tranny questions

blstang

New Member
May 23, 2006
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Auto transmission questions

hopefully you guys can at least answer or respond, unlike the corral.
ive done several searches here and at others and its still up in the air.
I have an 04 GT AUTO.

do i have a 4r70w or 4r75w?
how much power and tq can they handle?

thanks
 
hopefully you guys can at least answer or respond, unlike the corral.
ive done several searches here and at others and its still up in the air.
I have an 04 GT AUTO.

do i have a 4r70w or 4r75w?
how much power and tq can they handle?

thanks

I think its a 4R70W but Im not sure. I will tell you they can't hold much past 500rwhp because Im about 525-550rwhp and mine is on its last leg. I really started having problems around 450ish. Im going to the track tonight so I hope she lasts me. LOL
 
thanks, i dont think i will be at that HP level in the near future :(

is your tranny completely stock?

Yes its stock.

I went to the track today and it held up but my damn gears are killing me, I can't run a full pass because I bounce off the rev limiter with my 4.10s and my car hooks off the line then blows the tires away shifting into second. I just orderd a set of 3.73s so I should be OK to run a full pass and traction should be a little better too.
 
You have a 4R70W. The 4R75W came in the 03/04 Mach 1.
If you do the J-mod, you could probably get by with up to 400hp and have a reasonable life out of it if you don't beat on it all the time.
The 5R55S (5-speed auto) is in the 05' and newer Mustangs. Same tranny thats in the last T-bird and Lincoln LS. Is decent but not quite as durable.
 
400? Surely a 2004 model 4R70W can handle more than that?

Also, I doubt any of the J-mod stuff needs to be done to a 2004 version of the 4R70W. In fact I question whether the J-mod stuff applies to any 99-04 model 4R70W. As far as I know all the J-mod stuff applies only to 98 and older and was done at the factory on 99+

Please correct me if I am wrong because I have always wondered about the j-mod stuff being needed with 99-04 version of the 4R70W...
 
You def have a 4R70W. It can handle a lot of power, the trick is to make it reliable w/ this power which is a lot harder. A big-as-possible tranny cooler is the first step, but if you want something that will handle 425+ or so consistantly w/out having shifting problems getting the j-mod and hardened parts during a rebuild it an exellent route to go for putting down those horses. Right now 95% of my tranny's parts are rated 500+, w/ my stall converter at 525+. Building up the tranny is the only real way to be sure you know what's going to hold up
 
400? Surely a 2004 model 4R70W can handle more than that?

Also, I doubt any of the J-mod stuff needs to be done to a 2004 version of the 4R70W. In fact I question whether the J-mod stuff applies to any 99-04 model 4R70W. As far as I know all the J-mod stuff applies only to 98 and older and was done at the factory on 99+

Please correct me if I am wrong because I have always wondered about the j-mod stuff being needed with 99-04 version of the 4R70W...
i was wondering the same thing, because if the 99+ have it done already, then i would want a shift kit, but if it wasnt done at the factory i want to do the j-mod!
 
Also, I doubt any of the J-mod stuff needs to be done to a 2004 version of the 4R70W. In fact I question whether the J-mod stuff applies to any 99-04 model 4R70W. As far as I know all the J-mod stuff applies only to 98 and older and was done at the factory on 99+

Please correct me if I am wrong because I have always wondered about the j-mod stuff being needed with 99-04 version of the 4R70W...

The Jmod does NOT come stock on a 99+; you must do it yourself or have someone do it for you. You are basically modifying the OEM valvebody plate and removing springs. The Jmod can be done on any of those year model 4R70W transmissions and is a fairly easy way to get a great improvement in the auto slushbox.

A Jmod'd valvebody and a torque convertor=big fun and no traction :nice: