Cam gears- materials,design,failures

[Nismo32R]

i've got tomei one on my car......heard HKS ones wont last long as they use alunimium teeth where as Tomei, GReddy, OS Giken and etc are using steel teeth....correct me if i'm wrong

i payed around $420 delivered from Nengun

[lwells]

How many engines would be missing their cam belt covers if adjustable timing gears were matt poo brown rather than pretty anodised purple or blue or gold?

I mean, Trust even made a clear cover....

LW.

[T0nyGTSt]

I use OS Giken. They're forged and complete overkill for that purpose.

T.

[Race__24]

I wouldn't have thought that three screws would be sufficient enough to hold the gear in place. not due to the strength of the bolts but because the force is a lateral one. Being ally i would tend to think that after time the bolts might eat into the material, causing them to loosen.

Having said that i could be totally wrong, but personally, I like................

OVER KILL!!!!!!

[proengines]

The force on the bolts is not really a shear force. The bolts dont transfer the majority of the force, they clamp the 2 halves of the gear together and the friction between the 2 mating surfaces provides the drive. the load of the bolts is mostly tensile.

If you're worried about 3 6mm bolts providing enough clamping to drive the cam, never look at an OS-giken twin plate clutch, they use 6 or 8 6mm bolts to hold the pressure plate on and these can transmit 600Nm of torque.

[otto]

On the "series 1" design of the HKS cam gears, the metal used for the teeth the belt sits on is too soft, and I have seen a few which have worn away pretty quickly (under 15,000kms). You can identify the series 1 design as having the purple center and blue outer edges.

The "series 2" design is made out of the same metals as Tomei's cam gears, and I havnt heard or seen any problems with the Tomei ones.

I know this sounds dumb, but how does a rubber belt wear out an alloy pulley?

[proengines]

It's not the belt that wears the pulley, it's the dirt and dust that gets squeezed through between the belt and gear. The dirt can embed in the belt and continually wear away at the pulley, similar to sandpaper. It's a good reason to run a belt cover.

[Sydneykid]

It's not the belt that wears the pulley, it's the dirt and dust that gets squeezed through between the belt and gear. The dirt can embed in the belt and continually wear away at the pulley, similar to sandpaper. It's a good reason to run a belt cover.

Completely agree, plus over tightening (the belt tension), I have seen some that you could play like a violin.

[MrMayhem]

Im another for seeing a few pairs of the earlier hks gears wearing, apprantly teh new generation ones have a harder gear material,

[Sydneykid]

Im another for seeing a few pairs of the earlier hks gears wearing,  apprantly teh new generation ones have a harder gear material,

I have seen 2, one had the belt so tight it's a wonder it didn't run the front camshaft bearings. It also had loose pulley bolts. So the pulleys were floppy around. Any wonder it wore the teeth. The second one I was called in to have a look at. It had no top cover and they had reused the old belt on the new pulleys. The bottom cover had so much dirt in it, when they took it off, I could have grown roses.

I couldn't blame the pulleys in either case.

[otto]

i guess anything installed incorrectly isnt gonna last i bet if the pulleys are wearing the tbelt cant be to far from letting go

[carl h]

ive the trust pullies on my rb20 and they seem to be quite a piece of kit.

too bad the car hasnt moved out of my driveway in awhile, so ive no idea on the wear patterns.

i do run the covers all the time for fear of a stray stone wrecking the engine.