How does the stall converter behave, does the car move below stall speed?

**99bluebird** · 06-18-2007, 06:19 PM

I am rebuilding the trans and am thinking about getting the 9.5" 3000 stall converter from performabuilt. However I am imagining it as though I have to mash the gas and it revs to 3000 before jerking forward and breaking my neck, all day long. Since this is my daily driver I do not want much shock. In other words, will it start moving on its way up to the "stall" speed (stock moves the car uphill idling).

**Stretchs T/A** · 06-18-2007, 06:27 PM

just drive the car normally, it just takes car a few more rpms to get moving from a stop, it won't flash up to 3000, then take off. I have a 3600 stall, and it's not bad at all. A 3000 stall is a great DD stall.

**99bluebird** · 06-19-2007, 09:32 AM

So will it move at idle or 1500 rpm?

**blackTA6585** · 06-19-2007, 11:27 AM

I have a 3600 and it moves at idle but very slow not like stock. let off the brake and it will slowly start moving if thats what you mean.

**chevyguy8413** · 06-19-2007, 11:47 AM

Originally Posted by 99bluebird

I am rebuilding the trans and am thinking about getting the 9.5" 3000 stall converter from performabuilt. However I am imagining it as though I have to mash the gas and it revs to 3000 before jerking forward and breaking my neck, all day long. Since this is my daily driver I do not want much shock. In other words, will it start moving on its way up to the "stall" speed (stock moves the car uphill idling).

The car WILL move before you reach stallspeed...that is the manufacturer's spec for "power braked" maximum rpm or , in some cases, the "flash rpm" if you instantly floor the accelerator at a standstill. In normal driving, however, the sensation is one of "slippage" inasmuch the engine reaches higher (not maximum stall) rpm before motion begins....The higher design stall speed ...the more the "slippage" sensation will occur.

The intent is to let the engine reach higher rpm/'s before it is "loaded"...to accomodate the torque curve of greater duration/lift camshaft characteristics. Of course, using a higher stall speed convertor on the street compromises fuel efficiency. ANother significant side effect is increased heat in the trans fluid, which obviously mandates using an external, aftermarket trans cooler.

**99bluebird** · 06-19-2007, 02:31 PM

Thanks that is exactly what I was asking. I guess I was thinking stall speed meant when it would grab, not power braked. Makes much more sense that way. So say my car is at 2700rpm going 75mph and I have a 3500 stall converter, will the converter still lockup below stall speed?

**chevyguy8413** · 06-19-2007, 05:23 PM

Originally Posted by 99bluebird

Thanks that is exactly what I was asking. I guess I was thinking stall speed meant when it would grab, not power braked. Makes much more sense that way. So say my car is at 2700rpm going 75mph and I have a 3500 stall converter, will the converter still lockup below stall speed?

In the conventional sense of "locking up"..meaning the pump, stator and turbine are at the same speed....no...you will experience convertor "action" at nearly any speed, the differential of the pump and turbine speeds being dependent on throttle position.
Newer "lockup" convertors, on the other hand, usually are programmed so the clutch engages only under light throttle loads, and at minimal rpm. This has nothing to do with the amount of "slippage" designed into the convertor itself.

**PFM** · 06-20-2007, 12:09 PM

Originally Posted by 99bluebird

Thanks that is exactly what I was asking. I guess I was thinking stall speed meant when it would grab, not power braked. Makes much more sense that way. So say my car is at 2700rpm going 75mph and I have a 3500 stall converter, will the converter still lockup below stall speed?

Yes the convertor lockup is controlled by the CPU program and will lockup at whatever mph its programed to lock at. After that it will stay locked until you either go below the lockup speed or you foot gets heavy.

**slims00ls1z28** · 06-20-2007, 03:54 PM

Originally Posted by 99bluebird

Thanks that is exactly what I was asking. I guess I was thinking stall speed meant when it would grab, not power braked. Makes much more sense that way. So say my car is at 2700rpm going 75mph and I have a 3500 stall converter, will the converter still lockup below stall speed?

Yes.

**99bluebird** · 06-20-2007, 07:20 PM

So what mph is stock lockup speed set at?

**slims00ls1z28** · 06-21-2007, 01:54 PM

dunno mine is grossly off due to gear change.

**chevyguy8413** · 06-23-2007, 03:03 AM

Originally Posted by 99bluebird

So what mph is stock lockup speed set at?

Typically, convertor lockup occurs approx. 45 mph...but is throttle pressure sensative....that's sort of a minimum

**99bluebird** · 06-23-2007, 10:07 AM

So if most of my driving is >50mph my gas mileage will not suffer to much from the 3000 stall converter as opposed to stock?

**slims00ls1z28** · 06-23-2007, 02:10 PM

Ya its only the take offs that will cause the decrease in gas mileage as it will still slip some taking off. As far as highway driving is concerned you won't know there is a stall so long as you don't nail it.

**chevyguy8413** · 06-27-2007, 06:55 PM

Originally Posted by 99bluebird

So if most of my driving is >50mph my gas mileage will not suffer to much from the 3000 stall converter as opposed to stock?

going for gas mileage with /without a stall c/vertor means going above the overdrive minimum shift point, and convertor lockup speed...at that point, you will be optimizing fuel efficiency...as i said in earlier comment, typically around 45 mph with stock gearing in many cars....hope that helps..