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CG 125 Front suspension issue, not again!?!!

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Cyclingbiker
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Joined: 05 Aug 2012
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PostPosted: 16:24 - 24 Apr 2013    Post subject: CG 125 Front suspension issue, not again!?!! Reply with quote

Hi all I am having yet another persistent problem with my ever-breaking-down CG.

This time it is an ever present knock or tap when I go over potholes or speed humps. It's coming from the front somewhere but I can't pin it down really as it only occurs when I'm moving.

I suspected the headset bearings a few weeks ago and last weekend I stripped the whole front end of the bike down and replaced the bearings with some new tapered roller bearings from "Pyramid Parts". The old ones were also taper rollers which surprised me a bit as I was expecting loose ball bearings to fall out. Anyways I changed the bearings and also changed the fork oil while I was at it, twas a lovely mauve/white colour when it came out too, and put the recommended 85cc of 10w suspension fluid back in each.

The knock is still there, the lock ring is tightened as far as possible without making the yokes too hard to turn. No noticeable play is present when messing about depressing the forks when rocking back and forth stood still. There some type of knock audible from the left fork leg so I assume it may be related. Damper assembly maybe?

Some help would me appreciated Thumbs Up Karma
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Honda CB500s (1999) - Honda CG 125 BR-J (1991)

Mod 1 - Passed - 12/11/12 --- Mod 2 - Passed - 26/11/12
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tomh
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Joined: 12 Nov 2011
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PostPosted: 17:52 - 24 Apr 2013    Post subject: Reply with quote

I had a similar problem with my 2001 CG but never dealt with it. It was the peice of metal that sticks out in the left fork leg for the brake had worn or was the wrong size (Original wheel but not original forks).

This meant there was a bit of movement on the brake plate. If you press the front brake and move the bike backwards then forwards you would be able to see it move.

I bodged it with a feeler gauge for a week until that fell out.
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Cyclingbiker
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PostPosted: 19:30 - 24 Apr 2013    Post subject: Reply with quote

TomH wrote:
I had a similar problem with my 2001 CG but never dealt with it. It was the peice of metal that sticks out in the left fork leg for the brake had worn or was the wrong size (Original wheel but not original forks).

This meant there was a bit of movement on the brake plate. If you press the front brake and move the bike backwards then forwards you would be able to see it move.

I bodged it with a feeler gauge for a week until that fell out.


Many thanks for the insight, I'll look into it come tomorrow evening when I have some free time to tinker Thumbs Up Karma
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Honda CB500s (1999) - Honda CG 125 BR-J (1991)

Mod 1 - Passed - 12/11/12 --- Mod 2 - Passed - 26/11/12
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27cows
World Chat Champion



Joined: 01 Nov 2009
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PostPosted: 19:52 - 24 Apr 2013    Post subject: Reply with quote

I had this with a CG (drum brake model). In the end I bodged it by wrapping PTFE tape round the bit of fork that engages in the drum plate to take up the slack. Worked like a charm.
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blurredman
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PostPosted: 19:29 - 27 Apr 2013    Post subject: Re: CG 125 Front suspension issue, not again!?!! Reply with quote

Cyclingbiker wrote:
The old ones were also taper rollers which surprised me a bit as I was expecting loose ball bearings to fall out.



I replaced the head bearings for those tapered about June 2012..

Laughing
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.
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Cyclingbiker
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PostPosted: 22:18 - 27 Apr 2013    Post subject: Re: CG 125 Front suspension issue, not again!?!! Reply with quote

Blurredman wrote:
Cyclingbiker wrote:
The old ones were also taper rollers which surprised me a bit as I was expecting loose ball bearings to fall out.



I replaced the head bearings for those tapered about June 2012..

Laughing


Ah that explains that then Laughing

At least that ruled that out anyway as the cause of the knock. I took the wheel off again today and had a look at exactly how much play there is between the lug on the fork and the slot in the brake plate. It turns out there was quite a bit, enough to cause an audible knock by rotating the brake plate by hand without the wheel in place but with the spindle fitted. I found a roll of thick "helicopter tape", bought it about 2 years ago to stop certain parts of the pushbike getting the paint rubbed off by gear/brake cables and scratched by whatever the bike is leaning on.

I couldn't get it to adhere well as the sticky backing was quite weak so it was tricky to keep in place whilst the wheel was slotted back in but I managed to get there in the end. I'll grab some superglue sometime and permanently fix the tape to the lug to get it sorted once and for all. For now though the knock seems to have disappeared but I'll keep a close eye on it Thumbs Up
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Honda CB500s (1999) - Honda CG 125 BR-J (1991)

Mod 1 - Passed - 12/11/12 --- Mod 2 - Passed - 26/11/12
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Cyclingbiker
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PostPosted: 22:10 - 09 Jun 2013    Post subject: Reply with quote

I have since wrapped the lug with a few layers of black electrical tape to provide a better fit for the slot in the brake plate. Unfortunately the knock and the corresponding vibrations through the bars still persist Confused

The Haynes is most unhelpful, only suggesting that "Slack steering head bearings" or "Worn fork bushes" are the two possible causes of juddering when the front brake is applied. The symptom is not exactly what I experience, it mostly happens going over potholes or uneven surfaces with or without brakes applied but is more pronounced under braking. The two possible causes don't add up in my case, the former has been ruled out as they have been recently replaced and the second is irrelevant as the CG is not fitted with fork bushes.

Part of me suspects worn wheel bearings as a possible cause. Ideally I need someone to hold the bike firm whilst I check for play in the bearings to make sure.
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Honda CB500s (1999) - Honda CG 125 BR-J (1991)

Mod 1 - Passed - 12/11/12 --- Mod 2 - Passed - 26/11/12
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Mark65
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Joined: 16 May 2008
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PostPosted: 07:28 - 10 Jun 2013    Post subject: Reply with quote

Have you tried looking at the clocks, namely the mounts, jam some cloth under them( from the riders side) and try the bumps again.

Mark
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Teflon-Mike
tl;dr



Joined: 01 Jun 2010
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PostPosted: 09:10 - 10 Jun 2013    Post subject: Reply with quote

Cyclingbiker wrote:
second is irrelevant as the CG is not fitted with fork bushes.

Oh Yes it WILL be...
You have a metal fork slider, bearing on the chrome stanchion.
There will be a 'bush' or bearing surface.
May not be a servce replaceable bronze bush; may not even be a seperate part; could just be a section of the fork slider casting.... but it is there all the same... and if its worn past tolerence, it will give slop, and let the forks clonk.

If its not a seperate individually, service replaceable item; just means that the 'fix' is to replace the entire fork-slider.

However.... Damper-rod would be my first line of enquirey.

Damper rod is retained via a cap-head screw in the bottom of the slider, and is a known bastard to get out, or re-fit.

Hex head usually fills with crud, and is so far recessed into the slider past the axle spindle boss that you often cant get an allen socket down to it, and using the long end of an allen key, dont give much leverage.

Then the rod is only retained on the other end by the pre-load on the fork-spring.... so if you have taken the spring-cap off before strupping the fork.... it just turns and doesn't undo...

Putting back together? Well, you need to get the screw started in the damper rod before you fit the spring, or you never get the darn thing to line up. but again, has tendancy to just turn as there's nothing holding it.

People often forget, to tighten fully, once they have the spring-cap in.... by that point they are usually rightly pissed off and knackered, and with a fair few 17mm hex dents in thier forhead... so it's fogivable... and then after struggling to get the front wheel in place... bolt is inaccessable.

But, if the damper rod bolt not tight? Well you as like could have some bits and pieces flopping about down there inside the fork, that could clonk.

Worth checking. Maybe strip the legs, check the bush surface sized with calipers, to see if that could be the problem; then re-assemble paying heed to the damper rod assembly and that bugger-bolt at the bottom... see if clonk goes way.
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blurredman
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Joined: 18 Sep 2010
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PostPosted: 09:30 - 10 Jun 2013    Post subject: Reply with quote

Cyclingbiker wrote:
Part of me suspects worn wheel bearings as a possible cause. Ideally I need someone to hold the bike firm whilst I check for play in the bearings to make sure.


I replaced the front wheel bearings too.


I also came accross this issue and braced the side of the lug with the plate with an inch of tie wrap (inserted it while putting together then cut when all tight)
____________________
CBT: 12/06/10, Theory: 22/09/10, Module 1: 09/11/10, Module 2: 19/01/11
Past: 1991 Honda CG125BR-J, 1992 (1980) Honda XL125S, 1996 Kawasaki GPZ500S, 1979 MZ TS150.
Current: 1973 MZ ES250/2 - 18k, 1979 Suzuki TS185ER - 10k, 1981 Honda CX500B - 91k, 1987 MZ ETZ250 (295cc) - 40k, 1989 MZ ETZ251 - 51k.
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