1990 FLHTCU air suspension

[Snag]

 
   Well , I think I finally figured out why my front air suspension keeps losing air and oil . The first four or five years it was just fine , then it began losing air , then oil . Replaced the seals , and it held for about 2 weeks . Tore it down again , realized I'd installed the seals upside down ... so I flipped them over and put it back together . That held for a few days , then back to the leaking . OK , there's gotta be something else going on here , so I got new bushings and installed them , along with the same "new" seals . This time it took a little longer , but once again it started leaking .
   Went riding with friends last weekend and they pointed out how bald my tires were ... so I ordered some new ones . Since I have the wheels off anyway I decided to try one more time to figure out why the forks leak . Got 'em torn down and noticed there were some very very fine scratches in the seal area on one leg . So I chucked it up in the lathe to spin it and polish it with some 1000 grit . And holy "Potty mouth" , this thing is bent !!
  Turns out that both upper tubes are bent , one has TIR of .140" , the other has .075 runout  - and I've never hit anything with this bike . My new tubes will be here in a few days ... I have new seals , o-rings , copper washers , and will pick up a new hose and clamps before I reassemble it . The new bushings show no wear so I'll use them again . I need a recommendation , do I need to use any kind of sealant on those copper washers or do I install them dry ? I know they're installed dry for brake fluid applications , but air might be a different matter , I just ain't sure . I do plan on setting the new seals with a film of RTV to make sure they don't leak around the OD .

  Snag

[DynaPat]

YIKES! That's a little scary. I'd never even think to check them for runout or a bend. I'll make a note in the appropriate section of the manual to do that when the time comes.

That can't be a good thing.

[Snag]

YIKES! That's a little scary. I'd never even think to check them for runout or a bend. I'll make a note in the appropriate section of the manual to do that when the time comes.

That can't be a good thing.

I never thought to check 'em either , just a chance happening that I stuck that tube on the lathe to make polishing it easier . I don't think you need anything other than a flat surface to check , like a piece of window glass or a mirror . Any bends will show up right away when you roll it across a flat surface . I'd have put it back together , and it'd still be leaking . Anyway , there's an outfit called LeatherUp.com that had the best price . Got a pair of stock length Biker's Choice tubes coming from LA Cal. for 125 bucks with free shipping , should be here midweek . My wife was havin' a great time tweakin' me about being bikeless for the long weekend . I shut her up though , said I'd ride her instead ...

  Snag
  DOM

[FSG]

Put the copper washers on dry.

How are you normally doing the front wheel / axle / right leg alignment ?

[Snag]

Put the copper washers on dry.

How are you normally doing the front wheel / axle / right leg alignment ?

Dry it is on the washers . I'm not sure I follow you on the alignment question . I usually slide the axle in , tighten the nut , tighten the clamp then torque the axle nut . Lets the legs align themselves so the axle nut doesn't pull the legs together .

[FSG]

I usually slide the axle in , tighten the nut , tighten the clamp then torque the axle nut . Lets the legs align themselves so the axle nut doesn't pull the legs together .

No that is backwards and missing a step.   

Torque the axle nut first.

Put a 7/16" drill bit through the hole in the right side end of the axle and pull the right leg out so it's against the drill bit.

Now tighten the right leg clamp.

Here's a pic of my 1990 FLHTCU before I put a chair on it.  It's now been retired to a younger brother who is raising his kids in the chair.

[Snag]

I usually slide the axle in , tighten the nut , tighten the clamp then torque the axle nut . Lets the legs align themselves so the axle nut doesn't pull the legs together .

No that is backwards and missing a step.   

Torque the axle nut first.

Put a 7/16" drill bit through the hole in the right side end of the axle and pull the right leg out so it's against the drill bit.

Now tighten the right leg clamp.

  Doesn't pulling the leg out to the drill bit put outward loading on the seals and bushings ? If the holes in the triple trees are straight and parallel that should not be necessary . I can't do that on mine unless I remove an added spacer . I added one to move the whole axle to the left enough to put a SS axle cap on the round end . It didn't stick out enough to use my custom made caps .
  I looked the procedure up in my FM , nothing said about doing it that way ... but it does say that the valve stem should go on the left . Mine is on the right , has been since I bought the bike . Looking at the depth of the bearing cups and the length of the spacer built in to the speedo drive , if I flip that rim over the speedo drive unit will bottom out on the seal before the spacer contacts the bearing . That just can't be right .

  Snag , puzzled this morning and wondering what else previous owners have screwed up . 

[Snag]

  Well , looks like I'll be flippin' the rim  . I checked the depth on the speedo drive , and while it's close , it doesn't bottom out on the seal as I was afraid it would . This might explain some other issues I've had , like calipers not-quite-right and a tendency to drift off to the right .
  Of course this also means I'll have to completely align the suspension ... might as well go ahead and drain the tank today . It's just so much easier to access the top heim link with it out of the way .
  Sure seems like one thing leads to another , this started out just to be a normal tire change . Oh well , it'll be that much less I gotta worry about down the road .

[FSG]

Doesn't pulling the leg out to the drill bit put outward loading on the seals and bushings ?

No. That hole is in the axle for a reason and it's not just to stop the axle from turning while you tork the axle nut.

If the holes in the triple trees are straight and parallel that should not be necessary .

While that is true I've seen front fenders pull the lower legs closer together.

I can't do that on mine unless I remove an added spacer . I added one to move the whole axle to the left enough to put a SS axle cap on the round end . It didn't stick out enough to use my custom made caps .

  The round end is on the right side, the axle nut is on the left. 

Rather than add any spacer just drill/tap the round end and screw on the extra length to provide something for your SS Axle Cap.

Valve stem should be to the right.  The manuals have errors.

This might explain some other issues I've had , like calipers not-quite-right and

That could easily be down to a wheel bearing change and the incorrect side bearing cup having being seated first. 

[hdbikedoc]

 :potstir:Don't remember pulling right leg out with drill bit till hd switched to 4 piston calipers and sealed wheel bearings ,my stock 1990 axle would have to be loaded big time for this to work ?

[Snag]

That could easily be down to a wheel bearing change and the incorrect side bearing cup having being seated first.

  If the bearings are seated properly to the shoulder in the wheel , it won't matter which was seated first . I'm going to give a lot of thought to flipping that wheel over , manual sez valve stem to the left , someone else here says to the right - and my rear is on the right . I wonder if that changed when they moved the speedo drive to the left . Anyway, I'll be removing all but the stock spacers , see where stuff lines up . Actually , I'll test fit it both ways , if it lines up better with the stem to the left , I'll be flipping the tire over . Why couldn't the damn thing just be centered ?

  Snag , now even more confused . 

[Old Crow]

Terry, my bikes are as follows:

'87--valve stem left, axle nut left, right side of fork flush with the inside of the hole FSG talks about, speedo drive on the left.

'82--valve stem left, axle nut left, right side flush, speedo drive on the right.

just a couple more data points.