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Old 06-11-2012, 11:33 AM   #46
Renner
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Originally Posted by 240sx4u View Post
I went nuts trying to get the twist out and pulled it .25" past where I wanted it with no changes.
In my experience, .25" isn't much. The lower yoke is pretty resilient.
I'd take it to at least 1" deflection in the desired direction and then measure, repeat as necessary.

This of course without the top plate.
Once the top plate is added it may likely push all out of nominal again.
I've played with shimming the top brace to get good results, haven't tried that with a top plate yet though.
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Old 06-11-2012, 11:35 AM   #47
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Holy cow, maybe I was just being too gentile with it. Thanks for the tip!
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Old 06-11-2012, 07:28 PM   #48
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Okay, this time I started by trying to get things aligned so the tubes are parallel at the top and bottom. I had great luck with heat and a big pipe clamp. I was able to get them perfectly straight. Awesome! Brute force + heat.

Now, it's time to deal with my "rocking glass". I put a piece of plywood between the fork tubes with a hole cut in one end and cranked it up with the ratchet strap. I need to move it .003 I would guess. I went about .25 on this one and used heat. Letting it cool overnight and hoping for results. The ply may not be strong enough in this case, I may need to use something more stable after seeing just how far I had to squeeze the top and bottom. I will find out tomorrow.

Seems I am making progress, I'm pretty excited! Let's pray the top plate goes on OK and doesn't pull the whole shenanegans out of whack. Time will tell. Ill update tomorrow maybe, if not wed.

Thanks guys!

Evan
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Old 06-12-2012, 08:00 PM   #49
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This is so frustrating. Through lots of tweaking I got everything pretty darn straight and square and I knocked it all back out of whack or something putting the headlight bucket back on. Things were a little further out by the time I was ready to put the top plate on. After putting the top plate on and torquing (using a tq bar) everything is pretty much back to worthless. I went ahead and reassembled praying it would work but it sticks like hell. Granted I haven't put fork oil in yet but seems like this is a lost cause. This fork design is terrible.

I understand the toaster tan brace might help, but if the bottom holes aren't in the right spot due to abuse it seems that there is absolutely no hope of getting everything aligned. It seems to me that a billet lower and billet upper would be the only way to ensure things were actually lined up right.

Sorry for the rant, and thanks for the help.
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Old 06-12-2012, 10:05 PM   #50
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Originally Posted by 240sx4u View Post
Guess what? I haven't fixed this yet.

I am back at it, I need this bike mobile and out of my way. I found yesterday when I tighten the top nuts into the plate everything is pretty straight. Everything goes to shit when I tighten the lower triple.
SNIP..

At this point I may roll the dice and get another used lower triple.
Thanks.

Evan
Once you've eliminated all of the other possibilities, the solution (Sometimes!) becomes obvious and I'd say that you need to replace that lower triple clamp.

When I was building my bike I had a similar problem that I discovered after I had smoothed and polished the lower triple and assembled the front end. The only solution was to start over with a known good part.

You could try straightening the bent part after heating it with a torch but thats a horse of a different color.

PS: If everything else is dead nuts on, a billet top triple should drop right into place. It did on my RS with the TT clamp and it did with the Hot Rod and the San Jose top clamp as well but I replaced the tubes on both bikes with new ones from "The Frame Man".
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Old 06-13-2012, 05:31 AM   #51
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Reflecting back on this, now that I have cooled off..

Maybe I should have left the parts clamped up longer to make sure they actually took the set. I can't really afford the toastertan brace but if it's the only solution I will have to just wait and order one.

Evan
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Old 06-13-2012, 06:35 AM   #52
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In my experience, the lower yoke can be persuaded to hold and keep the tubes parallel and coplanar.
Installing a top plate or clamp will nearly always introduce deviation, as the dimensions center-to-center of the holes/bores for the fork tubes are not likely to be within .001” of each other when comparing the two parts.
1x difference between the two will show as (roughly) 4x deviation in the length below the yoke.

I have several spare top plates on a shelf measured accurately to four decimal places.
If you can get an accurate measurement of your yoke’s center-to-center distance (for instance measured off the tubes and adjacent to the yoke) I may be able to provide a top plate better matched than the one you have.

A top CC/TT top clamp would really be much better.
And if there’s some slight difference in that center-to-center dimension between a clamp and your yoke, it can be shimmed-out to suit well & easily.
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Old 06-13-2012, 07:05 AM   #53
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How would you go about shimming an aftermarket brace? I really appreciate the offer for the plate, but I think the reality is I need to buck up and order the toaster tan brace or san jose' unit and just be done messing with it. That way if it has to come apart again in the future, I will have a fighting chance of getting it right.

Now, which brace to choose... the CC or TT? The CC is obviously way cheaper at 119 vs. 157 but cheaper isn't always better.
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Old 06-13-2012, 07:48 AM   #54
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You need a straight lower. If your upper was "U" shaped, it didn't get that way on its own.
That same impact also affected the lower tree.
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Old 06-13-2012, 07:50 AM   #55
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Yeah, which is why I was talking about replacing the lower. Reading makes me think I can straighten these back out but I am skeptical the holes will remain in the right place after bending and tweaking the hell out of the lower.

Evan
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Old 06-13-2012, 08:53 AM   #56
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Originally Posted by 240sx4u View Post
How would you go about shimming an aftermarket brace?
Shim stock as required, in the appropriate quadrant of the bore.
Because the bore is a pinch clamp, it will effectively change the location of the center.

I think it is a lot to expect that BMW & CC & TT all work to the same manufacturing tolerances.
Good fork overhauling mitigates the variation during assembly.
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Old 06-13-2012, 08:54 AM   #57
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Originally Posted by 240sx4u View Post
Yeah, which is why I was talking about replacing the lower. Reading makes me think I can straighten these back out but I am skeptical the holes will remain in the right place after bending and tweaking the hell out of the lower.

Evan
Set up bind and make it stupid tight. Put the lever as high/near the lower triple as you can leave room for the torch work. Heat the lower with propane for 10 minutes. Relax, the drip point of the spec grease in the head bearing is above the temps reachable in such a massive heat sink.

Cinch the binding more if you can. Leave it overnight. Keep good notes on actual measures before and after each session. Mine were 3mm out of wack and I got mine to 0.3mm and delovely smooth.

Took 3 session without heat to see no change. Then some 5 sessions with heat to dial them in. About 2 weeks.
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Old 06-13-2012, 09:21 AM   #58
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Straighten the lower t/c in a press. I've done it a few times, good as new.
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Old 06-13-2012, 09:57 AM   #59
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I see what you are getting at now, and it makes a whole lot more sense than screwing around with that top plate that I am currently using. I am going to give another shot at getting the tubes lined up tonight. I suspect I didn't leave them in the new position long enough to really take the set well.
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Old 06-13-2012, 06:01 PM   #60
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I ordered the TT triple, hopefully it helps. Ill update after it arrives and I give it another try.
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