've got are linear.

 

Still snow up your way? - I was there a month ago and it was higher than the van.......................

Edited by dandywarhol, 02 May 2013 - 02:01 pm.

[JohnnyW]

Still snow up your way? - I was there a month ago and it was higher than the van.......................

 

Cath told me you were in the village, sorry I missed you. Was snowing a couple of days ago and there's still tons of snow on the mountain tops, they're going to be skiing at Cairngorm till the end of May at this rate!!

 

JW

[jayninja]

I've just tried to set-up the TDM's suspension starting with the front end (that's probably wrong for a start !). Using  the old cable tie on the fork tube method and aiming for 30mm static sag the best I could get was 45mm - I haven't ridden the bike yet but I wonder if I need stiffer springs ? Surprised though as I'm only 72Kg.

[TYREDNGRUMPEE]

I've just tried to set-up the TDM's suspension starting with the front end (that's probably wrong for a start !). Using  the old cable tie on the fork tube method and aiming for 30mm static sag the best I could get was 45mm - I haven't ridden the bike yet but I wonder if I need stiffer springs ? Surprised though as I'm only 72Kg.

 

The setup guide is great if you have a modern race machine with suspension directed towards maximum control and doesn't really take account of the oddball arrangement you are faced with owning a TDM.

 

You'll never get the suspension to work within the parameters the guide suggests. sag figures etc.

 

But you can still setup the TDM to work well.

 

Your aim is to get both front and rear suspension working together in concert. Use an appropriate amount of preload on the rear, don't over damp the action and find front end settings that complement what you have at the rear.

 

Just investigate how many times Yamaha have updated the front end springs throughout the 900's evolution. 

 

I'm on the heavy side, so must weigh in at 120kg with gear. My Mk2 is sweet fuelled up and loaded with panniers and camping gear.

But just try backing settings off when I'm not loaded. The ride changes as the fuel tank empties, upsetting the balance.

It's just a waste of effort, so my solution is just to leave well alone and ride the hard/balanced settings, as they're on what you could call the soft side of hard anyway and move about to compensate..

 

Simply put, it's a compromise and don't waste your time trying to achieve the impossible.

[jayninja]

Great advice, thanks.

[TYREDNGRUMPEE]

I aim to achieve a setup that means the bike isn't upset hitting an uneven surfaces through bends (too much), doesn't complain at quick direction changes and goes where you tell it to.

[fayeslane]

I aim to achieve a setup that means the bike isn't upset hitting an uneven surfaces through bends (too much), doesn't complain at quick direction changes and goes where you tell it to.

2002 900. Hyper pro springs front and rear plus 4 position dogbones set on raising the rear end 25mm. Total cost about $400 Oz dollars. Handling is very good, ride is firm but not harsh, brake dive is reduced. Bike is quite composed even when the pegs are scraping and feels like there is a greater margin for error when pushing. Last couple of bikes were BMW R1200GS and a Multistrada 1000. TDM is now better than the Multistrada but less composed than the BM although on my regular loop my corner speed is higher on the TDM. Getting the rear shock revalved to my weight and riding style would be icing on the cake.

[Toydepartment]

The original springs are progressive.

 

The only IMO to get the suspension to work well is to fit Race Tech emulators - day and night/chalk and cheese etc. 

 

 

I've just checked out the Race Tech web site, it's in America! I've found the Emulators you mention, does this kit include the springs?

 

The fork springs they do look linear, can you get them from over this side of the pond or do we have to go through the importation tax business which seems to be about 40% of the total cost from my experience. 

 

I think I'll start (when I get the bike this weekend, hopefully) with the 25mm spacer recommended earlier in the thread as I am about 120KG in my gear.

 

A couple more questions,

 

With the additional weight when compared to a 70KG racing snake, what thickness of oil would you recommend, still 15wt?  

 

When using the 25mm preload spacer how do I measure the air gap? Do I add 25mm onto the usual air gap, measure to the top of the forks, then put the spacer and springs in? Or, just set the air gap at the standard length, 130 mm (?) and then throw in the springs and spacers?

[dandywarhol]

As post #1 says, a spacer won't compensate for a spring too soft for the load it is supporting. On the Race Tech site you'll see a chart for recommended spring rates/load. BUT, they tend to be for racing/fast road use - I found the recommended rate for my weight was a bit stiff so I went back to original 2003900 springs and emulators.

 

From memory, I went back to a 12.5 weight oil so I'd say 15 or "heavy" would suit you. I like Motul oil. Set up the air gap as normal without the springs/spacer (I'm assuming the spacer is hollow) and see how it goes. If the springing feels too soft, which it probably will with stock springs, then add some more oil to take away some of the air "spring"

 

Here's where you get Race Tech stuff in the UK - Google is your friend (if you want to be followed   )  http://pdq1.com/brand.php?BrandID=11

[Toydepartment]

How are the forks for flex?

 

As no one has mentioned fork braces and the like, I am assuming that a combination of decent size stanchions and an effective mudguard frame are man enough for the job?

[dandywarhol]

Yup - unless you plan fitting uber sticky tyres - and then the frame will complain!

 

The std forks are structurally fine - just the internal workings that can be improved on - and even only then if you are used to previous bikes which suspend well. 

[Leegaard]

I'm in the same boat.
Around 120 kg or 18 stones ish with my gear on.
This means around 40 procent dynamic sag on my 09 TDM 900 with one ring left I the front and as hard as possible in the rear.
I've been around asking and have found two solutions so far.

Hyperpro progressive springs made for my weight

Ohlins linear springs.
Fork springs are only made in 80 NMR and he could not tell me the rate on the original springs.
Rear spring in 180 Nm ( original should be 120 Nm ) but the dealer could not tell me if it would fit on the original shock. If length on spring is diff the rate will not be correct.

Both sets are around 500 US, and if I could be sure to get it right, I've would go for the linear springs, but there is a lot of question marks.

Anybody knows what the rate on original fork springs are, and how to convert between Nm and Kg?


Have anybody tried Hyperpro progressive springs front and rear ? I'm not sure what to expect because some people are happy with Hyperpro, and others say that it is shite.
Would think that linear springs would give almost same ride as now, just a bit harder ?

[harvey krumpet]

Been on a bit of a fettle lately. Had no issues with me suspenders up until fitting BT T30's. Bike skipped under heavy throttle between bumps in the road. Then a mate rode it & exclaimed the shock was way to hard, which is interesting because he rode it 6 months ago with a different tire & said it was fine but the forks were notchy....

He has very sensitive buttocks. We took the shock out and sure enough the compression had been up hard against the thread & needed a heat gun to loosen it & the rebound was wound right up. Rebound is now 5 clicks from bottom & compression is as soft as it will go. I'm going to set the bike up from soft everything. A day of riding the same wallow a few times should do it.

[celticbiker]

Not many people realize that the Tyre is an integral part of the suspension.
The carcass and side wall construction directly influences the way the suspension is set up in order to keep the Tyre on the road

[dandywarhol]

I'm in the same boat.
Around 120 kg or 18 stones ish with my gear on.
This means around 40 procent dynamic sag on my 09 TDM 900 with one ring left I the front and as hard as possible in the rear.
I've been around asking and have found two solutions so far.

Hyperpro progressive springs made for my weight

Ohlins linear springs.
Fork springs are only made in 80 NMR and he could not tell me the rate on the original springs.
Rear spring in 180 Nm ( original should be 120 Nm ) but the dealer could not tell me if it would fit on the original shock. If length on spring is diff the rate will not be correct.

Both sets are around 500 US, and if I could be sure to get it right, I've would go for the linear springs, but there is a lot of question marks.

Anybody knows what the rate on original fork springs are, and how to convert between Nm and Kg?


Have anybody tried Hyperpro progressive springs front and rear ? I'm not sure what to expect because some people are happy with Hyperpro, and others say that it is shite.
Would think that linear springs would give almost same ride as now, just a bit harder ?

Nm is torque and kg is a force so there's no conversion.

 

Sounds like you're talking about 0.8 kg/mm (0.8kg moves the spring 1mm) - spring rates vary on different model year 900s, I think it tells you somewhere in here http://www.jbx9.t15....x.php?page=SUSP

[harvey krumpet]

Not many people realize that the Tyre is an integral part of the suspension.
The carcass and side wall construction directly influences the way the suspension is set up in order to keep the Tyre on the road

Yup. This new tire has markedly changed how the bike feels. Never worried about the suspension on either of the TDM's for years then hello skippy.

Mind you, I'm very impressed with the T30 regardless and things can only improve now that the shock moves.

[greasemonkey62]

I bought my TDM 900 new in 2013 and have always thought the front end too soft as it dives under braking, and the rear does seem to wallow on some corners, I have not touched the suspension since new as I have no experience in this area and don't want to mess it up, I am over 16 stones which won't help I suppose.

[Bjørge]

Setting up spring preload is very easy, as this description (faximile of the original manual ?) shows: http://www.manualsli...00.html?page=29

You can't "mess it up" ! If you want to be able to return to todays settings, just write down the position of the preload screw and also, count how many turns from (e.g.)bottom suspension adjustment screw is.

[Hombre]

The fork oil change on my 2004 niner was overdue and I decided that this time I would look closer at pre-load setting. I have always considered the harshness over ripples and bumps to be down to the fork design. The full stroke of the forks is 140mm and with pre-load adjusters at minimum and a full tank, 40mm of that is taken up with the weight of the bike. With my 100kg / 15.75 stone aboard, that takes up another 15mm. The initial spring compression, forks extended, is 25mm with the fork cap in place. Therefore, the spring compression, bike upright, is 25mm+40mm = 65mm.


When I removed the springs, I noticed they were dual rate. As far as I know, they are standard springs - I bought the bike at 13,000km / 8,000 miles. Their length is 350m, the same as quoted on JBX pages. So what do they look like when compressed by 65mm? Using some threaded studding, the pictures show that the softer rate is fully compressed at just 300mm. Basically, the spring acts as a stiff linear type.


In order to meet recommendations from various sources for sag with my 100kg aboard, in the past Ive set maximum pre-load. I have now set pre-load at minimum and will increase it should I find it necessary.

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