M3 screws seperate
 

Hi Guys,
The screws holding the hinge pin blocks onto the Cat SX are prone to bendages, and I highly recommend people check these after each meeting at the minimum - after each heat if you feel the car is getting some abuse.

Until now, these screws have only been available in a large pack of screws - so you end up with many other screws to get just the ones you need. Which isn't such a bad thing at first, but eventually you'll end up with loads of other screws. :lol:

But now, Nortech have come to the rescue, and are supplying the M3 screws individually. They are as follows:

M3 x 10mm cap head
M3 x 12mm cap head
M3 x 20mm cap head

If you haven't already got spares, I recommend any Cat SX owner to carry many of each of these to ensure that when they bend (they will), the screws can be replaced straight away and the SX will continue to handle like the awesome machine that it is. :thumbsup:

http://www.nortechracing.co.uk/

Chris

You can never have too many screws Chris!! :p

:thumbsup:

Those are M4 if i remember correctly.....those that are screwed into the bulkheads

Dont think soo dude

You have a kit don't you? Have a look in the manual. :lol: They are M3 though.

Agreed!!! :thumbsup:

you are right, my mistake.:blush:

And yes, they are prone to bendages.

So, TEIN, the question is - will Nor-tech ship to Singapore? I reckon he will.

I have tried several times to buy these now and when I get to the pay part it just goes to a Paypal error screen??? How do I pay!!????

you have pm :)

Selling screws is like making love to a beautiful woman :thumbsup:

you mean we're being screwed :lol:

:lol: i never had the intention to get screws half the globe from UK. I reckon that Nortechs are quality stuff but its simply not cost effective for me....But i have no choice when it comes to the CAT's spares. :yawn:

I am putting high tensile M4 screws on mine, can't be bothered with these bent M3's.

Bent mine today and it resulted in a broken outdrive :cry:

I think I will do the same on mine... do you have pictures of mods you've made?

I'd be careful guys, you may end up damaging other parts :(

G

Agree with you Northy, more damages on wishbones are predictable... :yawn:

BTW, I made the mod on the front end yesterday and I will do the same on the rear end today... Some pics very soon ;)

I was thinking more like putting more stress into the gearbox sides and chassis :o

G

Here is the mod consisting of replace the M3 screws of bloc pivot by M4 screws.

The front end with machined button head M4 screws:

http://img504.imageshack.us/img504/3674/dscn8663xv3.jpg

http://img504.imageshack.us/img504/500/dscn8664ho0.jpg

http://img504.imageshack.us/img504/6505/dscn8665nq5.jpg



The rear end with machined socket head M4 screws:

http://img440.imageshack.us/img440/8545/dscn8666qs7.jpg

http://img504.imageshack.us/img504/6151/dscn8667na9.jpg

http://img440.imageshack.us/img440/3407/dscn8672as2.jpg

Hi Olivier,
Now thats hardcore :thumbsup:

Fancy bagging up conversion kits prepped to be built this way? (as many of us, such as me, won't want to do this mod) Im guessing it'd need gearbox halves front and rear, all the purple blocks and the 12 screws? ;):thumbsup:

How much?

Nice job! I'll have a conversion kit as well if there will be one :D

I have M4 screws in mine also. Sorry didn't see the post asking for photos before, I will sort some out later.

Northy, it is not possible for the mod to put more stress on the transmission housing, if anything it takes away stress.

It's not exactly a hard mod to do, although I will put a step-by-step guide in my follow up review soon to be finished.

It must put more stress into the gearbox sides....

G

The gearbox sides have enough material in them (especially the front) the pivot blocks are more of an issue when drilled out.

I even know team drivers running the car with the front end modified

Who? :confused:

I must admit I had thought about it.

G

How? It takes it away.

Just got in from work and I'm doing maths again already....

M3 = Nominal diameter 3 mm
M4 = Nominal diameter 4 mm

Stress = Force / Area

Therefore stress is inversely proportional to area.

Circumference = pi x d

M3 = 3.14 x 3 = 9.42 mm
M4 = 3.14 x 4 = 12.56 mm

Obviously this is a 33.3% increase in surface area, thus stress around the screw will drop by 33.3% also. So therefore the stress will be reduced on the housing with a bigger bolt.

Thanks Chris !!!!

I do not plan to produce a machined M4 and M3 screw set but if some of you want I could make an effort... I would prefer to let you drill and tap the require parts (gearbox halves, bloc pivots, spacers) 'cause it take a while and I have to do it for French guys who already ask me :D

Once I will do the job on french side, I will consider your demand Chris as my small contribution to Team Schumacher UK :D

Olivier

The ration between M3 and M4 is quite still the same but you must consider the core diameter of the screw: 2.5 for M3 and 3.3 for M4 ;)

The key is in detail. Never clever to correct someone without reading their post. I was clearly referring to the nominal diameter of the screw body.

oOps sorry Glypo, it was just my 2 cents on the topic.... :blush::cry:

BTW with your considerations above, I agree with you calculation ;)

Ok, but if force x is put onto the purple wishbone pivot pin hangers, and is enough to bend the screws, if you put bigger screws in, and then apply force x again, isn't there more pain on the gearbox sides now as the screws don't bend to 'save' the gearbox sides? :confused:

G

i agree with you G, the force absorbed by screw bendages is transferred to another part. That could mean more broken wishbones, or bendages to the gearbox.

But also in theory the calculations make sense, but what is lost marginally is surface area of gearbox half by putting bigger holes in.

Personally, I can't see the gearboxes bendage-ing, so it'll be wishbones. But if running the mid-flex wishbones whats to say that we won't even bend m3 screws... :confused:

oh, there are just too many variables, and ive had too much wine to think about it. :thumbsup:

Oh right, I see your logic now and why you say more stress.

For sure, as the screws bend, they will absorb some force. However the screws don't bend too much, and even so they do not break. A breakage releases loads of energy.

The small bend will absorb maybe 2-5% of the impact energy, the rest has to travel through the transmission housing as stress and strain. And once they are bent, the extend to which they can bend further is limited so the transmission housing then takes 100% of the impact.

So I think this mod adds no extra stress really, and saves hassle of bent screws. I will test it out next weekend at the MK GP, that track will no doubt test their strength. Nice and easy to do too, you only need two drill bits and a M4 tap :)

Sorry for double post, you posted as I was replying. (I also have had a little to drink so replies seem to take longer with other distractions).

The hole cut makes no difference, as the gap is filled by the screw so there is no real strength loss in terms of that.

and a bigger leaver moment from the bigger screw, ie bigger bar easyer to bend,

Nope. Moment = force x perp. distance from pivot.

The M4 screws I have used (high tensile steel cap screws) are the same length as the standard M3's.

Forgot about this. Anyway, tonight when putting my medium flex wishbones for the MK Racing GP tomorrow I remembered and took a couple of snaps.

M4 high-tensile scew mod. Takes 20 mins max - and hopefully will solve the issue.

http://www.glypo.com/reviews/sx/m4-2.jpg

http://www.glypo.com/reviews/sx/m4.jpg

Any chance you could maybe put a hing pin straight the way though?

A

I see where you are coming from, and yes and no is the answer.

There are two mount points, you could put a pin through the first mount point, but the diff is in the way for the second. There is no movement at that point though, so no need for a pin, and it won't add much strength over a screw of the same diameter.