Author Topic: Front end rattle?  (Read 5280 times)

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Offline 38rudge

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Front end rattle?
« on: October 20, 2017, 01:32:39 AM »
Not had my CB750K2 that long but I find that when going over sharp ridges or a series of road irregularities that I get a rattling/jarring sound from the front end a similar sound to something slapping against the front mudguard?

Thought it might be the speedo cable, so I removed that  and went for a ride but still the same problem? Are these bikes known to have this sort of problem? Is it likely to be the front fork springs rattling?

Negotiating normal undulations does not cause any noise only sharp bumps. Has anybody else experienced this and found the cause and a cure? 

Offline dave500

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Re: Front end rattle?
« Reply #1 on: October 20, 2017, 01:41:34 AM »
check those head light support tube/ears,they can slide up and down the forks and rattle.

Offline 38rudge

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Re: Front end rattle?
« Reply #2 on: October 20, 2017, 03:26:20 AM »
Thanks for the reply and suggestion.

The headlamp brk's and rubbers are all new and very firm if I try to move them, so not sure that they may be the source?

Has anybody else any suggestions or know if this may be a fork spring problem?

Offline dave500

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Re: Front end rattle?
« Reply #3 on: October 20, 2017, 04:18:41 AM »
yeah ok,i have one soggy rubber and it makes an annoying rattle the same way as yours,youve looked at and adjusted the steering bearings?if they are the stock ones they may have a dead or flat spot in the race where you cant really adjust the slack out without going too tight?they can be upgraded to tapered roller types if that's the case,kits are quite cheap for these if needed.

Offline my name is nobody

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Re: Front end rattle?
« Reply #4 on: October 20, 2017, 04:31:09 AM »
In addition, check the caliper hinge for vertical looseness/wear.Ttry applying front brake when going over bumps and see if noise goes away when caliper is applied.

Offline dave500

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Re: Front end rattle?
« Reply #5 on: October 20, 2017, 04:35:27 AM »
good call nobody!i had wear in that spot and managed to wrap some thin shim around the pivot,not perfect but stopped a little rattle and the fingernails down the black board #$%*ing squeal!

Offline my name is nobody

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Re: Front end rattle?
« Reply #6 on: October 20, 2017, 04:52:03 AM »
good call nobody!i had wear in that spot and managed to wrap some thin shim around the pivot,not perfect but stopped a little rattle and the fingernails down the black board #$%*ing squeal!



Yup, it can absorb vibration (which sets up noise) in some cases too. Lubing helps as well. There was a fix for
that condition in a TSB from Honda, and a shim with a part number. Came up on this board a looong time
ago posted by the late Raul Guellego(sp?). Terry knew him well.

Offline Dunk

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Re: Front end rattle?
« Reply #7 on: October 20, 2017, 05:25:52 AM »
In addition, check the caliper hinge for vertical looseness/wear.Ttry applying front brake when going over bumps and see if noise goes away when caliper is applied.

^ This.  You can make a shim with feeler gauges. Measure the vertical slop and use a feeler a couple thou smaller than the gap. Punch a hole in it and trim to size, lightly grease and install.

Offline 38rudge

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Re: Front end rattle?
« Reply #8 on: October 20, 2017, 11:58:46 AM »
Thanks for all the replies and suggestions.

Bike already has tapper bearings fitted, but will check their play. No apparent play on the brake caliper arm but will try applying the brake to see if that makes any difference?

The noise is fairly loud and as previously expressed producing the sound like something banging/chattering  against the mudguard or something in the front of the bike. Can't find anything loose?

Offline TwoTired

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Re: Front end rattle?
« Reply #9 on: October 20, 2017, 12:53:16 PM »
I can't hear your noise.

But, on the off chance the sound is misdirected...
Have you checked the drive chain tension?

I had a noise during braking from down below.  Checked front end for bits in contact under compression. Found nothing.

Eventually....

Fricken chain was too loose and smacking the chain guard during decel.  Sound bounced off of something up forward.

Why didn't I find that sooner?  :-[
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Offline Don R

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Re: Front end rattle?
« Reply #10 on: October 20, 2017, 01:02:30 PM »
 Both of my K0's do that, I'm interested to find it also. It's for sure in the fork area. I'll check my brake for play too.
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Offline disco

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Re: Front end rattle?
« Reply #11 on: October 20, 2017, 01:14:58 PM »
My K2 does it as well. K6 does not. I have a new set of PROGressive springs to install. They have a small plastic ‘preload’ that comes with kit. I’m thinking that’s the problem with mine. No preload is allowing the springs to rattle slightly over corrugations.
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Offline my name is nobody

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Re: Front end rattle?
« Reply #12 on: October 20, 2017, 01:15:25 PM »
Also, check the rubber grommets inside the bolt holes of the fender braces for rot/wear.

Offline Old Moe Toe

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Re: Front end rattle?
« Reply #13 on: October 20, 2017, 04:57:26 PM »
My K2 made a noise just like that.
Ended up being the little rivets that attach the front fender/guard to the mounting brackets had worn loose.
Couple of taps with a hammer to the rivets fixed it.
Might not be your problem but you never know.

Offline ilikepinkcrayons

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Re: Front end rattle?
« Reply #14 on: October 20, 2017, 06:35:44 PM »
Maybe the bird's nest of junk in your headlight bucket? Long shot, but it's a thought...
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Offline 38rudge

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Re: Front end rattle?
« Reply #15 on: October 21, 2017, 01:19:09 AM »
Also, check the rubber grommets inside the bolt holes of the fender braces for rot/wear.

Mine is the earlier K2 without the rubber bushes on the stays.

Offline 38rudge

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Re: Front end rattle?
« Reply #16 on: October 21, 2017, 01:22:10 AM »
My K2 does it as well. K6 does not. I have a new set of PROGressive springs to install. They have a small plastic ‘preload’ that comes with kit. I’m thinking that’s the problem with mine. No preload is allowing the springs to rattle slightly over corrugations.

I have also fitted  progressive fork springs that came with a couple of aluminium pre-load spacers. However, when refitting the fork caps the whole lot is under tension, so dont believe that it is due to no preload?

Offline 38rudge

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Re: Front end rattle?
« Reply #17 on: October 21, 2017, 01:23:41 AM »
I can't hear your noise.

But, on the off chance the sound is misdirected...
Have you checked the drive chain tension?

I had a noise during braking from down below.  Checked front end for bits in contact under compression. Found nothing.

Eventually....

Fricken chain was too loose and smacking the chain guard during decel.  Sound bounced off of something up forward.

Why didn't I find that sooner?  :-[


I will certainly check the chain play. But it is a new chain and sprockets which I do check and adjust regularly.

Offline dave500

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Re: Front end rattle?
« Reply #18 on: October 21, 2017, 01:48:40 AM »
don't forget these are old bikes,even new they wernt exactly perfect?its been years since cars had a manual choke,lotta guys expect to push the button and have it idle straight up?the art of having a feel for the fueling has gone away in that reguard?sure your not being fussy?
« Last Edit: October 21, 2017, 01:51:19 AM by dave500 »

Offline disco

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Re: Front end rattle?
« Reply #19 on: October 21, 2017, 06:10:28 AM »
My K2 does it as well. K6 does not. I have a new set of PROGressive springs to install. They have a small plastic ‘preload’ that comes with kit. I’m thinking that’s the problem with mine. No preload is allowing the springs to rattle slightly over corrugations.

I have also fitted  progressive fork springs that came with a couple of aluminium pre-load spacers. However, when refitting the fork caps the whole lot is under tension, so dont believe that it is due to no preload?

OK well that just blew that theory! 😜 I don’t know where to go with my front end now. I’ll have to keep an eye see how this pans out.
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Offline Jerry Rxman Griffin aka MuthaF'er

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Re: Front end rattle?
« Reply #20 on: October 21, 2017, 10:24:25 AM »
Be sure you have the correct volume of fork oil.
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Offline BobR

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Re: Front end rattle?
« Reply #21 on: October 21, 2017, 02:59:09 PM »
 Have this too. Been that way since I got the bike in 98 and fixed it up. Recent renewed interest in riding it has me finally looking to fix the annoying clunk. Might be a stupid question but are there any internal "bumpers" to soften full fork extension? Seems to me that's when I get it. Bob
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Offline Don R

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Re: Front end rattle?
« Reply #22 on: October 21, 2017, 03:23:03 PM »
Both of my K0's do that, I'm interested to find it also. It's for sure in the fork area. I'll check my brake for play too.

 They both have vertical travel in the caliper arm. Now I know what mine are doing. Next up, how to tighten them up a bit. ? I'll try dunk's suggestion first. I have a whitney punch, let's see if it will punch a feeler gauge.
« Last Edit: October 21, 2017, 03:25:12 PM by Don R »
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Offline BobR

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Re: Front end rattle?
« Reply #23 on: October 21, 2017, 08:12:12 PM »
 I just checked my caliper arm. Decent bit of up/down movement. Going to make a small shim and try it. Bob
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Offline BobR

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Re: Front end rattle?
« Reply #24 on: October 22, 2017, 06:33:20 AM »
 Upon inspecting the caliper pivot arm assembly I realized the two top bolts (the ones that also attach the fender) only need to be loosened slightly , and while holding downward force on the upper pivot holder re-tightened. Virtually all play is gone. The upper mount bolt holes allow small up and down movement so if they are removed to mess with the fender or whatever a lot of play will be introduced into the caliper pivot arm unless downward pressure is applied when tightened. HTH Bob

Update: It should be noted my assembly is different than the one shown in the manual here. (See next post with pic)

« Last Edit: October 22, 2017, 11:34:16 AM by BobR »
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Offline BobR

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Re: Front end rattle?
« Reply #25 on: October 22, 2017, 07:01:10 AM »
My assembly. The one piece style pictured in the manual wont have the same type of issue/solution. HTH Bob
« Last Edit: October 22, 2017, 08:15:14 AM by BobR »
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Offline BobR

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Re: Front end rattle?
« Reply #26 on: October 22, 2017, 03:22:48 PM »
OK update:  This is only pertinent to those that have this style set up. I took the caliper off. Then loosened the two bolts holding the upper bracket of the pivot. Used a vise grip(with electrical tape wrapped on the ends) to clamp down the bracket a little. Checked the movement. As long as the spring could return the arm I was happy. Reassembled-voila! Zero play!
  Now unfortunately I cant say if the clunk is gone as I haven't ridden it yet. The play however is gone. HTH Bob

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Offline jonda500

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Re: Front end rattle?
« Reply #27 on: October 25, 2017, 03:25:27 PM »
Have this too. Been that way since I got the bike in 98 and fixed it up. Recent renewed interest in riding it has me finally looking to fix the annoying clunk. Might be a stupid question but are there any internal "bumpers" to soften full fork extension? Seems to me that's when I get it. Bob

I will be following this thread as I also have a front end rattle and a loud clunk when I rock the bike back on the center stand so that the forks fully extend???
John
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Offline BobR

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Re: Front end rattle?
« Reply #28 on: October 25, 2017, 04:30:55 PM »
Have this too. Been that way since I got the bike in 98 and fixed it up. Recent renewed interest in riding it has me finally looking to fix the annoying clunk. Might be a stupid question but are there any internal "bumpers" to soften full fork extension? Seems to me that's when I get it. Bob

I will be following this thread as I also have a front end rattle and a loud clunk when I rock the bike back on the center stand so that the forks fully extend???
John

 Ive yet to ride mine since I took out the play in the caliper holder. Will report back when I do. bob
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Offline AndyH

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Re: Front end rattle?
« Reply #29 on: October 25, 2017, 08:29:22 PM »
Have this too. Been that way since I got the bike in 98 and fixed it up. Recent renewed interest in riding it has me finally looking to fix the annoying clunk. Might be a stupid question but are there any internal "bumpers" to soften full fork extension? Seems to me that's when I get it. Bob

I will be following this thread as I also have a front end rattle and a loud clunk when I rock the bike back on the center stand so that the forks fully extend???
John

+1 John.  I was thinking lack of fork oil but now I'm not so sure... :-\
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Offline BobR

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Re: Front end rattle?
« Reply #30 on: October 28, 2017, 02:20:34 PM »
  Got a chance to ride the bike today.  The majority of clunking is gone AND no more brake squeal! That alone is worth the price of admission! Still get a bit of a clack hitting hard bumps -not as loud and sounds more like something around the headlight. If you have the caliper arm bracket like mine-take the play out as I described. If its a one piece like the one pictured in the manual, make a shim. HTH Bob
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Offline Desert-SOHC

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Re: Front end rattle?
« Reply #31 on: October 28, 2017, 03:56:18 PM »
Mine does it too, I'll have to check the caliper.
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Offline ef9tuning

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Re: Front end rattle?
« Reply #32 on: October 31, 2017, 11:43:49 AM »
My 78k would make a similar sound as you're describing. I found out it was the gas tank rubber strap/holder causing a clunk sound over some bumps!
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Offline Desert-SOHC

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Re: Front end rattle?
« Reply #33 on: October 31, 2017, 01:26:43 PM »
Yup, my caliper was moving, tightened it with pressure on the bracket.  1 more noise is gone... ;D
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Offline Dunk

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Re: Front end rattle?
« Reply #34 on: November 12, 2017, 06:54:14 PM »
I tried to take my own advice on this one and the first attempt failed. I could not punch the required size hole in the feeler gauges I had, not wide enough so they broke each time I tried. I measured the end play in the caliper bracket at .005". I learned a aluminum beverage can is .004" thick, what's .001" between friends? Punched out a washer to shim it and reassembled. Should be more better!

Offline Dunk

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Re: Front end rattle?
« Reply #35 on: November 12, 2017, 06:57:38 PM »
.....................

Offline Dunk

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Re: Front end rattle?
« Reply #36 on: November 12, 2017, 06:58:12 PM »
..........................

Offline Dunk

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Re: Front end rattle?
« Reply #37 on: November 12, 2017, 06:58:46 PM »
....................

Offline scunny

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Re: Front end rattle?
« Reply #38 on: November 12, 2017, 09:55:08 PM »
Are you related to Terry ?
nice thinking by the way.
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