flywheel/ring gear

[Loren(ABCAN)]

I am having a bugger of a time getting the new ring gear on to the flywheel on my 48 8n. First off I had to use a zip cutter to remove the old gear. I then ran out of acetylene trying to heat up the new gear and it still would not go on. I then tried to put the ring gear in the oven for 1/2 hour at 400. no go. Next I tried putting the flywheel in the freezer overnight and then brought the gear and the flywheel down to a local garage where they used their acetylene torch to no avail. The gear was almost cherry red and still it would not go. I have inspected the flywheel and noticed that there is a groove where the ring gear sits - I would guess that it is about 0.010" deep by the thickness of the ring about 1/4" or so. Has anyone seen this before? I have brought the parts down to a machine shop and asked them to measure the pieces to see if the ring will ever expand enough to fit. I may get them to turn the flywheel down so the first part of the wheel is the same diam as the area where the ring sits. Any ideas out there?

 

[gahorN]

I put the flywheel in the freezer overnight, heated the ring gear to 400 degrees in the oven, and with the flywheel pulled out of the freezer and IMMEDIATELY on the floor, dropped the HOT gear onto it, hit it with a brass hammer all the way around... and it went right on.


Chery red might be too hot for the temper of a ring gear....I don't know...

 

[Dunk]

It should have the reduced area were the ring gear sits.

If you get it too hot, it may mess up the temper.

I figure 450* to 650*, most gas bar-bah-que grills can do 650*, it usually takes a self cleaning oven to that, and then they lock the door, and won't open it till they cool.

The cherry red part scares me, how dark was it where that was being done?

You may have something from the "Land Of Almost Right".

Hobo's page on that:
http://www.theviperr.com/hobo_dnn/H...N/Transmission/RingGear/tabid/75/Default.aspx

 

[Loren(ABCAN)]

Yeah that was kinda what I was hoping would happen. Unfortunately not so much. Did yours have that groove I was talking about?

 

[Sean (TX)]

(quoted from post at 20:23:14 08/11/08) Yeah that was kinda what I was hoping would happen. Unfortunately not so much. Did yours have that groove I was talking about?

ll N series flywheels have that groove. I froze my flywheel over night and used the BBQ after the oven trick failed. Dropped right on.

 

[OKDAD]

Did mine about a month ago. Got the new gear from one of the major N parts suppliers. As suggested on this forum I did NOT get the gear red hot. Heated it with a acy torch until it was blue. Also one side had a slight bevel on the inside. That went on first. Slipped right on.

If I was you I would take yours to a machine shop and have them do it. They can tell you if it is outa spec.

Good Luck

 

[Sean (TX)]

(quoted from post at 21:33:29 08/11/08) Did mine about a month ago. Got the new gear from one of the major N parts suppliers. As suggested on this forum I did NOT get the gear red hot. Heated it with a acy torch until it was blue. Also one side had a slight bevel on the inside. That went on first. Slipped right on.

If I was you I would take yours to a machine shop and have them do it. They can tell you if it is outa spec.

Good Luck

Good tip...Everyone forgot the bevel...Didnt look at Hobo's tips but I am sure it is in there..

 

[Dunk]

(quoted from post at 22:37:12 08/11/08)

(quoted from post at 21:33:29 08/11/08) Did mine about a month ago. Got the new gear from one of the major N parts suppliers. As suggested on this forum I did NOT get the gear red hot. Heated it with a acy torch until it was blue. Also one side had a slight bevel on the inside. That went on first. Slipped right on.

If I was you I would take yours to a machine shop and have them do it. They can tell you if it is outa spec.

Good Luck

Good tip...Everyone forgot the bevel...Didnt look at Hobo's tips but I am sure it is in there..

I hope yall have the bevel right.

Yall are confusing me a tad here about that.

The low part of the bevel faces the bendix, which is the rear of the tractor when installed.


Or there is always the possibility that I am totally off my rocker....

 

[old]

Last one I did on a TO20 feg. What I did was put the ring gear in the oven, turned it on to 500 degrees. I had put the flywheel in the freezer the night before. When the oven got up to temp as in the heat light went off I took the flywheel out of the oven. Pulled the ring gear out of the oven and dropped it on, yes dropped it on and it almost fell to far down. You can not wait 5 minutes from the oven to the flywheel. by putting it in a cold oven then turning it on it heats slowly if you heat the oven up first it heats to fast and can cause problem

 

[Loren(ABCAN)]

I am unsure about the bevel but I did notice that the teeth have a chamfered edge which faces the rear of the tractor when installed correct? That is to allow the starter gear engage the ring gear more smoothly i would assume. I never tried putting the ring on the wheel directly after removing from the oven because my wife would probably not like me having the flywheel on the island. However the trip from the oven to the garage is approx 10 or 15 quick steps. Are you suggesting that is too long of a time to have the ring out of the oven?. I like the bbq idea I will try this next after I get the ring and flywheel back from the machine shop. This way I can have the flywheel on the deck infront of the bbq. Now that I know that the flywheel has the groove on yours too I probably won't have it removed at the machine shop. I had suspected that the flywheel was a jobber replacement at one time and was slightly different than the oem one. The ring is still a steely blue color so I hope that the temper is still ok. The shop that I brought it to today was dimly lit so it wasn't exactly cherry red but it did have a bit of a glow to it. Thanks all for your suggestions, I will give an update once I 'git r done' as they say here in oil country.

 

[OKDAD]

Yes the bevel on the teeth go towards the rear to aid in starter bendix engagement. There should be a very slight bevel on the inside edge that ends up on the forward edge.

As far as time from heating the gear to it dropping on the flywheel you only have a few seconds before it shrinks. I had my gear on a pair of jackstands with the flywheel on the floor next to it. With welding gloves on as soon as entire gear was blue I turned off torch and dropped the gear on the flywheel. Took maybe 4 seconds max.

At least that's how I remember it! Good Luck!

 

[Loren(ABCAN)]

Ok did the flywheel next to the oven thing today and still no luck. Called the tractor parts store where I got the ring to order a few other parts and got to talking with the guy there. He said that each time you heat the ring and let it cool the ring gets smaller. I'm not so sure that it gets smaller but maybe it doesn't expand as easily as the first time. Any thoughts on this? At any rate I ordered a new ring and I'm going to get the shop where I get the parts give it a try.

 

[OKDAD]

You may have something there. As suggested on this site I removed bearing races by running a weld bead around them and they would literally fall out. Was told that is an old blacksmith trick. The heat from the weld bead makes them shrink. That may be what happened to the ring gear. I am no expert but I think that is the best plan.

 

[gahorN]

Welding will shrink a part because the weld-bead is hot/expanded when it is laid down, but cools and shrinks pulling the object smaller with the bead as the bead cools.

That doesn't compare to simply heating an entire part and then letting it cool.

The local heat applied via torch to the subject ring gear is what conerns me. I'm concerned about the temper of the gear, and I think I'd want a different gear for that reason....not because it may have shrunk. (I don't think it could shrink due to an even heating process.)

Measure your new ring gear, and warm it in a 400 degree oven...NO HOTTER than that. It should slip right onto the cool flywheel. I'd consider machining the flywheel if it didn't (provided the gear is confirmed to be the correct part and the correct size.)

 

[OKDAD]

My point was if there wasn't already a problem with the size of the the gear there probably is now! Remember he got it red hot at least once. That said I don't understand why that would make it too small. I would think the metal would loose temper and yield making it too large.

Out of couriosity I did a little research on thermal expansion of steel. Appears to be about 6 micro inches / degree F. So cooling the flywheel from 72F to 32F shrinks it about .000248 inches. Increasing the temp of the ring gear to 400F from 72F increases its ID by .00203 inches. Most interference fits are .002-.003 inches. Very little room here for this to work I think. Rasing the ring gear temp to a "blue color" which Halcomb Steel states is 560F gets you an increase of .00303 inches. Since this is a ring being uniformally heated you probably have to double these numbers to get the actual diameter increase. Note that "red hot" in daylight is shown to be about 750 F.

Measuring these diameters is not feasable for most folks. A job for the machine shop.

I am sure someone will correct me if my logic is flawed!

Take Care,
Ike

 

[Loren(ABCAN)]

Ok finally got it. I had to order a new ring gear and then brought the flywheel to the shop where I got the ring. I guess I wasn't too far off as the guys there had a heck of a time too. The one mechanic said he had done about 100 ring gear installs and never seen one as hard to do as this one. They even called the new holland dealership to see if anyone had ever had this kind of problem on the 8n's. Apparently they had to get it cherry red to get it on. I hope the teeth don't explode off after the first try.

 

[Dunk]

(quoted from post at 18:57:30 08/20/08) Ok finally got it. I had to order a new ring gear and then brought the flywheel to the shop where I got the ring. I guess I wasn't too far off as the guys there had a heck of a time too. The one mechanic said he had done about 100 ring gear installs and never seen one as hard to do as this one. They even called the new holland dealership to see if anyone had ever had this kind of problem on the 8n's. Apparently they had to get it cherry red to get it on. I hope the teeth don't explode off after the first try.

I got my fangers and toes crossed, I hope I don't git a cramp!!!

Keep us posted!!!

 

[Hobo,NC]

I put a ring gear on a 600 this week,,, the ring gear never turned blue,,, it did fall on tho,,, hope its not a loose'n cuzz its installed on the tractor

What makes a N so difficult is the gear has to go over a raised place on the flywheel,,, never seen another flywheel have that fudgen raised place,,, the 600 did'n,,, I don't see eunny practical purpose fer it,,, neber paid enny attention to it till I think Bob mentioned it,,, this is one job that should B left to a experienced mechanic,,, problem is not many new mechanics replace'em enny more,,, shinnese sell automotive new replacements cheaper than the labor to repair a old unit,,, one day soon we will pay dearly for that

A fire ax is hard to beat for this job,,, only reason I fudged with the BBQ grill was to see if it could B done,,, takes a hot'n tho,,, I do heat my differential ring gears on the BBQ grill cuzz I want a controlled temp over the whole gear,,, you can fudge up a days werk and a days pay rite fast it not done rite

 

[Dunk]

(quoted from post at 22:18:46 08/20/08)
A fire ax is hard to beat for this job,,, only reason I fudged with the BBQ grill was to see if it could B done,,, takes a hot'n tho,,, I do heat my differential ring gears on the BBQ grill cuzz I want a controlled temp over the whole gear,,, you can fudge up a days werk and a days pay rite fast it not done rite

I wish I could remember what I heated the ring gear in the rear end of my '88 Blazer with.

I can't remember at all.

 

[redleg]

So has this superheated ring survived allright? I just did mine yesterday and had to get it pretty hot. took me a few trys and some acetylene too.

 

[Hobo,NC]

(quoted from post at 05:19:53 08/26/08) So has this superheated ring survived allright? I just did mine yesterday and had to get it pretty hot. took me a few trys and some acetylene too.

Passed the tail lite warranty,,,,went out then drive way yesterday

 

[Loren(ABCAN)]

I've cranked the tractor over a bunch of times now and all seems to be a-ok.