Author Topic: My forks are not happy  (Read 18753 times)

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Offline Nathan S

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Re: My forks are not happy
« Reply #30 on: January 21, 2016, 02:38:10 pm »
There's a top-out spring visible in your second and third photos?

Yes, drilling out the damper rods is the preferred option!

The damper rods should be square and centred, but after 40+ years and some questionable machining, anything is possible. Old Yammie forks had fibre sealing rings on the head of the damper rods, which would help to keep them centred and minimise wear if they ran into the inside of the fork tube (along with the obvious task of improving sealing).
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Offline Jumbo J

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Re: My forks are not happy
« Reply #31 on: January 21, 2016, 03:08:26 pm »
There's a top-out spring visible in your second and third photos? actually nathan those springs did not come out of the forks after i got them back. i was experimenting with them, and besides with them installed the travel is further reduced than it already is after the damper rods have been shortened :(

Yes, drilling out the damper rods is the preferred option!

The damper rods should be square and centred, but after 40+ years and some questionable machining, anything is possible. Old Yammie forks had fibre sealing rings on the head of the damper rods, which would help to keep them centred and minimise wear if they ran into the inside of the fork tube (along with the obvious task of improving sealing).

Offline GMC

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Re: My forks are not happy
« Reply #32 on: January 21, 2016, 03:14:02 pm »
I’m not a suspension guru (my disclaimer) but I have fitted some emulators.
They are a tight fit so a bit fiddly to fit in small diameter fork tubes, while yours may be scraping I don’t believe the damage to the fork sliders could be caused by some alloy ‘paste’
That is some serious damage to the sliders and it looks to me that the forks are missing the bushes from the top of the lower sections resulting in the forks being metal on metal during their travel.
Also for that amount of shrapnel I would expect the emulators to be quite damaged as well but it looks like minor damage.
Look up a parts diagram and do a roll call for all parts.

As already mentioned the damper rods should have been drilled out as the original damper holes are still controlling the oil flow before the oil reaches the emulators, therefore making a lot more compression damping. Whoever fitted them didn’t follow the instructions making fitting of the emulators a wasted effort.

The damper rods should not have been shortened as this reduces travel, the springs should have been shortened to make room for the length of the emulators
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Offline Nathan S

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Re: My forks are not happy
« Reply #33 on: January 21, 2016, 03:18:40 pm »
Most of the old forks didn't have bushes. But I otherwise agree.

Jumbo, In case it isn't perfectly clear by now: don't go back to whoever fitted the emulators.
« Last Edit: January 21, 2016, 03:23:59 pm by Nathan S »
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Offline brent j

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Re: My forks are not happy
« Reply #34 on: January 21, 2016, 04:23:40 pm »
When I fitted emulators to my TM125 forks I removed the cap on the damper rod and the floating piston. I made new damper rod tops to suit the emulators directly and fixed these to the damper rods.
The new damper rod tops had an “O” ring to seal against the inner fork tube and stop metal to metal contact.

When I striped the forks I found wear marks on one side of the damper rod top which indicates the damper rods are not sitting central.
I machined the bottom of the damper rods so they were square and made sure the damper rods sat in the centre of the fork tube. Now there are no more wear marks and no dirty oil.

I believe most of your problem is the damper rods not sitting central and the original floating piston is allowing this. The offset damper rod is allowing the emulator or the mounting bush to rub on the inner fork tube.
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Offline fred99999au

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Re: My forks are not happy
« Reply #35 on: January 21, 2016, 06:40:25 pm »
Quote
no mate they rock around anything but snug!

On some emulators I have seen small rings which allow a snug fit into the top of the damper rod.

As Nathan said, dont go back to the bloke who did this.

Offline Momus

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Re: My forks are not happy
« Reply #36 on: January 21, 2016, 06:44:51 pm »
As stated that emulator fit job is a good stufff up in several respects..but easy enough to fix

Re the chrome damage which is probably unrelated, how straight or not are those stanchions?
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Offline Jumbo J

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Re: My forks are not happy
« Reply #37 on: January 21, 2016, 07:14:17 pm »
As stated that emulator fit job is a good stufff up in several respects..but easy enough to fix

Re the chrome damage which is probably unrelated, how straight or not are those stanchions?
I also paid for the stanchions to be straightened by the same guy.

Offline Nathan S

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Re: My forks are not happy
« Reply #38 on: January 21, 2016, 08:28:45 pm »
As stated that emulator fit job is a good stufff up in several respects..but easy enough to fix

Re the chrome damage which is probably unrelated, how straight or not are those stanchions?
I also paid for the stanchions to be straightened by the same guy.

Well, that's something to worry about...
Put a straight edge on the tubes, and then again after rotating them 90*. Report back.

I must admit that Momus' point was embarrassingly obvious after he'd made it.
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Offline fred99999au

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Re: My forks are not happy
« Reply #39 on: January 21, 2016, 08:31:31 pm »
Please tell me that this bloke is not a member here. or anywhere?

Offline Momus

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Re: My forks are not happy
« Reply #40 on: January 21, 2016, 09:30:26 pm »
Chrome hardness? If you have been teamed by a pro the stations may have been decoratively plated; so the chrome is very thin.
« Last Edit: January 21, 2016, 09:57:25 pm by Momus »
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Offline fred99999au

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Re: My forks are not happy
« Reply #41 on: January 21, 2016, 11:01:48 pm »
I think in earlier post that they were re-chromed properly. Makes me still think that the chrome is not damaged but picking up alloy for another reason.  Like someone else mentioned , are the stanchions straight?

Offline yamaico

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Re: My forks are not happy
« Reply #42 on: January 22, 2016, 12:45:35 am »
If the tubes have been rechromed they would have to be straight as they are ground between centres as part of the process.

Offline evo550

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Re: My forks are not happy
« Reply #43 on: January 22, 2016, 12:53:11 am »
Most of the old forks didn't have bushes. But I otherwise agree.

Jumbo, In case it isn't perfectly clear by now: don't go back to whoever fitted the emulators.
So what did they use instead of bushes ? I would have thought they needed some type of bushing.

Offline Nathan S

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Re: My forks are not happy
« Reply #44 on: January 22, 2016, 10:01:50 am »
If the tubes have been rechromed they would have to be straight as they are ground between centres as part of the process.

Bent axle or triple clamp?
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