Torque converter increased stall?

[LilCop2002]

The torque converter in my 2010 has crapped out with 156K miles on it, with approximately 145K being mine running hard through the southern heat. Since the transmission needs to come out anyway, I'm going to have a mildly upgraded rebuild.

The local transmission shop has an OEM-style TC replacement arriving Monday but he asked if anyone had done a higher stall on one and wanted to get a custom built one with a 400 higher stall rate.

What do the big heads here say? Is there a need to try for a higher stall or is my OEM-style sufficient? I don't see a reason for an upgrade but if the transmission is already sitting on the table I thought I'd inquire.

Thanks, guys!

 

[Ecoboost_xsport]

Gearhead makes an upgraded one, but not sure if the stall is increased and if so by how much....

 

[LilCop2002]

I thought I saw Jordan with a GH but never saw any details on it here nor on GH site.

Having used the search function, I haven't seen anywhere that a higher stall was discussed/warranted.

 

[RonPorter]

Increasing the lower rpm power will increase the stall by a few hundred rpm. Just sayin......

 

[FiveLeeter918]

Circle D has done them for several members, but last I heard they weren't interested anymore. Gearhead has one, but from my understanding it's upgraded internals not a higher stall (might even be slightly lower, can't remember offhand).

 

[DadMobile]

Gearhead is OEM stall but from I was told they working on TC’s with different stall’s.

 

[802SHO]

This is a great thread and it’s very interesting indeed...what is different about the GH torque converter specifically and why isn’t it on their website? @mattr66. I bought GH’s torque converter from a person that bought it and never installed it, and I don’t even know what exactly is different about it...just that it supposed to be better, and the way Ford should have made it...is the general consensus. If @mattr66 could be so kind as to give some official details that would be much appreciated.

When I bought GH Gen3 turbos they weren’t on their website either, at the time.

 

[Jordan_R]

Upgraded internals with same stall in the GH converter

 

[Ecoboost_xsport]

Upgraded internals with same stall in the GH converter

Thats what I've heard as well. But thatbisnt very specific. Curious as to what internals and how much stall.

I emailed him some time ago about the TC and he said they are "about 20% more stout"

 

[Zpak]

Having replaced one at 59,000 miles and realizing post mortem it was exhibiting symptoms of its demise at 23,000 when I got the car, I’d take any improvement.

 

[mattr66]

More stall puts extra load on the lockup clutch in the converter. You don't need more stall because it would actually make less power before the converter locks in 3rd gear because of less load on the turbos. There would also be more of an rpm drop when the converter does lock in 3rd gear with higher stall. We really need a shorter gear split between 2nd and 3rd gear....

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[RonPorter]

More stall puts extra load on the lockup clutch in the converter. You don't need more stall because it would actually make less power before the converter locks in 3rd gear because of less load on the turbos. There would also be more of an rpm drop when the converter does lock in 3rd gear with higher stall. We really need a shorter gear split between 2nd and 3rd gear....

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Well, not exactly. Higher stall converters were around long before mfrs started adding the lockup feature in the 90s.

Remember there are three parts in a converter, and the stall involves the slip/torque multiplication factor, before the stator (sp?) makes it a fluid coupling. Higher stalls are more "slip", more heat,
and were great for heavily cammed small blocks that made no power until higher rpms.

As was mentioned above, better intermediate gearing, or a lower final drive ratio, could be a better choice than a higher stall speed.

 

[mattr66]

Well, not exactly. Higher stall converters were around long before mfrs started adding the lockup feature in the 90s.

Remember there are three parts in a converter, and the stall involves the slip/torque multiplication factor, before the stator (sp?) makes it a fluid coupling. Higher stalls are more "slip", more heat,
and were great for heavily cammed small blocks that made no power until higher rpms.

As was mentioned above, better intermediate gearing, or a lower final drive ratio, could be a better choice than a higher stall speed.

Higher stall would not benefit our cars unless there are other changes made to the rest of the drivetrain at minimum. We already have a converter that can't hold the power because the diameter is too small, thus it just blows through it as is and doesn't put the power to the ground. It isn't a good idea to decrease the unlocked efficiency even further for multiple reasons including that, the engine's short powerband, wide gear splits, and lack of lock clutch area..... These cars are heavy and make a lot of torque. The lack of converter efficiency is evident when the torque converter locking makes a major difference in acceleration....

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[mattr66]

Our converters have a custom billet stator to help redirect fluid for maximum possible efficiency unlocked, brazed fins for durability, and more lockup clutch area with a higher energy material.

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[RonPorter]

Yep. Increasing stall speed just basically reduces efficiency. Fine on an old sb Chevy or Ford that had no power below maybe 3,500, so rpm below that range was a throwaway with a higher stall.

And if the car accelerates better during lockup, that negates the entire effect of a torque convertor anyway.

Sounds like a lower stall speed, together with a lower lockup rpm, is the true need. Are there any parts from other Ford applications that could help to tighten up the internal gear ratio spreads?

 

[stripSHO]

Increasing the lower rpm power will increase the stall by a few hundred rpm. Just sayin......

Problem is these cars can already make far more torque than the brakes can handle on the starting line. I leave at 2600-2700 rpm, 3 to 5 psi, timing the spool just right so I don't push right through the brakes and red light. Add a transbrake and I have no doubt the stock converter will let you leave on 20 psi @ 3000 rpm or more. Then the question becomes whether the transmission clutches will hold.

 

[mattr66]

Problem is these cars can already make far more torque than the brakes can handle on the starting line. I leave at 2600-2700 rpm, 3 to 5 psi, timing the spool just right so I don't push right through the brakes and red light. Add a transbrake and I have no doubt the stock converter will let you leave on 20 psi @ 3000 rpm or more. Then the question becomes whether the transmission clutches will hold.

I had one customer smoke his trans twice before he realized that you can't brake stall at wot....

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[jtreber]

Yep. Increasing stall speed just basically reduces efficiency. Fine on an old sb Chevy or Ford that had no power below maybe 3,500, so rpm below that range was a throwaway with a higher stall.

And if the car accelerates better during lockup, that negates the entire effect of a torque convertor anyway.

Sounds like a lower stall speed, together with a lower lockup rpm, is the true need. Are there any parts from other Ford applications that could help to tighten up the internal gear ratio spreads?

Here's an interesting tidbit. Way back in my chev small block days and TH400. In the mid 60's GM made a vaiable stall converter with a solenoid controlled variable pitch stator. There was a company that modified these converters for racing and controlled the stator with a toggle switch. So basically you had 2 different stall speeds available, ideal on the street. Also you could flip the switch after a launch with rising rpm where torque multiplication was no long there and it would be like another gear and you could do this under full load. We ran these for years.

 

[mattr66]

Here's an interesting tidbit. Way back in my chev small block days and TH400. In the mid 60's GM made a vaiable stall converter with a solenoid controlled variable pitch stator. There was a company that modified these converters for racing and controlled the stator with a toggle switch. So basically you had 2 different stall speeds available, ideal on the street. Also you could flip the switch after a launch with rising rpm where torque multiplication was no long there and it would be like another gear and you could do this under full load. We ran these for years.

The ole "switch pitch"..... I remember when Texas Turbo had that on their square body pickup.

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[Billy VK]

OK I don't know much about these cars as far as drivetrain so I gotta ask.... what are the signs that the torque converter is beginning to fail?...