2017 3A92 engine with roller cam.

[Eggman]

Mirage rollers don't look like have a needle bearings in them.

I would expect a bushing, not bearings. Don't bushings manage high loads better than bearings?

[Daox]

Bushings and bearings can be designed to handle any load. Generally, bearings will last longer, have lower friction losses and also cost more than bushings.

[Eggman]

Bushings and bearings can be designed to handle any load. Generally, bearings will last longer, have lower friction losses and also cost more than bushings.

Thanks. I didn't think bearings would be the best choice for such a small application.

[deleted user]

There is a bath of oil the cam lobe passes through on it's way to the bucket, basically a dip in oil every revolution of the cam. Probably a roller on a pin pressed through the rest of the cam lobe. Not so sure it is necessary unless it provides an increase in efficiency which it does not seem to do. The buckets themselves spread the load and wear over a much larger part of the face of the bucket with no side loads or excess oil going to the valve under the bucket.

Reason there is no adjustment is two fold. Lash is as high as .010 inch and that range allows adjustment intervals to be spread out to the point where they are not recommended for any maintenance, just done when head work or other valve work is required.
Wear is very minimal in this design allowing 1 million mile of wear without adjustment. That's the way it was on my 1992 Sentra an extremely reliable engine, with cam chain and same valve train arrangement as this Mitsu.

regards
mech

[Daox]

They may use a journal bearing like the camshaft and crankshaft use (rides on a film of oil). I believe you have oil already running through the camshaft for the MIVEC, so running it out to the roller's shafts shouldn't be a huge deal.

[Daox]

there are a lot more efficiency changes in the engine like the top piston ring is different and coated with something,the timing chain inner link plates are made to "stick out" little bumps to reduce friction rubbing on the guides vs.the 'old' design where the entire edge of the chain assembly is rubbing on the guides...there are a lot more but we were in a hurry when I was shown some information.

Any chance you could get your hands on the presentation info and ensure it finds its way to the forum?

[3dplane]

Any chance you could get your hands on the presentation info and ensure it finds its way to the forum?

I don't know Tim! I already had a heated "conversation" with our rep over me posting "proprietary" information on the rear axle alignment thread. That's how I know that they are reading that thread.Or they used to.They may not give a darn anymore since then though.

Next time I see him,I will ask what's ok to post. This cam info came from training material/test and they usually (all manufacturers) like to stay very secretive about their inside information.

Or maybe I should handle it according to how they are helping all of us with bad axles past 12K miles and just post the entire material here and see how they like that? That's what they deserve in my opinion but I'll ask first

[Daox]

Thanks for looking into it!

[Daox]

Has anyone ever heard of a camshaft with rollers on it? I tried to do some google digging and I came up with absolutely nothing. As far as I can tell, the roller is always on the lifter.

[deleted user]

Has anyone ever heard of a camshaft with rollers on it? I tried to do some google digging and I came up with absolutely nothing. As far as I can tell, the roller is always on the lifter.

Never seen one before, the advantage is less reciprocating mass in the valve actuation mechanism which allows for lighter valve springs- less potential valve float.

regards
mech