Topic: case cover screws replacement

[upperlake04]

Hi All - almost time to get the F3 engine back in the frame.  Thanks for the paint query Orc.

I'm wondering how to replace  the alternator and crankcase cover screws without stripping anything or having any come loose later.     Andy750 just suggested lithium grease, not anti-seize for lubrication - I can do that.  Don't want to fcuk it up and cause more chores

 Its tough being a newby mechanic and having to get everything right the first time   If only my shop was equipped with Terrys stripper and TTs pair of dykes     sorry, couldn't help myself there;)

[Peter]

I am not sure about any replacements, but ARP Fasteners or another Aftermarket manufacturer may make replacements that are torx head rather than philips... a honda desgin flaw.  If all you can come across are philips head replacements, an impact driver is the right tool for the application.  You won't be able to generate the needed torque and simultaneous down ward preasure w/o stripping the head using a conventional screw driver.  An impact driver is cheap from any parts store hardware store.  If you are unfamiliar, it looks like a screw driver with a fat handle designed to be struck by a hammer. 

[Raul CB750K1]

There has been a lot of discussion about the screws. I personall find hard to believe that it was a design flaw, as many aspects on these old hondas had proved to be very well thought with plenty of forward thinking. My personal opinion is that they used soft philips screws to avoid overtightening and stripping the threads. Maybe they make it easy and less time-consuming the assembly process, but that escapes me.

Back to topic, I found a local shop that sells bolts and screws by-the-piece, so I just got a list and bought a custom set, but you can probably find ready-made sets on internet and/or eBay.

Raul

[upperlake04]

an impact driver is the right tool for the application

I have one of those, used it to remove the screws. It only works counter clockwise, but I could get another one, they can be bought cheap.  Precision? wouldn't the size of hammer determine the torque?

My personal opinion is that they used soft philips screws to avoid overtightening and stripping the threads.

Sounds reasonable. The heads and the threads of screw and engine case are fine and I'd like to reuse them. Would a philips head bit on a torque wrench work?

[mick750F]

   The best way to keep from over tightening case cover screws is to apply the proper amount of torque. Sorry, I don't have that info in front of me right now. When I switched mine over to stainless with allen head I used aluminum anti-seize, some will tell you that copper is better. I know who Andy is citing when he mentions the use of lithium grease and trust what he has to say. However, Andy was talking about the crank cases, a much more critical connection and not a situation where you'd be switching to stainless fasteners where you'd want the anti-seize to prevent corrosion through electrolysis. I don't know if lithium grease would do the same job...maybe someone else can chime in on that.

Mike

[mick750F]

an impact driver is the right tool for the application

I have one of those, used it to remove the screws. It only works counter clockwise, but I could get another one, they can be bought cheap.  Precision? wouldn't the size of hammer determine the torque?

My personal opinion is that they used soft philips screws to avoid overtightening and stripping the threads.

Sounds reasonable. The heads and the threads of screw and engine case are fine and I'd like to reuse them. Would a philips head bit on a torque wrench work?

   I wouldn't use an impact driver to tighten the screws. They don't take that much torque going in. Removing is a different story.

Mike

[Jerry Rxman Griffin aka MuthaF'er]

Check with member Jim Spillane. Keep it in the family. He does stainless sets. Perhaps he can either put together a black allen head set (thats what I did 30+ years ago) to match your black engine or provide a list of the sizes and quantities you need. I would use an impact driver only to remove stuck nuts and bolts. If you are apt to strip threads (I have one stripped now and get to learn to helicoil) then you could always get an allen socket set and use your torque wrench (which I didn't). I have both an allen socket set and a torque socket set.

When do you decide to use anti-seeze, blue thread lock or red thread lock is a question I don't think I could properly answer. I think one of our experts could give us all some advise on that subject.
 
Jerry

[upperlake04]

All right -  thanks for the good advice. 
 The manual shows shows 5.1 - 8.0 ft/lbs torque is correct for 6mm machine screws. Expect the experts know by the 'feel' what is about right, but I really don't want to practise on this engine.  I can mickey mouse a new phillips head bit to my torque wrench,  but then wouldn't the downward pressure needed to keep the bit in the head use some of the torque value?   Also, the screws are different lengths and amount of screw thread into the engine case varies
  Maybe I'm fussing to much, but stripped aluminum spooks me.

[Peter]

There in lies the dilemma, with out being able to apply ample downward pressure one runs the risk of mangling the head of the screw.  True The impact driver offers no finesse or precision, which brings me back to offering aftermarket substitutes where even a standard socket wrench will get the job done.  My advise is based on the fact that my bike will end up as a bobber rather than a concours restoration.  I figure as long as any substitute has the same threaded dimensions, a torque wrench ought to do the rest.  I also would recommend keeping the same metal b/c aluminum and steel have different stretching characteristics and load capabilities.

[puppytrax]

Member James Spillane spillane@metrocast.net sells stainless socket head cap screw sets for the 750. He recently came into possession of the correct screw sizes for 750K3, 750C, 750F, 500K2, and 550F cycles. Presumably, he will offer kits for these models soon as well...   

Socket head cap screws [Allen head] allow a finer degree of torque. "5.1 - 8.0 ft/lbs torque is correct for 6mm machine screws" sounds like an awful lot...are you sure it wasn't in/lbs???...My ft/lb torque wrench doesn't even register any value below 10 ft/lbs...   

[Tim.]

"5.1 - 8.0 ft/lbs torque is correct for 6mm machine screws" sounds like an awful lot...are you sure it wasn't in/lbs???...My ft/lb torque wrench doesn't even register any value below 10 ft/lbs...   

Not sure what you mean - on one hand you think 5-8 ft/lbs is a lot, but then you say your wrench doesn't even register a value that low?

[upperlake04]

Lots of food for thought - thanks all for your time

  Yes, the most accurate way to go is with the hex or torx head capscrews but thats way too fancy for this project. The goal is to get the left for dead bike on the road and see what I've got. Patch, repair or buy used. I can see it for Phase 2 next winter though;D

  The by guess or by golly approach didn't seem right so you got me thinking. Heres what I came up with. I hope the engineering is correct. Torque wrench set to spec , clamped in the vise. Sample 6mm screws with acorn nut tightly fastened on the end, put into socket on torque wrench. Tested a bunch of screws from  5.1 - 8.0 ft/lbs (61.2 - 96 in/lbs) with a hand held screwdriver. The lower to middle range seemed about right but at 96 in/lbs  the screw head started deforming, the threaded part might have started twisting, and my skinny arms thought they might not be able to finesse it much more. 

 I think this is good practise for the real thing
   

[wardmoto]

Hondas case screws are slightly softer than swiss cheese...get all the bastards out and replace them...I used www.stainlesscycle.com for my 350F...they have everything and they are polished head allen screws except for pan head applications like timing covers.  Put back in with anti sieze

[Raul CB750K1]

Upperlake, that seems to be a good idea, but shouldn't the vice grips catch the torque wrench in the handle? Otherwise the torque wouldn't be accurate, isn't it?


Well, I don't have the facts, but I have the feeling that if you use a t-handle to tighten allen bolts on the side cases they will be tight enough and you will never strip the threads regardless of the force you use -this doesn't apply to you Duster... HAHAHAHA)

I recently joined the engine cases of my CB350, and having no torque specs, I just used the smallest 1/4 ratchet drive, pressing with just two fingers. Once I couldn't tighten more, I used the full hand for another tiny fraction of a turn, and that's it.

Raul

[puppytrax]

Not sure what you mean - on one hand you think 5-8 ft/lbs is a lot, but then you say your wrench doesn't even register a value that low?

It's a lot for a 6mm screw!!!   

I'm not sure where you are geographically; but a torque wrench reading in ft/lbs is a 1/2" drive wrench here (typically 18" long). Torque wrenches reading in in/lbs would be 1/4" drive or possibly 3/8" drive - Ii don't have one of either.

My 18" x 1/2" drive ft/lb torque wrench won't read below 10 ft/lbs because the spring used to "click" (it's an audible torque wrench) is rated at more than 10 ft/lbs...

[upperlake04]

Upperlake, that seems to be a good idea, but shouldn't the vice grips catch the torque wrench in the handle? Otherwise the torque wouldn't be accurate, isn't it?

You may very well be right Raul. My thoughts went in the other direction. If the torque wrench was set to spec and its socket slipped over a nut which was clamped in the vice, and then torqued to click with a meter long cheater pipe over the wrench handle - wouldn't it click at the same torque value but just use less muscle?  Difficult to intuit this one.    Hope an engineer will comment on this.

It's a lot for a 6mm screw!!!

I really hope you're wrong PT   Somethings wrong if I'm out by a factor of 12

[Raul CB750K1]

Upperlake, that seems to be a good idea, but shouldn't the vice grips catch the torque wrench in the handle? Otherwise the torque wouldn't be accurate, isn't it?

You may very well be right Raul. My thoughts went in the other direction. If the torque wrench was set to spec and its socket slipped over a nut which was clamped in the vice, and then torqued to click with a meter long cheater pipe over the wrench handle - wouldn't it click at the same torque value but just use less muscle?  Difficult to intuit this one.    Hope an engineer will comment on this.

It's a lot for a 6mm screw!!!

I really hope you're wrong PT   Somethings wrong if I'm out by a factor of 12

Now you got me thinking Upperlake, because I've always assumed as a fact that you must grab the wrench by the handle, but on the other side, the wrench arm is fixed so it shouldn't make any difference where do you apply the force. The "clicking" head pivots very near the head itself, and the twisting handle adjusts the spring force in such a way that once you are using more torque than set the head "clicks".

Now let's assume the same example. You get your wrench on the vice and just the head protrudes. Instead of twisting a nut or bolt, you apply a perpendicular force to the head until it clicks. Now you grab the wrench by the handle and apply the same force in the same direction. Assuming the arm is perfectly rigid and there is no bending, shouldn't the head click at the same force?


And I thought all those physics classes were worthless...  ;-)

Raul

[mick750F]

It's a lot for a 6mm screw!!!

I really hope you're wrong PT   Somethings wrong if I'm out by a factor of 12

   5.1-8.0 ft-lbs is what the Honda factory manual calls for as a standard torque value for a 6mm screw.

Mike

[upperlake04]

Now let's assume the same example. You get your wrench on the vice and just the head protrudes. Instead of twisting a nut or bolt, you apply a perpendicular force to the head until it clicks. Now you grab the wrench by the handle and apply the same force in the same direction. Assuming the arm is perfectly rigid and there is no bending, shouldn't the head click at the same force?

You lost me there Raul    I think you might be agreeing with me    but I didn't take any physics classes so you'll have to draw a picture 

[Raul CB750K1]

Grab the wrench on the vice in such a way that only the head protrudes. That is, you grab it just below the hinge point. With the palm of your hand you press the head until it clicks.

Now you loosen the vice, and grab the wrench by the handle. If the arm is perfectly rigid, with the palm of your hand you should be using exactly the same force to make the head click, isn't it? Then I think I'm agreeing with you, but I should have to make a draft trying to discern what's different and it's too late. Maybe tomorrow... ;-)


Raul

[puppytrax]

   5.1-8.0 ft-lbs is what the Honda factory manual calls for as a standard torque value for a 6mm screw.

...In *aluminum*...Please post how that works for you...

[upperlake04]

Grab the wrench on the vice in such a way that only the head protrudes. That is, you grab it just below the hinge point. With the palm of your hand you press the head until it clicks.

Now you loosen the vice, and grab the wrench by the handle. If the arm is perfectly rigid, with the palm of your hand you should be using exactly the same force to make the head click, isn't it?/quote]

Thats clear now Raul. Thanks.  The force is equal either way. The wrench doesn't care which end is stationary or moveable or how much leverage is used to make it click. All that seems to matter is the amount of force required to overcome the mechanical internals. I'm happy with that   Are you pros getting a chuckle with this?

...In *aluminum*Huh...Please post how that works for you...

PT - a scan from the Clymer Cb750 SOHC Fours 69-79 manual. Not too clear but the top line reads 'crankcase and crankcase covers    5-8 ft/lbs    70-110Cmkg'

[puppytrax]

...In *aluminum*Huh...Please post how that works for you...

PT - a scan from the Clymer Cb750 SOHC Fours 69-79 manual. Not too clear but the top line reads 'crankcase and crankcase covers    5-8 ft/lbs    70-110Cmkg'

Sorry - my bad...That was just supposed to be three question marks...not a "Huh" face...

The crankcase I can understand...good size bolts there...but the side covers???

Oh, well...If the manual says it, it must be good!   

[cd811]

I used black hardend(grade 8 I believe) Allen screws on mine...they looked cool...easy to torque down...but after rain,  they look like #$%*...wish I had used stainless or chrome

[Andrew Foss]

just bought a stainless hex set off of ebay (buy it now, 30 bucks), and i will never worry about those damn phillips head case bolts again. though the downside is that the kit did not come with any indicator of what goes where, but almost everything will be put in as the other comes out so there should not be much guesswork.
-andrew