Cracked variator fan? By gooter (Read 1,990 times)

[gooter]

In the process of changing from rollers to sliders on my Duke 250....I noticed these small cracks propagating out from the inner portion of each fan blade.

The cracks are not through to the other side. I did notice that on several sites while looking for a new fan...eBay and some other parts places...the same cracks are visible on the vendors pics of the same fan.

Is this just how this fan is casted at the factory or is it a flaw?

[cyborg]

I looked at the raw data image and blew it up till it was as big as a diner plate,,,,,I believe this is a casting problem in the die cast mould,,, not in the part,,,it is just a shadow of cracks in the mould ,,,I would keep an eye on them tho to make sure they are that and don't get bigger if I am wrong,,,that would be ugly if it exploded,,, one way to tell if it is a shadow of a crack is use a scotchbright buffer pad attachment on your dremel tool and massage one of them to see after it gets smoothed out if there is a crack but I think it is not

[gooter]

Apr 14, 2015 19:12:08 GMT -6 cyborg said:

I looked at the raw data image and blew it up till it was as big as a diner plate,,,,,I believe this is a casting problem in the die cast mould,,, not in the part,,,it is just a shadow of cracks in the mould ,,,I would keep an eye on them tho to make sure they are that and don't get bigger if I am wrong,,,that would be ugly if it exploded,,, one way to tell if it is a shadow of a crack is use a scotchbright buffer pad attachment on your dremel tool and massage one of them to see after it gets smoothed out if there is a crack but I think it is not

That's what I'm seeing as well, cyborg....I'll clean these parts up tomorrow and give them a good inspection. If the "new" fan pics I'm seeing on the vendors websites look exactly like mine....must part of the casting process.

[cyborg]

What sites are you going to?,,,I want to have a look as well

[cyborg]

I went to google images and typed in 250cc variator,,,,some had the marks and others did not,,,I'd buff an area to see if I'm wrong,,,I still think you will find no crack once it's cleaned up

[gooter]

Apr 14, 2015 20:01:05 GMT -6 cyborg said:

I went to google images and typed in 250cc variator,,,,some had the marks and others did not,,,I'd buff an area to see if I'm wrong,,,I still think you will find no crack once it's cleaned up

Here's one vendor pic that makes me feel better about my fan...there are some more on eBay, as well.....I'm afraid to order something that is exactly what I have...don't need two fan face plates that look cracked?

[cyborg]

Yes I wouldn't sweat this,, I think it's part of the game

[gooter]

Apr 14, 2015 20:38:59 GMT -6 cyborg said:

Yes I wouldn't sweat this,, I think it's part of the game

This at least is good info for anybody else with a question about their variator fan...I've got so much great info from these forums...saved me tons of money and not mention the grief of just replacing parts that are not defective.

[rks]

The one on my 150 looks a lot worse off than yours......I too, was ready to order a new one, but after cleaning it, and a closer look with a magnifying glass, and running a tooth pick lightly back and forth over each imperfection, I found what appeared to be cracks, were actually areas of raised/excess metal left over during casting.

[Guitarman]

Yep. I think it's flashing left over from the mould.
Clean them up and I bet there is no crack. Junk moulds.
Used to see that all the time in plastic injection moulding.

[gooter]

Yikes....I think I might have ordered too heavy of slider weights....ordered 24 gram....weighed my oem rollers are 22 grams....I guess I was thinking the rollers were 24 or 25 gram from the factory from reading other posts....should've weighed them first...then ordered.

I wanted to get a slight increase in top end....right now I'm at 60mph wot on my phone gps speedometer app....I'm 180lbs or so...I ride 2 up often so I'm worried about losing my acceleration. Anybody have any luck drilling these sliders out....uni bit...drill bit?

[scooter2]

Apr 15, 2015 18:41:34 GMT -6 gooter said:

Yikes....I think I might have ordered too heavy of slider weights....ordered 24 gram....weighed my oem rollers are 22 grams....I guess I was thinking the rollers were 24 or 25 gram from the factory from reading other posts....should've weighed them first...then ordered.

I wanted to get a slight increase in top end....right now I'm at 60mph wot on my phone gps speedometer app....I'm 180lbs or so...I ride 2 up often so I'm worried about losing my acceleration. Anybody have any luck drilling these sliders out....uni bit...drill bit?

You could try them out and see. A drill will be difficult. They tend to grab, plus you won't know how much metal to remove unless you calc it out. www.sequoia-brass-copper.com/weight-calc.html If you use a drill, a vice might come in handy, but you risk bending the sliders. You can dull the corners of the leading edges of the drill to reduce grabbing. a 3/8" X 1" tube of brass with a .010 wall thickness would be almost two grams, so if you used a bit that was .020 bigger than your hole, I'm guessing you'd be close, but it's a WAG because I have no idea how wide a slider is or how big around your hole is.

A dremel might be easier but unless you cut them all evenly, you could get some imbalance. A reamer would be another option.


Just be careful. Any imbalance could put unnecessary wear on your system. I'm not 100% sure, but I think a 0.1 gram weight imbalance at 7,500 rpm on a 150 sized variator exerts a force of about a half a pound. Is that a lot? I don't know.

[Guitarman]

The extra 2 grams just means you're getting to WOT a little faster, that's all. That small of a change really isn't going to lose you much of your top end.
If it bugs you that much, then put 20 gram sliders in.

[gooter]

I used a drill press to run a test on one of my old rollers...just matched a large drill bit to the roller....ran it all the way through....spun a little in the vise.

That test yielded about a 5.75 gram difference....a little to heavy bite on that test...got 5 more roller test subjects...lol....will try a smaller drill bit...take less of a bite....scrounged around for a reamer...all too small.

I'm going to try the 24 gram...but definitely going to find the right drill bit to whittle away at these rollers to see if I can get a nice even hole and take off a little at a time.

[gooter]

Apr 15, 2015 20:21:20 GMT -6 Guitarman said:

The extra 2 grams just means you're getting to WOT a little faster, that's all. That small of a change really isn't going to lose you much of your top end.
If it bugs you that much, then put 20 gram sliders in.

Correct me if I'm wrong Gman....heavier weights=more top end(more mph)....lighter=better low end(hole shot)

I'm going to gain top end and lose some hole shot from the 2 gram increase in weight..right?