Clutch plate bearings

ChristianF

New Member
Joined
Oct 8, 2018
Messages
17
I just had my 2nd clutch bearing failure. The inner race of the clutch plate and the freewheel inside just seem to grind those ball bearings to bits, and it's causing the whole thing to lock up and effectively bypass the clutch plate. I had to replace the clutch wheel on my other engine because of this exact thing, and now on this new engine the same thing is happening. Do you guys have this issue with your bearings grinding themselves to pieces? How can I prevent this in the future?
 


FNTPuck

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Joined
Jul 2, 2018
Messages
614
I just had my 2nd clutch bearing failure. The inner race of the clutch plate and the freewheel inside just seem to grind those ball bearings to bits, and it's causing the whole thing to lock up and effectively bypass the clutch plate. I had to replace the clutch wheel on my other engine because of this exact thing, and now on this new engine the same thing is happening. Do you guys have this issue with your bearings grinding themselves to pieces? How can I prevent this in the future?
Like Spare_Parts said, China had a bad batch of clutches that got poor tolerances on the main race. Due to the dirt cheap, unhardened, non-round bearings they use the extra slop causes them to eat the bearings in anywhere from 10-100 miles. I had 5 kits and all 5 turned the bearings to paste before 50 miles each.

Luckily, there is a relatively simple and cheap fix. If the race isn't too damaged, you can tap out the center section using a vice, clean the races, sand any burrs if needed, then replace the 3mm bearings with one size larger 1/8th bearings. It will take 52-53 instead of the stock 57 used, and due to the larger diameter not only will the clutch last longer but there is considerably less slop so the bevel and crank gear shows less wear as well.

I have personally used G25 Stainless bearings and G5 Silicon Ceramic and recommend the stainless since they are like 1/10th the price. The exact ones I used were $8 for 500 of the stainless but now shows as $15 for 500(9 clutches worth!):

The ceramic ones are killer, but honestly a waste of money since the bearings are only used when in neutral or pedaling. They sure do feel nice in your hand, but on the bike you can't tell the difference. I can say I just swapped my ceramic bearing clutch to its THIRD motor and it still feels almost the same as when I installed it so they definitely last! Here are the ones I purchased but they are STEEP at $20+ for 100 which can only fully do one clutch:

Some random pictures...

Clutch taken apart. Backing plate, bevel gear, and bearing race:
87794


Damaged backing plate (I lightly sanded the burrs down before installation):
87795


Crappy stock soft bearings vs the 1 size larger trick ceramic ones:
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New bearings installed in bevel gear. Note that this piece just clicks in with your hands, but the backing/center part needs to be tapped or pressed in evenly. I used a properly sized pipe that only fit on the lip of the race, a vice, and small hammer.

87797


I've done 8 or 9 of them so far on both my personal bikes and for customers and not a single failure yet. I recommend the stainless, the ceramic are honestly a waste of money and way overkill for this application.
 

Otto Neumann

Member
Joined
Oct 30, 2017
Messages
79
Hi @FNTPuck, I received my spare clutch just a few days ago, the one that were on the engine had
practically no extractor threats, and seems that I found this threat just at the right time:

To get out the central section, should I lock the entire thing in a vice with some padding, to prevent
any damage to the bevel gear, and gently tap on the 3 studs with a rubber mallet?

I ask because I simply never did it on this specific piece and I don't want to run the risk to damage it

It's my first 2 stroke build, and I want to make sure to get it done in the right way:
After the total waste of 100 bucks on a kit (*) I'm rebuilding an 80cc completely out of aftermarket
parts, by getting the components singularly and inspecting them individually for any defects or failures.

(*) Small bevel gear and clutch extraction threats practically inexistent; Dislodged crank bearings; excessive play on the conrod;
Broken crankcase seal, and due to a cast defect, the case broke around the frontal cylinder stud, and the entire corner fell out.
 

FNTPuck

Well-Known Member
Joined
Jul 2, 2018
Messages
614
Hi @FNTPuck, I received my spare clutch just a few days ago, the one that were on the engine had
practically no extractor threats, and seems that I found this threat just at the right time:

To get out the central section, should I lock the entire thing in a vice with some padding, to prevent
any damage to the bevel gear, and gently tap on the 3 studs with a rubber mallet?

I ask because I simply never did it on this specific piece and I don't want to run the risk to damage it

It's my first 2 stroke build, and I want to make sure to get it done in the right way:
After the total waste of 100 bucks on a kit (*) I'm rebuilding an 80cc completely out of aftermarket
parts, by getting the components singularly and inspecting them individually for any defects or failures.

(*) Small bevel gear and clutch extraction threats practically inexistent; Dislodged crank bearings; excessive play on the conrod;
Broken crankcase seal, and due to a cast defect, the case broke around the frontal cylinder stud, and the entire corner fell out.
Don't tap on the studs, they are just pressed in and can fall out if you hit them. Tap from the circle center part with a socket or something that fits inside - just takes a couple swift hits, nothing too crazy.
 

Otto Neumann

Member
Joined
Oct 30, 2017
Messages
79
Don't tap on the studs, they are just pressed in and can fall out if you hit them. Tap from the circle center part with a socket or something that fits inside - just takes a couple swift hits, nothing too crazy.
Thanks, I suspected that as well, I found a broom handle that fits inside like a glove, I'll go that way.
With 53 free bearing balls it's going to be an hell, but I'll eventually manage to get it done, I have an idea:

How about applying a really minimal amount of grease, in order to "stick" the bearings into place while reassembling the part?
I can always remove it with some brake cleaner

Do you know the size and length for the screws that holds the crankcase lose?
I can't find any info around and it's driving me nuts!
 
Last edited:

FNTPuck

Well-Known Member
Joined
Jul 2, 2018
Messages
614
Thanks, I suspected that as well, I found a broom handle that fits inside like a glove, I'll go that way.
With 53 free bearing balls it's going to be an hell, but I'll eventually manage to get it done, I have an idea:

How about applying a really minimal amount of grease, in order to "stick" the bearings into place while reassembling the part?
I can always remove it with some brake cleaner

Do you know the size and length for the screws that holds the crankcase lose?
I can't find any info around and it's driving me nuts!
Yea, use a thin film of grease to hold them in there. Don't remove it later, it keeps it living. Just enough to hold the bearings and give them some lube...too much can fling onto the pads and cause slipping.

You don't have to split the case to remove the clutch from the engine. If you are doing it to get to the clutch shaft to change the bearings there or put a heavier spring in, the case halves are held together with somewhere around 6-8 bolts of a few are different sizes.
 

Otto Neumann

Member
Joined
Oct 30, 2017
Messages
79
Yea, use a thin film of grease to hold them in there. Don't remove it later, it keeps it living. Just enough to hold the bearings and give them some lube...too much can fling onto the pads and cause slipping.

You don't have to split the case to remove the clutch from the engine. If you are doing it to get to the clutch shaft to change the bearings there or put a heavier spring in, the case halves are held together with somewhere around 6-8 bolts of a few are different sizes.
I will use Copper or Lithium grease!
I know that, the clutch and the axys slips out all in one piece, sorry there was a typo (Close not lose); I meant, I can't find any info regarding the size and length of those 6-8 bolts.

I found on ebay the 1/8" bearings, both in Carbon steel and Zirconium Oxide, but the steel ones has a G16 grade rather than a G25, will it make any difference?

 

FNTPuck

Well-Known Member
Joined
Jul 2, 2018
Messages
614
I will use Copper or Lithium grease!
I know that, the clutch and the axys slips out all in one piece, sorry there was a typo (Close not lose); I meant, I can't find any info regarding the size and length of those 6-8 bolts.

I found on ebay the 1/8" bearings, both in Carbon steel and Zirconium Oxide, but the steel ones has a G16 grade rather than a G25, will it make any difference?

The G grade is the quality, lower number=higher quality and more uniform roundness. Honestly the stocks are probably like G100 soft and lumpy crap so almost anything would be better. I have used G25 stainless steel and G5 ceramic and although the ceramics roll super smooth in your hand they are like 10x more expensive and you can't tell the difference while riding the bike. I recommend the G25 stainless ones.

Supposedly according to some people only some clutches can take the larger 1/8" without binding, but I have done 9 clutches and every single one worked perfect with the 1/8". 5 were from defective CDH/Zeda clutches from late last year and 4 were from new non-defective ones I purchased online.
 
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