Opinions sought, mechanical question

[MarkV]

I don't understand why two new pistons for a '53 Oliver 99 are that much differnt from two old pistons in a '53 Oliver 99. Guess that is why I let the dealer work on my tractors.

MarkV

 

[daTeacha]

I think they don't make the original style anymore. The new ones are the only thing out there that's got the right diameter and wrist pin location. They are not OEM by any means.

 

[schmism]

I don't understand why two new pistons for a '53 Oliver 99 are that much differnt from two old pistons in a '53 Oliver 99. Guess that is why I let the dealer work on my tractors.

MarkV

so how does one know the "old" ones are OEM. why couldnt a second over hall been done in the 70's with whatever they could get at that time? (cept they did all 4)

 

[patrick_g]

If the repair takes the direction where contributions are in order, someone needs to PM me as I am unsubscribing to this thread. I think the pony died a while back.

Pat

 

[daTeacha]

Oh boy, this is getting worse. I just found out this morning that they pulled the new one from 3 and put it in 4, so now the heavy ones are in 2 and 4. Some other source told them it would be better if the light and heavy ones were running in tandem. The stroke was measured at 7", not the 5.6 I calculated, and the displacement has been increased via the installation of an M & W (?) kit some time ago to "about 500" cid. It is unknown if the kit increased the bore, stroke, or both. The flywheel supposedly weighs 200 lb.

The owner has had the tractor for 8 years, during which time it just sat in non-running condition. He came to own it through marriage. It formerly belonged to his wife's deceased father.

This is starting to resemble a TV soap opera or something.

 

[rback33]

Oh boy, this is getting worse. I just found out this morning that they pulled the new one from 3 and put it in 4, so now the heavy ones are in 2 and 4. Some other source told them it would be better if the light and heavy ones were running in tandem. The stroke was measured at 7", not the 5.6 I calculated, and the displacement has been increased via the installation of an M & W (?) kit some time ago to "about 500" cid. It is unknown if the kit increased the bore, stroke, or both. The flywheel supposedly weighs 200 lb.

The owner has had the tractor for 8 years, during which time it just sat in non-running condition. He came to own it through marriage. It formerly belonged to his wife's deceased father.

This is starting to resemble a TV soap opera or something.

I think I would start to slowly walk away from this one... no good is going to come of it. Part of the problem is that she needs to decide who to listen to and stick with it. At least all the TBN info is channeled through one voice to her so she isn't confused.

 

[daTeacha]

Unless she's lurking here.

Like I said earlier, my only involvement has been to weigh the pistons. The guy who owns it is making most of the decisions about what gets used and how it's done. She's just running the wrenches and paint. It's not a school project, something for 4H. I get the occasional update.

 

[Tom_Veatch]

...
The heavy pistons can be dealt with by pairing them so that they counterbalance each other.
...

I assume the crank counterweights are sized properly for one of the two reciprocating weights, but not both.

I don't know how many throws the crank has - maybe two, maybe 4. As best I can visualize the dynamics, the best case would be 2 throws with 3 main bearings. A heavy and a light on each throw with the heavies closest to the center(3 mains) or the ends (2 mains) would get you about as close as you are going to get with pistons mismatched to that degree.

If there are 4 throws, again assuming the crank counterweights are sized correctly for one of the piston weights, you're going to have a serious dynamic imbalance no matter what you do. If the heavies are on the same phase - both moving the same direction at the same time - you've got a bad "up and down" shake, no matter what throws they're mounted on. If they are on opposing throws - one going up while the other is going down - you'll minimize the "up and down" shaking but the inertia loads will couple and increase the "fore and aft rocking" shake. That could be minimized by placing the heavies in the center cylinders, #2 and #3 if I have it pictured right.

If it were a case of the student being unable to come up with the scratch to replace all the pistons and rebalance the crank for the new piston weights, I'd toss my billfold in the ring to help with the expense. But, to my understanding, it's the "frugal" nature of the owner who is already getting free labor for the rebuild that is preventing the job from being done correctly. That being the case, I'm much less inclined to offer financial assistance.

I'll second the motion already presented that the young girl be informed that what she is being required to do is a poor way to do the job and that it will not be her fault when the tractor shakes its fenders off. That in itself might be a good learning experience - good results may or may not come from doing the job right but only bad results come from doing it wrong.

 

[scott_vt]

If it were a case of the student being unable to come up with the scratch to replace all the pistons and rebalance the crank for the new piston weights, I'd toss my billfold in the ring to help with the expense. But, to my understanding, it's the "frugal" nature of the owner who is already getting free labor for the rebuild that is preventing the job from being done correctly. That being the case, I'm much less inclined to offer financial assistance.

Amen Tom,
And well said !!! Theres nobody cheaper than me Some times theres no short cut ! Tell the guy to buy two pistons for crying out loud !

 

[jimmysisson]

All that time switching pistons and rings around he's probably got the pore ole thing wore out already. The pony may have died but I want to hear about the funeral.
Jim