Progressive fork springs

[Al]

A year on, thought it was time for an update.
Been at Odiham, Oulton Park, Spa and Cadwell and there have been some changes albeit slight but due to some incidents, unforseen circumstances and natural developments, some adjustments have had to be made.

Bearing in mind that these settings are for track use i am posting to highlight the subtleties in changes, to give an indication of how much difference, small adjustments make with this set-up.

The original set-up, once it was initially in a place that was suitable.

Rear rider (full) sag 12.5 mm
Front rider (full) sag 37.5 mm
Fork main spring pre-load 5mm (equal to the minimum recommended)
Emulator valve springs Yellow (64 Lbs / inch)
Emulator valve spring pre-load 3.5 turns.
Fork oil 20W (True S.A.E.)
Oil level is 135mm bottomed with springs out and emulators in.
16 mm of fork top leg protruding through the top yolk.
Front tyre pressure 29 PSI
Rear tyre pressure 35 P.S.I.
Tyres Conti Attack CR2
Weight at front wheel 105 KG
Weight at rear wheel 106 KG.

Settings now. Changes highlighted in red.

Rear rider (full) sag 12.5 mm
Main linear springs Bike sag is 26mm Front
Rider sag (full) for both bike and rider) 37.5mm
Fork main spring pre-load = 11mm, achieved with several plain washers above the plastic tubes.
Emulator valve spring pre-load (Yellow 64 Lbs) 4 turns from just open.
Oil weight 15W (true SAE) I'm likely about to change back to 20W
Oil level 120mm from top of tube, compressed fully, springs out, emulators in.
20mm of fork leg sticking out above top yolk.
Air pressure = zero when bike on wheels.
Front fork full travel under full brake was 3 1/4 inches


Everything else not highlighted in red stays the same. You could say that those items which are highlighted are the ones that make the most difference or that they are the ones that will never be right to satisfy different criteria. Eg. different tracks or differing conditions.

Dont think i posted the part numbers for the bits i have fitted either;

Valves; FEGV S 3501
Linear springs; FRSP S 2938 (0.95 Kg/mm)

These are in standard J forks / standard J yolks.
Emulators would likely be the same number but spring rate would differ depending on various things like bike and rider weight / intended use etc. etc.
I could see a possible problem with 1100 B forks / yolks / bars in that i think the bars hold the upper legs to a given fixed height. I think that may end up with the front end riding too high but not sure if that can be got round somehow with maybe a tubular spacer outside the stauntion.

Anyone been playing with these on a road set-up??

AL

[Fred the Zed]

Great info Al.

Mods and changes mapped out brilliantly. Will the same part nos fit other Zeds... Z1R for example? I need to sort the seals on my 78 Z1R so I might as well change the springs and oil and try the emulators out.

Fred

[Al]

How ya doing Fred?
No not those numbers for the Z1R. They divide the series down into sets and yours would be included in the Street, Kawasaki, KZ1000, 1977 to 1980 collection.
Not being patronising but those are the selections you need to make from this page

http://www.racetech.com/VehicleSearch

http://www.racetech.com/VehicleSearch#g ... ar=1977-80

Think it said 36mm forks for the 1R, where the J ones are 38mm.
It looks as if the Shed may need some "Fork Emulator Adaptors" AD 3003 P.
But i would really speak to them to confirm this first.

If youre sure about what you want then fine but they list spring rates for about six or seven different needs!

Mine are 50% stiffer than standard from 0.65 Kg/mm to 0.95 Kg / mm.

Shout out if i can help. When i opened the spring box the last thing i expected to see was a bit of thick walled plastic tube!!!!!!!!!!!!!!:shock:

AL

[Fred the Zed]

Cheers Al!

[Fred the Zed]

Time for an update on Zorded's great thread...

I've eventually got around to ordering the bits and pieces from PDQ for my 78 Z1R..

As I'm a hefty bear at 16st odd:

0.85kg Springs: FRSPS 2341085

Adaptors for Z1R: FEV AD3003P

Emulators: FEGV S3001

All in, including postage was a total of £296.05. (But prices about to go up)

3 week wait for the parts from the US.

Race Tech reckon 15w oil.

Fred

[Z1parR]

Nice one Rich
Thanks for sharing your findings and experience .

[Fred the Zed]

Nice one Rich
Thanks for sharing your findings and experience .

Its what makes the Z1OC world go around.