Melbourne Suspension Revalve

[Garry_Coates]

Some more useful information for early models (<=95):

1. 41 mm Fork tubes for Police and ABS models are 614 mm in length while the standard is 633 mm.

633 mm seems to be what a lot of honda sports bikes use so swapping with them is possible eg CBR600F.

2. Fork spring length for police and ABS models is 474 mm while the standard is 416 mm.
3. 95 model 41 mm fork seems to have the same internals as the 96 43mm fork

So a 95 ABS model has shorter tubes, longer springs and different internals to standard 94 or earlier models!?

4. Just about every Honda conventional showa fork in the the 41/43 mm size can use the same Racetech 20mm compression and rebound valving options. Therefore must be similar.

Lots of fork cartridge options for the  96 and later models with 43 mm forks. Not so much for the 41mm earlier models unless either use cartridges with other adjuster fork caps or modify 43 mm adjuster caps to fit.

Well, I thought it was interesting.

Regards
          Garry

[Piet]

Garry,  where did you find the info on the lengths of the forks?  I was in touch with a guy in Germany who sells new fork tubes and he said that the left and right sides were different.  This seems unlikely to me.  But who knows.  Thats what made me ask the question.  I need to fix a fork seal soon.  I must have damaged it on install when I did my winter maintenance.  When I do the install I might get a chance to check it.  However knowing where to find info like that is gold sometimes. 
I am saving up for the Traxxion deal.  It sounds just perfect.  To be honest as I am not happy with the Progressive 465 rear I might purchase the Penske rear first.  My front end with Sonic fixed rate springs feel so much better than previous, so the Traxxion might be pushed out a bit.

[Garry_Coates]

Hi Piet,
       I found it doing some long searches on "Honda ST1100 Fork tube length". I cannot remember the website(s).

I confirmed it by calculating the fork tube volumes for each length and taking a ratio of them (0.96998)
 and comparing it against ratios of:
  a) recommended oil volumes (L&R)
  b) recommended oil levels (L&R)
     
They are close to this ratio.  I do not understand why the recommended oil level is different (13ml) for each side though and anything is possible with the ST as it seems to have a unique front end. 

Remember that the left and right fork tubes are not interchangeable anyway - different part numbers with probably different fittings at the bottom to cater for either cartridge or oil damper oil lock pieces..   

If you are buying fork tubes then I would disassemble and measure to be certain.  If you have a slight fork tube ding then that can be lightly sanded to remove sharp edges.

My main reason for this research is to compare with other bikes with showa forks for likely cartridge use.

Hell, I maybe wrong have a look at what I found at racetech:-

http://racetech.com/download/FORK_TUBE_TNK_RTweb_revised.xls 

Only two part numbers shown are for the non-ABS ST1100s 41mm fork (MT3 part numbers) which would suggest that one tube is longer than the other! No reference to ABS part numbers (MY3)?!

I will need to look at this again some other time

Regards
          Garry

[Piet]

Hi Garry,  When I installed the Sonic springs (not so long back) I can definitely confirm that the fork legs are different.  The RH fork (sitting on the bike) has the cartridge in it and there is a captive piece in the bottom of the fork tube that is not there in the LH tube.  What I did not do was check the lengths.  I wish I had.  Because I still have my original springs I went down stairs half an hour ago and measured the original spring at 470mm, So it had sagged 4 mm from new.  I know for a fact mine is ex police (Qld Police) but was completely returned to original look with the exception of the switches on the handlebars and the forks (not so obvious).

The guy in Germany said the fork lengths were different LH to RH and his dimensions were 633 and 613.  This matches  the spreadsheet you sent from RaceTech.  Thats a great spreadsheet by the way.  Top marks on spotting it and thank you for sending it on.  I have added it to my file of useful info I have been collecting.

I am going to try and fix the leaking fork seals on Thursday-Friday so when I have them apart again I will measure them.  I did not have a proper seal driver first time round and I must have wrecked the seals.  I have that sorted now.  I also ordered some fork gaiters (won't arrive in time) and some new brake pads because they got some fork oil onto the pads.

The Police models do have different part numbers for the forks don't they?  So if its not a case of 613mm for Police and 633mm for std production, then it makes one wonder what the difference is? 

I was hoping to hear back from the guy in Germany but so far no further response.  I will keep in touch.
 

[Garry_Coates]

Hi Piet,
         I am glad you found the info of use. The best information I have found is using:

1. Racetech spring rate search
2. Racetech gold valve options: http://racetech.com/download/FMGV-ForkGoldValves.xls 

Using 1 to confirm the details of the fork: showa, conventional, 41 mm gold valve options

And then using 2.  to confirm details of valves: 20mm, compression, rebound  etc make it easy to compare front ends. Just missing fork travel and dimensions.

Just got home from a 800 km ride with an ABS problem I need to diagnose.

Merry Christmas 

[Garry_Coates]

Piet,
      a good reference for all models is at: http://www.st-1100.com/st1100-parts.html. Put in your police model and go to the relevant parts fiche. I am betting you find that police model bikes have same suspension parts as ABS bikes of that year.

Regards
         Garry 

[Garry_Coates]

Hi All,
      I have been doing further research on using existing showa fork cartridges. The best two options are VTR1000f and CBR600f3 as the both have 41mm fork caps and 8mm cartridge bolts. I have dispensed with other brands as Honda has by far the best part searches and available information.

I am concentrating on the VTR as the F3 has been used by just about everybody in fork conversions. Certainly none in Australia I get get for the right price.

One point of concern is the VTR has much shorter fork springs (310mm) than the ST ABS version (470mm) which I am investigating. This leads me to my questions.

Does anybody have an ST1100 1995 or later fork cartridge accessible they can measure?

I would like to confirm the cartridge length and maximum travel of the piston.

Please note that the 1995 ABS model has the same spring as earlier ABS models but different cartridge so not sure what the difference is.

Regards
         Garry

ps: I have already bought VTR cartridges from eBay so I can measure them directly

[Garry_Coates]

I have just got back from my first ride with the VTR fork internals fitted to ST which has been successful. I ended taking them to Krooz Tune in Melbourne as I could see it was not a simple installation. David there has done a number damper rod to fork cartridge conversions for a variety of bikes.

He had to make a fitting for the LHS fork tube to work with the VTR rebound spring and other internal changes to fit them. All up about three hours work to revalve the VTR cartidges and fit them to the ST. He used my existing WP springs and retained 146mm of fork travel which easily enough (120mm was my minimum requirement).

Open cartridge forks get air trapped in them when you bring them home in the car on their sides. I need to do a little more riding before making any tuning changes. Then I will refit the handlebar cover which still fits with the VTR fork caps.

Regards
          Garry

[Piet]

Hi Garry,

Looking forward to hearing how you went.
Obviously the external hardware like brake calipers and guard still fit as per original. 

So is it now a case where one side has adjustable compression and the other rebound?  It sounds like both fork tubes are now identical unlike the original ST11.

Regards,  Piet.

[Garry_Coates]

Hi Piet,
       I just used the VTR fork internals not the external bits. Both sides are the same with only pre-load and rebound externally adjustable. But from experience changing rebound on Saturday also changes compression probably 80/20 or 70/30. Forks where re-valved to suit ST and run 5wt oil. TRAC left in place but does not affect the cartridges.

I discussed the rebound adjustable one side / compression the other with David. While it can be done he did not recommend it as it compromises the cartridge dampening to some degree.

From my experience if compression and rebound a close to right the external adjustment will probably be sufficient. Worse case is go to slightly heavier oil for compression and adjust rebound to compensate.

This will do me. If I am prepared to spend $2k on suspension I would graft late model USD forks and wheel from a CBR.

One consequence of not using TRAC is a much better feel when hard braking.

Regards
          Garry

[Garry_Coates]

It has taken me a while to get 2000 kms ups with an injured knee from trail bike riding. I have settled on the external adjustment settings and all is good.

It is funny how quickly you adjust to improvements and factor that in while cornering. I have to remind myself of what it was like before getting both front and rear suspension done. Not bad for less than $750 parts and labour.

Regards
           Garry

[Garry_Coates]

With 183,000km up on the ST it is time to have the suspension freshened up. The nitron rear shock (108,000 km) has been completely rebuilt with a 500lb spring and modified dampening. That now makes both ends > 50% higher spring rates than stock. I would love to talk to the original designer of the ST about this as the oem springs barely carry the bike without a rider. It is always surprising how much the rear suspenion affects the front. This time for good as there is less fore/aft movement and better tyre feel.

I am now reviewing options for the front. It is either a purpose built kit or just freshen up the VTR1000F cartridges previously installed.

I would love to hear of any relevant changes done by others.

Regards
           Garry

[Garry_Coates]

A quick update on front fork options:
1. Nitron and Matris have cartridge kits that will work for 41mm forks but will take some customising. This is in addition to the Traxxion AK-20s already discussed.
2. Nitron 22mm cartridge kit seems to be the better option as there seems to be interest here and the valving looks good. I have not found anybody here interested in customising Matris for the ST.
3. The steps for nitron
    a. Take your forks to a nitron certified suspension tuner
    b. They will strip the forks and consult with Nitron
    c. Nitron will send the custom kit to the suspension tuner for installation (2+weeks)
    d. Pay the tuner approx $1800 and collect the forks
    e. Install them and fine tune adjustments

I am pretty much happy with the Nitron steps except for 3d. It is hard to justify for a bike with 183,000 km. I will probably then persevere with the VTR cartridges. 

Regards
         Garry
 

[Garry_Coates]

Just noticed  on ebay "ANDREANI FORK HYDRAULIC CARTRIDGE HONDA CBR 600 F 1991 94 FORK Showa 41". This would fit the ST1100 up to 1995 plus police models for about $900 landed in Australia. Would have to work out changes required. I noticed no external rebound springs though which probably means derived from racing. Maybe within the cartridge.

Regards
          Garry

[Garry_Coates]

Update:

I ended just refurbishing the existing ST1100 fork and VTR1000 cartridge setup and using the same 5wt oil. To get a little softer compression:
1. Removed 3mm preload
2. Increased air gap from 170 to 185mm

Fork travel now increased from 115mm to 133m. Low speed compression still a little too strong but the rest is fine.

Regards
          Garry

[Garry_Coates]

At 225,000km just did another fork refresh as both seals have leaked during the 42,000km since last change. The anti-dive (left) fork tube is showing signs of wearing through the chrome. Anybody need to get the tubes re-chromed? 

Regards
            Garry

[STeveo]

Send them to RAD hard chroming in Brisbane. Had many good rebuilds with them. Cost around the $450 mark for the pair.

[Garry_Coates]

TNK will ship one of these to Australia for about $350 at the moment. I would need to confirm the TNK tube has the same sidewall thickness as for ABS1 (1mm thicker internal). Either case will require stripping the internals from the original.
Regards
          Garry