Yamaha TRX850 Enthusiasts Forum

I have a few projects piling up that involve a shop press, namely headstem bearings on a few bikes & a pitbike head stem to press in, how many tonnes can I get away with? I can get a 6 tonne bench top press for $120 or 12 tonnes for around $270.

6 tonnes should enough for general bearings right?

I'd go with the 6 tonne. You'll even get 2 stroke cranks pressed apart with that. Make sure that the press frame and general structure is up to supporting that sort of load though. Well made and sturdy, with a high degree of adjustability being desirable. You'll still find you'll be requiring all sorts fixtures to support various components. Channel in various sizes works well. Engineering shops should let you have offcuts free or very cheaply.


Mark.

Bearings will be no problem, but headstems can require more. Quite a while back I had Peter Stevens remove a steering pin and they had to use the 20 tonner. Don't know about pressing them in though. On the occaisions I have required that I just got a local engineering shop to do it for me.

If 20 tonnes is required , alarm bells should be ringing loudly. 20 tonnes means the interference is far too much. If fitting a bearing to a stem, stop long before 6 tonnes, let alone 20 tonnes. Remove bearing and inspect and relieve stem journal by polishing with fine emery, also check the bearing is started square to the stem axis.

If high loads are required to remove a bearing, then weaken the hoop stress by partially cutting the bearing with a steel cutting disc in a grinderette.

If removing a stem from a bottom yoke, then seriously heat the yoke so as to release its grip on the stem by thermal expansion. If all else fails and the stem is component that needs to be saved, then cut the yoke to weaken the interference fit.

Oh, and stems mostly have a very fine thread at the top that is easily damaged. Find or make a top hat spacer to protect the thread when pressing.


Mark.

Awesome, great info, thanks guys!

Yep, 6 tonnes is enough!

The $120 press ended up being $200 with freight or a 2 hour drive to pick it up Luckily, Supercheap Auto emailed me saying that club members get 20% off tools this weekend 5 min drive & $179.
Was a bit nail biting for the first bit, but all good! Now I need to work out how to get the VFR swingarm in there to press out the axle...

Pleased that you're up and running with the press already.

Mark.

sanddune51 wrote: Pleased that you're up and running with the press already.

Mark.

Cheers for the info, it'll come in handy.

Basically paid for itself today, played around by pressing out a few bicycle crank bearings I had lying around, then I got stuck into this:
Happy days!