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View Full Version : Replacing a flywheel ring gear



Hap Waldrop
03-31-2010, 07:47 AM
It's been good long while since I had to do this, and a recnt topic here, but one of yesterday's chore was to replace a ring gear on a 948 fylwheel. I had thrashed 948 crank so I bolted the flywheel to it and put the deal in my big vice, used a pice of 1" steel round stock and hammer to knock the old ring gear off, it took maybe 5 minutes or less, no real drama. The cleaned and glass beaded the flywheel to spruce it a bit. Took the flywheel sat it on cender block, grabbed the new ring gear out towards the very edge with vice grips so I had a good handle to hold the ring gear while it was heated and make sure to postion the vice grip towards the edge so it did not interfere with the fitment of the new ring gear against the flywheel with the vice grips in place. Fired up the torch, I held the ring gear while my buddy heated it, we worked our way around the ring gear, making sure to not turn it red or anything, just get some heat to it to expand it, first try it was a just barely too snug to drop on, a few more minutes of heating and it simply dropped on, let it cool down slowly and va~la, new ring gear installed. I had forgotten how easy a job this really was, piece of cake. If you took it to a machine shop this is exactly how they would do it, and by far the best way to do it, if you have acess to torch, then don't let this job scare you, it was very easy job.

JPSmit
03-31-2010, 08:44 AM
:bow: Hap I swear one day I am going to come down and just sit in the corner of your shop and watch. I won't make a sound, just learn from the master - thanks

Trevor Jessie
03-31-2010, 10:00 AM
On larger ring gears you can just lay it on the flywheel and heat it until it drops on. This doesn't seem to work with small ones (haven't got my head around why just yet)

Gundy
03-31-2010, 10:19 AM
:bow: Hap I swear one day I am going to come down and just sit in the corner of your shop and watch. I won't make a sound, just learn from the master - thanks

Don't worry....if you come to Hap's shop you'd have
trouble getting a word in edgewise.

Only guy I've ever meet who gives me a run for the money in
story telling department.

:thumbsup:

Guest
03-31-2010, 08:38 PM
On larger ring gears you can just lay it on the flywheel and heat it until it drops on. This doesn't seem to work with small ones (haven't got my head around why just yet)

Less material needs to grow more per inch to get the clearance Clarence.

spritenut
03-31-2010, 08:48 PM
I chisel off the old one and heat the new one in an oven on broil for 20 minutes, It drops right on and it is heated evenly.

nomad
03-31-2010, 10:19 PM
I agree with spritenut on the chisel. A good sharp cold chisel between the gear teeth cuts it quick or expands it enough so it slips off. Then heat with a torch and I use the spit test for temp. Spit explodes and disappears its hot enough. Sits and boils its not!
KA.

Hap Waldrop
04-01-2010, 08:12 AM
[
Don't worry....if you come to Hap's shop you'd have
trouble getting a word in edgewise.

Only guy I've ever meet who gives me a run for the money in
story telling department.

:thumbsup:



Yep, you get David and me together, and it's real tough to get a word in :smile: :smile:

David, while I got ya, you and the Ms. going on the FBCC overniter to Maggie Valley, MJ just made our reservations. It's time for another get-away my man.

Guest
04-01-2010, 09:03 AM
I chisel off the old one and heat the new one in an oven on broil for 20 minutes, It drops right on and it is heated evenly.

I baked at 500* for an hour and froze the wheel and still couldn't get it to go one w/ a hammer. Threw it in some hot coals and that did the trick.

Gundy
04-01-2010, 09:33 AM
When is the trip scheduled , Hap?
We sure need a get a way soon!

Edit: Crap....that weekend I'll have to miss the omelet party
AND the Maggie valley trip. It's my weekend to keep my 90 year old Mother.
Ya'll have fun. Toss back a few for Lynn and I.

Coastalman
04-01-2010, 05:07 PM
David, is the May 8th trip still on?
Charlie

Gundy
04-01-2010, 05:40 PM
David, is the May 8th trip still on?
Charlie


Yep. I'll bump that thread as we get a little closer.
Maybe this weekend.

I'll be doing that trip tomorrow because the weather is
soooooooo fine. 85 for a high. Checking out some lunch spots
and their beverages. Doing a little shopping. Taking the B
for it's first spring topless run.
Maybe take a few pics to get the May 8th crowd appetite
a going.

TulsaFred
08-28-2011, 10:32 AM
Had to replace my flywheel ring gear today.
I don't have an oxy-acetylene torch, so I used my outdoor gas grill.
That grill gets real hot, reading 700 degrees on the thermo.

Picked it up off the grill with pliers and it dropped right on the flywheel, no problem.
After a few minutes it cooled, shrunk and mated just fine.

Who needs a torch!

Fred

regularman
08-28-2011, 07:14 PM
You can also do this without heat. Put the flywheel in a freezer or hit it with some freon and the ring gear with fit. I used this for the last set of press in wrist pins I put in an engine. I heated the rods in an oven and cooled the pins with refrigerant and they went in with no pressing at all.