Hitman, I thought I saw somewhere in this forum
something about having more sluggish shifts after upgrading to a high stall torque convertor. Is this true?

 

Well, sorry I didn't reply sooner I was taking someone out... j/k <img border="0" title="" alt="[Wink]" src="gr_images/icons/wink.gif" />

Converters are the "black holes" and "voodoo" of cars and trucks. They are strange, complicated, and misunderstood.

First, stall is based on input torque. I.e. an anemic, low compression 350 may be able to stall a converter to about 2000 rpm. A hot, higher compression with good heads 350 may be able to get that stall up to 2600 rpm due to making more torque. That is with the same converter. It really depends on your motor.

Stall also is in different forms. There is flash stall, brake stall, and actual stall.

Flash stall is, with no traction problems, the peak RPM or the quick jump of the engine RPM's on with the converter. This isn't the best way to measure stall. Insane amounts of torque can make a 3000rpm stall to 4200rpm+
Brake stall is, holding down your brake and gassing the ride with the other foot. That doesn't work too well either b/c you will generally begin to light up the rear tires.
Actual stall is if you had a line lock on your trans (holds R+D together) so you don't move and your RPM's rise to your stall speed. If you have a 3000rpm stall, that is what your engine should rev to with the line lock on. You would launch off of that.

Softness depends on the stall and size you go with. High stall, small converters are "loose" converters if you will. Larger diameter usually help keep the looseness away and keep the factory towing up. These act more stock with higher stall. The softness is more likely to be with the part-throttle shift than the WOT ones.

Looseness is hard to explain. Like you'd have to give the vehicle a bit more gas to get moving and depending on diameter. Generally your part throttle putting around rpms are about 2000-2200rpm.

Precision Industries recommends a TransGo shift kit (at least they used to, prolly still do) to be installed with the converter. Check out all the car mags like: 5.0 Mustang, CarCraft, Hot Rod, GM HighTech, etc they all install shift kits with the converter install.

A high quality TransGo kit addresses trans problems and corrects them. 3-4 burn up, 2-4 band loss, etc. They boost line pressure but also keep more fluid on the clutch packs, and get rid of the slop shifts.

I recommend at least the Corvette servo but prefer the Superior billet servos. On the passenger side of the trans is the 2-4 band apply servo and the overdrive servo. I think it is silly to not install both of the bigger servos at the same time you install a shift kit as you have to clearance the band. The servos increase holding capacity (the OD billet is 10% greater over stock. Intermidiate billet is 35% more apply over 'Vette servo, so I'd figure about 50% greater than the non-'Vette servo)

Finally, with a high stall converter, install a large transmission cooler. Even if the instructions say it is okay to use the factory cooler/heat exchanger get one. They are cheap insurance. $50 cooler or $2000 transmission?

 

and where can one pick up these "Superior billet servos" ?

 

Intermediate servo: http://www.kdsperformance.com/supser700r44.html

Overdrive servo: http://www.kdsperformance.com/ovsupser704l.html

Shift kit:
http://www.kdsperformance.com/tranhigpersh1.html

KDS has great prices on their stuff. Chad is the person to speak with up there. I purchased all my parts for ~$250.

 

Good info. <img border="0" title="" alt="[Cool]" src="gr_images/icons/cool.gif" />

 

Just hope it makes sense. There is a lot of stuff in there to read.

 

Yea,its diffenatly long.But not wasted space.

 

Where does the overdrive servo go?

 

Where does the overdrive servo go? And would it be wise to just add the better servos and not the shift kit with the new convertor? I didn't know that I could burn up the tranny by installing a convertor. Thanks for all the info, you are the **** hitman!!!

 

The OD servo goes on the outside of the 1-2 2-3 servo closest to the outside of the trans. They all go in the same hole so do them all at once. These servos are a must have with a converter. They firm shifts up alot(can leave 5 feet of rubber on the 1-2 shift). Also, they make the shifts quicker, and more precise.