Technical Would you run it? Magnuflux looks bad...

Guys,
I am mid rebuild of a Borg-Warner overdrive to swap into my '48 plymouth.
I finally got everything apart and clean enough to mag particle inspect. Everything looks OK so far, except the output shaft.
It looks to have fatigue/stress cracks.
What would you guys do? Run it as is? Have it shot peened? Try to track down a NOS replacement (likely hard to find)
Thanks!

 

Know anyone good with Tig?

 

Surface cracks in the case hardening. Shot peaning wont touch it. Take a few thou off locally on a grinding machine may clean it up but it may have been like that from new

 

I have some great Tig welders at my work, as well as a small lathe I am allowed to use. No OD grinder though. That is the surface that presses into the rear ball bearing, so it cant bee too undersized.

 

NO...welding. It WILL break ! Plus to grind, weld, and remachine...it will cost more than a new trans. !!!

If you will be driving the car in a more "hot rod" fashion, racing stop light to stop light, etc., find a new / different shaft.
I'm betting it's surface cracks you have. From your pictures, I see no single, deep, or large crack(s).

If your just cruising around, car shows, doughnuts in the morning, NOT racing your buddies, put it together and drive it.

Mike

 

The crack pattern is intriguing and suggestive, but if I mag tested something and got a bad test result I'd trashcan the part - why else would I mag test it??

 

Run it.

 

I’d run it

 

Unfortunately there are 4 parts in this transmission that are very difficult to find, and this is one of them. I would be happy to trash can it, if there was much of an option for a replacement

 

Is that magnaflux,,,,,looks like a funny shade of light on it ?

I have never heard of a shaft cracking like that ,,,,,it’s almost one solid crack .
Usually the splines will twist first,,,,,they look perfectly straight in the pic .

Im willing to bet that is a false reading there .
I would try going over the whole piece with a Scotchbrite pad to remove any buildup of contamination,,,,and test it again .

Tommy

 

U didn't say the engine you have in it. Unless its got some serious torque and you're going to use all of it, just go with the thing. That shaft looked pretty hefty, IMO I'd just go with it.

 

Surface checks from grinding, they won't hurt a damn thing, I would bet that it has been that way since new.

 

I agree that looks like surface cracks from initial manufacturing, during the grinding of the hardened surface. You could confirm using dye penetrant, if very shallow the cracks should not show up much, indicating they are very surface depth.

 

Id Run it . Piece of cake

 

Thanks Tommy. I am not certified to do the NDT at work, just have access to the stuff and 15 minutes of training. I will do as you say, get the part super clean, and grey scotchbrite the area.
I also can hit it with penitrant dye. May get a different result?
Equipmentis Magnaflux brand, I am unsure of the brand of the spray. The blue is oil, thisbis the one part I checked that i hadnt put through my degreaser bucket.

Engine is lightly hotrodded 217 flathead six. A real monster I tell you!
I do "hot rod" around in it as much as I can, but it is a 95hp engine in a 3200lb car. So....

I just dont want to get this thing together and break it. I am trying to take the effort to make it the best, bullet proof trans I can. If it was nearly any other part, I would just replace it.

 

Did you Magnuflux it yourself ?

what crack detetection system did you use ?

those look like surface cracks , possibly from the hardening process when originally manufactured.

to see that many cracks I would assume a overheat condition ( bad bearing or low fluid )
I don’t see any other discolouration on the part .

coukd you pass by a machine shop and have them put an eye ball on it and confirm YAY OR NEIGH ?

 

Slow typing I am . Sheesh .

 

I would run it. If it had a lateral crack that was several inches long, I would be concerned. Because that was probably run in a low hp. application, I'm having a hard time thinking that is anymore than surface cracks.

 

I'd run it, all the while looking for a NOS, or good used one, in case it does break.

 

Do you plan on sending all 95 horsepower through that thing? I'll put my money on a bet that you'll be fine running that thing, as long as the yoke fits tight.

 

Given the scarcity of replacements, I’d run it and wouldn’t think twice about it. It’s not like you are going to mat the gas and sidestep the clutch.

 

Run IT!

 

So it looks like you used a dye penetrant and a UV light
I think you are seeing the 'fretting' from the inner bearing race that fits against it...or from manufacture when it was surface finished
I'm inclined to believe isn't anything structural in the shaft.... if it was mine, I'd run it and forget it
Out of curiosity...clean it real good and repeat the test and see if you get the same pattern

 

From an ex-welder whose seen a LOT of MT tests.....doesn't look like any cracks I've ever seen !!
Ever heard the phrase....'Swallow an elephant and gag on a gnat ?!'
You're fretting (see how I worded that !!) over nuth'in. IMHO
95 HP break that thang?..I thank not. Run it. Drive it normal.
6sally6

 

Wanna bet it outlasts him??

 

Probably from original machining. The "cracks" are all in line with the ends of each of the spline teeth cuts.

Hot rodding is all about going fast and breaking parts. I would install that trans, then do my best to break it, so no one else would ever have to be concerned about it. Can't ever recall hearing about the entire end of an input shaft breaking off. Seen some really screwed up splines, and busted gear teeth, but never a broken input shaft.

 

It almost looks like there was a bit too much interferance on the press fit of the bearing. Probably been like that since the original assembly.

Gary

 

Thanks for all the advice guys. Glad to hear that it is likely a normal condition.
My plan is to
clean it better, using grey scotchbrite to brighten the area.
Re magnuflux it.
Clean it, dye pen it.
Check the fit of the bearing.
Report back.
Run it.

To note: the area does not look like it has gotten hot. It is not scored or visibly suspect in any way. The bearing that came off seems perfectly fine, other than a little dirty.

 

Would cryogenic treatment be an option to eliminate any further stresses that may lie below the surface?

 

Which trans is this?