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Benino

cliff's notes:
torch the crank shaft to expand it
freeze the pilot bearing to contract it
slide hammer outward on the pilot bearing.

Full story:
I spent the whole day today with the help of my friend Kevin removing my pilot bearing on my 1980 N/A so I thought I'd share.

First I threaded a bolt into the pilot bearing and tried to pull on it. I threaded it through the box end of a wrench and tried to pull on that. I also tried to pry on the bolt with a crow bar. no luck. I decided I needed a little more force so I build this slide hammer:

I cut the steel shaft off of an old 924 hatch shock and welded the correct bolt to thread into the pilot bearing housing on one end. I put a heavy 35mm socket on the shaft and then welded a big washer on the other end of the shaft to make a crude slide hammer.

I hammered out on the pilot bearing . . . but nothing.
I figured I needed more foce. so I added a 7lb axe head to my slide hammer:

No luck. We decided to torch the end of the crank shaft to make the metal expand. I remembered from my physics class that if you torch a circular metal piece with a hole in the middle, the hole also gets larger. The problem is that the pilot bearing housing would also expand with the heat. First We tried torching the crank shaft and then holding ice on the pilot bearing to expand the hole and contract the bearing and then pull on it with my slide hammer. This didn't work, so I got out a bottle of compressed air. If you turn one of these up-side-down and pull the trigger the air that comes out is freezing cold and it will freeze anything it comes in contact with. We torched the crank shaft and then froze the pilot bearing. It still took a huge amount of force on my slide hammer to pull the bearing out but it worked.

bottle of compressed air:

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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

924RACR · Posted: Sun Oct 21, 2007 9:45 pm Post subject:

Very ingenious - congratulations!
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Vaughan Scott
Webmeister
'79 924 #77 SCCA H Prod racecar
'82 931 Plat. Silver
#25 Hidari Firefly P2 sports prototype

dgKnecht · Joined: 17 Nov 2002 Posts: 42 Location: Palatka, FL

bro, that is one of the hardest parts i ever changed,
i tried different pullers and hammering on the wrench,
eventually i got it out with just tightening down a bolt threaded
thru the bushing and pushing on the end of the crank, i thought
the bolt was gonna break before it let go....got lucky i guess

kudo's on the new tool !! Glad you had success.
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78 924

--all of us have been through some bad times.....i once had a job where i had to drive a Chevette

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

Love the hammer, but you could make it more dangerous if there were blades on BOTH sides of the axe head!

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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

!tom · Posted: Thu Oct 25, 2007 4:03 am Post subject:

Lizard · Posted: Thu Oct 25, 2007 6:24 am Post subject:

why not just get a bolt with longer threads, and turn it in and use the mechanical leverage to push it out.

that is how I have always removed it.
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3 928s,

joecitizennn · Joined: 12 Sep 2005 Posts: 2096 Location: no mans land

Anybody ever heard of the hydraulic method of removing a pilot bearing? It is alot easier than the above.

dgKnecht · Joined: 17 Nov 2002 Posts: 42 Location: Palatka, FL

!tom · Posted: Thu Oct 25, 2007 8:35 am Post subject:

joecitizennn · Joined: 12 Sep 2005 Posts: 2096 Location: no mans land

Grease+bits of rag.

THe trick is to put a little bit of grease in the hole, then stuff grease saturated rag peices in behind. Keep stuffing them in till the hole is filled. If you are lucky you can find or modify a punch that just fits in the pilot bearing hole. Hammer the greasy cloth in, then extract the punch and stuff some more greasy rags in. Hammer them in. Keep it up the pattern, hammering harder and harder untill the bearing pops out. If it works, it was easy. If it dosent then it wasnt easy!

Ha Ha.

It will never work if you just put grease in there.

Benino · Posted: Thu Oct 25, 2007 1:48 pm Post subject:

I tried threading the bolt in first but it bottomed out and kept spinning in such a way that it felt like it was starting to strip the threads. The bearing wasn't spinning either. I felt like I was more likely to strip them out completely by threading it in more than by pulling straight out.

I soaked it with liquid wrench for a week before pulling.
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1980 Porsche 924 N/A USA
1980 Porsche 924 turbo USA
1987 Porsche 944S USA

endwrench · Joined: 07 Dec 2002 Posts: 1631 Location: Victor, Montana

Extremely impressive ingenuity!!! If at first you don't succeed..........

Todd
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'79 924NA. Rebuilt 9.5:1, MSDS header, Mega Squirt Injection, MJLJ-EDIS Ignition, 1.6L Whipple Charger and Intercooler, 10lbs Boost, 944 Trans, Custom HD Clutch.
"simsport" said....superchargers are better than turbos its official!....