Whining noise when decelerating

[Greg7]

Wondering if this piece in the center is the other end of what broke off....
IMG_20201107_215953840~2.jpg

[Big T]

Greg,

Follow this http://members.dslextreme.com/users/...t_pictures.pdf

And, if you haven't been here http://members.dslextreme.com/users/bikecliff/

[Greg7]

Hey, sounds like you did some productive searching. Good.

Depending on which post you found, maybe you saw why I was asking the questions/clarifications I was asking about if any vibration.
When I had the threaded shaft (with nut that holds the u-joint onto the secondary drive) break off the back the secondary driven gear I noticed vibration on deceleration (felt thru foot pegs and frame) (that got more noticeable, then worse, over a couple months). You didnt seem to mention an obvious vibration ... so I did not suggest to you that we suspect this failure (if it were to be this failure, the Zooks Repair being a good repair option - if - if you are a machinist.)

But, but, let me ask an oter detail question, just to verify/clarify: When you say you checked and the u-joint had no play in it: Did you just check play in the rotation?, or did you also check for any play forward and back?
Any play back forward and back (toward front , toward rear) would indicate this failure, then we can talk about the Zook Repair or other options.

I can not add anything about the frothed up lube in the boot (I had a bit of thick black goo), other than there is a big o-ring between the secondary drive flange and the engine case to keep the gear lube in the secondary drive. (not suppose to be the gear lube in the ujoint area) And the frothy like that is usally attributed to water in the lube then it getting whipped up by the mechanical machinations in there (ujoint wizzing around in this case). Maybe is a crack in the boot or one of the clamps not entirley in place or something like that letting in water on occasion. Isn't suppose to be gear lube in there, but I dont think a little bit is a problem, and I suspect doesnt take much oil and a little water to make a lot of froth.

So it seems the threads on the end of the bevel gear did shear off

[Gorminrider]

aha. I was wondering. "Whining" catches my eye. Looks like zooks syndrome. Been there, done that. Try a search of 'whining" in this "4 Cylinder Engine/Drivetrain/Clutch" section but mainly,

http://members.dslextreme.com/users/storagecliff/images/bevel_gear_shaft_repair_zooks.pdf

[Greg7]

aha. I was wondering. "Whining" catches my eye. Looks like zooks syndrome. Been there, done that. Try a search of 'whining" in this "4 Cylinder Engine/Drivetrain/Clutch" section but mainly,
http://members.dslextreme.com/users/...pair_zooks.pdf

Thanks. I'll be bringing it to work with me tomorrow to start repairing it. Still trying to figure out how to get the stud that's broken and then it out of that spring loaded coupler though.

[Grimly]

Just buy a replacement low-mileage pumpkin for 30 bucks.

[Greg7]

Just buy a replacement low-mileage pumpkin for 30 bucks.

I did that too. I don't know if you'd call 80k low mileage though. But it was the only one of a handful I found that listed the mileage and didn't look beat to hell.

[Redman]

So it seems the threads on the end of the bevel gear did shear off

Your picture is the final drive end (rear wheel),
(not the secondary drive at back end of engine), right?

if is at the final
drive, is not what I was mentioning.

[Greg7]

Your picture is the final drive end (rear wheel),
(not the secondary drive at back end of engine), right?

if is at the final
drive, is not what I was mentioning.

Yes it is of the final drive end. The Zook syndrome/repair applies to this.

[Grimly]

I did that too. I don't know if you'd call 80k low mileage though. But it was the only one of a handful I found that listed the mileage and didn't look beat to hell.

Depends how they've been treated, of course, but 80k is nothing to these.
300K on mine, but I bought a spare, just in case. I'll have to fit new seals on it, but mechanically it's fine.

[2BRacing]

Yes it is of the final drive end. The Zook syndrome/repair applies to this.

No, the Zook syndrome/repair that was documented in the link in post #34 actually refers to a similar issue, but on the engine side, and not on the final drive side.

This is the first time I have seen a break on the final drive side.

[Greg7]

Problem solved. It was because of the sheared off thread on the end of the bevel gear. I swapped out the one that came on the new used pumpkin and everything is good now. Now time to adjust valves and balance carbs....