Circle D stall converter questions

Hey guys,

I'm running a simple 2300 TVS setup that makes 550RWHP on 93 pump gas. 6R80 auto with 3.15 gears and 1 piece aluminum DS (axle exchange). Car has 16000 miles on it. Driven with spirit and sees a T/T event upon occasion for 3-4 passes. 10.8X best ET's on 1.6x 60's.

Installed a Circle D stage III 2C (3200-3400 stall) in the car a few months back. Since the install I am hearing what sounds clutch chatter at 1500-1600 RPM when applying initial light throttle that is more audible as the gears up shift (3,4,5,6). Then it goes away. WE've been up under the car and verified that everything is snug, that the ds loop is not banging against the exhaust or DS, that the suspension bushings are good, exhaust is clearing and tight throughout, and the diff, ds, and trans have no lost motion, etc. There appears to be no slippage in the datalogs I have made and my tuner concurs with their review of the same. Conclusion is that it's NVH transmitting down the driveline from the performance grade clutches in the stall converter.

I love some feedback from anyone running a Circle D that may have had this same similar symptom and what you have found to resolve it.

Last evening someone told me that they had heard of this in stall converters in general in some applications and that adding a transmission friction modifier resolved that issue. Anyone tried this in a 6R80?

Thanks.

converter chatter has been present in both my circle d's - I usually hear it at idle(more so before going FI) never heard of adding a friction modifier- I would call circle directly before adding one, IMO.

^^^ Thanks. I don't like the idea of a modifier in the tranny at all personally but wanted some feedback on it. I only run what Ford put in the tranny originally. I feel a little more comforted knowing this. I look forward to making some passes with it soon if I can get another decent night like they had at the track last night though the air was a bit heavy.

they chatter at idle for sure. I could hear mine when I was n/a...now it gets drowned out in blower whine.

I've had my Circle D 4C converter in for 2 years I barely hear a whine at idle almost like an idler pulley barely starting to go out and you can hardly hear it and nothing else my converter works perfect I've never had any of these issues you guys are talking about

Starting to sound more like a problem with the converter after all. I hear nothing while at idle. The noise is louder in the higher gears. 5th is the worst at 40mph at 1500 RPM. All under normal driving. Its definitely TCC related as the noise goes away if the TCC unlocks or stays locked and engine speed rises above 1700 RPM in any gear.

It's coming out and going back to be gone through by Circle D under warranty. I never had this issue with the stock converter. I should have just geared down to a 355 ring and pinion. Why not? The 10R80 first gear is 4.6X and Ford is offering it with a 355 gear option for 2019.

redfirepearlgt said:

Starting to sound more like a problem with the converter after all. I hear nothing while at idle. The noise is louder in the higher gears. 5th is the worst at 40mph at 1500 RPM. All under normal driving. Its definitely TCC related as the noise goes away if the TCC unlocks or stays locked and engine speed rises above 1700 RPM in any gear.

It's coming out and going back to be gone through by Circle D under warranty. I never had this issue with the stock converter. I should have just geared down to a 355 ring and pinion. Why not? The 10R80 first gear is 4.6X and Ford is offering it with a 355 gear option for 2019.

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well because a 3.55 R&P won't deliver 1/10 the performance of the right converter for starters. I have both though so win, win.

A 3.31 swap from 3.15 would likely get me to my goal of just keeping the car in the 10's regardless of DA on the occasional TT night at the local track. It's not a competition car. Just a simple little boosted 93 octane Mustang GT that has run 10.82 at 130 best. Most passes are 10.90 - 11.15 ET range for the 1/4 on 1.60 - 1.70 60's.Its a 93 pump gas car. No interest in E85 at this point or interest in adding more boost though I could.

I'll know more when the stall converter comes out. It's apparent no one here or on another site has any similar issues or insight on what I have going on. It was worth a try. On to bigger and better things.