YM 3000 Flywheel

[chriswheeler]

Hi all,
Installing a new clutch in my YM3000 and wondering if there is a min/max spec out there for resurfacing the flywheel. Step in the flywheel has already been resurfaced as some point in it's life. Measurement I'm looking for would be the min/max from the face of the flywheel to the surface the clutch disc contacts on the flywheel. If this step is to deep, won't matter what new parts I bolt up. Looked in the service manual, ( I have one ) no spec. Also have a JD950, and the service manual for that, no spec. This step on mine now measures .185 deep measured with a depth mic. Would appreciate any info if you have it, thank you,
Chris

 

[Car Doc]

I cant see the flywheel but if it worked before why couldn't you just take a 2" 3m roloc disc on a die grinder and surface it with that? A rivet groove will not hurt anything if its got one fwtw.

I do cars and trucks all the time that way that have hydraulic clutches where you cant surface them if you wanted to and it works just fine on cars that run thousands of miles a month not just a few hours a year. hth :thumbsup:

 

[chriswheeler]

The reason I split the tractor is I had run out of clutch adjustment and the drive was starting to slip. After the split I discovered that the clutch disc and pressure plate were in fair to good shape. Clutch disc wasn't into the rivits and measured almost .300 thick. Looking at the setup hard, throw out, springs, fork and pilot bearing are in good shape. Looking at the flywheel closer, it appears at some time in it's life someone has resurfaced the area the clutch contacts. This area is cut below the flat face of the flywheel by .185 or so. Thinking there should be a spec where the surface would be cut to deep and remove proper pressure from the clutch disc, or with new parts provide much less adjustment for wear. If it was just a matter of resurfacing the flywheel, no problem, I'm a machinist with a lathe at home to do the job just fine. But I realize that at some point this surface can be cut below a usable spec. And that is where the question comes from. Min/Max spec on resurfacing the flywheel. This tractor is a VN recon, so anything is possible. ( you would not beleave what I've found and fixed so far. Still all things considered not a bad deal if you don't mind turning a wrench )
Chris

 

[California]

...is a VN recon, so anything is possible. ( you would not believe what I've found and fixed so far. ...

Considering the source - I wonder if your .300" disc is correct for that model. Maybe you could calculate the thickness of disc you need to restore a normal range of adjustment then find a suitable thicker disc off something else? Or maybe have your disc relined with much thicker facing.

I expect your pressure plate was reconditioned by grinding it down too.


Someday I'd like to read a description of the oddities you have encountered.

 

[Car Doc]

Id ponder turning down the surface the pressure plate mounts on then since you are the guy doing the machining. In theory that will put more tension on the disc and force the PP fingers outwards hopefully giving you more adjustment. A shim between the crank and flywheel may be necessary as well? hth

 

[chriswheeler]

And that is exactly what I'm trying to get done here. If I can find the min/max spec, I can face the outer surface of the flywheel that the pressure plate bolts to and bring it back into spec for the clutch face if need be. Just need to find out what that spec is. Our friend Vanna in Sac didn't have anything to do with this one, most likely came out of the shipping container this way. Think I've got 7 years out of this so far, I've got no complaints. Here is another heads up for all with a loader. Pulled the flywheel to install a new pilot bearing. Found that 5 of the 9 bolts that hold the bell housing to the engine broken off with the heads rubbing the back side of the flywheel. Heads were trapped by the casting with more than 50% of them ground away by the friction of the flywheel. On and off for years I've had a " noise " couldn't locate. Guess what, I found it. Lucky I didn't break this tractor in half !! Drilled and used easy outs to remove the bolt stubs, ran a 10 X 1.25 tap into the block to clean up the threads. Threads in the block are OK. Bolts used on the bellhousing were of a low grade, combine that with the load exerted by the front loader, they didn't last. ( Koyker 160) Thinking anyone replacing a clutch needs to remove the flywheel and check the bell housing bolts. I'll machine a new pilot bearing today and be ready. Sure wish I could get my hands on that spec. Might have to contact Hoye Tractor and see if they can measure a new one for me.
Chris

 

[Car Doc]

I will give you what I have in my 336 manual use at your discretion.


clutch disc measurements

disc od-8.46"
facing thickness both sides-.327-.350" wear limit .300"
rivet head depth-.05- wear limit .112" (this makes no sense but thats what it says fwtw I think thats backasswards)

As far as the flywheel all it says if its not within .008" straight replace it so I take that as there is no surfacing allowed. hth

(now in that lies the challenge as far as I am and I presume you are too concerned Id go for it is my advice!)

 

[chriswheeler]

Car Doc,
The pilot bushing is pressed into the flywheel itself, no setback with the flywheel necessary unless the surface the clutch disc rides on is grossly out of spec. Then the throw out bearing travel becomes a issue. ( good idea though I could sure make that spacer easy enough) Plenty of spline for the clutch plate drive as well. I have enough room to machine 1/8" off the face the pressure plate mounting surface if need be. But don't want to assemble this and find that there is so much pressure that I can't disengage the clutch ?? And there is the issue of the throwout bearing moving in and still getting enough to disengage. Best fix so far, ( if I need one ) would be to find out the min/max on the step in the flywheel. Guess the easy answer might be to just try to buy a new flywheel. Machinist in me would go for a fix first.
Chris

 

[Car Doc]

Hey Chris the shim is more for adjustment in the lever that is mounted in the bell housing where you are moving the PP farther away from the fork shaft CL. :thumbsup:

On the Jap cars I work on even as much as .050" will drastically affect how the clutch acts.

 

[chriswheeler]

Thanks Car Doc,
No surfaceing allowed, I can clearly see lathe tool marks on this one, makes for a new flywheel purchase I guess. Give Hoye a call, see if one is available, thanks for your time and effort,
Chris

 

[California]

... most likely came out of the shipping container this way.

That's what I meant too. I think they were as surprised by the unexpected variances as were their customers. I miss Van.

 

[Car Doc]

Thanks Car Doc,
No surfaceing allowed, I can clearly see lathe tool marks on this one, makes for a new flywheel purchase I guess. Give Hoye a call, see if one is available, thanks for your time and effort,
Chris

Welcome Chris,

If they cant come up with one and if you are faced with a do or die situation there are flywheel shims available. Lots of 4 and 6cyl Toyota's use them for instance.

I know you can turn the flywheel to suit and as far as the shims dimensions like I say if its a do or die just drilling new holes should be a piece of cake and with your lathe skills the od/id should not pose a real problem either. jmho

If I can help further I will and I may be able to come up with a shim or 2 for sake of discussion and application if you have your crank end dimensions for me. :thumbsup:

My gears are working so here is something to ponder-with the flywheel and clutch assy / off the machine completely assembled AS IS old parts.

A person could simply take measurements of the finger tips to flywheel etc and then by pressing them see how much distance they need to move in order to disengage the disc. edit: As a rule the fingers are usually almost flat when assembled maybe a bit on the convex side but only a little. The fingers get more convex (twords the tranny) as the disc etc wears and it takes more movement to disengage and it has less clamping force also as the result of the wear.

I can see it in my head using a press so if that helps great. In my world there is always a way to fix something. I am somewhat famous for the ability to fix anything no matter what it is.

 

[chriswheeler]

Thanks for the thoughts Car Doc,
I have pressure plate, clutch disc, throw out bearing in transit now from Hoye. Thinking the same way, there is a pressure plate finger to clutch face measurement in the manual. Thinking about compairing that measurement assembled to what the old parts measure assembled and decide what to do. Shims between the end of the crank and face of the flywheel are looking like the best answer. Because there doesn't seam to be a min/max on the step machined in the flywheel, I might end up calling Hoye and asking what a new one measures to see where this one is. ( that is if they have one ) What ever it is out of spec, cut that off the outer surface of the flywheel and add shims that thickness. .050 isn't much, and it would be good to get it right the first try. The large stationary engines I'm used to working on were much more forgiving in this area. ( cat 3512's and 3516's, Detroit V20, Waukesha ) Thanks for the help,
Chris

 

[chriswheeler]

Yes California,
I miss her to, both Van and her brother were good honest people to deal with. Hope they both do well in the future.
Chris

 

[Car Doc]

Chris,

Welcome. To further clarify the shims proper installation would be needed only if you did not have enough travel/adjustment in the fork or if the fork was in jeopardy of going over center on the t/o brg. And only for adjustment purposes not added clutch clamping pressure. (I know you already get that but just saying so I know we are on the same page)

The machine work I see you needing is simply to machine down the boss the pp is sitting on. I would probably take a few thousandths off the face also to make sure they are true to each other fwtw. And that is from my recollection of the last Yanmar I had down the step on it was cut into and below level of the flywheel face the clutch disc engaged.

 

[chriswheeler]

Parts got here last night. I've got the flywheel off and on the bench. Thinking about bolting the clutch/pressure plate stack together and measuring the difference. Come up with a plan of action from there. Can see the clutch disc is .050 thicker to start with. See how much distance I've gained with the new parts. Looking at the step left by the tool bit where the flywheel was cut, I can measure about .015 with a depth mic. If need be, will take the .015 off the outer face where the pressure plate bolts on, and shim between the flywheel and crank that same .015. I have shim that thick here, easy job to make one. That should place the flywheel/pressure plate/clutch disc in the proper position again. Another fun repair of a VN recon. They did some strange stuff overthere "rebuilding" these things. Thanks Car Doc for the help and thoughts, hope I'm pointed in the right direction.
chris

 

[Car Doc]

A little goes a long ways in a pressure plate considering they normally only move around .125" anyway at the disc so its all in leverage and how you use it.

 

[chriswheeler]

The new stack measured .300 thicker than the old parts stack. That's a bunch, almost 5/16" thicker. ( that is measured with all of the pressure plate bolts in and tight ) Near as I can tell the difference is coming from the pressure plate and not the disc. Thinking I'm going to bolt this thing back together and give it a go. The .015 cut on the disc surface is nothing compaired to the fresh pressure plate and disc stack. Most likely it's going to work out fine unless something else is messed up. Now the fun starts,
Chris

 

[Car Doc]

The new stack measured .300 thicker than the old parts stack. That's a bunch, almost 5/16" thicker. ( that is measured with all of the pressure plate bolts in and tight ) Near as I can tell the difference is coming from the pressure plate and not the disc. Thinking I'm going to bolt this thing back together and give it a go. The .015 cut on the disc surface is nothing compaired to the fresh pressure plate and disc stack. Most likely it's going to work out fine unless something else is messed up. Now the fun starts,
Chris

Sounds real good Chris! Who knows they probably machined the old PP instead of replacing it.

We ran into that in my business years ago with rebuilt clutches they would just re-machine them and I think probably every other one we put in had some sort of problem.

We switched gears and went with all new assembly's or wouldn't do the job at all if someone is cheaping out.

I cant even remember that last clutch I put in that ever had issues they are bullet proof now days. good luck

 

[chriswheeler]

I think your guess is right on the money. Disc on the old pressure plate is .090 thinner, almost a sure thing it was machined. Mix that with some used and tired springs and there is the .300. Mostly together now, but won't get to test for awhile. Keep finding things that need to be fixed. FEL mount has mixed bolts, mixed sizes as well, stripped threads in the casting. Have to drill and tap the casting between the bell housing and trans to take the same bolts, Willl change the 14 mm to 5/8" X 11 because that is what I have the taps for. I'll use grade 8 allen heads because of the load on them. California and I had the same dealer in Sacramento, now out of business. They were great people, wasn't anything they wouldn't do for you. I'd buy from them again, no regrets. They talked about quality problems with the folks in VN doing the rebuilds. They even made a few trips over there to try to fix the problem. Can see exactly what they were talking about now, see what drove them out of business. Have to wonder what is next ??
chris