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B fork springs.

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warren3200gt
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B fork springs.

#1 PostAuthor: warren3200gt » Sun Jun 09, 2019 9:39 am

Guys, which of the springs below work best in B forks?
Top pair are 555mm long.
Middle are 545 long but thicker wire
Bottom are 505mm long.
I have a pair like the bottom pair in them at the mo but travel seems very limited at about 1 inch and stiff. Manual shows a pic like these as correct but 495mm long. Would 10mm longer really make that much difference?
Either off the top pair will be a pig to get in as they protude out the top and will need compressing to get the cap in.
The bottom pair are flush with the top of the fork leg and need compressing a tad to get the cap on.
Running 15w oil at 170ml. Manual says 10w. would 10w make that much difference?
Any suggestions as I took off a pair of A4 forks which were fine and gave about 3 inch travel but are not correct for the bike.
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PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

kev edwards
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Re: B fork springs.

#2 PostAuthor: kev edwards » Sun Jun 09, 2019 7:52 pm

From the info i Have Warren, the springs should be 511mm, if less than 485mm they need replacing, so the longer ones appear not to be for a B or A model.

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warren3200gt
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Re: B fork springs.

#3 PostAuthor: warren3200gt » Sun Jun 09, 2019 8:28 pm

What workshop manual do you have Kev? Mine says 495 standard, 485 knackered.
I've put the a4 ones back on it for the moment until I can resolve the issue.
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

kev edwards
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Re: B fork springs.

#4 PostAuthor: kev edwards » Mon Jun 10, 2019 1:55 pm

I guess its a Z1B 900, the 495 is correct, you should have more travel though, maybe the wrong springs right length possibly to thicker wire.

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warren3200gt
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Re: B fork springs and brake pads (now)

#5 PostAuthor: warren3200gt » Tue Jun 11, 2019 3:38 pm

And it all becomes clear! The stanchions have been re chromed at some point and had high points in the chrome and were sticking in the lower leg as it slide in. A quick polish with nice and abrasive solvol autosol seems to high "adjusted" it and now it slides in and out without jamming.
Rebuilt them and filled with 10w and have smooth 3 inch travel on both fork legs. Next irk is squeeling pads. Tried copperslip and it works for about half an hour so need to swop out the pads. Which are non squeely?
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

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ADRIAN H
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Re: B fork springs and brake pads (now)

#6 PostAuthor: ADRIAN H » Tue Jun 11, 2019 3:54 pm

warren3200gt wrote:And it all becomes clear! The stanchions have been re chromed at some point and had high points in the chrome and were sticking in the lower leg as it slide in. A quick polish with nice and abrasive solvol autosol seems to high "adjusted" it and now it slides in and out without jamming.
Rebuilt them and filled with 10w and have smooth 3 inch travel on both fork legs. Next irk is squeeling pads. Tried copperslip and it works for about half an hour so need to swop out the pads. Which are non squeely?


I use 15W oil in forks, was told gives a better resistance / feel. Not sure of the difference with 10W.
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warren3200gt
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Re: B fork springs.

#7 PostAuthor: warren3200gt » Tue Jun 11, 2019 4:01 pm

Me too Ade, but the book said 10w so was interested to see the diff. Once it stops raining I'll take it out and then drain and refill with 15w and see what the diff feels like. Think 15 just stiffens up the front end a tad,
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

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warren3200gt
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Re: B fork springs.

#8 PostAuthor: warren3200gt » Sat Jun 15, 2019 4:13 pm

Update, back to back 10w v 15w fork oil ride.
so the only minor difference noticable was the rate of compression and rebound was slower with 15 than 10. So if you "push on" you'd want 15, if your just crusing around you'd want 10 for comfort but the difference is negliable.
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

needaz1100r
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Re: B fork springs.

#9 PostAuthor: needaz1100r » Sat Jun 15, 2019 4:41 pm

warren3200gt wrote:Update, back to back 10w v 15w fork oil ride.
so the only minor difference noticable was the rate of compression and rebound was slower with 15 than 10. So if you "push on" you'd want 15, if your just crusing around you'd want 10 for comfort but the difference is negliable.


It gets a bit deeper than that. The holes that the oil is forced through in order to slow down the movement of the forks can get "clogged" if the oil is too thick. The flow can momentarily actually stop, like a crowd of people trying to get through a door, they get stuck so no-one is getting through, it's caused by the build up of pressure pushing sideways as the fluid is compressed, rather than being slow, which can make the front seem at best very harsh, at worst could cause a loss of tyre traction.

The other issue with too much damping is pump down, which is if you hit a series of bumps with each one compressing the fork before it has rebounded past where it started.

Only use heavier oil if the spec calls for it, eg GS1000 spec is for engine oil in the forks, I run 10 weight fork oil in those and they are fine.
Cheers,

Mark.

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warren3200gt
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Re: B fork springs.

#10 PostAuthor: warren3200gt » Sat Jun 15, 2019 5:03 pm

Im sure your right and the full tech on forks is a science in itself. Its just nice to get some suspension travel up front from the correct forks for the model.
As an aside I trawled through the archive for a brake squeal remedy before trying different pads as the copper slip on the back of the pads only partially worked for me. A member (cant recall who, sorry) suggested and had tried cutting two hacksaw slots at 90 deg to each other crossing off pad center. So thought Id try it before getting new pads. Don't know why but it works! :D
PUM 488 June 2023
76 Z900A4, 77 Z650B1, 77 KZ650B1, 77 Z1000A1, 82 Z1000J2, ZRX1100R.

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flateddie
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Re: B fork springs.

#11 PostAuthor: flateddie » Sat Jun 15, 2019 9:38 pm

I stopped mine with some brake pad backing tape from EBC
Z1b, z1000a1 x 2 , Aprilia v4 Tuono factory, SV1000


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