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Old 01-10-2012, 07:35 PM   #1
240sx4u OP
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Aligning airhead forks.. having some problems /5

Man, this is driving me nuts. I am trying to get these forks aligned. I had finally gotten them "twisted" so I had no glass clicking. I left them pulled twisted for 24+ hours per adjustment. First couple times it wasn't working so I just went further.

I finally got no clicking, or so close that I couldn't get a consistent click with the glass.

Now, I checked the fork "paralell-ness" and was at .001 checking at the top (as high as I could get the dial indicator and mag v block) and at the bottom of the tubes.

Great right? My thoughts too. I install the fork nuts and tighten them to basically finger tight with a wrench and instantly I am out .009 dammit.

The top plate is new. I have no freaking idea what I am doing wrong. Is there anything I can do to isolate the problem part???

Thanks guys, this is so freaking frustrating. I parked this thing over a year go when I started this and got sick of screwing with it.
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Old 01-10-2012, 07:53 PM   #2
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Your lower triple clamp is probably bent as well make sure your fork tube installed height is correct.
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Old 01-10-2012, 07:54 PM   #3
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Well, it makes sense the lower could be bent. What is the correct amount of tube that is supposed to protrude through the top? Maybe that's the whole problem.
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Old 01-10-2012, 08:12 PM   #4
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I don't have the Haynes book near by, but its listed in the suspension specification area.
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Old 01-10-2012, 08:13 PM   #5
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Ok, i have one. thanks!
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Old 01-10-2012, 08:30 PM   #6
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Nothing could be bent. That's the thing about it that can drive you nuts. Tightening down every nut on the whole setup changes everything. A magnetic V block is the smart way to go. Hand held is going to change everything all the time. Just pressing a hand held dial indicator against the bottom of the tube and there is a couple of thou. Tighten down the bottom or top clamp bolts will get the tubes pulled all over and then there is the fender/fork brace nuts. Usually just tightening it down 2ftlb differently makes all the difference in the world. The "gold standard" article on Duane's site barely mentions this critical fact. They have got you reaching for block and tackle when chances are you just need to retighten everything a million times till one time it is straight. That is still way easier than their method. That is all it takes most of the time unless something is bent. The tubes are easy enough to check. The trees not so easy. I have seen quite a few aftermarket top trees that were way off. It's hit and miss with the whole setup. It can be very frustrating! And other times they go together no problem.
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Old 01-10-2012, 08:32 PM   #7
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That's basically what happened. Everything looked great, but then I farted and it was all screwed up again!


So basically what you are saying is "put it together, if its wrong, put it together again"
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Old 01-10-2012, 09:28 PM   #8
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For instance, I have had to tighten, then loosen and then retighten fender mount nuts 100 times before one of the times I did it and it all stayed straight. This way and that way so many different times I can't remember what way actually worked. Sometimes it's one nut, sometimes it's all of them. I personally think you are nuts if you think you have come up with some rhyme or reason to it because there isn't any.
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Old 01-10-2012, 10:28 PM   #9
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I restored a /5 25 years ago and toured around Europe once as a solo and once with a sidecar...we did about 30 000 kms.I never even knew about Duanes front end setting up or that the short wheelbase /5 handled poorly...or that you could not attach a sidecar to a/5 without frame mods...and we thought Haynes manuals were rubbish.( they have improved)...then the internet came along.
I think the bad handling was due to the US style bars as no one else seemed to have issues and sidecars can be fitted to /5's without issue ...facts on the internet need researching.

One observation I have found with forks is some sliders can develop a very slight bend over time, rotating these can help.
In the olden days I used to fit new seals and fork oil as per the Haynes manual then before tightening up the bolts and top nuts put the brake on and move the forks up and down.....no longer an approved method I gather.
Saying that I have just fitted Racetech springs, emulators, tubular fork brace and machined up spacers and damper rods to some R90 forks and I will be setting them up next week...I might try the dial guage method and see.
Should be interesting to see how the hotly debated forks and ATE brakes work out on the track.
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Old 01-11-2012, 02:14 AM   #10
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Surely if these forks are so sensitive that getting the tightening sequence wrong can pull them out of alignment, they will twist out of alignment in the day to use to the bike?

Charles
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Old 01-11-2012, 04:59 AM   #11
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Quote:
Originally Posted by chasbmw View Post
Surely if these forks are so sensitive that getting the tightening sequence wrong can pull them out of alignment, they will twist out of alignment in the day to use to the bike?

Charles
That is what I am thinking...

Me? I am using the old slide it up and down with everything loose and then carefully snug everything.

I might throw a piece of glass on there just for fun. TOo bad my granite surface plate is simply too heavy...I could really drive myself crazy with that.
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Old 01-11-2012, 06:22 AM   #12
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It's possible to set-up the forks to within .004" flat & parallel when complete.

It's not absolutely necessary, but the action works best that way.

Results aren't pass/fail but a matter of degree: .004 alignment works best, .010 not bad, .030 ok maybe... just estimating and I don't know when the variation becomes "too far out & excessively bad".
But near-perfect alignment is possible and not too difficult to achieve with some practice.

240sx4u: The stock top plate is barely adequate.
Get an aftermarket top brace if it's within your means.
This will make it easier to get the forks true and keep them there.
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Old 01-11-2012, 06:49 AM   #13
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Interesting. Sounds like I need to assemble the bike as-is and see if I have stiction problems with the front end.

I don't have the means to purchase an aftermarket top brace, which is why I went ahead and got a new oem one on ebay (cheaply I may add, thanks to the guys here). I just need to get this stupid bike back together so I can at least move it around the garage. It's had forks removed for about a year at this point.

Interestingly, it seems like my fork tubes are pretty much parallel until I tighten down the aluminum lower clamps. I wonder if torquing the fork tubes to the top plate first may be a good way to go.

Maybe my lower clamp is bent all to hell too. Who knows.

I normally really enjoy working on things, but these forks just suck.
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Old 01-11-2012, 08:01 AM   #14
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The lower triple can be off by a little and cause these problems. I tried using Duane's trick of forcing the forks apart and leaving them that way overnight. But once the pressure was off, the forks returned to the previous position - nothing changed.

After several attempts with no change, I realized another solution was needed.

What worked was to clamp the tubes, then align them - using a spreader or whatever works - then heat the lower triple to relax its 'set'. Once cooled, the spreader was removed and the forks stayed aligned.
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Old 01-11-2012, 08:12 AM   #15
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I judiciously beat the triple with a dead blow hammer in an attempt to relieve stresses without luck. I guess it's time to try the heat gun.

Thanks for the suggestion.
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