stuck case screws

[hoogerbooger]

Is it safe to use a hit with a mallet type of impact driver to undo stubborn case screws......or do I risk bending the casings ?

Trying to take B40F outer timing case off. Screws are a mix of slotted, some with shallow slots, a couple a bit mashed. 4 not keen on moving.

advice/tips welcome

[V500]

It's an alloy case so impact driver every time. Never fails.

[hoogerbooger]

FOR CLARITY: I don't have a electric/pneumatic impact driver......only an old style whack it with a mallet manual one........hence my question.

[cdsdorset2]

A lot of the times just hitting a normal screwdriver will free the screw.

[DAVE BRADY]

Hi,

Before any brute force is used apply some penetrating oil and allow it to soak in.  If possible lean the bike right over so it pools around the screws and leave it over night.  Also a good fit 'T' handle screwdriver gripped with mole grips enable maximum pressure and torque to be allied without the screw driver twisting out of the slot.

Dave.   

[V500]

FOR CLARITY: I don't have a electric/pneumatic impact driver......only an old style whack it with a mallet manual one........hence my question.

Nor me, but an impact driver is good enough. Don't know about whacking a screwdriver though...

[cornishbob]

this may sound stoopid but...

a drizzle of coca cola and left a couple of hours (maybe another drizzle after a while) then GENTLE use of an impact driver.

OR...

sowing machine oil... i laughed too until i tried it

[cdsdorset2]

Just put the screwdriver in the screw. Just a sharp tap with the hammer will very often break the bond between screw thread and case. Better than force and ramping the screwdriver out of the screw causing damage.

[cornishbob]

1 drop of coke or sowing machine oil will be beneficial . trust me i'm a haberdasher

[hoogerbooger]

Is that diet or full fat coke?

Not that it matters as I have neither...but I do have Singer sewing machine oil. I may give it a go if plusgas fails.

I guess the action of a " whack-it" impact driver is potentially better than an electric as I presume the impact from those is only rotational and on the very shallow screw heads it's down to you to press against the screw hard enough that the bit doesn't jump out.....whereas the whack a mole version is driven inwards at the same time.

I did use it on 3 that did come out but pretty lightly....then thought is it sensible to whack the remaining stubborn ones harder. Will get back to this after weekend.

[hoogerbooger]

2 more out after plusgas and switching to lump hammer from rubber mallet. Light short sharp blows only.

Mmm. ....reticent to strike harder on the last 2. .

Might be able to borrow an electric impact driver....but that might pose more risk of jumping out and gouging the casing?

Does anyone use an electric and have knowledge/ advice

[Mike40M]

Correct me if I'm wrong. I think they are Phillips 3. Met a few people using #2 and destroyed screws.
My very old impact driver which only has #3 does a decent job. If used with a Triumph sized hammer.

[Stubaker58]

I've usually had success with a hammered impact driver. Hold and twist then whack!
As said above the bits are a good fit on BSA cross head screws.
It's only when the screws are damaged that crested drilling the head off; I don't understand why but with the head off and the cover raved the stub usually comes out easily with mole grips.

[hoogerbooger]

All the screws on this case are slotted. Two different sizes.

The impact driver bits fit pretty well. One screw head fairly mashed but bit not jumping out....just haven't budged them at my level of whack.

[hoogerbooger]

Well electric impact driver was no help and dangerous. Not enough whack and jumps out.