The Ford Barn

qmdv · 10-03-2022, 07:49 PM

So I have a new bearing for a 39 trans input shaft. Really really tight fit. I have the shaft in the freezer now and am planning on heating bearing in the oven. Any other tips will be appreciated.

svm99 · 10-03-2022, 08:06 PM

The bearing should be a press fit onto the shaft. I do them without freezing the shaft or heating the bearing. I wouldn't suggest heating the bearing as the pre-lube will melt from the bearing.

Hopefully others will chime in here.
Paul J

cadillac512 · 10-03-2022, 10:06 PM

Heating the bearing will be fine...I keep it to 450F or less. It should just drop on if you work quickly with a cold input shaft. I do like to have a length of pipe that slips over the shaft and bears on the inner race just in case it needs a bit of help going on. Lube isn't a problem since the bearing runs in oil anyway. Just oil it before assembling the trans.

cas3 · 10-03-2022, 10:51 PM

I have never had a problem with just pressing it on. In the modern world, I like a sealed bearing, then remove the inside seal so it gets transmission oil like it should. I also like to search the bearing numbers to find old stock USA made bearings

Terry,OH · 10-04-2022, 05:36 AM

Usually light press fit. There may be flat spots on the input shaft.

rotorwrench · 10-05-2022, 11:19 AM

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I never use more then 250 degrees F on a precision bearing. It can damage them. The thermal installation only goes so far on longer shafts. I would just press it on but make sure the parts are completely clean.

Mac VanPelt's transmission book is a must have. He is a good source for parts as well. The bearing that fits in the input shaft is better if an original part or NOS. Some of the new ones are crap. I would reuse one that is still in good condition and not think twice about it.

10-03-2022, 07:49 PM	#1
qmdv Senior Member Join Date: Dec 2012 Location: Payette, ID Posts: 946	New bearing on trans input shaft-really tight fit So I have a new bearing for a 39 trans input shaft. Really really tight fit. I have the shaft in the freezer now and am planning on heating bearing in the oven. Any other tips will be appreciated.

10-03-2022, 08:06 PM	#2
svm99 Senior Member Join Date: May 2010 Location: Garlic Country of CA Posts: 557	Re: New bearing on trans input shaft-really tight fit The bearing should be a press fit onto the shaft. I do them without freezing the shaft or heating the bearing. I wouldn't suggest heating the bearing as the pre-lube will melt from the bearing. Hopefully others will chime in here. Paul J

10-03-2022, 10:06 PM	#3
cadillac512 Senior Member Join Date: Apr 2019 Location: Kansas Posts: 1,172	Re: New bearing on trans input shaft-really tight fit Heating the bearing will be fine...I keep it to 450F or less. It should just drop on if you work quickly with a cold input shaft. I do like to have a length of pipe that slips over the shaft and bears on the inner race just in case it needs a bit of help going on. Lube isn't a problem since the bearing runs in oil anyway. Just oil it before assembling the trans. __________________ "It don't take but country smarts to solve the problem" (Smokey Yunick) '41 Merc Town Sedan / 260" 8CM engine '66 Fairlane four door / "warmed up" 302

10-03-2022, 10:51 PM	#4
cas3 Senior Member Join Date: Jan 2011 Location: Beverly Kansas Posts: 5,298	Re: New bearing on trans input shaft-really tight fit I have never had a problem with just pressing it on. In the modern world, I like a sealed bearing, then remove the inside seal so it gets transmission oil like it should. I also like to search the bearing numbers to find old stock USA made bearings

10-04-2022, 05:36 AM	#5
Terry,OH Senior Member Join Date: May 2010 Posts: 5,186	Re: New bearing on trans input shaft-really tight fit Usually light press fit. There may be flat spots on the input shaft.

10-05-2022, 11:19 AM	#6
rotorwrench Senior Member Join Date: Jun 2010 Location: San Antonio, Texas Posts: 17,410	Re: New bearing on trans input shaft-really tight fit Sponsored Links (Register now to hide all advertisements) I never use more then 250 degrees F on a precision bearing. It can damage them. The thermal installation only goes so far on longer shafts. I would just press it on but make sure the parts are completely clean. Mac VanPelt's transmission book is a must have. He is a good source for parts as well. The bearing that fits in the input shaft is better if an original part or NOS. Some of the new ones are crap. I would reuse one that is still in good condition and not think twice about it.