A10 Front Fork Spring rates

[PaulC]

Hello everyone.

I'm lucky enough to have a Taylor Dow TLS front brake which gives great stopping power, so good, that my bike can dive quite alarmingly if I'm too fierce with it. I am a heavy rider, which doesn't help when my weight all moves forward.

My first question is can you buy a stronger or progressive spring that might help? I have explored oil options but understand that the oil only assists with controlling rebound and it is springs I need to think about.

Second question is, assuming the answer to my first is "yes", how easy a job is it to change springs and can I do it without taking off the entire fork assembly, headlamp and handlebars. My Haynes manual says not, but doesn't say exactly how I do remove only the bits I need to remove.

Any thoughts gratefully received

Many thanks
Paul

[bsa-bill]

sidecar springs are stronger if you can still get them, don't think sidecar springs are available in  progressive form others might know.
You will need to remove the fork assembly but not the headlight if you have the trouser type.
a simpler and maybe better fix would be to get a set of double damping rods (Eddie Dow again) these are available here http://www.norbsa02.freeuk.com/goffyfork.htm, this would damp down your diving problem I think

[PaulC]

Thanks for your reply, Bill.

I clicked on the link you sent and it seems I already have rods like that in my forks, held to the top nut with domed s/s nuts. When I bought my bike it came with absolutely no history about rebuilds, upgrades or servicing, so I'm only finding things out as I go along. I found the rods when I changed the fork oil last summer and only now know from your reply that they may be Eddie Dow. I'm assuming that whoever fitted them, may have fitted the whole kit and my fork performance is already better than "normal". If so, perhaps the solution is for me to,lose weight .

Thanks again.

Paul

[bsa-bill]

you can also play around with different viscosity of fork oil, they don't use a lot so not too expensive to try a thicker oil or even mix grades to get what you like (probably  best stick to the same make)

[Topdad]

Hi Paul, I suffered the same problem my bike first went back on the road , seems I'm blessed with an 8" (Musky stop it remember your status !!) singlesided front stopper which works , used to really pound the forks down . Doesn't help that like you I'm a delicate creature   ,16 stone at last count and got fed up with sore wrists . The cure was simple, fitted a damper kit from George Prew the  Goldie guy and what a difference , takes about 20 mins to fit , they've been fitted for 8 yrs and still fantastic, cheers BobH

[Topdad]

Paul, his e-mail address is   www.goldstar-rgs-gp.co.uk , cheers bobH

[PaulC]

Thanks Bob. I'll try him.

BTW at 16st, I'd consider you to be on the under-nourished side compared to me!

Paul

[chaterlea25]

Hi Paul,
Bill and Topdad seem to be talking about the same thing ?? the dampers you already have
Progressive springs are available from SRM and probably other suppliers as well
The Dow type dampers work on the rebound so will make no difference to dive

John

[Topdad]

good morning John ,happy new year to you and yours ,how's Cork ? Please pass on my best also to your chemist in the town there ,Connor, if you remember He's my Lads (ROB ) best mate but obviously only if your time allows.
 Back to topic I really have lost all the dive since I've fitted the kit so are  Georges type different from the Dow type I thought they were basically the same ?

Paul, "BTW at 16st, I'd consider you to be on the under-nourished side compared to me!"  Couldn't have a word with my doctor for me could you , been telling him I'm really "half clemmed " has my old Gran used to say but he won't have it , cheers Bob.

[bsa-bill]

The Dow type dampers work on the rebound so will make no difference to dive

True enough John, I have a sneaking (unfounded) suspicion they stiffen up the action all round though, might just be the oil grade I use of course.
quite surprised that SRM state the progressive springs reduce dive, maybe their version is stiffer although stated for singles, but I'm not going to argue with those gents

[chaterlea25]

HI Bill and Bob,
I have done some miles on a ZB goldie that has had the SRM springs and Dow dampers fitted
I am probably a division or two down on the weight divisions compared to you guys but I found it rather hard on the rough "roads" hereabouts
On my own bike with the dampers  I use "medium" fork oil as I found SAE20 made the fork movent  too hard
quantity judged by "feel"

Yes, heavy (ier) oil used with the dampers will also stiffen the dive movement to some degree as the oil has to pass through and around the valve unit
Cheers
John

[unclerob]

Hi Paul, I think the problem with fitting progressive springs would be that they give less resistance than standard springs during the first part of fork travel and the rate increases the more the fork compresses. I would think that a new pair of standard springs or higher rate sidecar springs (if still available) would be more likely to improve things.
The other thing that could possibly be improved is to check everything in there works as well as possible, when suspension is compressed it takes more effort to actually start it moving than keep it moving (stiction) so anything you can do to lessen that initial resistance to movement would help.

[Kickaha]

Springs shouldn't be hard to find, the likes of Ohlins and probably Maxton, Hagon etc  do them you just need to give them a diameter and a length and what spring rate you want

Stuff like progressive for a particular model bike is normally a "one size fits all" regardless of rider weight

Look up some stuff on setting suspension sag to work it out properly
http://racetech.com/articles/SuspensionAndSprings.htm

[PaulC]

Thanks unclerob. I have read somewhere that putting a suitable piece of plastic pipe inside can act to keep the spring under extra tension before it is used in anger. Is that what you mean?

Paul

[duTch]

 By my understanding, progressive spring rate is simply that part of the spring is wound at more winds(pitch) per inch to give a softer rate, and other part/s is/are wound at a lesser pitch(harder), and I guess it would be possible to do multiple pitches over a Free length to give multiple spring rates...do a search for 'coil spring compression rate calculator'...I had springs made for my plunger by calculating with.....
http://www.pontiacracing.net/js_coil_spring_rate.htm....kept me entertained for quite some time....