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I had checked the slippage on my torque converter over a year ago and came up with about 8%. But after calibrating the speedometer and checking engine rpm at various speeds, it looks like the slip is more like 12-13% :eek:. This seems way too high to me. I don't know the brand of converter. The previous owner put it in, didn't know much about it, but it is supposed to have a 3000 stall speed (I can only get it to stall to about 2500 rpm).

I know my gas mileage on the freeway suffers with this much slip, but am I losing ET as well? My 60 ft time has been as low as 1.65 with a 3.50 gear, so it seems to launch fine, just wondering if I am losing much speed/ET on the top end. If I do get a new converter, what stall would you recommend for a street/strip car that sees a lot of freeway miles (180 miles RT to the track)?
 

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Stall can be effected by many things.
Weight, torque, rear gear. the torque converter itself could be going bad. The fins, (BLADES) inside could be bending or even bent.

Changing the fluid will have some effect.
A stall converter beats up on fluid!
I use "REAL" Type "F" Fluid.
I just had my Park position fixed and can tell a difference with the fluid change.

Just a idea!
Thinking out loud!
You know! If & butts!
Al
 

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Stall can be effected by many things.
Weight, torque, rear gear. the torque converter itself could be going bad. The fins, (BLADES) inside could be bending or even bent.

Changing the fluid will have some effect.
A stall converter beats up on fluid!
I use "REAL" Type "F" Fluid.
I just had my Park position fixed and can tell a difference with the fluid change.

Just a idea!
Thinking out loud!
You know! If & butts!
Al
type f shifts harder, correct?
 

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"Loose" converters generally slip a decent amount at low speed/rpm cruising..As long as it is efficient at WOT you're good...

P.S. I use el cheapo brand Type F fluid..
 

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what do you guys think about b&m trick shift this is what i use seems to be fine trans works great although my front seal is leaking a tad :eek: but that dont matter got a 8" 4500 converter coming :yes:
 

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what's "real" type f?
They have transmission fluid that is Dexron/Mercon Type "F" mix. It is not true Type "F" fluid.

And I have used all kinds of brands. The el cheepo Auto store brand is good for me! ALSO!
 

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what do you guys think about b&m trick shift this is what i use seems to be fine trans works great although my front seal is leaking a tad :eek: but that dont matter got a 8" 4500 converter coming :yes:

I have used it, don't see the big change, not cost effective. (IMO)

Now I have heard of some using the Hy-tran tractor fluid. This is a friction based Hydrolic fluid. lot of pro racers run this. I have no idea about street use.

Al
 

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Slippage

Trick shift is bad news for a trans. Similar to putting sand in your trans. Ask a really good trans builder. Regular Type F has better friction modifiers then regular ATF.

12% slippage is an very inefficeint converter.. Think of it this way, a well built converter, 10" may slip 4-5%, if yours slips 6-7% higher, you are baking the fluid, cooking the band, and compromising the clutches, and giving up mph and ET. I switched from a junk converter slipping that much to a tight well built version and picked up .3 and 4mph behind a healthy smallblock (10.2's at 127mph)
 

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Discussion Starter #10
12% slippage is an very inefficeint converter... I switched from a junk converter slipping that much to a tight well built version and picked up .3 and 4mph behind a healthy smallblock (10.2's at 127mph)
I agree it is very inefficient, just didn't know how much it might be hurting my ET. Your result speaks for itself :yes:. My motor is not nearly as "healthy", but if I could pick up 0.2 that would put me almost into the 11's :D. Just have to decide what stall speed I can live with on the street.
 

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Don't be afraid of high stall on the street. Be afraid of the temp it generates. More you shear hydraulic increases heat. More stall more heat. High stall RPM means that you will commit to cooling ATF. You will need a dedicated ATF temp gauge and most definitely a way to control the heat generated by the high shearing, rubbing and friction. You will need additional radiators to control the heat (Trans coolers).
Depends on how you drive. You can tool around town all day long with a 5000 stall and be temp fine. Put your foot into it any length of time and watch that temp gauge climb.
 

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Don't be afraid of high stall on the street. Be afraid of the temp it generates. More you shear hydraulic increases heat. More stall more heat. High stall RPM means that you will commit to cooling ATF. You will need a dedicated ATF temp gauge and most definitely a way to control the heat generated by the high shearing, rubbing and friction. You will need additional radiators to control the heat (Trans coolers).
Depends on how you drive. You can tool around town all day long with a 5000 stall and be temp fine. Put your foot into it any length of time and watch that temp gauge climb.
Correct. Although, a "good" 5000+ converter will slip a lot less then an off the shelf 10" "3000" unit...Never confuse stall speed as inefficiency...
 

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Discussion Starter #14
ATF Temp

My concern with high stall is related to the frequent hills I have to drive, including one mile of 10% grade to get to my house and the Conejo grade on 101, about 3 miles of 7-8% grade. What is an acceptable ATF temp for short and extended time periods? Does ambient temperature have an impact like it does with engine cooling?
 

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My trans guy, John Winters (JW Transmission), told me to keep the trans temp below 200 deg. Wasn't easy, went through a few different coolers. Wound up with a double stack from Derale, it has it's own fan.
 

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Discussion Starter #18
How do you tell if your torque converter is slipping and how
do you tell what percent? I dont have a speedometer.

Thanks
First, welcome to the site! Great place to get info :yes:.

You need to have MPH, engine rpm, gear ratio and tire diameter. I put the formulas in a spreadsheet and set it up the way I want, but you can download a program that will do the same thing at www.virtualengine2000.com or similar sites. If you input rpm, gear ratio and tire diam, it gives calculated MPH without converter slip. Add RPM until you get the right MPH and that is the amount of converter slip. Divide slip by total rpm to get percent.
 

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12/13 % is way too high especially on something that only stalls around 2500-3000.

I have a ten inch that stalls around 4200 and it slips around 5% on the top end. The tranny temp hardly even registers on the gage because I am only holding at 3000 on the 2 step. I think I have seen 160 degrees max so far. But it is the launch hold that spikes the temperature pretty quick.

I had an 8 inch that was very loose, so loose I thought the first time I tried it running it up on the trailer I thought that there was not enough tranny fluid in the system. But it sure let the rpms go high on the launch.
 

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before changing convertor change fuid to type F, if you notice more slippage than before could be the fluid breaking down and maybe trans starting to slip, this may take care of both, then check % again. Run a nice big cooler.
 
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