mustangtestuser

I've been using a 75 shot of nitrous for a little while and so far so good. However, I've been reading some really negative things about the 5r55s. I'm seriously considering going back to a 50 shot.

The previous Mustangs had 4r70w transmissions. Those were rated for 700 ft lb of torques ours are only rated for 550 ft lbs. That's a big difference.

I also have a question about torque converters. Doesn't the converter multiply torque by something like 2.5 until it reaches the stall speed? Is that right? What's the stock stall speed? I read it was 2,600 rpm?

At 2,600 rpm the the transmission can produce at least 270 ft lb at the crank. I'm no math whiz, but 2.5 X 270 = 675 ft lb. Is Ford using a healthy dose of torque management to compensate? Or maybe my analysis is off?

Bmr4life

I have no clue how to figure it out, but your analysis has got to be wrong somewhere.

mikeysGT

i've been running a 100 shot for a few months now with a very good custom tune. no problems whatsoever at the track. just made 6 passes this past weekend with 420rwhp/523rwtq and haven't had any problems...

cdawg

Alternative Auto Performance has done several articles on the transmission. They seem to think it is pretty stout. Look around on this site, there has been at least one update that I know of...with zero problems.

http://www.alternativeauto.com/misc/r-and-d-gt.html

mygt500

They are for the application the OP is using it for.....once you get into tracking the car with M/T slicks and one piece DS and other supporting mods the trans can a will become the weaker link. When that happens is beyond me as there are so many variables.

cdawg- you in Michigan? I had my S/C installed and tuned by Lidio and he really likes the stock transmission. He has over 550 RWHP on his shop car with the stock converter and stock tran and changed the shift points and tightened up the firmness and not one problem after 30+ passes with a Whipple and meth inj and neck snapping torque.

OP if your concerned about the 75 shot please don't be... I think your trans will hold up fine and there is a shop in CA and I am sure you can find one near you too that has "upgraded" some of the internals to handle the TQ.....if in CA it's called Larry's Transmission shop and psfracer (another forum) has that done to his trans and the car is in the 10's and its a DD driven to and from the track. here is a link for you
http://www.upcrowd.com/ViewPage.asp?...11721751111090

You can call Larry and I am sure he would be happy to tell other trans shops in your area how the stock AUTO trans will hold up to over 600+ RWTQ with minor modification to your stock trans....if he wont you send him yours trans and he sends you one back! (improved of course)

cdawg

naw, not in Michigan...Kansas.

mygt500

I see ...did you stumble across Alternative thru research or did you find one of my many links on the forum by yours truly...LOL

cdawg

hmm, not sure. I've had that bookmarked for quite a while.

mygt500

Cool was just curious!