Sachs Crankshaft Bearings

[tofriedel]

I have a major problem.  I am rebuilding a 125 and I cannot get the outer races out of the cases.  I have used heat gun, hot plate and torch with no success.  Normally, with a little heat the races fall out with a tap from a mallet or a little nudge by banging the case on the workbench.  These races will not budge.  All of the other bearings came right out.

In the past, with 100's through 495"s, I never had a problem, but these are giving me fits.

Does anyone have a solution?  I need the help.

Thanks in advance for any assistance.

Tony

[wade195]

Tony

I have found with races in general not specific Sachs engines if you are good with a welder you can run a bead around the races and after they cool they will just fall out.

Doug

[t20sl]

Tony:  Doug's solution works great.  It is how I was taught to remove valve seats in heads. But if you want to save races put cases in your oven, if your wife permits and your not woried about seals.  Heat to about 350-400F.  Bearings will fall out usually.  Ted

[Rain Man]

I use my kerosene heater to heat my cases, while I'm heating the garage.
 Already running ice screws up here in Maine !!

Raymond
 Down East Pentons

[john durrill]

Tony,
 The oven is a very good way. If the cases are clean they dont cause a problem at home. We use an aluminum cookie sheet to set the case on. Then set the oven at 300 F. for 1/2 an hour. Try tapping the case with a wooden hammer handle. To set up a vibration. Bring the temp up 50 degs F at a time and most times 350 or 400 F will work and they drop out. If your off doing something you can hear them hit the cookie sheet when they fall. The temps in a lot of our Penton manuals are in C. even if they say F. so you should cause no damage . I double checked my Sachs engine temps against the factory German manuals to make sure.
John D.

[Ron]

Tony,
Mine dropped out at 350deg F in about 1/2 hour. I did pre-heat the oven.
RonW

[PentonRestoration]

While I haven't tried removing bearing races with this method, have you considered using freeze spray?

I had a set of clutch and brake levers and perches which had been out in the weather for twenty years.  The steel screws were seized into the aluminum threads.  Since I'm restoring the first bike I owned, I wanted to try to save them.  I tried various penetrating oils, force, etc.  Then I tried freeze spray, the CRC brand failed miserably, then I tried this brand (see link).  It took out all the screws and the cable pins.

It worked like a miracle.  

http://www.mcminone.com/product.asp?catalog%5Fname=MCMProducts&category%5Fname=3830011&product%5Fid=20%2D3000&CMP=googlpn

Use caution, it will freeze your skin instantly.  It chills down to about -40.  

Jerry
1972 125 Six Day
CRF150
CRF230
CRF450X

[tofriedel]

Thank you for all who responded.  I will let you know of my success with your methods.

Your suggestions are much appreciated.

Tony

[tofriedel]

It worked, but it took 400 degrees F, which is 204 degrees C.

All is well.

Jerry, I have a can of freeze spray coming & I will try that on a subborn swing arm bolt.

Thanks for your help.

Tony