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Progressive rate fork springs

liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

Progressive rate fork springs Empty Progressive rate fork springs

Post by liverpool_f_ on Wed 13 Feb 2019, 8:41 pm

Hi all,

I am looking to do a complete front fork rebuild with new stanchions and replace everything possible on my high mile CB. Has anyone fitted any model of progressive fork springs for example;

https://www.ebay.co.uk/itm/For-Honda-CB-500-1994-1995-Wirth-Fork-Springs/401107934018?epid=1565756141&hash=item5d63e55b42:g:xJ4AAOSwC3dakkvJ:rk:11🇵🇫0

I am looking for softer front forks as mine are like a rock. It might help to soften them that I will be replacing all parts with new and they might move with more freedom. I don't, however, want to fit these springs if they are in fact heavier overall.

Also, has anyone done a full rebuild, like new? Would you suggest replacing absolutely everything? Stanchions typically get reused but mine are pitted so they are getting done. Heres the parts list/diagram.

https://www.lingshondaparts.com/partscatalog/catalog/listing/catalog/hondamc/catkey/A/modelid/1589/block/13MY52I1/blockref/F__0800/

Any experience would be greatly welcomed.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Wed 13 Feb 2019, 8:41 pm

I am also considering going down a viscosity grade on the oil to reduce the firmness a bit. Anyone gone that way and was it worth it?
skyerae
skyerae
the 800
the 800

Posts : 264
Location : Deepest darkest Scotland.

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Post by skyerae on Thu 14 Feb 2019, 7:34 am

Mine were moving fine on a lower mileage CB but the seals were leaking (they were most likely the original 24 year old ones) Replaced the seals and one or two other small bits.I used the same springs and replaced the oil with the one recommended by Honda and the Haynes Misinformation Manual - they agreed for once. Didn't seem to make much difference but the shocks were working beforehand.

Something can't be right if they are like a rock, they should be stiff but not solid. Have they ever been overhauled, my oil (when I drained it) was a lovely milky colour and was way less then there should have been, it had all leaked down the fork past the seal? I did a lot of research into progressive springs and decided against them.
wrighty
wrighty
Three's a Charm
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Location : Market Deeping Lincs

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Post by wrighty on Thu 14 Feb 2019, 7:58 am

Do you know what grade of oil is currently in the forks? Going up in oil weight will slow the forks ability to react. I have given my forks a bit of preload by putting spacers on top of the standard springs but left the oil weight standard (10 weight) so as not to slow the compression or rebound.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Thu 14 Feb 2019, 6:05 pm

They have had the seals done a couple of times, not by myself. They often didn't last very long, I think because the stanchions weren't in the best shape. Don't know the grade that was used when they were reassembled, but I am assuming it was the stock grade. I only have my FZ6 to compare the suspension with. Even thought the FZ6 is considered to be on the sporting side in terms of the handling, the suspension is much more compliant.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Thu 14 Feb 2019, 6:07 pm

Also, for you lot that have done fork work in a home/driveway situation, how did you support the bike?

I am thinking centre stand and some old place keeper forks of some sort when mine are off but that involves finding and possibly buying forks that I won't need after the job is done
skyerae
skyerae
the 800
the 800

Posts : 264
Location : Deepest darkest Scotland.

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Post by skyerae on Thu 14 Feb 2019, 7:12 pm

I used the centre stand and shoved a few odd blocks of wood under the front of the engine. I had the wife push the back wheel closer to the ground and jammed the wood in. It worked a treat, will have to do this to the VFR800 when I replace the head race bearings.
wrighty
wrighty
Three's a Charm
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Posts : 141
Location : Market Deeping Lincs

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Post by wrighty on Thu 14 Feb 2019, 8:04 pm

I used main stand and car jack with a piece of wood under the engine. Not the most stable but ok if you're careful.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Thu 14 Feb 2019, 8:33 pm

My hydraulic jack is pretty terrible. I left it in position whilst getting a tyre changed with close to disastrous results. I have a crappy solid jack from the car but it is rather flimsy as most of those things are.
motofan
motofan
Two Tone
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Posts : 133
Location : Normandie, France

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Post by motofan on Fri 15 Feb 2019, 12:20 pm

If it'll hold a car think it'll hold a bike!
I use wooden blocks about a foot long by 6" x4"  they stack and are nice and stable.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Sat 16 Feb 2019, 11:37 am

So is there no one on here with progressive springs installed who can verify one way or another if they are stiffer or more firm?
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Sat 16 Feb 2019, 11:39 am

@motofan wrote:If it'll hold a car think it'll hold a bike!
I use wooden blocks about a foot long by 6" x4"  they stack and are nice and stable.

It will lift a car! Certainly wouldn't trust it to hold one!
kungfupoodle
kungfupoodle
Godzilla
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Post by kungfupoodle on Sat 16 Feb 2019, 1:05 pm

@liverpool_f_ wrote:So is there no one on here with progressive springs installed who can verify one way or another if they are stiffer or more firm?

Your front end shouldn't be solid as a rock anyway but progressive springs ought to feel a little softer in the comfort department. They will allow the wheel to move further over bumps making the ride softer while progressing up to control pitch under braking and acceleration.

The general consensus is if you ride a lot of uneven B-roads you will be better off with progressive. If you stick to smooth roads or a lot of track work then standard is the way to go.
motofan
motofan
Two Tone
Two Tone

Posts : 133
Location : Normandie, France

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Post by motofan on Sat 16 Feb 2019, 3:09 pm

@liverpool_f_ wrote:

@motofan wrote:If it'll hold a car think it'll hold a bike!
I use wooden blocks about a foot long by 6" x4"  they stack and are nice and stable.



It will lift a car! Certainly wouldn't trust it to hold one!
Yea, you're right, I wouldn't work under a car on it's own jack affraid
skyerae
skyerae
the 800
the 800

Posts : 264
Location : Deepest darkest Scotland.

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Post by skyerae on Sat 16 Feb 2019, 3:10 pm

That might be the case but I used my standard forks on B-roads the 22 mile trip on the way to work and then again on the 22 mile return trip. It did get lively at times but this was part of the fun......... Smile
Jameshambleton
Jameshambleton
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Post by Jameshambleton on Sun 17 Feb 2019, 12:45 pm

I'm 99% sure that stock fork springs are progressive in any case?
wrighty
wrighty
Three's a Charm
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Posts : 141
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Post by wrighty on Sun 17 Feb 2019, 12:52 pm

@Jameshambleton wrote:I'm 99% sure that stock fork springs are progressive in any case?

Having just had mine out to change the oil I can confirm that. As the bike was 15 years old when I got it I wasn't sure if they were the original springs, but mine are certainly progressive.
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Tue 19 Feb 2019, 10:13 pm

@Jameshambleton wrote:I'm 99% sure that stock fork springs are progressive in any case?

That is news to me. Maybe the question is then, do any of the other brands of springs offer a different ride quality compared with the OEM?
Jameshambleton
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Post by Jameshambleton on Wed 20 Feb 2019, 6:08 pm

@liverpool_f_ wrote:
@Jameshambleton wrote:I'm 99% sure that stock fork springs are progressive in any case?


That is news to me. Maybe the question is then, do any of the other brands of springs offer a different ride quality compared with the OEM?

OEM changed throughout of the years with sometimes no spacer or 100mm long spacers. Thus different spring rates, and potential re-valving as well, I have one set of oem forks that are hard with maybe 20mm of travel as the others have 70+mm of travel, also depends on your fork oil weight and airgap - the airgap is the most important out of the lot really.
stormbringer
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Post by stormbringer on Wed 20 Feb 2019, 7:49 pm

Did a complete rebuild of mine a few years back. Old oil was silvery and bushings were not. New bushings, new oil (10 weight) and off I went. No issues. Has taken me everywhere including romanian mountain roads littered with deep potholes. No issues. All OE. If your front is stiff and unwelcoming, replace oil and bushings and nothing else. Actually, mine has the opposite issue; too soft. It'll dive under pressure, almost bottoming out. Maybe I should check oil level... As @jameshambleton said; the airgap is important. Is your oil level correct?
Melitos
Melitos
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Post by Melitos on Mon 25 Feb 2019, 8:36 pm

I've rebuilt my forks 2 years ago with new bushings, seals and Wirth progressive springs. Quite happy with the front end, not too stiff.

http://www.cb500club.net/t5084-50k-km-overhaul-and-winter-upgrades#47292

http://www.cb500club.net/t5084-50k-km-overhaul-and-winter-upgrades#48210

BR,
Antti
liverpool_f_
liverpool_f_
the 900
the 900

Posts : 448

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Post by liverpool_f_ on Wed 27 Feb 2019, 7:23 pm

Thanks for the info folks. 

@stormbringer wrote:Did a complete rebuild of mine a few years back. Old oil was silvery and bushings were not. New bushings, new oil (10 weight) and off I went. No issues. Has taken me everywhere including romanian mountain roads littered with deep potholes. No issues. All OE. If your front is stiff and unwelcoming, replace oil and bushings and nothing else. Actually, mine has the opposite issue; too soft. It'll dive under pressure, almost bottoming out. Maybe I should check oil level... As @jameshambleton said; the airgap is important. Is your oil level correct?

I am correct in thinking there is no way to check the level without disassembly? Also, I don't understand the concept of the air gap in terms of this suspension. Can someone elaborate?

From the Lings parts page, what part numbers are you suggesting get replaced for a complete rebuild?

https://www.lingshondaparts.com/partscatalog/catalog/listing/catalog/hondamc/catkey/A/modelid/1589/block/13MY52I1/blockref/F__0800/
Jameshambleton
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Post by Jameshambleton on Wed 27 Feb 2019, 10:22 pm

@liverpool_f_ wrote:Thanks for the info folks. 
I am correct in thinking there is no way to check the level without disassembly? Also, I don't understand the concept of the air gap in terms of this suspension. Can someone elaborate?

Easiest way is just to drop the forks out of the yokes (remove the front wheel 1st!!) if not you'd have to mess about with removing the handlbars ect.

The airgap is basically an air damper, when your forks compress not only is the oil forced through the shims but the oil that is forced through also compresses the air at the top of the fork leg.
If you didn't have the air you'd get 0% travel, with the air it helps to give some movement of the forks. The air is also a second damper of sorts... as the air compresses this causes some resistance to the oil flow in addion to the shims.
Beresford
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Post by Beresford on Wed 27 Feb 2019, 11:53 pm

A few years ago one of my fork legs was losing oil past a worn seal, and until I got round to fixing that, I just from time to time removed the top cap and tossed in some oil. If the level was nearly correct, the suspension worked. If I put in too much oil the forks were rock hard and immovable. The handling was interesting at that period !

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