adjustable cam sprockets for 91-95 belt

[Juglenaut]

2024 does not out perform all steel alloys in all specs. It may however excell in different areas over steel alloy. the only real benefit is it weight factor.

The steel that the cogs are made out of OEM have high tensile and are made to work hot. The hardness of the cogs out perform even forged vanadium steel.

I am not opposing this idea, I am just stressing other options.
Since the cog moves the cycles of limitations can be reached sooner than just starting the car every time, and since it is a two piece then there are stresses involved.

Like I said the timing system has a considerable amount of tension pulling on the belt, every time the cog moves the tension or weight is placed on a different part of the cog so in a sense the shear stays in the same place as the cog rotates, this weight pushes on the top part of the cog putting the force directly on the inner cog retainer outer side and shared with the inner side retainer bushing. After 500,000,000 rotations the 2024 aluminum will start to conical, in other words in one year it will fail faster if a daily driver.

This is not a belt driven cog like that of which you see on some motorcycles. GM made these cogs the way they did for a reason, and to save a few grams on rotating mass is worthless if it fails.

I will write it down that you actually know the physical properties of aluminum in most substrates. Sorry I can't read your mind I will try harder next time.

I don't know where you get your forged goods from but aluminum and steel alloy are about the same. Actually 2024 cost about the same has moderate grade stainless and some high grade steels.

Cogs are getting pushed, pulled, and torqued is that uniform....

[dohcfiend]

hey juglenaut, how do you think a 1 piece application would hold up?

being if i wanted them copies of the stockers? originally i wanted them out of 7075(which i thought was strongest and the most wear resistant type) but i have to do a little digging into 2024 it seems.

i am kinda in the same boat with you on them being adjustable. but i can also see that adjustable aluminum gears have been made be4 for honda's and they hold up fine.

lastly, if i did have aluminum replacements, would i need that lock washer made out of aluminum too or should i keep the original and use it to lock down the aluminum gears?

[Juglenaut]

7075 T6 (even at T4) out performs 2024 at T6.

7075 will if it is alittle thicker at the bolt mounting. 2024 would work nicely like I said, but it has draw back worse than 7075 which more so matches graded steels used in medium hardened bolts.

2024 t6 only advantage is weight factor. Heat is a major factor when choosing a aluminum alloy.

[Kohburn]

qualities vary somewhat depending on the manufacturer of the alloy - but generally speaking 2024 and 7075 are close to the same in strength - 2024 is used more in automotive aplications due to its superior corrosion resistance - 7075 will work fine as long as its coated/anodized

6061 would actually be fine and most likely outlast the rest of the engine - its not quite as hard as 2024 or 7075 and not quite as strong but is usually cheaper to machine - takes to a nicer apearance whenm anodized - and is still plenty strong for this application --

heat is a factor when using aluminum for pistons, not for pulleys - if you get the aluminum hot enough to cycle it on a belt cog then you just metled your belt in half

most of these allows are rated for over 100,000,000 cycles of reveresed strain of over 20,000psi... that means 20,000 one direction then 20,000 the opposite direction 100 million times before fatigue will happen. thats not compression then tension.

GM doesn't make things on a production engine because its the worlds greatest design - they do it because thats what was cheapest way to get the job done. in high volume production the cost aluminum is higher than steel - but the cost of the machining required for low volume makes steel more expensive.

I appreciate your interest and all - but unless i ask for help to design something - i don't need it. You automaticly assumed that you were the only person on here that knows anything about metalurgy or mechanical design. I wouldn't have a business doing things like this if i didn't.

since nobody wants these feel free to hijack this thread all you want now

[bszopi]

Here is the interest and comments I had when I was working on a design back in the spring...

http://60degreev6.com/discussion/viewtopic.php?t=5416&start=0&postdays=0&postorder=asc&highlight=

[Kohburn]

its kinda sad that people aren't interested in this - just a quick glance around shows that most companies charge around 120 PER cam sprocket

[dohcfiend]

hey i was interested, i even sent a sproket for mockup. whatever happened with that anyway brad?

if nothing else kb, just get a set for yourself and show them off

[your_I.D.]

Why dont you modify the original gear. The extra ones I have are tapered on the backside. On both the inside edge of the outer gear and the outer edge of the center hub. Two rings one on each side. the outer would have to lock to inner hub with a couple of fingers.




rough idea of what I'm thinking

[your_I.D.]

guess my idea is similiar to kohburn's idea.

[Kohburn]

hey i was interested, i even sent a sproket for mockup. whatever happened with that anyway brad?

if nothing else kb, just get a set for yourself and show them off

if i can get 5 people serious about them at 300$ then i may still make them - i'm collecting names so if you want to be on the list let me know - if we manage to find more people the price will go down

[dohcfiend]

well as we discussed, i am not ready to take that particular route. i would just like a set of stock copies in 7075 aluminum, maybe add on that coating you were referring to. i may try to do a group buy but i doubt any1 but me would want them.

as long as they can be done for that price we discussed(or a reasonable ballpark thereof) i will be ready to do business around feb1.

[your_I.D.]

$300.00 a set. HMMMmmm Need a set of cores? Will they work on 97's? Is there a limit to how many degrees you can advance or retard, without moving center section on cam?

[Juglenaut]

I rather time it the way it have done it in the past.

Actually the pullys will get about as hot as the engine, if not alittle hotter...

No you ass u me, I have my own opinions so do you but I don't bash you. So who is the ass now probably both of us.

I never said it absolutly can't be done. I still stand of GM's engineering of this cog.

Bszopi's design concept effectively makes the inner disk stronger spreading the forces evenly. Half the weight double the mass.

[Kohburn]

$300.00 a set. HMMMmmm Need a set of cores? Will they work on 97's? Is there a limit to how many degrees you can advance or retard, without moving center section on cam?

nope - no cores - these are fully cut new teeth and all - they are designed to allow the 13* max in both directions - this is partially to prevent damage to the engine if the outer ring were to slip for some reason such as under tightening.

[SappySE107]

You can't retime accurately to compensate for belt stretch since it will change the position of the cam and sprocket together. Only way to know its back in time is with the cam flats unless you add a key, which would require more work from the owner or new cams.

Im also curious how well the cams will stay put and let you adjust them since there are only 3 positions that the cams will sit still decently for you to be able to adjust them. Also, would you be able to get in there without pulling the plenum and belt cover?

I still have no interest in a set as I can't afford them and I can do the timing changes I want already without using them. They work well for cars that are keyed because it allows them to change timing. We can already do that. You would also have to remove your cam gears to install these which means most likely for the 91-93 owners, pulling the rear cam carrier.

Just throwing this out there.