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Converter Slippage Down Track?
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Author:  Ken0069 [ Mon May 28, 2012 7:32 pm ]
Post subject:  Converter Slippage Down Track?

How much is too much? Right now mine figures out to right at 15% at the stripe?? That sounds like a lot to me? :-k

Author:  shrinker [ Mon May 28, 2012 7:39 pm ]
Post subject:  Re: Converter Slippage Down Track?

Did you factor in tyre growth? Add in about 4" circumference change for your speed range.

Author:  Ken0069 [ Mon May 28, 2012 7:42 pm ]
Post subject:  Re: Converter Slippage Down Track?

Just checked the Camaro logs from last year and that converter was only 11%??

Author:  Ken0069 [ Mon May 28, 2012 11:21 pm ]
Post subject:  Re: Converter Slippage Down Track?

shrinker wrote:
Did you factor in tyre growth? Add in about 4" circumference change for your speed range.


Didn't see this until just now. :-k Not sure what tire growth has to do with the difference between tranny output shaft RPM and engine RPM at the finish line?

What I'm basing the slippage on is the difference between engine RPM and driveshaft RPM at the stripe. I don't have the exact numbers in front of me now as I'm in bed but the engine is around 7600 and the output on the tranny is around 6400 in high gear.

The car is trapping @ 140 MPH with a 33" tire and a 4:56 gear in the rear. If you do the math on that you'll come up @ around 6500 RPM on the pinion yoke/tranny output.

Author:  shrinker [ Tue May 29, 2012 1:24 am ]
Post subject:  Re: Converter Slippage Down Track?

Thats Ok if you have input and output RPM. I thought you were going off track speed.

Author:  Beretta [ Tue May 29, 2012 5:25 am ]
Post subject:  Re: Converter Slippage Down Track?

Ken I am at 11% in the quarter mile..I would say it's loose but remember loose is constant...

Author:  Ken0069 [ Tue May 29, 2012 8:26 am ]
Post subject:  Re: Converter Slippage Down Track?

Beretta wrote:
Ken I am at 11% in the quarter mile..I would say it's loose but remember loose is constant...


Yeah well, I'd say that 15% is definitely loose, hey! :-k

Author:  rick360 [ Tue May 29, 2012 9:17 am ]
Post subject:  Re: Converter Slippage Down Track?

From what I've seen and heard there are different ways to make a converter and they have opposite effects.

-If you have a stator that is good at multiplying torque it will be loose downtrack.

-If you have a stator that is tight downtrack it will not multiply torque good.

You can't have both.

If a converter is loose downtrack you can't run as much gear, but it multiplies the torque better. If it's tight downtrack you can run more gear. Which way do you want to get rear wheel torque?

Note that I am talking tight or loose "downtrack" as this is a totally different thing than stall speed. Torque multiplication and stall speed are independent functions of a torque converter.

Rick

Author:  Beretta [ Tue May 29, 2012 9:57 am ]
Post subject:  Re: Converter Slippage Down Track?

Also I hear that you need to build a different converter for 1/8 than 1/4
And I have a diod

Author:  Coloradoracer [ Wed May 30, 2012 6:04 pm ]
Post subject:  Re: Converter Slippage Down Track?

I was at approx 11-13% on mine, and the car could almost zerox timeslips (1/4 mile). My front pump broke and I smoked the trans, so after getting it back together, I sent the converter back out for a cut and clean, and to have it tightened up just a bit. The consistency was there before when it was substantially tighter, but I needed it looser for my combo. I'm going getting it tweaked a few hundred rpm........We'll see what it does when it gets back.

Author:  Ken0069 [ Wed May 30, 2012 7:53 pm ]
Post subject:  Re: Converter Slippage Down Track?

The converter in the dragster now is a Trans Specialties that I bought from a guy on RJ that was suppose to be "low use". Had him send it directly to BTE and after they opened it up, it was indeed a low use piece. So I had them convert it to spragless and tweaked the stall up about 500 from where the one that was in the Camaro was.

It's at 5000 on the two step, then flashes to 6500 and at the gear change at 7600 it only drops 600 RPM. Then it's 7600 at the stripe.

It's loose enough down track that the first few passes I made I didn't even notice the gear change, but it did do the gear change because it was in high gear.

I've still got the converter that was in the Camaro and it is a little tighter than this one. It also has a sprag in it. That converter was 5000 on the two step, flashed to 6000 then the gear change at 7600. RPM drop at high gear was to 6300 then it was trapping around 7500. The Camaro had a 1:80 planetary and the dragster has a 1:69 so the RPM is going to drop less with that ratio.

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