New Rings for Old Tractor

tinsnip · Apr 24, 2006

I'm attempting to buy a set of rings for a relative who's restoring an old tractor. (sorry to be vague, but there's a chance he might be lurking in here somewhere). If I were to order a set of replacement rings, should I order them as spec'd in the original factory size or, since some light cylinder honing is being done, attempt to get a size slightly larger?

I am NOT a mechanic. This is at the very extreme edge of my poor understanding of how this stuff works. But does anyone in here have any advice on what would make the gift a winner instead of another headache?

GaryE · Apr 24, 2006

As long as it is just a light hone job and there was no ridge that had to be reamed, standard size should be ok. If there is any question, just measure the bore before ordering the rings.

Gary

Egon · Apr 25, 2006

It may depend on how many hours the sleeves or block have seen and what work may have been done to them in the past.

Egon

tinsnip · Apr 25, 2006

( As long as it is just a light hone job and there was no ridge that had to be reamed, standard size should be ok. If there is any question, just measure the bore before ordering the rings.

Gary
)

That's what i was hoping to hear. I am not able to get any new measurements on the bore. But I have seen it and it looked pretty clean. The tractor is over 50 years old though.

Soundguy · Apr 25, 2006

You had better hope that the sleaves / bore are not already worn out of tolerance, or oem spec rings won't do much. Also.. You had better hope that the machine has not been resleaved or overbored to a different spec.. or oem spec rings won't do much good.

hate to be the rain ont he parade.. but buying rings 'blind' for an unknown bore is like buying main bearings for a crank that has not been mic'd or plastigauged'...

Soundguy

tinsnip · Apr 25, 2006

You've confirmed what a little voice in my head has been trying to tell me. Given the trator's age and the fact that the current owner has only had it for a few years, it's impossible to know what the history might be for the rings/cylinder. Hmmm. Unless I get a new mic reading of the inside of the honed cylinder it might be a stupid idea. Kind of ruins the surprise though. (this is supposed to be a gift). Guess I could make a "gift certificate" for a set of rings and have him provide real specs. Probably safest.

Thanks for helping me think this through.

3RRL · Apr 25, 2006

Soundguy is right. You need to verify the diameters.
You can measure the bore with a telescoping gage and a mic or...(a bore gage of course)
Or you can use the 2 pin method or 2 pins and an accurate spacer block.
If you have a set of pin gauges and a 1-2-3 block, you can fit 2 pins and the 1-2-3 block inside the bore, switching the pins until they fit perfectly...then mic over the pins and 1-2-3 block.
This picture show this method.

3RRL · Apr 25, 2006

This is the 2 pin method.

tinsnip · Apr 25, 2006

Thanks for the pics. Very helpful. I will send him a link to this thread after I deliver the gift certificate and let him do the measurement so the replacements fit as they should. This has been great!

Now, anyone have a reliable source for replacement rings for a JD A circa 1950?

Spiffy · Apr 25, 2006

Wise choice!

I'll also add, he may want to check that bore and piston both parallel and perpendicular to the crank. I don't know how much money/effort he plans to put into the machine, but by the time you take the head off and get a nice valve job, I'd hate to throw new rings on a piston if it's too sloppy or way out of round.

Of course I have no idea how much clearance (piston bore difference) or far out of round is allowed on the old Deere's, but you should be able find plenty of info with a quick web search, or I think you'd find a manual with that info easy enough too. /forums/images/graemlins/cool.gif

tinsnip · Apr 25, 2006

He's a little reluctant to put a ton of money into the thing since he'll never get it back. So far it's been a labor of love. But he's got it stripped right down to the frame with only the tranny left to dive into. Pistons seem ok and otherwise pretty clean.

It's really my idea to put the new rings in since it seems unlikely it will ever be apart to this degree again in this century. He says he'll live with it if it burns a little oil, I just figure, what the heck, put in the new rings and then have no regrets once it's all re-assembled, shiny and better-than-new.

Spiffy · Apr 25, 2006

Makes sense to me! On those big bores, and the little it sounds like he'll run it; should work out great.

On smaller bores, I've seen new rings give less than impressive results and heard of [take 3rd hand info for what it's worth....potentially very little] it actually making for worse compression loss.

Sound's like he's doing a beautiful job on it! /forums/images/graemlins/cool.gif

tinsnip · Apr 25, 2006

Yeah, he's doing an amazing job. Each and every part has been removed and brought to good-as-new condition. Sheet metal is awesome! Very meticulous. That old JD still comes apart (with a little muscle and liquid wrench) after all this time. Very heavy iron! I'll get him to post some pics when it's done (even though this is technically not an antique tractor site).

Cheers!

3RRL · Apr 25, 2006

( Yeah, he's doing an amazing job. Each and every part has been removed and brought to good-as-new condition. Sheet metal is awesome! Very meticulous. That old JD still comes apart (with a little muscle and liquid wrench) after all this time. Very heavy iron! I'll get him to post some pics when it's done (even though this is technically not an antique tractor site).)

With that in mind, he should invest in getting the motor in top shape too. It would be a shame to have a super clean tractor with a crappy motor in it. He's almost there anyway.

RoyJackson · Apr 25, 2006

You really need to measure those bores first...or have someone measure them.
The gage to use is called a Dial Bore Gage. It's accurate to .0001". The measurement method 3RRL displayed will work well, but won't show a bell mouth (one end is greater in diameter to the other end) or an out of round (cylinder is ovaled) condition. You need to know that...either condition would probably require reboring the cylinders.

Soundguy had good advice...I hope you heed it.

RobJ · Apr 26, 2006

Since the bore is probably out of round a bit, especially near the bottom where oil wear happens (generally dirty air wear is near the top end), there is another option no one has mentioned. You can buy oversized rings, then file the ends as needed to get the proper ring gap. This gap is in all the manuals. Especially handy when not boring or replacing pistons. Also check the ring landing gap. Another wear spot on the pistons.

tinsnip · May 3, 2006

Update:

After reading all the good suggestions in this thread, i decided I had to forgo the surprise and outright ask him what will constitute a correct fit based on his most current measurements. When I questioned him about the bore size, this was his response:

"Found the bore checks I did. Not too bad for 50 years. Worst one measures 5.520, the other one 5.505. New they would be 5.500. (A sheet of paper is .003 thick)."

Based on those measurements, he's still comfortable with the standard ring sizes. He did express some curiosity about what you all would make of the measurements.

Thanks again!

Soundguy · May 3, 2006

the one that is .005 out doesn't bother me at all.. could even be an error reading. .. The one that is almost '7' sheets of paper out.. that one would concern me a tad.... How far out are the first set of OS rings?

Soundguy

cp1969 · May 3, 2006

.010 taper is still quite a bit and will translate into the ring end gap varying by .031" depending upon where the piston is in the bore at any given time.

It usually isn't too hard to rebuild or find replacements for the cylinders. If you do that, and replace the bearings, this old tractor engine will probably be good for another 50 years.

Depends on what you want to do with it. If it's just for occasionally pulling a wagon or something and you don't mind a little bit of oil consumption, replacing just the rings might be the way to go.