Who really knows/understands the 1st Gen CLASS/shock system ??

[KIC]

So, I am looking for information that will help me understand and solve my current problem. I have been dealing with what I thought was a shock issue, but might be the CLASS system. ( no errors on display)

 

Symptoms: My bike's rear has been sagging which actually resulted in my mud flap losing at least 3 to 4 inches of flap. The CLASS appeared to be working although it wouldn't hold air steadily. I took my CLASS apart and cleaned everything including the 3 solenoids.

 

I decided to replace the shock and have torn my bike apart.

 

I was talking to a mechanic friend and he said that a blown shock shouldn't affect the sag but would affect the bounce. He said a sag would be from a broken spring.

 

The spring and linkage on the bike is not broken.

 

So I put in the used rear spring from my 87 and tried the air system. It will not hold air in the Auto setting but seems to hold air in the manual setting. When I turn off the key, you can hear a solenoid release the air. So I played with it and it appears that the manual setting will hold air as long as the key is in the accessory position. If I turn the switch to on and then back to accessory then I can hear ( using a stethoscope) the loss of air in the CLASS area.

 

What am I missing here ?

 

Question: if the shock is good and all the air in the CLASS is leaking out because of key position, would the back drag ? Is my whole problem in the CLASS and not the shock ?

[cimmer]

It sounds like maybe the air release solenoid valve could be leaking air. There is a complete section in the service manual on the CLASS system and how to troubleshoot it in the electrical section. I would start there and see if that helps solve it. If you dont have the manual, there is a link to one in the tech section that you can download.

How close was the rear flap to the ground when you installed it or first got the bike?

Hope this helps.

Rick F.

[KIC]

It sounds like maybe the air release solenoid valve could be leaking air. There is a complete section in the service manual on the CLASS system and how to troubleshoot it in the electrical section. I would start there and see if that helps solve it. If you dont have the manual, there is a link to one in the tech section that you can download.

How close was the rear flap to the ground when you installed it or first got the bike?

Hope this helps.

Rick F.

 

No, the back never dragged even with the wife on it. Then it started to and slowly wore the mud flap down. When it sat on the side stand it looked alright. When VideoArizona ( David) sat on it Saturday before we tore the thing to pieces, as soon as he sat on it it went down to the mud flap. I should have realized that maybe it wasn't the shock, but it was out of my filed of knowledge.

[Marcarl]

I haven't heard of this problem before,, not saying it didn't happen, just that I don't really know what I'm talking about maybe. But!! The Class module does have cold solder problems, which normally would show an error message. Now these messages normally have to do with pressure sensing, so I'm not sure if there is an error for pressure release. Maybe there isn't, but that doesn't mean that there can't be a cold solder problem. Maybe take the module out and do a repair on the joints, just to be sure and to catch any future bugs.

[KIC]

I haven't heard of this problem before,, not saying it didn't happen, just that I don't really know what I'm talking about maybe. But!! The Class module does have cold solder problems, which normally would show an error message. Now these messages normally have to do with pressure sensing, so I'm not sure if there is an error for pressure release. Maybe there isn't, but that doesn't mean that there can't be a cold solder problem. Maybe take the module out and do a repair on the joints, just to be sure and to catch any future bugs.

 

That is now my plan C on my repair. I have to get the drive train and front tire back together tonight so I can access the CLASS board. I hope that might fix my problem, but I wish I hadn't had to tear everything apart to find out. We'll see what happens.

[frankd]

When I bought my 89, the rear suspension kept on loosing pressure. I found a connection in the line to the rear shock had come loose and was leaking. Snugging it back up cured the problem. There is only a small volume of air in each circuit, so a small leak has a big effect on air pressure. As I remember, the fitting was on the right side of the bike about 1/2 way between the shock and the solenoid cluster. If you want to tell if it's the lines or shock bladder you could disconnect the rear shock line from the solenoid, and adapt a schraeder valve to the line to the shock. Put about 60 psi. in the rear shock through the added valve. If it stays pumped up you problem is in the solenoid or Class module. However every time you check the pressure with a gauge, it'll loose pressure, so maybe you want to measure the distance from your mudflap to the ground and see if it's holding pressure that way.

[KIC]

When I bought my 89, the rear suspension kept on loosing pressure. I found a connection in the line to the rear shock had come loose and was leaking. Snugging it back up cured the problem. There is only a small volume of air in each circuit, so a small leak has a big effect on air pressure. As I remember, the fitting was on the right side of the bike about 1/2 way between the shock and the solenoid cluster. If you want to tell if it's the lines or shock bladder you could disconnect the rear shock line from the solenoid, and adapt a schraeder valve to the line to the shock. Put about 60 psi. in the rear shock through the added valve. If it stays pumped up you problem is in the solenoid or Class module. However every time you check the pressure with a gauge, it'll loose pressure, so maybe you want to measure the distance from your mudflap to the ground and see if it's holding pressure that way.

 

Good idea. I have checked all fittings with soapy water. Plugging the rear shock line would isolate where the problem might be. I am grabbing the CLASS of of my 87 today so I can easily swap it out and try it to see if anything changes. I gave my son-in-law the circuit board out of the 87 earlier this year so I am down to soldering the existing. I will figure it out. I just hope I can get it all done before Saturday's Full Throttle ride.

[cimmer]

Just a quick thought to try this.. pump up the system to the max, about 75 psi and then disconnect the wiring harness from the CLASS controler and see if that helps to hold the air in the system. It could be a leaking solenoid or one that is getting a small electrical signal from the class unit. Sounds like you have check about everything else.

Rick F.

[Prairiehammer]

This past summer, my '91 began to handle like crap (two up, loaded for camping with trailer). I discovered that the front forks had no air. I'd air up the suspension with the CLASS and all would be good for awhile (days). But then it would start handling crappy again and I would discover that the forks were at zero air pressure. Fire up the CLASS and air it all up. All OK for a mile or so, then crappy handling (no air in front).

I found that the CLASS controller was releasing the air, presumably because of road vibrations acting on the CLASS connector. Never did see any error codes. Resoldering everything fixed it.

[KIC]

Well. here is the end result. After tearing apart the rear portion of the bike, a job not suited for the faint of heart, I switched out the shock. But something did not seem right, the "old" shock seemed fine. After talking to my mechanic friend, reading the input on here, I decided to check the CLASS system real close. VideoArizona ( David) came back up last night to help me. We re soldered the CLASS board and it was still acting weird by showing it was pumping up and showing up to 82 lbs on manual, but then either released the air which you could hear once in a while, or going to 0 without any sounds of leaking air. David and I swapped the whole CLASS system with the one I pulled out of my 87 and it worked beautiful. Pumped up normal, held pressure, no issues. I checked it this morning and it help all night. I did not receive any errors during the time I thought it was working, and it looked like it was working. I was able to finalize the reassembly of the bike today and took it for a ride. It ran GREAT !

 

Besides the lady running the stop sign by my house and almost taking me out, the ride was enjoyable. The CLASS is working great !!!

[videoarizona]

That was a fun two days, Bill. Learned a lot, digging into your bike. Let's hope we don't have to do mine for a while yet! Grins!

Glad the ride went well.....!

[cimmer]

Glad you figured it out. Your guys work on this will help us all down the road if it occurs to our 1st Gens.

Thanks again.

Rick F.

[Flyinfool]

Did you ever find what the real problem was? Replacing everything is not always a good option if you don't happen to have a complete system laying around.

[KIC]

Did you ever find what the real problem was? Replacing everything is not always a good option if you don't happen to have a complete system laying around.

 

No. BUT...I do plan to try to narrow it down in the future since I would like to have a good backup CLASS system. I need to get the CLASS that we pulled out of my son-in-laws and replaced with one off of my 84 parts bikes. Once I get his 86 system, I can change out parts and try to isolate the problem child. I am thinking it is the air release solenoid.

 

I know we also re soldered the board, but it seemed to still have the problem, so I do not think it was the board. I didn't have a lot of time to play with it when we were working on it since we still had to reassemble the bike from the (unnecessary ) shock switch. When I get the other unit from NC, I will pull off my trunk and wire the old system in and replace parts until it works and then I will post the results here.

 

The weirdest part was what appeared to be false pressure readings. Either that or the solenoid just kept releasing air on its own and the CLASS didn't change the readings.

 

I do have to admit it was nice to finally fix the loose heat shield rattling around the back of the exhaust, easy to change the fuel filter and finding the metal obstruction in my exhaust.

 

The shock was a B!0t@h tho...

 

P.S. I just checked and the pressure is the same for the last 20 hours.

[videoarizona]

Bill,

 

We did have an E2 error after soldering the Class board using your 89 Class. So my first thought would be to follow the diagnostic schematic for the E2 error on your 89 Class mechanicals. Have to think the problem is somewhere in the air intake (if memory serves??) Could be the reed valve on intake.

 

Thinking out loud here....I think we had two problems. One...the computer board wasn't working properly due to solder issues on connector. The class system wasn't pumping up properly...the numbers moved to fast...like you had a super pump on there! And the computer was telling the solenoid to dump the air when you turned the key off. The second problem is the E2 issue (which could be related to the fast pumping if the reed valve is bad).

 

Last, we now know the 89 service manual is wrong regarding the linkages to the rear shock. That alone was "almost" worth the tear down/replace shock fun we had! Now we need to find out where to find the proper information on "how to" as well as torque values for the 89 rear shock service. As you suggested, maybe someone has a 90, 91 manual and it shows the proper rear end linkages. Anyone?

 

Glad it's working...have a great ride on Saturday!

david

[Marten Vanderwerf]

hi guys I have found to have the same issue on my 1984 CLASS system, checked and resoldered the board, checked resistance of solenoid 30 ohm they call for all were 28.8 ohms. checked complete system for leaks. Turn on ACC fill up front, fill up rear to max turn to off then back to ACC and it releases the air......crazy.... put thumb over solenoid air outlet and can fill air pass on key ACC change.

 

any ideas