250sx clutch problem

[barnett468]

Hello

Does anybody have the measurements of a New OEM manual clutch pack?

You already said you looked it up yourself in the manual, see the quote below, plus I gave it to you in post #26. Read my post if you want the info quickly.

Below is the spec from the manual you claimed you looked up. There is no thickness spec for the metal plates only a “warpage” spec. Your metal plates are most likely not worn by more than .001 but in your case this is irrelevant since your new clutch assy is positively as thick as, or thicker than an OEM one according to the friction disc spec provided in the manual combined with the “known” typical wear encountered in the metal discs . I’m pretty sure my posts contain all the spec info you need to know but I could be wrong.

Manual clutch friction disc spec, new =.103-.109, service limit .091

I was able to measure the spare metal and fiber plate along with the used clutch plates.

------------- NEW ------------- OLD

Metal plate:--- .056"----------- .054"

Fiber plate: --- .120"----------- .106"

Spring:-------- ?---------------- 34 mm

I cross-referenced these numbers versus the service manual and found them to be acceptable. I will have to take the motor apart to check what the new springs will measure.

Xxxxx

I'll have to check if I have the package the shoes came in.

That would be helpful but not necessary. I told you how to EASILY tell if your centrifugal shoes are most likely OEM or not in post #27.

xxxxx

Ill also check the thickness of the shoes in reference to the service manual.

That info along with the online manual and page number for it is in post #27.

xxxxx

Do you think I should install that spare friction and metal plate that came in the kit if nothing else is the obvious cause?

One should easily be able to extrapolate that from the information I provided in posts #26 and #27.

My answer is no, others may vary.

xxxxx

Would the added plates do anything adverse to the bike?

Providing the discs fit on the hub and left enough room for the pressure plate to fully disengage and still have it’s splines penetrated by the inner hub by approximately .100” [get out your calculator it’s your turn now] it would at the very least increase the preload of your previous springs to a point where the amount of force required to manipulate the shifter would be substantially increased which might damage the shift shaft [unlikely] and the additional preload may also cause the springs to coil bind during activation [this would need to be calculated] which could limit the amount of movement in the shifter to a degree where it could not shift gears.

Xxxxx

Thanks for the help.

Well, I for one would feel more like I was helping if you did not ask questions that were already answered in my posts.

[wildacres00]

I do have the service manual and checked only the service limit not the standard (my fault). Not quite sure why aftermarket fiber plates would be that much larger than OEM?

Whether or not I have the package the shoes came in was a response to your question which you followed up by providing how to tell if they are OEM or not which I will find out once I break the bike down.

If I should install the spare plates was a "grasping at straws" question.

I am thanking you for the time and effort you are putting into my post and I do greatly appreciate it. I do read your replies but sometimes things get a little lost in translation as to the intent because some questions are "grasping at straws", "thinking off the top of my head" and playing a devil's advocate roll in trying to determine why a brand new clutch does not work and how come it failed even though the service limits were not exceeded. In the case of the friction plates they are well within tolerance and springs are at the bottom of there tolerance band but that should not of caused my issue.

[barnett468]

Hello wildacres00


I do have the service manual and checked only the service limit not the standard (my fault).


No problem

xxxxx

Not quite sure why aftermarket fiber plates would be that much larger than OEM?


It’s a conspiracy by the overseas people.

xxxxx

Whether or not I have the package the shoes came in was a response to your question which you followed up by providing how to tell if they are OEM or not which I will find out once I break the bike down.


Your statement regarding that was actually posted 1:40 minutes and 2 posts after I posted that info though so that’s one of the reasons I asked if you were reading the posts, that’s all.

xxxxx

I am thanking you for the time and effort you are putting into my post and I do greatly appreciate it.


No problem you’re welcome however I'm not the only one who is, there are others like Howdy and Dougspcs that seem to be putting in a good amount of time and effort as well.

xxxxx

I do read your replies but sometimes things get a little lost in translation as to the intent because some questions are "grasping at straws", "thinking off the top of my head" and playing a devil's advocate roll in trying to determine why a brand new clutch does not work and how come it failed even though the service limits were not exceeded.


I personally think that if most people read anyone’s reply [even mine]slowly and more than once that the info will start to sink in and make more sense the longer you spend on it.

xxxxx

In the case of the friction plates they are well within tolerance and springs are at the bottom of there tolerance band but that should not of caused my issue.


No they should not have caused your previous issue with the old clutches but as suggested your new springs might.

I previously posted some exact preload specs for your old springs when either the old used clutches, new aftermarket clutches or new OEM clutches are used with them. This information is in posts #26 and #27, lol.

Anyway your old springs are more than fine with the new clutches, and within spec as you know so should work fine with new OEM clutches or your old ones. I still might try them in place of the new ones and try that before I go buying new OEM ones if I find no other obvious problem.

[wildacres00]

Ok so I took the bike apart and found that the new springs were in fact undersized. They measured 33mm while the old springs measured 34mm. Needless to say I will be reinstalling the old springs as suggested above and give that a shot. Also took some measurements of the drum and clutch shoes and both were within spec.

[wildacres00]

These are some photos I took of the clutch system. The clutch spring on the left is the new spring and the spring on the right is the original spring. Also notice the difference between the clutch pack pics, the first one is the original pack and the other is the aftermarket pack. The difference between the two is noticeable in the pic and measured .060" total There is a pic of the one way clutch and it shows that there is "outside" stamped on it so you do not install it backwards. Some photos of the the centrifugal clutch shoes.

[barnett468]

Ok so I took the bike apart and found that the new springs were in fact undersized. They measured 33mm while the old springs measured 34mm. Needless to say I will be reinstalling the old springs as suggested above and give that a shot. Also took some measurements of the drum and clutch shoes and both were within spec.

Hello

Ok, that's a start unfortunately I can not view your photos like others for some reason, can you post them to flickr etc and paste a link, i'd like to see what you are talking about.


I told you how to tell if shoes are oem or not so are they?

Your short new springs are not guaranteed to be the problem but i'm glad you are reinstalling the originals. Did you do the spring finger pressure test to see if one was weaker or stronger than the other or did you FORGET, lol.?

[barnett468]

Hello wildacres00


1. It looks like the clutches do not stack up as high as photo 2 which is what I calculated so that’s ok but the pressure plate has more clearance from the face to the clutch disc why is that it looks incorrect.

2. this assy looks fine to me.

3. spring diameter looks nearly identical but hard to tell. Same diameter wire and turns means same spring rate but again I’d use old ones anyway.

4. can’t see well enough on my phone

5. does not show the inner hub surface but you neasured it so if it is smooth it is ok.

6. can’t tell true color of clutch discs so you will have to use my description and photos i supplied to determine if they are oem yourself.

[wildacres00]

The color of the shoes appear to be brown as you were saying before but is a little difficult since it was oil soaked. Also I could not remove any material with the finger nail, they are very tough.

The spring wire diameter appears to be the same.

The clutch pack does have some space to it. I checked it a couple of times a made sure it was together. I'll take a couple more photos later today. I also took a photo with the spare plates that came with the kit. I'm thinking if I installed the spare discs with the smaller springs that it might work. I'm not going to do that though, Im going to use the old springs with the pack the same as the service manual.

I'll have to figure out the Flikr account and post the photos and links. I'll do that this evening, it's a family day today LOL.

[barnett468]

It is possibly the pressure plate for the clutch disk isn't seated correctly on the groves. The Fix: Pull the clutch, remove and turn the back plate 1/4 turn and see if the clutch pack closes tight and the plates won't turn. You should be able to squeeze the clutch pack together ( front and back pressure plates ) with one hand tight enough that the disk won't turn. If any disk does turn you probably have other issues to deal with. Howdy

Hello


Ok, the photos finally sank in, as it sits on the table the above is your EXACT problem. See how high above the basket the clutch center is. Both assemblies have too much clearance from the disc to the clutch center. Remove ALL plates install the splines of the clutch center [outer hub] into the grooves of the pressure plate. They should EASILY go together and the clutch center should enter the splines on the pressure plate by around 1/4”-3/8”. If they engage themselves by LESS than ¼” then the splines are bad and need repair.

You can put a mark on the splines with a felt tip marker around 1/4” up to more easily see how far they engage each other.

Take a photo of the top of the clutch center.

Use old orig springs I guess but it might be slightly hard to shift. Try it before assy and if it is use the new springs.

Take some photos

Reassemble with clutches and do as Howdy suggested above before final assy.

[wildacres00]

I think I understand what you are talking about and it doesn't look good, seems like there is barely any engagement. When I attach the two pressure plates together Without the basket I get OK engagement. It seems that when I place the pressure plates into the basket it pushes the outer plate out too far. Let me know if there is any other pics that might help or if I'm totally wrong. The bottom of the black line is 1/4" from the tip of the splines.

[barnett468]

Hello


I still can’t see the photos on the site only ny phone so I can’t really see what’s going on so as far as I go I can’t help you any more than to suggest the following. It does look like from the mark on the hub that it is not penetrating the pressure plate at all in the photo, not good.

Take the thin pressure plate, put it on your counter, take a venier caliper, stand the caliper straight up, measure from the clutch disc seating surface to the bottom of the grooves. If you do not have a caliper cut a piece from a manila folder 1/2” X 3”, mark it with an ink pen at around 1/8”, 3/16” and 1/4”. The depth should be around .175” [3/16”] or more. Put a mark on your hub like you did with the felt tip pen in the photo but now at whatever the depth of the pressure plate is from clutch seating surface to bottom of groves is.

Now the hub must EASILY penetrate the pressure plate with 0 force by around .165”-.175”. Rotate the hub 1 spline at a time until it does then mark top of hub on outer edge and pressure plate so hopefully you see the marks to line them up together with discs on. Now keep rotating hub until it EASILY penetrates pressure plate fully again, then mark plate [not the hub] only so it lines up with mark on hub. Continue until you’ve gone around 1 full rotation. If the hub only fully engages like 5 times or less maybe file the splines lightly then until it works in several more positions. This will help insure proper engagement after assy and prevent hub from sticking [hanging up] during use and will also make future assy much easier.