5r55s issue ?

[MYLILSS]

this is my first post, but I am new to the s197 scene, although I have been around the mustang scene as far back as I can remember. I recently purchased an 06 gt from a buddy, and now something is broke lol.

the car is an 06 gt hardtop, with a 5.0 stroker shortblock, cnc ported heads, all the bolt-on goodies, and a whipple 2.3 maing about 15lbs of boost. the car dyno'd 586 rwhp if I remember correctly when it was tuned.

the problem is that when I went to pass someone on the highway, the car downshifted and started climbing but then it was like the car had the clutch pushed in and went into neutral.

the transmission is a built unit, and has a tci converter, and aftermarket trans cooler. no noises come from the transmission when the car is idling, and the park brake still holds. it rows through the gears just fine, but will not move forwards or backwards. I was told it could be the input shaft but haven't jacked the car up yet. I am going to start working on the car here soon, and was just curious what I should look for as a potential fail point. I have been told it could be the input shaft but I don't have much experience with these cars, or even auto's in general

thanks

 

[Wild White Pony]

Your guess is probably correct, input shaft. Never let a boosted 5r55s downshift on it's own when passing. I drop out O.Drive and then manually shift if having to pass a car quickly.
If your trans was built it should of had a hardened input shaft, much harder to break. You must of dropped 2 gears on that pass.
If it is your input shaft, TCI and Level Ten have strong aftermarket input shafts to replace it with. I haven't broke a hardened input shaft yet but I think a few here have.

 

[MYLILSS]

thanks for the info. I am not sure to what extent this transmission had work done to it. for some reason my buddy was thinking the input shaft was left stock. I have been looking at the TCI replacement input shaft for a replacement should it be the culprit, as well as going ahead and doing either the trick flow or PA pan and dipstick kit. I am not a fan at all of these transmissions not having a traditional type dipstick.

also, I will try to remember that about the downshifting more than 2 gears. I've always been the manual transmission type, so I am adjusting to the ways of an auto.

 

[retfr8flyr]

With your power levels, you are at the maximum limit for the 5R55 trans. You will have to be very careful with at those levels. As described, don't do any downshifting under power, don't get into boost in 5th gear and such. If you kind of baby it, it should last for you, after you fix the problem. If it looks like it's going to cost some bucks to fix it, I would highly recommend not spending any money on it and go with a 4R70W setup instead. You would be much better off in the long run.

 

[MYLILSS]

retfr8flyr,

would the TCI 5r55s transmissions not be worth looking into ? they have two versions claiming to be rated at 850 and 1200 horses. I had contemplated going with one of those should this transmission be toasted ...

 

[Brezick]

The 5r is never going to handle that much power, i dont care what the companies claim.

 

[JimIII@JDM]

The 5r is never going to handle that much power, i dont care what the companies claim.

With a TCI or Level 10 transmission we've run about 750 HP through them at the drag strip. They'll last a season or two like that. We've built 5 cars that ran consistently in the 9's with the 5R. Actually 2 of those cars ran 9's on a bone stock 5R55 trans! As soon as we put them in a street car making that kind of power our customers can't keep them together. 3rd gear band is a common failure as well as the input shaft, even the upgraded hardened units. The transmission just wasn't make to handle the abuse from a 700+ HP street car where it's constantly up shifting and down shifting. The worst thing you can do is a highway speed kick down from OD to 3rd gear. It stresses out the band and flexes the input shaft so much they snap.

 

[retfr8flyr]

retfr8flyr,

would the TCI 5r55s transmissions not be worth looking into ? they have two versions claiming to be rated at 850 and 1200 horses. I had contemplated going with one of those should this transmission be toasted ...

With a TCI or Level 10 transmission we've run about 750 HP through them at the drag strip. They'll last a season or two like that. We've built 5 cars that ran consistently in the 9's with the 5R. Actually 2 of those cars ran 9's on a bone stock 5R55 trans! As soon as we put them in a street car making that kind of power our customers can't keep them together. 3rd gear band is a common failure as well as the input shaft, even the upgraded hardened units. The transmission just wasn't make to handle the abuse from a 700+ HP street car where it's constantly up shifting and down shifting. The worst thing you can do is a highway speed kick down from OD to 3rd gear. It stresses out the band and flexes the input shaft so much they snap.

Read what JDM just said. The physical size of the parts in the 5R just wont allow it to handle huge power levels no matter how well it's built, or what a company says it will handle. That's why I said you have to baby it. My trans is basically the TCI Super Streetfighter because it was built with all their parts. It has held up so far but I also baby and make sure I don't downshift under power, that's the real killer for this trans. I know it's the weak link in my car and if I had know then what I know now I, would never have built up my 5R. I personally wouldn't spend money building up the 5R, I would go for a 4R70 or the GM 4L80E setup. When, not if, it fails in mine I will be going with an 4L80E setup. It's actually a stronger transmission then the 4R and would cost about the same, starting from scratch.

 

[07 Boss]

this is my first post, but I am new to the s197 scene, although I have been around the mustang scene as far back as I can remember. I recently purchased an 06 gt from a buddy, and now something is broke lol.

the car is an 06 gt hardtop, with a 5.0 stroker shortblock, cnc ported heads, all the bolt-on goodies, and a whipple 2.3 maing about 15lbs of boost. the car dyno'd 586 rwhp if I remember correctly when it was tuned.

the problem is that when I went to pass someone on the highway, the car downshifted and started climbing but then it was like the car had the clutch pushed in and went into neutral.

the transmission is a built unit, and has a tci converter, and aftermarket trans cooler. no noises come from the transmission when the car is idling, and the park brake still holds. it rows through the gears just fine, but will not move forwards or backwards. I was told it could be the input shaft but haven't jacked the car up yet. I am going to start working on the car here soon, and was just curious what I should look for as a potential fail point. I have been told it could be the input shaft but I don't have much experience with these cars, or even auto's in general

thanks

This happened to me a few months ago and I figured it was the input shaft, bought one and tore it down only to find it was the converter. it stripped where the input shaft fit in (stator?).

 

[MYLILSS]

thanks for the info guys. lots of things to consider it looks like. depending on what I find, I may look into one of the custom conversions rather than messing with repairs of the transmission in this car.

 

[tmcolegr]

With a TCI or Level 10 transmission we've run about 750 HP through them at the drag strip. They'll last a season or two like that. We've built 5 cars that ran consistently in the 9's with the 5R. Actually 2 of those cars ran 9's on a bone stock 5R55 trans! As soon as we put them in a street car making that kind of power our customers can't keep them together. 3rd gear band is a common failure as well as the input shaft, even the upgraded hardened units. The transmission just wasn't make to handle the abuse from a 700+ HP street car where it's constantly up shifting and down shifting. The worst thing you can do is a highway speed kick down from OD to 3rd gear. It stresses out the band and flexes the input shaft so much they snap.

http://s197forum.com/forum/showthread.php?t=6398&highlight=5R55s