CPS Bolts

[BaySHO Performance]

Some tips on CPS bolts: the phillps head bolts are a stupid idea. The cross in them can easily get damaged, leading to potential problems getting them out next time.

I replace them with M4-0.7 x 10mm hex head cap bolts. Readily available at your hardware store. 16 gauge single strand wire to help with installation, Wire good for camshaft sensor vane bolts as well.

 

[AREA 91]

Anti seize

 

[BaySHO Performance]

An update: the wire to hold the bolt steady doesn't work. But the bolt flops about in 7mm socket. Two options:
By this magnetic socket kit from Home Depot for $35:

https://www.homedepot.com/p/Sunex-1...o3co__JGurySJ9bFowiW4cq-3tnIgDeIdHuDxfXc4pqjY

Only the 7mm will be used. Or, save your money and fill the socket with dielectric grease. Keeps the bolt straight and works like a charm.

 

[Irish Pride]

Or use your fingers to start the thread. I've never had a problem threading in CPS bolts.

 

[BaySHO Performance]

Not too bad when installing the original Phillips bolts. Much tougher with the 7mm hex.

 

[itwonder]

Thanks for posting the thread size. How about a torx drive button head instead?
https://www.amazon.com/Stainless-Bu...M4-0.7+x+10mm+torx&qid=1563501024&s=hi&sr=1-3

 

[BaySHO Performance]

No reason why those won't work, although may be more difficult to get started when reinstalling them.

 

[NoSlo]

Socket Head Cap Screw, M4-0.7mm Thread, 10mm Long, Fully Threaded, Alloy Steel, Unbrako class 12.9, Black Oxide (3mm allen key)


Install with a 3mm hex socket: easy-in with fingers, then a 1/4 drive screwdriver or rachet.

I would verify that longer-headed screws clear the timing belt before closing up the engine.

The real deal for reference:


The dot on the head lets you know the Yamaha screws are neither Philips nor Posi-drive, but rather JIS fasteners. Made in Japan. Using the right bit will help.

If you have "problems" removing you can use a handheld impact screwdriver and some extensions. Drop the subframe an inch or more on that side, or drill a hole through the wheel well if you really need a good angle.

 

[zoomlater]

Don't these need to be stainless steel

 

[NoSlo]

Don't these need to be stainless steel

The originals are, judging by their non-response to a refrigerator magnet just strong enough to pick up a similar ordinary screw.

edit: stainless might be better because it won't interact with the magnetic field of the sensor (but 100lb of engine block?)

 

[BaySHO Performance]

I'd also be concerned about clearance with the Socket Head Cap Screws.

 

[itwonder]

I'd also be concerned about clearance with the Socket Head Cap Screws.

Me too, which is why I was thinking button head torx. However, button head stainless is available in hex drive too, if one prefers that to torx.
https://www.amazon.com/M4-0-70-Butt...screws&qid=1563550704&s=hi&sr=1-2-spons&psc=1

 

[BaySHO Performance]

Used the 7mm hex heads the other day. Piece of cake to install with a 1/4" extension bar and dielectric grease in the socket to stop the bolt flopping about.

 

[NoSlo]

Home Depot has Hillman M4-0.7 x 12 mm. Internal Hex Button-Head Cap Screws (16-Pack) (Stainless) for online order only. It has a low-profile head. The shortest length of this screw not from China is 12mm, perhaps too long for the hole. The hex wrench used is quite small.



The ideal fastener is available on eBay from China - A ****** bolt (also called a washer head) that has a shoulder so you can hold the screw steady in a socket, along with a Phillips drive so that a future mechanic isn't surprised without the right tool to finish the job:

 

[zoomlater]

I give credit to Mike at Shosource for mentioning stainless screws to me when I was looking for replacements awhile back. I wasn't aware of the JIS fastener useage, another reason to replace these during the next CPS replacement.

 

[rubydist]

in the crank sensor, you want to use non-magnetic stainless fasteners to avoid interference with the magnetic signal in the pickup. I would not consider using regular steel fasteners.

When this thread started, I thought you were talking about cam sensors, as the usual designation is CPS for the cam sensor. Steel fasteners are fine in that.

 

[zoomlater]

So are these for the crank position sensor or cam position sensor. I just pulled the fasteners from a 93 ATX cam position sensor and they did not look like this and there was no dot.




The dot on the head lets you know the Yamaha screws are neither Philips nor Posi-drive, but rather JIS fasteners. Made in Japan. Using the right bit will help.

If you have "problems" removing you can use a handheld impact screwdriver and some extensions. Drop the subframe an inch or more on that side, or drill a hole through the wheel well if you really need a good angle.[/QUOTE]

 

[NoSlo]

So are these for the crank position sensor or cam position sensor?

Crank position sensor, which can ordinarily be removed with a stubby Phillips screwdriver (and then rotate the engine to a gap in the vanes).

The camshaft position sensor (CID, for cylinder ID) instead uses 5.5mm-head bolts, which are found in a few other places in the car, so a useful socket to have.

 

[NoSlo]

... I wasn't aware of the JIS fastener useage, another reason to replace these during the next CPS replacement.

Another reason not to replace them with a happenstance lookalike -- unlike Philips screws, JIS are designed not to cam-out.

Philips screws were designed specifically for auto assembly, before torque limited clutch tools. Instead of breaking the screw, the driver would be forced out of the screw head. This has cursed us since.