Shanepa

I have a 1999 ford mustang GT I recently installed a Vortech V-1 supercharger kit.

The car is automatic and shifts real hard on the low gears and seems to slip so I want to know whats out there to fix it. I am assuming I should get a shift kit? but no idea which one is good or if getting the gears tunned would be enough to fix everything. I just don't want the tranny to go bad on me.

Soldier GT

if I were you I would take it to a local tranny shop and have them look at it..

MU71L4710N

do you have a handheld tuner? you can check the shift firmness with that. otherwise, who tuned your car? did they mess with your firmness?

NinjaMonky

Upgrade time, recomendation: t-56.

0949er

i would love a t56.... how many miles on the tranny?

NinjaMonky

I love mine, but still need to get revervse lock out switch taken care of.

Shanepa

Its 52,000 miles on everything and I don't want to get a new tranny this one seems fine it just slips because of the charger. I had no problems with it before just thing its not used to the power.

Hangwire

Shift kit wont fix your problem. The 4r70w doesnt need an aftermarket part to work correctly. Chances are this transmission has been overheated and then operated under stress or operated for along time with the previously overheated fluid in there. Overheating your transmission fluid(220+ F) has permanent effects on its viscosity and ability to do its job. It is scary how easy it is to get your trans in that temp range, 3-4 80% throttle pulls while screwing around on the street and you will be approaching that temp quickly. You may have to rebuild some of that tranny if this is the case. I suggest an aftermarket transmission cooler for all 99-04 Mustangs with an Auto(4R70W). Other than a few modifications, the biggest difference between an F-150 and Mustang 4R70W was an external transmission cooler in these years. Take a look at this link and see if you get some info that helps.

http://www.tccoa.com/articles/tranny...on/page4.shtml

0949er

try changing your tranny fluid if you havent done that yet... it is due up for a fluid change. Helped my shifts out (at 50k miles), but i DO have a manual...

One thing that sucks for you though is that your tranny holds a lot more fluid then a manual. I wana say that they hold something stupid like 10+ qts (vs ~2.4 )