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DT400

Sprag clutch slipping..maybe?

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Hey all hope this finds everyone well in these weird times.
The Rubi has been running and operating perfectly for the last 2-3 years so I haven't been to active here.
Long story short 3 or 4 years ago the engine was rebuilt with a new crank and Hondamatic...yes a new Hondamatic not used or reworked.
My problem is during deceleration in 1st gear at slow speed like going down a steep hill on a trail the engine looses engine braking at 6mph. Anything above that and the centrifugal clutches stay engaged but below 6, I am guessing this is the 1st gear input rpm where the flyweights keep the clutched engaged, and below 6 is where the springs pull the weights back in. the ATV acts like it's in neutral. I also get a rattling sound when the clutches disengage. If I keep the speed over 6 in 1st I keep engine braking, if I drop below and the clutches (seemingly disengage) and the speed picks back up to over 6 the rattling gets worse but no engine braking but if I rev the engine to engage the clutch I get engine braking back again. Shouldn't the sprag clutch keep the engine braking going as long as the drive-train at the input to he Hondamatic is wanting to turn faster than the engine idle rpm? Also the faster I go RPM wise like in 5th gear I get a gear whine, it sounds exactly like straight cut gears that are out of alignment ( where you get higher rpm as well as load on the gear train.)
So to me it sounds like the sprag clutch is slipping which would explain the loss of engine braking and the rattling sound. Also I figured the bushing in the clutch drum, the bushing that rides on the new crank surface was out of spec it would allow the gear to cant and cause the out of alignment gear whine I was hearing.
So I figured I new what was wrong, but to my surprise when I tore the front of the engine down everything seemed fine...the sprag clutch works perfectly and immediately the clutch drum bushing seemed fine but during mic'ing the bushing is out .003 .

 

2003 Rubi.

Any ideas?

Darrell

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i don't know much about the rubi's ?, but i do know the one-way clutch bearing does effect engine braking. did you inspect the clutch where the bearing rides ?, chatter marks ?, if so ?, it would be wise to replace both as a set.

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26 minutes ago, shadetree said:

i don't know much about the rubi's ?, but i do know the one-way clutch bearing does effect engine braking. did you inspect the clutch where the bearing rides ?, chatter marks ?, if so ?, it would be wise to replace both as a set.

That's the odd thing about it. Yes I did inspect the drive plate the drum and the sprag clutch. And other than a very slight amount of bluing on the drive plate Hub where the bearing rides nothing has any galling, flat spots, blueing, chattering, shiney spots or anything out of the ordinary and by hand the clutch does not turn backwards in the least but apparently it is slipping with the weight and Torque from the ATV and the Driveline.

 

I have ordered all three new parts make sure everything is back to factory spec as well as Springs and clutches even though they're good just so I know I'll never have to mess with it again.

 

Darrell

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4 minutes ago, DT400 said:

That's the odd thing about it. Yes I did inspect the drive plate the drum and the sprag clutch. And other than a very slight amount of bluing on the drive plate Hub where the bearing rides nothing has any galling, flat spots, blueing, chattering, shiney spots or anything out of the ordinary and by hand the clutch does not turn backwards in the least but apparently it is slipping with the weight and Torque from the ATV and the Driveline.

 

I have ordered all three new parts make sure everything is back to factory spec as well as Springs and clutches even though they're good just so I know I'll never have to mess with it again.

 

Darrell

you may have wasted your money on all those parts ?, but its better to replace them all at once. i say this on the spending part, because the inner clutch with the weights is where your one-way clutch bearing is what operates the engine braking. the round part of the center weight that sits down inside the one-way clutch bearing, when it starts to get chatter marks on the steel ?, the one-way bearing will skip some times. also..the lobes wear down on the one-way bearing..even to the naked eye..you can not see this !. i hate that you are having to buy all new parts ?..but at least you are going about it the correct way !. and i hope your buying right from honda..and not ebay or amazon ?!..please buy oem parts from honda !, and keep this thread updated on your work ?, as others may see this, and discover their atv is doing the very same thing !.

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5 minutes ago, shadetree said:

you may have wasted your money on all those parts ?, but its better to replace them all at once. i say this on the spending part, because the inner clutch with the weights is where your one-way clutch bearing is what operates the engine braking. the round part of the center weight that sits down inside the one-way clutch bearing, when it starts to get chatter marks on the steel ?, the one-way bearing will skip some times. also..the lobes wear down on the one-way bearing..even to the naked eye..you can not see this !. i hate that you are having to buy all new parts ?..but at least you are going about it the correct way !. and i hope your buying right from honda..and not ebay or amazon ?!..please buy oem parts from honda !, and keep this thread updated on your work ?, as others may see this, and discover their atv is doing the very same thing !.

Honda OEM Parts all the way I stay away from Chinese crap.

I ordered everything that had to do with the sprag clutch because there are no specifications as to service limits. And there was no smoking gun as to the reason for the problem. So since everything looked fine but something was wrong and the last thing I wanted to do was save a few bucks and have to tear it back down again because I didn't replace one part. I'm replacing the clutches because all I have is a minimum Dimension out of the maintenance manual but not a maximum so I don't know how much I've actually used over the years in friction material. And I'm replacing the Springs just because they're cheap. You're right I likely purchased more than what I actually needed but to me not having to tear it down again for the same problem is worth a few extra bucks and this way I shouldn't have to do it ever again. I'm the type of mechanic that believes and doing it right the first time, if it's questionable replace it especially if it's something that requires a lot of time or effort to get to. Likely I could have just replaced the sprag clutch and the drum since the drum bushing was out of spec.

 

Darrell

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10 minutes ago, DT400 said:

Honda OEM Parts all the way I stay away from Chinese crap.

I ordered everything that had to do with the sprag clutch because there are no specifications as to service limits. And there was no smoking gun as to the reason for the problem. So since everything looked fine but something was wrong and the last thing I wanted to do was save a few bucks and have to tear it back down again because I didn't replace one part. I'm replacing the clutches because all I have is a minimum Dimension out of the maintenance manual but not a maximum so I don't know how much I've actually used over the years in friction material. And I'm replacing the Springs just because they're cheap. You're right I likely purchased more than what I actually needed but to me not having to tear it down again for the same problem is worth a few extra bucks and this way I shouldn't have to do it ever again. I'm the type of mechanic that believes and doing it right the first time, if it's questionable replace it especially if it's something that requires a lot of time or effort to get to. Likely I could have just replaced the sprag clutch and the drum since the drum bushing was out of spec.

 

Darrell

and i already like you !..lol.

  • Haha 1

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