Changing the springs on the ZX 636 forks

[maxz1000]

After my fork swap the front end was a little soft, so I have finally got around to ordering some RaceTech springs with some 5W PJ1 fork oil.

The stock Z1000 fork spring rate is 0.850 kg/mm
The stock ZX 636 fork spring rate is 0.900 kg/mm (not sure how accurate this value is )
However as the people in the West are slightly heavier than our Japanese counterparts, checking the manual the 636 it is set up for a 68kg rider
I used an on-line calculator and came up with the following:
198kg bike + 87 kg rider (without gear, as calculator puts in a factor for riding gear) the recommended spring rate was 0.96 kg/mm. The nearest size was 0.95 kg/mm so I ordered a set for the ZX 636.

Part number FRSP S3627 095, street / PR Fork Springs 35.5 x 270 mm .95 kg/mm




This is no 5 minute job...

Anyway after removing the forks, i have completed the first leg.

The first job is to remove the fork cap:


Then using the spring compression tool, insert the supplied fixing tool to give you access to the lock nut. I was by my self, so used some ratchet straps to compress the springs as this is a two person job, unless you have bought the £100 tool.


Once the top half has been removed, remember to take note of the position of the lock nut... you will need this on re-assembly



The ReceTech springs are longer than the standard ones....
Point to note, if you go the Ohlins Route they are the same size and do not need to be cut, I would suggest this is the way to to...
1.0 kg/mm = part number 08714-10
0.95 kg/mm = part number 08714-95

I spend some time searching various treads and there is much confusion with the RaceTech instructions, I could not figure out what they were trying to say as it is one instruction fits all. I have also not had a response from the UK supplier

Anyway, I went down the route of the same over all length which meant I cut the plastic spacer. Note in the picture below I had a washer on the end of the spring... I removed this and decided to cut off 20mm... To do this the holes are lost and you will need to drill a hole of 5.5mm diameter in order that you can again compress the spring with the compression tool.







Then set the oil level to 109mm +/- 2mm, this tool is great and make the job easy and accurate.


Then install the new spring, spacers and cap with the pre-load wound fully back.

[maxz1000]

You will need this for the job

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[Deleted]

hows the new springs going, what is the sag like now? how dose it ride?

[maxz1000]

hi buzz... all back together and I have covered about 100 miles on it... much better... will post more in a few weeks.. busy at work at the moment.. bummer ;D

[Deleted]

whats rebound like like for instance wheelie haha u dnt get a thud from masive releas from the spring lol or have u coverd tht throgh dampening

[Deleted]

Nice post Max!

Always well thought out and you really do have a lot of special tools too!

My friend with the bike shop has everythig you could imagine...I need to pop in and speak to him too...will do next week RE: shock's

Keep it up

F

[maxz1000]

Thanks Frag... OK very happy with the front end... so I would recommend 0.95kg/mm springs and a 5W oil. But when using RaceTech cut only 15mm off the plastic tube. To set my sag I had the pre-load with only one ring showing. But saying that I was no where near the full travel and have since backed off the pre-load a full turn with the rationale that when the bike is on its upward travel, ie over a bump the wheel would remain in contact with the road longer.

z1000turbo, I have not tried any wheelies yet Think you best get some practice as that bike of yours will be on its back wheel all the time ;D

[Deleted]

I loved wheeling my zed before I doing this turbo'ing, but hell knows what it is gonna be like with this set up of mine best hold on and see what happens lol

[maxz1000]

If I was to do this again I would fit progressive fork springs having experienced the rear in this set up.