Date: 28-03-24  Time: 21:50 pm

Author Topic: Front fork springs.  (Read 4936 times)

happycallis

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Front fork springs.
« on: 03 July 2018, 03:51:34 pm »
Hey all,


What's everyone's preference for front fork spring kits .I have seen the hyperpro, ohlins, having and so forth. If I temereme rightly one was preferred to the others. I do ride in a spirited manner and will sometimes have a pillion too .


Cheers


Matthew

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Re: Front fork springs.
« Reply #1 on: 03 July 2018, 04:07:12 pm »
Your first step is to decide on whether you want progressive or linear springs. With progressive most folks go with Hyperpro so that will be your answer if you choose to go that way.

I chose to go the linear route and if you decide to go that way it is important that you get the right springs for your weight most suppliers will help you with this but there are also some online calculators too. I bought my 10.0 springs, bushes & seals from K-Tech.

If you want help deciding linear vs progressive then I'll get my popcorn out and enjoy the ride  :lurk  (and maybe chip in).
« Last Edit: 03 July 2018, 04:07:46 pm by PieEater »

happycallis

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Re: Front fork springs.
« Reply #2 on: 04 July 2018, 05:25:32 am »
Honestly I'm not sure, I think I was looking at the ktec kit a while back. Chances[size=78%] are I will be pairing it up with the R6 rear shock conversion too. Whats the best for faster road riding. [/size]

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Re: Front fork springs.
« Reply #3 on: 04 July 2018, 07:00:08 am »
For faster road riding and track riding I would suggest linear springs are definitely the way to go  though again make sure you get the right ones for your weight.

Edit:

See http://www.promecha.com.au/springs_advanced.htm

"Progressive springing is much less popular for road-racing, with linear main springs used almost universally. There is a good reason for this: going around corners compresses your suspension, by quite a lot with modern race tyres. With progressive or dual rate springs, that means the suspension is going to be stiffer than when upright. However mid corner is also where you most need good grip and would really prefer your tyres not to be bouncing off the ground."

"Dual or progressive rate springs are really a compromise that allows low-speed comfort without excess bottoming, which is why Honda fit them to road bikes. Racing is not about compromise, so they don’t get used for that."
« Last Edit: 04 July 2018, 08:21:33 am by PieEater »

happycallis

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Re: Front fork springs.
« Reply #4 on: 04 July 2018, 08:51:50 pm »
For faster road riding and track riding I would suggest linear springs are definitely the way to go  though again make sure you get the right ones for your weight.

Edit:

See http://www.promecha.com.au/springs_advanced.htm

"Progressive springing is much less popular for road-racing, with linear main springs used almost universally. There is a good reason for this: going around corners compresses your suspension, by quite a lot with modern race tyres. With progressive or dual rate springs, that means the suspension is going to be stiffer than when upright. However mid corner is also where you most need good grip and would really prefer your tyres not to be bouncing off the ground."

"Dual or progressive rate springs are really a compromise that allows low-speed comfort without excess bottoming, which is why Honda fit them to road bikes. Racing is not about compromise, so they don’t get used for that."



Cheers for that info. Ktech springs it is the.  Just need to see which ones I need.

PieEater

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Re: Front fork springs.
« Reply #5 on: 04 July 2018, 09:30:40 pm »
No problem, I was expecting more of a bun fight, but I don't think you'll go wrong with K-Tech linear springs.


K-Tech recommend a 10w fork oil but if I were doing mine again I would consider the oil on this thread - http://foc-u.co.uk/index.php/topic,2748.msg224797.html#msg224797 (last post).

kebab19

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Re: Front fork springs.
« Reply #6 on: 05 July 2018, 09:40:23 pm »
I have just fitted K-Tech 0.95 springs with 2.5w oil, 140mm gap.  Haven't been out on her yet but will report back once I do

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Re: Front fork springs.
« Reply #7 on: 06 July 2018, 08:36:18 am »
I have just fitted K-Tech 0.95 springs with 2.5w oil, 140mm gap.  Haven't been out on her yet but will report back once I do


Why choose such a light oil, K-Tech recommended me 10w with their linear springs, that's quite a difference?
« Last Edit: 06 July 2018, 08:37:20 am by PieEater »

kebab19

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Re: Front fork springs.
« Reply #8 on: 08 July 2018, 10:59:37 pm »
Why choose such a light oil, K-Tech recommended me 10w with their linear springs, that's quite a difference?

The oil was already in there - still fairly fresh from the previous 'RavenRider' fork mod that I carried out about 6 months ago.Anyway, after this evening's sortie, the 0.95 springs appear to be a little too firm / harsh for my lightweight form (13 stone inc. gear)...unless it's the thin oil causing the issues.  Which it might be, considering Racetech & Traxxion charts indicate this spring rate is close to optimum (for me)  :\   
Not sure now whether to plump for 0.9, 0.85 or just compromise with Hyperpro progressive springs...

Hugh Mungus

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Re: Front fork springs.
« Reply #9 on: 09 July 2018, 05:51:21 am »
Fork oil is confusing because we've always gone on 10w or 15w etc but someone said it's about 'centistokes' or something like that anyway and he was putting 2.5w oil into FJR1300 forks because of this centistoke factor. I can't really say I understood what the Foc he was on about so I just bought some 10 and 15 and mixed them to make 12.5 ish.

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Re: Front fork springs.
« Reply #10 on: 09 July 2018, 09:16:59 am »
Why choose such a light oil, K-Tech recommended me 10w with their linear springs, that's quite a difference?

The oil was already in there - still fairly fresh from the previous 'RavenRider' fork mod that I carried out about 6 months ago.Anyway, after this evening's sortie, the 0.95 springs appear to be a little too firm / harsh for my lightweight form (13 stone inc. gear)...unless it's the thin oil causing the issues.  Which it might be, considering Racetech & Traxxion charts indicate this spring rate is close to optimum (for me)  :\   
Not sure now whether to plump for 0.9, 0.85 or just compromise with Hyperpro progressive springs...

9.5N springs for your weight sounds way too much, I'm on 10N springs and am 20 stone. Lighter oil will probably be making the situation better rather than worse as it will be going through the damping adjusters much more freely than a heavier oil. I would give K-Tech a call or drop them an email and ask their advice they are normally happy to help - http://www.ktechsuspension.com/contact.

kebab19

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Re: Front fork springs.
« Reply #11 on: 09 July 2018, 06:40:10 pm »

9.5N springs for your weight sounds way too much

Aye, I think it is - not sure why the American suspension specialists think it's the right rate.  In the past I've used 0.85 and 0.90 springs in the forks of other bikes: on hindsight I should have stuck with the lower spring rates but thought that maybe there was something different about FZS forks.
Thanks for the link, just emailed them about spring rate and oil weight.




kebab19

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Re: Front fork springs.
« Reply #12 on: 10 July 2018, 04:59:10 pm »
Slightly underwhelming response from K-Tech:

Hi,The springs may be a bit on the hard side but the oil is definitely too thin, we would recommend 10wt oil with a 145mm air gap/oil level.  Best RegardsSo no definite spring rate recommendation for my weight. I think I'm going to switch to the 0.85 springs, along with heavier oil. I have a sneaking feeling 0.90 might still be a little too harsh for me, particularly on some of the back roads I get my kicks from. Will report back again ...eventually  ;)

happycallis

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Re: Front fork springs.
« Reply #13 on: 19 July 2018, 08:36:58 am »
Springs have finally arrived so thats this weekend sorted out. Ended up being recommended the 0.95 with 5w oil. Just need to figure out what air gap I need to run.

Edit: Just contacted Ktech to see what they say
« Last Edit: 19 July 2018, 08:43:20 am by happycallis »

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Re: Front fork springs.
« Reply #14 on: 19 July 2018, 10:50:23 am »
If it helps, when I asked K-Tech about the correct air gap they (Chris Taylor) said 140-150mm I went with 140mm.

happycallis

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Re: Front fork springs.
« Reply #15 on: 22 July 2018, 11:04:44 pm »
Just finished fitting them. They recommended 140mm air gap which I went with. Does anyone have any base setting to set the forks too?

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Re: Front fork springs.
« Reply #16 on: 23 July 2018, 09:30:10 am »
Following this thread with interest.


As a very amateur mechanic (read cr*p but willing to give it a go!!) how easy/ hard would it be for me to attempt changing the front fork springs and oil?


I feel like my '02 thou could do with a 'sprucing' up and think that the suspension could be a good place to start.

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Re: Front fork springs.
« Reply #17 on: 23 July 2018, 11:13:58 am »
Have a read up on the task beforehand, a few notes on a sheet of paper can help. Then just take your time and feel very pleased with yourself when it's done. Don't guess on anything, there's always someone here to answer any question however basic.
Good luck :) .
Whizz kid sitting pretty on his two wheeled stallion.

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Re: Front fork springs.
« Reply #18 on: 24 July 2018, 02:26:29 pm »
Following this thread with interest.

As a very amateur mechanic (read cr*p but willing to give it a go!!) how easy/ hard would it be for me to attempt changing the front fork springs and oil?

I feel like my '02 thou could do with a 'sprucing' up and think that the suspension could be a good place to start.


I'd recommend a Haynes Manual to start with so you can familiarise and prepare yourself for the task at hand yourself and follow step by step instructions when you're ready.


I find the most difficult parts of the job tends to be undoing the cartridge bolt that allows you to separating the fork leg from the stanchion and also driving in new fork seals. You can of course bypass those steps if you don't want to replace the seals and bushes but if you're planning on keeping the bike it makes sense to do those if they haven't already been done.


As has already been said if you need advice on any aspect of the job post up and someone will help.
« Last Edit: 24 July 2018, 02:27:38 pm by PieEater »

happycallis

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Re: Front fork springs.
« Reply #19 on: 26 July 2018, 05:58:27 pm »
Does anyone have the STD suspension settings for the front forks they could post up pls just so I have somewhere to start with as not sure what's going to be best for the new springs.

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Re: Front fork springs.
« Reply #20 on: 28 July 2018, 10:38:16 pm »
What’s the result then?I want to do mine n all

kebab19

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Re: Front fork springs.
« Reply #21 on: 29 July 2018, 08:24:06 am »
Just under 13 stone in kit, 0.85kg springs, 10w oil, oil height 140mm.Preload minimum, compression 12 clicks out from max, rebound 5 out from max (started with standard 7 and 4 respectively).
In a word, disappointing.  Longer version - from a handling perspective, far better at holding lines, but remains harsh, kicking up over bumps.  Perhaps I've been spoilt by suspension setups from other bikes, but to me, over bumpy back roads (where I spend a lot of my time) the bump compliance is still nowhere near good enough.  I bought this bike with the possibility of touring in mind, but that's not an option until it can go over uneven roads without delivering  impact shocks to me through the bars.

As a final fork mod, I'm cutting the internal preload spacer down by 10mm and reducing oil height to 150mm to see if it becomes marginally softer.
After that, I'm not sure re options.  Unlikely to go down the R1 fork route again.  Might fit R6 5SL forks again or get someone like Maxton to modify the internal valving.

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Re: Front fork springs.
« Reply #22 on: 29 July 2018, 11:32:19 am »
If your primary aim is to achieve a more plush ride for touring / comfort then progressive springs would be a better choice. By their nature linear springs are harsher compared to progressive / dual-rate but offer more predictable handling allowing you to carry more speed through corners etc. but they shouldn't be overly harsh as to make the bike unpleasant to ride. Have you tried reducing compression damping as this should soften the action of the forks?   
« Last Edit: 29 July 2018, 11:33:26 am by PieEater »

kebab19

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Re: Front fork springs.
« Reply #23 on: 29 July 2018, 03:54:59 pm »
I've previously replaced standard dual rate springs with linears for my old TRX850, Bandit 1200 and FZS600 bikes: all were comfortable enough afterwards. 
With only 11k up on the clock the forks shouldn't be worn out yet - nonetheless, I am begining to suspect that my fork leg stanchions might even be slightly warped / out-of-true, restricting / slowing down the fluidity of inner stanchion movement.

Compression damping was reduced from 7 to 18 clicks out, didn't seem to make any noticeable difference.  Although I've yet to test my final modifications, it probably won't make that much of a difference.  So I'm now thinking whether I should throw another £500+ for the suspension pros to sort out the damping, spend roughly the same amount buying & fitting Andreani or Race Tech fork internals or just switch over to other forks.... rapidly turning into a bottomless money pit  :\   

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Re: Front fork springs.
« Reply #24 on: 29 July 2018, 04:14:36 pm »
Blimey, I’m on std fork spring with 10w oil. Just as you say it kick off bumps all the time, I read on here somewhere the forks have too much comp so I’ve would it all off, it’s better but not as good as other bikes I’ve had. I’ll try some progressive springs.