Transmission inconsistency Question

[Sam Capizzi Jr]

3 weeks ago I had a trans line come off the cooler. I fixed line at track and added about 5 quarts of dextron/mec to Type F in my 904. (Dex was my only option at the time). My problem is that the car went 13.65 on the next run which was normal but the following run went 13.45 and stayed fast the rest of the night while there was heat in the tranny. Fast forward to last night. Same deal. Off the trailer 13.62@ 95 Next run 13.41@ 96.5 Made 6 more runs within 2 hundredths Perfect. Then we had a 2 hr delay and the car sat in lanes. Car runs 13.65 at 95 Could the mixing of fluids cause this and if so should I go back to type f or dex.

Thanks in advance
Sam

[MR DERBY CITY]

If you decide to drain the five qts. , I will gladly buy it from you M.J.

[jmantle]

Originally Posted by Sam Capizzi Jr

3 weeks ago I had a trans line come off the cooler. I fixed line at track and added about 5 quarts of dextron/mec to Type F in my 904. (Dex was my only option at the time). My problem is that the car went 13.65 on the next run which was normal but the following run went 13.45 and stayed fast the rest of the night while there was heat in the tranny. Fast forward to last night. Same deal. Off the trailer 13.62@ 95 Next run 13.41@ 96.5 Made 6 more runs within 2 hundredths Perfect. Then we had a 2 hr delay and the car sat in lanes. Car runs 13.65 at 95 Could the mixing of fluids cause this and if so should I go back to type f or dex.

Thanks in advance
Sam

I wouldn't think it would make that much difference but if you put Dex 6 in it, it's a semi synthetic and a lower viscosity than type F. It was designed to reduce the drag in the newer 6 and 8 speed transmissions so it might have an effect.

Jim Mantle V/SA 6632

[Mark Yacavone]

I never saw straight Walmart dex do that.
Maybe you're looking at the wrong fluid. Maybe it likes the oil hot.
What's in it?

[Sam Capizzi Jr]

Same 10w-40 Walmart oil from about 50 runs ago. Before that line came off that tranny fluid was 3 years and 400 passes old. New Trans fluid was just basic dex/mec from autozone....

[Mark Yacavone]

Sam, With a "challenge" combo like that, I believe I'd put about 4 and 1/2 0-20 Mobil One in it.

[ss3011]

Dextron is a series of fluids that were developed by GM. GM controls the licensing of the fluid. If a company wants to sell an ATF that says Dextron on the bottle, they have to submit samples to GM, it then goes through a testing program to prove it performs like a Dextron Fluid should, and if it passes then it is allowed to be called a Dextron Fluid. Type F fluid acts quite differently then Dextron. My recommendation is to drain your mixed batch of fluid , and replace it with either Dextron, or Type F. Full synthetics seem to be the best, and seem to be more consistent cold to hot. Try and keep fluid between 150, and 200 degsF.

[J.R. Haddad]

Sam, you added the fluid after the line broke and picked up 2 tenths. My recommendation is as follows: STEP AWAY FROM THE CAR AND DO NOTHING!! J.R.

[Adger Smith]

The fluid mix could be messing with a sprag or the sprag could have been hurt when the line came off. I had a BB Mopar customer that HAD to have heat in his to make it consistant. He put a spragless converter in it and the heat issue went away.

[Sam Capizzi Jr]

lol. Yeah the two tenths is great but it's impossible to dial in the later rounds. Cost me a lot of money in the last 3 weeks. The week it came apart I made it to the final and car picked up 7. Next week, 5 cars left with bye to the final on the line at the can am combo race. Picked up 5. And last night slowed down 18. No Bueno.

I'm going to drain it all. Use dex and see what happens.
Try a lighter weight motor and make sure trans is at 150 when staging.