Front Fork Troubles

[BUZZIN]

Progressive springs installed by previous owner.  

5 1/8th between triple clamp and fork seals. Didn't do the centerstand sag trick noted above, but I could tonight if need be. Let me know.

[/size]

Mike, thanks for taking the measurement, and also for the personal e-mail message.  I appreciate it.

[Venom]

"Toad in the Hole"  If i remember mt childhood days right is a british sausage (kinda like our hot dog but better) stuck in the middle of yourshire pudding (kinda like bread not like our type of pudding)

for more info check out this link

http://www.uktvfood.co.uk/index.cfm/UKTVFoodpreview/recipes.newrecipe/ID/517456.shtml

[BUZZIN]

Well I finally got new Progressive Springs in the bike, and it does ride a whole lot better without bottoming out.  I believe the previous bottoming out problem is due to some extent to the junk stock springs, but mostly to the oil level.  The Clymers shop manual calls for a volume of 382 ml (?), and also a measurement from the top of 3.9 inches.  Since I didn't take the fork legs out of the triple clamps, I can only estimate a measurement of 11 1/2 inches from the top.  Based on what was left in one of the bottles, I would say the mechanic put in approx. 13 oz. in each fork leg.  Why the difference?  Which one is correct?

The instructions with the Progressive Springs states not to exceed 5 1/2 inches from the top.  I added some, and would guess that I'm at about 9 1/2 inches now.  I'm using 15W fork oil.  To me it seems like it could still be somewhat firmer.  I was thinking of adding the balance of the open bottle to each leg, but not exceed the 5 1/2 rule.  Should I go higher?

[Kerry]

These measurements are usually taken with the spring removed and the fork fully compressed, which could make a BIG difference.  If you try to use the same measurements on an extended fork you might end up popping a seal or something.

[BUZZIN]

These measurements are usually taken with the spring removed and the fork fully compressed, which could make a BIG difference.  If you try to use the same measurements on an extended fork you might end up popping a seal or something.

[/size]

Thanks, I did have the springs out and propped up the front end to compress the tubes, and still had an initial measurement of about 11 1/2 inches from the top.  Now I'm at approx. 9 1/2 inches, but think that the ride could be a bit more firm.  Does anyone with experience think that I should add more oil?

[Kerry]

First, I want to make sure that I understand how you're compressing the forks.  They're still in the triple clamps ... I guess that's OK.

Have you removed the front wheel so you can compress the forks one at a time, or are you doing it some other way?

I have helped two different people install Progressive springs the "non-lazy way" by removing them from the bike, etc.  The first guy (richard) is a pretty hefty kid, so we filled his spring-less, fully compressed, vertically oriented forks up to the 99mm level (same as for the stock springs; the 3.9" value you got from the Clymer manual).

For the other bike we filled to the Progressive-recommended level ... 139 or 140mm if I recall correctly.  (Which translates to 5.5 inches.)

The only thing I can't remember for sure is how much oil we needed for the job.  But I don't think we used more than 1 bottle for either bike.

So yeah, something is fishy.  Maybe your mechanic swigged a few ounces by mistake?  :dunno:   Either that or there's a fundamental problem with the on-the-bike method of compressing the forks....

[BUZZIN]

First, I want to make sure that I understand how you're compressing the forks.  They're still in the triple clamps ... I guess that's OK.

Have you removed the front wheel so you can compress the forks one at a time, or are you doing it some other way?

I have helped two different people install Progressive springs the "non-lazy way" by removing them from the bike, etc.  The first guy (richard) is a pretty hefty kid, so we filled his spring-less, fully compressed, vertically oriented forks up to the 99mm level (same as for the stock springs; the 3.9" value you got from the Clymer manual).

For the other bike we filled to the Progressive-recommended level ... 139 or 140mm if I recall correctly.  (Which translates to 5.5 inches.)

The only thing I can't remember for sure is how much oil we needed for the job.  But I don't think we used more than 1 bottle for either bike.

So yeah, something is fishy.  Maybe your mechanic swigged a few ounces by mistake?  :dunno:   Either that or there's a fundamental problem with the on-the-bike method of compressing the forks....

[/size]

I did take the front wheel off, as my intention was to compress and measure the oil without spring one leg at a time.  However, the the fork brace screw heads were starting to strip out, so I decided to compressed both legs together.  I propped them up as high as they would go, unless it requires the compression of the rebound spring.  If thats the case, then I have a measurement problem.  Otherwise the only difference between vertical and lazy is that the oil level is not perpendicular to the sides of the tubes due to the fork angle.  This only inhibits my ability to take a very accurate measurement, but it does get me in the ballpark.

Maybe the mechanic did take a swig of the fork oil.  He is a little weird.  This is probably why I haven't heard from him looking for payment for the work that he did.

[Kerry]

Nope, compressing the rebound spring is NOT part of the procedure.

Are you measuring with something like a stiff wire?  Theoretically you could take measurements along the highest and lowest slopes of the tube and average them, but it may not work very well in practice.

Anyway, if richard like his Progressive-based ride with the oil level at 99mm, I'm sure you can stand to add some more.  You're close to twice, aren't you?

Just empty the bottle and call it good.  

[BUZZIN]

Well, I just got done pulling the caps and springs again.  Then jacked up the front end to compress the tubes and sliders.  Took an initial measurement of about 9 1/2 inches from the top.  I then found that I still had almost 7 1/2 oz. left from the second 16 oz. bottle of fork oil.  This really tells me that the reason for bottoming out was due to low oil level.  I raised the level to about 5 1/2, which is the maximum recommended by Progressive.  And I still have 2 1/2 oz. left over.  When you get this high in the fork tube, 1 oz. appears to raise the level by about 1.6 inches.  I used the engine dip stick to measure.  Just carefully point it down the center of the tube until the bottom side of the cap touches the top of the tube.  Then measure down to where it's wet on the stick.

I put zip ties on each fork leg touching the top of the dust seal, and then went out for a ride looking for some bumps.  I never bottomed it out, but I wouldn't say that the ride is stiff or hard at all.  Actually I was looking for a stiffer ride.  It's still too soft.  The zip ties say that I compressed the forks 3 1/8 inches, so I must have come close to bottoming out.

Does anyone have any other ideas on how to make the ride more firm???

[Gisser]

More firm?  Or, more resistant to bottoming?  
Remember, Progressive Springs are progressively wound
-or at least dual rate -to give a compliant ride over minor bumps and firm up after an inch or so of travel.  
IIRC, you mentioned using 15-weight fork oil -which I find to be very firm.  
If you add a bit more oil the fork will be more resistant to bottoming and won't affect the stroke much otherwise
due to the math involved in compressing air.  
There's always heavier oil and if that doesn't provide a satisfactory result
the next step you could cut coils to increase the spring rate
and you wouldn't want to do that until after you've at least set your sag
and have thoroughly tested the setup.  
Plenty of options, just on step at a time.

[BUZZIN]

More firm?  Or, more resistant to bottoming?  
Remember, Progressive Springs are progressively wound
-or at least dual rate -to give a compliant ride over minor bumps and firm up after an inch or so of travel.  
IIRC, you mentioned using 15-weight fork oil -which I find to be very firm.  
If you add a bit more oil the fork will be more resistant to bottoming and won't affect the stroke much otherwise
due to the math involved in compressing air.  
There's always heavier oil and if that doesn't provide a satisfactory result
the next step you could cut coils to increase the spring rate
and you wouldn't want to do that until after you've at least set your sag
and have thoroughly tested the setup.  
Plenty of options, just on step at a time.

[/size]

Gisser, is that what it is, the air gap is more compressable than the oil?  So if I raise the oil level (less air) the ride should become progressively more firm.  I calculate that if I empty the balance of my fork oil evenly into each leg (16 oz. in each), I should be at approximately 3 1/2 inches from the top.  This is less than the stock recommendation with wimpy springs and spacers, and a lot less than Progressive recommends.  Is there a chance that the seals will blow out?  Would anyone recommend going this high?

[Gisser]

Gisser, is that what it is, the air gap is more compressable than the oil?  So if I raise the oil level (less air) the ride should become progressively more firm.  I calculate that if I empty the balance of my fork oil evenly into each leg (16 oz. in each), I should be at approximately 3 1/2 inches from the top.  This is less than the stock recommendation with wimpy springs and spacers, and a lot less than Progressive recommends.  Is there a chance that the seals will blow out?  Would anyone recommend going this high?

____
No harm in experimenting.  Just suck out the excess if it doesn't suit you.  Seals won't blow.  I used to run 10 lbs. of air pressure in each leg of my older GS with no problem.