Thread: Chirp from the sc clutch?
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Old Sep 11, 2016 | 03:56 PM
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onehundred80
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From: Ontario
Default Re: Chirp from the sc clutch?
Originally Posted by Nikko
Hey BB. The one thing I might be able to add to this is that about 2 months ago, the SC circulator pump in my SRT initially became intermittent, and then crapped out altogether. That, of course, made the SC initially engage intermittently, and it quickly went to not engaging at all, due to the higher intake temp. (It went from fully functioning, to intermittent to totally non-functioning in the space of about 15 minutes).

When it was intermittent, the dropping in and out of the power increase SC provides was EXTREMELY noticeable... like when it went out, a Prius would probably have blown my doors off, and that might not even be an exaggeration.
Before I changed the circulator pump, when SC would disengage abruptly at or near full throttle, even my wife said "what the #&(@ was THAT"??? I mean, it felt like I turned the key off, the dropoff was so dramatic.

It certainly SOUNDS like your blower is not engaging when it should, but based on how my car reacted when the pump was out completely, I'd think if the blower is not engaging at all below 3k rpm, the lack of power below 3k would be very obvious.
Measuring the gap with a feeler gauge seems to be of obvious importance, but even Code 3's instructions say "check the gap between the backplate and the clutch. It should be between .20 and .30mm. The important point is that once tightened, the pulley and clutch spin freely of each other, while being as close as possible".

Before I added a shim yesterday, the SC to backplate gap WAS under .20mm, but the SC did spin freely, and I could still stop the SC clutch with my bare hands when the engine was running. Makes me wonder if I really needed the shim at all?? Without the shim, the SC engagement was really smooth and undetectable when driving. It still is now that the shim is in, but it makes me wonder if there would be increased wear or stretching with the pulley springs.
I guess we'd also have to factor in some room to accommodate heat expansion, so who knows??


Anyway, I hope some of this might be of help.
You originally state that the gap was just over .20 mm maybe .22 mm and when you added a 1.00 mm shim it was just under .30 mm maybe .28 mm. From those figures we can calculate that the gap shrank from .22 mm to (.28 mm - 1.00 mm) = .04 mm which is .0015". I think that with such a small difference we can say that there was no change as it is very hard to measure that amount with feeler gauges on such an awkward part with a clutch plate that moves.
However if it is true then the springs have relaxed by more. As designed the springs hold the clutch plate against the stops, if the stops were removed the clutch plate would move even further away from the magnet, this is because the springs are preloaded to keep the clutch plate firmly against the stops. If the plate has moved and reduced the gap then there is now a gap between the plate and the stops.
If this is true then the gap will continue to get smalleruntil the plate rubs against the electromagnetic clutch. when the plate is not energized and the car idling.
One pulley was to be set up twice, an initial setting then when the springs had relaxed to set it up again, by this time the plate would not be sitting against the stops at all. I think that that would lead to the early failure of the springs because they were not springs at all. The OEM springs are much thinner than the after market springs because they are real springs, the others get their strength by being thicker only. I do not know if the springs on later pulleys were improved.
My prediction of the after market pulley spring failures are being born out.
Some people poo poohed me at the time and later, and after some springs failed, said that was the price of improvement.
The OEM springs have to fail and have failed in some rare cases but that is just something that happens after continual flexing, it will happen much sooner in non spring material.
 
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