[jolanda]

I do have some issues with the bolt fixing the upper pto pulley to the crank shaft. But that is another thread. ;-)

I have reviewed some JD part list pictures to find the root cause of the problem. And I am very much surprised about a "break shoe" marked as "25" on the attached picture, My Jonny doesn't have a part like that! Where is this mounted and how does that work?

Will the break shoe stop the open clutch or will this also stabilize against vibration ?

Best Jolanda

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(Message edited by treed on November 01, 2014)

 

[bobd]

If my memory is correct, the PTO brake shoe (item #25) mounts to a support that extends from the underside of the engine base/cradle. When the PTO is disengaged, the lower half of the clutch (item #5) drops down and makes contact with the PTO brake shoe which helps to slow its rotation. The upper half of the clutch (item #2) will continue to rotate with the engine but the lower half will eventually stop. The brake shoe has nothing to do with vibration dampening.

As a side note, the bushing (item #6) is what the needle bearing (item #4) rides on. What may not be apparent from the illustration is that the bushing (item #6) has a step on the top portion that fits snugly into the upper PTO clutch (item #2). IF your machine shop bored out the upper PTO clutch (item #2) all the way through (in order to accommodate your increased crankshaft diameter) then the bushing (item #6) will no longer be supported/centered by the upper clutch (item #2). That in turn would shift the full burden of supporting/centering the lower PTO clutch onto the bolt/cap screw (item 7) which attaches it to the crank. Sadly it was never designed to work that way and may be the source of the bolt failure that you spoke of in your other thread.

 

[tommyhawk]

Sure glad you stopped by, "MR. 60, 70, 100" as there is no one better versed than you to solve these problems! (Bob is the 60,70,100 guru, hands down, Jolanda)
Bob, do you think it's possible to shrink fit a sleeve to the pilot end of the bushing/bearing race to make it work? If that end just acts as a pilot, could the sleeve be made from a good steel alloy and not as hard as the part the bearing rides on? Would the upper seal still ride on the hardened part of the race? Loaded questions for sure, but I'm at a loss without having all these parts in front of me. Since the bearing races are no longer available from JD, there are no dimensions to help me figure it out.

Jolanda, the brake shoe is the same part number on the 60 and 70, so add it to your list of used parts to search for. No Longer Available (NLA) new from JD.
I will look at the frame and engine mounting plate on a 70 to see if it gives any clues for a 100 brake shoe mount. The only 100 I know of is 80 miles away.

tommyhawk

 

[tommyhawk]

Look for the welded on part on the engine mounting plate that has a slotted hole like this 70 plate. The 100 mount is quite different, but should have a bracket something like this. The slotted hole allows some adjustment of the brake shoe.

Can't see much in this photo of the 100 clutch, but I think the brake shoe mount is toward the rear of the engine mount. Perhaps save the picture and enlarge it a bit?

tommyhawk

 

[jolanda]

Thank you very much for the answers including these pictures! I made 3 illustrations of the changes we made on my upper pto pulley and the bushing riding the needle bearing. In my opinion everything should be working fine with that... But you guy probably find in issue with that.

Pic 1 visualizes the original pto for the original stepped crank shaft.

Pic 2 marked in red the areas we drilled out. We needed to change the holes for the bolt fixing the crank shaft while the new engine has a 7/16" and not the original 3/8" thread.

Pic 3 shows the resulting 1" extended pto pulley.

I do have another question about the pto clutch break shoe. For sure it will slow down the disengaged lower pulley from the pto. Am I right that another important task for the break shoe is to limit the movement of the disengaged clutch?

I found a metal bracket in my garage today. This should fit perfectly to the mount point for the break shoe. I think I will modify this bracket in the next days to use it temporarily until I find an original break shoe in Germany. (which has a probability close to zero.... ;-)


Best from Germany, Jolanda

 

[jolanda]

(Message edited by treed on November 04, 2014)

 

[bobd]

Your illustrations of the PTO modifications are excellent. As long as the clearances are tight I see no obvious problems with these modifications. Regarding the brake shoe, YES it will also prevent the lower PTO clutch from dropping down too far. A question for you, is the vibration issue your experiencing occurring anytime the engine is running or only when the PTO is engaged? If it is all the time then I would inspect the three rubber isolators which mount the engine cradle to the frame. If it is only when the PTO is engaged I would check the bearings in the lower PTO half for wear. I have also seen a damaged drive belt or something lodged down inside a sheave groove cause vibration.

 

[tommyhawk]

Jolanda, just a little tip on posting multiple pictures. Post one, then hit the "enter" key 2 or 3 times, then add next picture and repeat the process. This will stack the pictures vertically on the page and not make it run wide so one has to scroll right and left to see the pictures and verbiage.
No foul! We've all done it until someone helps by explaining the issue. Terry will fix it for you as time permits.

Another plus for having the brake shoe or a substitute in place is the clutch won't fall off while changing the mower belt.

Another possibility for vibration is the upper clutch bore not being very nearly concentric with the sheave. This would be felt when the engine is running even if the PTO is not engaged. Not likely with machinists in your part of the world though!
Bob has suggested close examination of the rubber engine mounts or isolators. I had to get creative to fix those on my son's 100. New ones were not available at the time. I believe the rear one was the worst on it.

tommyhawk

 

[jlewisa]

Jolanda and all. Thanks for this excellent series of posts. I am following with great interest. I have recently replaced my friction cup with a relined unit but have had problems with the assembly remaining tight on the shaft. I used the bolt provided with the relined cup.
As it turns out, it was longer than the original.
I did not think to check before installing. After installing the original (verifying the length with the book) I evidently did not tighten to the correct torque. The whole thing came apart again.
Third time's a charm?? I hope. Each fix involves dropping the deck. I am getting pretty good at that. LOL It is still fun working on the 100.
John L.

 

[jolanda]

Thanks for the advises (also about posting multiple pictures - I try to follow that)

It was a quite successful day for me and my little JD 100. I have cleaned and degreased all pto parts, crank shaft, bolts and spring washers and double checked all clearances.

Blocking the flywheel and fixing the crank shaft bolt worked well. I decided to use a spring washer and no loctite 243. BTW how are you guys blocking the crank shaft / flywheel ? I followed the procedure described and the official B&S service handbook.

I did a 1h test ride with assembled pto and checked the bolt fixing the pto in the crank shaft. Everything was tight !

I have also built a pto break shoe. I am very much aware that I will never be nominated for an industrial design award for this small piece of iron but its working fine. ;-) see picture

The vibration issue is (partly) solved too. I think the missing break shoe was the root cause. The disengaged lower clutch pto pulley was "dancing" and vibrating on the bushing rinding the needle bearing. Now its slowed down by disengaging the clutch and the movement is limited to 3mm now.


Best Jolanda

 

[tommyhawk]

That's great! If you want, you can epoxy a piece of friction material from an old brake shoe or disk brake pad to the metal shoe and it's as good as the factory one.
Excellent photo by the way.

tommyhawk

 

[woodpecker41]

Jolanda what I do to stop the engine from turning is this. I take the spark plug out. Then using new clean 1/4 inch or 4 to 6mm nylon rope I try to fill the combustion chamber with enough so the piston can't turn over. Make sure you leave enough rope out to remove it and use good quality rope with no dirt or lint on it. Roger

 

[jolanda]

Roger, thats an interesting approach ! Thanks for this brilliant idea.

 

[jolanda]

Tom, funny I had the same idea ! ;-) I will change my mountain bike disk break shoes soon. One of those should fit perfectly. I have never used epoxy.. Do I get this in an auto part shop?

Best Jolanda

 

[woodpecker41]

In the USA you can buy epoxy glue in Hobby Shops, Hardware Stores or even Walmart. It is just a 2 part very strong glue. You mix the two tubes of glue together and have a 5 to 15 minute window to have it in place before it starts to harden. You only mix what you need at a given time. They make quick dry and slow dry. Slow dry is the stronger of the two. They both set up the same but quick dry is fully dry in a couple of hours and slow dry is at least 24 hours. Roger