Bottoming out.

CapnDenny1 · Jul 5, 2010

My wife and I went for a short ride on the '82 1100 Interstate this afternoon. Before I went I checked the air in the tires. My front was at 10 psi and the rear was at 25 psi. I went ahead and put the recomended 30 psi in the front and the 40 psi in the rear. It was a lot easier to push around the garage after that! I didn't check to shock air. I figured it would be a stiffer ride than last time with the higher pressures in the tires.

Anyway on our ride it seemed like we were bottoming out on the hard bumps. Not just on the big ones, and sometimes it would make loud noise and I could feel it through the frame of the bike. I think it was bottoming out. When I got back I check the air in the rear shocks and it was about 35 psi. I filled it to 50 last fall, but hadn't checked it since. Would only having 35 psi in the rear shocks be low enough to cause it to bottom out on a moderate bump at speed?

Is it possible that my rear swingarm bushing is bad, or something else? Wouldn't that make noise on the little bumps too though, not just the big ones? I guess I can just put the 55 psi in there and see if that fixes it?

Thanks,

Dennis

AApple · Jul 5, 2010

Before I rebuilt the rear shocks and installed the Progressive springs, mine did the same thing, with just me on it. It was hitting(bottoming) hard enough it was scarin the crap outta me. Even with the max air in the rear shocks it would bottom. I think part of my issue was one shock was low on fluid, since it was seeping from the seal. With the new springs, seals, and fluid, I can now run 10psi safely, without fear of bottoming. With Mama, I do have to add air to the shocks, but not up to the max. :mrgreen:

CapnDenny1 · Jul 5, 2010

I thought the progressive suspension replaced the air and springs. Is it cheaper to rebuild the shock and just buy a new progressive spring? The 416 series is $300 on ebay. How much do just a set of springs cost?

But it does sound like my springs are just bad, and maybe the shocks too?

Thanks,

Dennis

AApple · Jul 6, 2010

The springs go inside of the shocks. They are rebuildable, as far as replacing the springs, and the seals. I got my springs and seals for less than $100 from cheapcycleparts, but they no longer carry the springs. I'm sure the springs would be available from Progressive(and possible other parts vendors), tho.
Dan has posted my write-up on replacing the springs on the Manuals: Service, Owners, Misc. page. Scroll down to the "Progressive Suspension Installation pdf's:". :mrgreen:

I used the Progressive springs for the 1100, and have been really pleased. The bike rides comfy, with no harshness, or bottoming. The 1200 springs would fit, but we threw the idea around here some, and came to the consensus that they might be a bit too stiff for an 1100, unless the bike carried some weight all the time. :blush:

oldhack62 · Jul 6, 2010

Also note that if you put too much air into the front shocks, the resultant sensation will emulate "bottoming out". I learned this the hard way, when my pressure gauge quit functioning and I kept adding air trying to get a reading. When I tried a different gauge later, I discovered I had almost 60 psi in the front fork! I'm lucky I didn't blow out a seal!
Anyway, reducing the psi to 30 eliminated the "clunk", and provides a very smooth ride.

mcgovern61 · Jul 6, 2010

AApple":2hibci29 said:
I think part of my issue was one shock was low on fluid, since it was seeping from the seal.

Boy do I feel like a dummy!

My rear shocks tend to bottom too, even with 56 psi in them. I just remembered that when I took them off the bike in 2007 to rebuild the bike, I didn't know they had fluid in them and it leaked out on my garage floor. I NEVER PUT ANY OIL BACK IN!!! Perhaps if there was a little oil in them they might not be so bad! (Although they do hold their air for months at a time. I put in 56 psi in April and it is still 54 psi today!) :thanks:

CapnDenny1 · Jul 6, 2010

I checked the pressure and it was at the same point as last night when I filled it. I put it on the center stand and the pressure didn't change. That seems a bit odd.

When you put air in the rear shock, shouldn't the rear end of the bike rise up some? Or does it just increase the stiffness of the spring? But that's the sam ething unless it was all the way up even when on the tires.

I guess I don't know how this system works, but isn't adding air the same thing as turning the adjusters on a non air spring over shock suspension. You are just pre-loadign the springs more when you add air right? Shouldn't that raise the back end of the bike? That's what happened when I put air in the front shocks. The front of the bike went up an inch or two.

Is it possible that the seal is just frozen where it sits, and when I put air in there it just pressurizes the lines and the small space at the top of the shock, but nothing moves.

I'd love to put the progressive springs in there, but the money just isn't there. But maybe I could replace the seals in the stock shocks if that might help.

Can anybody exlain how this system works?

Dennis

joedrum · Jul 7, 2010

dennis its the springs honda used air to compensate for weak springs in a idea this would ride better and it proably did at first but these bikes are 30 yrs. old now and the weak springs of new are now realy weak springs ...just wore out grabbage and air can not compensate for such wore out springs even if the is in perfect working order....new porgressives will take complete control of the rear end make it perfect ....the front forks are the same way progressives springs make them right to ......until you do this its not going to get any better.....

mcgovern61 · Jul 7, 2010

CapnDenny1":2l3r7cii said:
When you put air in the rear shock, shouldn't the rear end of the bike rise up some? Dennis

Ahhh, an interesting point. Let the air our and see if the rear drops. It should drop a minimum of 1 1/2" to 2". If no drop, then air is not making it into the shocks themselves. When I put air in mine (mind you I do not have oil in mine :swoon

the rear rises 2" (which is a pain because I have short legs).

If you find no difference with air in or out making the rear rise or fall, I would assume that the shraeder valve is blocked or frozen. Do you have an onboard compressor or inflate manually?

CapnDenny1 · Jul 7, 2010

It is manually inflated. I think it's making past the valve because it takes a few pumps with a hand pump to get it up to pressure. I'm thinking there is some sort of upper seal which the air pushes down. I think in mine that must be frozen at the top of it's travel. Probably from sitting with no air in them for a few years.

As I said I'd love to get the progressives, but got no $$.

I can't really ride it like this so I guess I can take one of them off and see what's up.

Thanks,

Dennis

AApple · Jul 7, 2010

The air is added compression help for the springs. The main objective is to keep the suspension at a specified height. The outer chrome housing is the air and oil chamber for the shocks. The only seals are on the top, where the air lines go into the shock, and the bottom, where the two parts of the shock assy, seal. If the shock is low on oil, the air will not do much good. Air is compress-able, where oil is not. Adding air to the shocks will raise the ride height, whether there is oil in them or not, but it will not be able by itself to keep the shocks working as shocks...they need the oil. The actual "shock/damper" portions of the rear shocks have 4 holes in the very tops of them, to allow the oil to get inside of the damper. This is what allows them to actually absorb the road, and cushion the ride, same as a normal automotive shock.
Let all of the air out of the rear shocks, and put the bike on the side stand. Then pump some air into them. The rear should rise at least 1-1 1/2", even with no oil in them. It's hard to believe the air lines are stopped up for both sides, unless they have been disconnected for some time...

If you take a look at the "exploded" view of mine I made when I re-did my rear shocks, you can see they are fairly simple in design.

click for link :mrgreen:

These are just a few of the pics...you can see more by d-loading the write-up from the Manuals: Service, Owners, Misc. page.

mcgovern61 · Jul 7, 2010

Great explanation Joel! I still feel like such a dummy! 2 1/2 years of riding like this (bottoming out that is) and never thinking about the spilled out oil!

Dennis, what is the chance that yours are low on oil?

CapnDenny1 · Jul 7, 2010

So that upper piece doesn't seal anything. The plastic piece on the left of the springs in your picture. It's just the pressure of the air pushing down on the oil onto the shock damper? I was thinking there was a seal above the springs, but maybe that is wrong.

So if the oil is just low, that would mean you have a larger volume of air. When you compress that by pushing up on the shock the air wouldn't provide as must resistance as it should. If there was less air and more oil at the same pressure then it would have a much higher rate, as they call it in spring lingo.

So maybe I just don't have enough oil. The oil may have leaked out already.

Am I correct in how the air works? It just adds to what the spring does, but doesn't actually pre-load the spring?

Dennis

raywill · Jul 7, 2010

AApple's Post on the OEM rear shock rebuild using Progressive springs a few weeks ago inspired me to go for it. The rear springs were so tired I could compress them with one hand...and I'm suffering fom old man muscle deterioration.

Got my Springs and Seals from Bike Bandit- Thanks Dan F. for that heads up.
I adapted spring compressors and struggled 3 days but finally got the job done. I would recommend going to Progressive's Web site and ordering the Compressor they recommend, around $36. It would be worth it in time and frustration trying to do it with adapted home tools. That still comes in at $100 or more savings over the 412 or 416 replacement shocks

I've noticed Steering on the freeway over the patched potholes and other surface unevenesses is more sure.

Previous WIngs I've owned I installed Progressive 412 and 416 rear shocks. I think they would give a better ride above this rebuild, but not by much for the large jump in cost.

dan filipi · Jul 7, 2010

Here's a link to the '82 rears at bikebandit https://www.bikebandit.com/progressive-s ... 6&t=1&td=1

I didn't search for the seals but I bet they have them.

raywill · Jul 7, 2010

Bikebandit has the seals-$13.76 for2. The Progressive Springs are Item #91856 and cost $55.76 for What they call Kit D. Here's the link to Kit D- https://www.bikebandit.com/progressive-s ... ings-kit-d

AApple · Jul 7, 2010

CapnDenny1":13oe65ti said:
So that upper piece doesn't seal anything. The plastic piece on the left of the springs in your picture. It's just the pressure of the air pushing down on the oil onto the shock damper? I was thinking there was a seal above the springs, but maybe that is wrong.

So if the oil is just low, that would mean you have a larger volume of air. When you compress that by pushing up on the shock the air wouldn't provide as must resistance as it should. If there was less air and more oil at the same pressure then it would have a much higher rate, as they call it in spring lingo.

So maybe I just don't have enough oil. The oil may have leaked out already.

Am I correct in how the air works? It just adds to what the spring does, but doesn't actually pre-load the spring?

Dennis

The white-ish colored plastic part on the left in the pic is the upper spring seat. It keeps the two springs centered in the housing, and keeps them from coming into contact with each other at the top of the assy. I'm sure it also has a purpose for keeping the noise down.

:rant: :sensored: :rant: :sensored: :rant:

Otay...I GIVE UP.... :sensored: :sensored: :sensored:
I've replied to this post THREE TIMES now...each time I get to the last couple of words, my 'puter does something stoopid, and I loose it all. Just now, however, it went blank, and brought back about 1/2 of the post I wrote THIS MORNING!!!
I quit...

dan filipi · Jul 7, 2010

Dontcha just love computers! :head bang:

AApple · Jul 7, 2010

:sensored: NO!!!!

CapnDenny1 · Jul 7, 2010

I appreciate the effort Joel. I think I am getting the picture. I could rebuild them, but from what I'm seeing the Progressive 416 is probably the best option. $300 isn't that much. I may try just increasing the pressure for now. I am going to do a test to see if when I let all the air out that the bike actually lowers. And if when I add pressure does it actually rise up any. So far I'd say no to both questions. What is suprising is that it does hold air pressure. But if the oil is low then perhaps it doesn't increase enough when compressed. It sounds like an interesting problem. How much force is required to compress the air/oil mixture knowing the relative sizes of the air chamber and the shock tube. Then if the oil is low what are the numbers. Got some cypherin' to do.

Thanks for the help,

Dennis

Bottoming out.

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