Torque converter questions
 

Looking for the voice of experience.
Is it common and proper to ask a torque converter company to modify a different brand of converter? Problem is I have a major brand converter that was made exactly to my specs and it launched like crap so I paid them to redo it and now it launches great but I now have over 15 percent slip at the finish line. Just don’t want to embarrass myself by asking a company to fix someone else’s shortcomings.

Explain that to the new converter company and see what they say.... I'd first reach out to the first guys and hear them out.

But yes, I'm sure all converter companies hear that a lot... Especially from Pontiac guys

It’s probably more common than you think. Some will do it some will not. Some will take a competitors brand in on trade. We switched from .We bought two abruzzis one was good one they missed the mark on. We sent one to Hughes to get reworked & I’ve had Hughes the last 11 years.

1/8 or 1/4 mile application. Do you have the correct rear gearing in the car? If a race only application, have you tried hydraulic fluid instead of trans fluid? Is the converter flashing and falling back within your power band? Do you have a data acquisition system in the car to determine the % slippage now?

Everyone running into the 10s or better should at least have a data logging tack to refer back to .

Thanks for the responses.
So John, 1/4 only , l use the rear gear to regulate rpm at the stripe. 4.10:1 105 inch tire , 138-140 mph. 6900 rpm 4.5 stroke. Stock poured block billet splayed caps.
Race only and car shows. I built the car as a retirement dream.
Please give me a specific hydro fluid to try.
As far as flashing the converter the shift light doesn’t go out between first and second and barely goes of for one second in high gear.
This isn’t a serious race effort, just a second childhood thing. I don’t have data acquisition hell I still struggle with my cell phone!!!
John we are practically neighbors, I’m in Phoenixville.

If the shift light isn’t going out on the gear change switching to jd hygard will not fix that problem. That only gets you around 200-250rpm. Sounds like you need the converter tightened up at least 800rpm. Ptc probably has the most experience with Pontiac converters. What size converter do you have now?

The converter is 8” seems to flash to 5500. During high gear stationary burnout at around 5500 my guys told be my back tires stopped spinning before I released the brakes. The sensation in the car felt like wheel spin but it was actually the converter. Crazy.
Thanks for your input and I’m pretty sure the way your car runs you’re breaking a few laws of physics! Nothing can be that fast.

Get a mount for your phone and attach it to your roll bar and focus it on your tach and gauges for data acquisition. This will tell you rpm across the stripe and you can calculate your slip. My converter flashes to 5000 rpm and slips 6.8% as an example.

See what Lane at PTC can do for you. I bought a 9" PTC from him to replace a trick 8" TCI. The car did not 60 foot any quicker or MPH better. But it gained over a tenth in ET.
They know the Pontiac torque curve.

I'll recommend giving PTC a call too. I've had on of their 10" converters with a mechanical diode in my car for several years and it's been great! Behind my 520, it flashes to 5400 and goes through the traps at 6500 at 137 mph. Slip calculator shows 5%. Drives great on the street too!

Never get rid of that converter.

The ptc converter that works on anything. 9th12ssmd

I've always been told that a converter with a mechanical diode she note be used for street miles. How often does your car see the street?

Thanks to everyone for the responses. The job of a torque converter is a real conflict. We all want it to slip like hell at the starting line and then not slip at all at the finish line. I will definitely call PTC this week and see if they’re willing to straighten out another brands converter. If I can get the slip to 10 percent or less maybe I’ll put a little more gear back in the car.
This forum is a fantastic resource

I bought this converter second hand. It was spragless at the time. I sent it to PTC to adjust it to my application and I wanted them to put the sprag back in it but they highly recommended I go with the mechanical diode at my power level.

That converter went in at the beginning of the 2016 season and has finished 6 Drag Weeks plus occasional cruise nights. I'll drive it to work a few days a year too. I'd guess 7-8K miles on it. The trans has a diode in place of the intermediate roller clutch too.

Cool, thanks for the info

There’s a lot of knowledge in the building but Kenny is the man.

So gentlemen I called PTC and talk to Lane . He said “We work on other brand converters” just fill out a spec sheet and put it in the box and ship it here. He said there slip is 5-8 percent. If I don’t loose the stahl and get near 10 percent I’ll be able to bump the rear gear to 4.30 for a little better 60ft. According to the various converter slip calculators on line I’m at 17-20 percent and how can calculators with the same input numbers have different answers?? But that’s another question for another time. Thanks again. I’ll let you know how this works out.