ive done a search and couldnt find anything useful.

my stock 700r4 has 62k on it...has been behind a 305 tpi, and has been hooked up to 2.73 gears its whole life. shows no signs of problems, fluid is still good.

im in the process of swapping in an SDPC 350 tpi vortec headed engine...i only have the money for a trans-go shift kit at this point, beings my pockets are pretty empty after that engine.

will the 700 hold up to the torque/hp output of that engine?
its rated at 356 hp and 416 tq...however most dont ever see that much out of it. Its mainly a daily driver...with friday nights and an occasional tuesday night at the track.


also...a 4th gen 3.42 posi rear, with a new heavy duty aluminum girdle...how long will that hold up? i will have spohn lcas attached to it...possibly slicks every once in a while...

 

It "should" hold up to that!

 

hey, ive been searching and this is my exact question, what exactly are the stock trans meant to hold?? I just bought a car with the 700R4 recently rebuilt with reciept and i was wondering what HP and TQnumbers it will hold. I would like to put in a stronger motor...

 

From my experience with the 700R4 you should be fine. I put a minirammed 383 into my GTA a couple of years ago and kept the stock 700R4. However, as a percaution and seeing as I could afford it, I did have the 700R4 rebuilt with a new shift kit, servo, clutches, etc. But I did not buy aftermarket parts. The transmission mechanic I know has enough experience to know the "tricks" to making the 700 stronger without the cost of aftermarket, so the majority of the parts in the tranny where still stock.

Over the past two years, and hundreds of passes on the 1/4 the tranny had no issues. Until this year! On top of the already 380rwhp and 400rwtq I am making I decided to throw a 150 shot "off the line" at the car. Everything went great for the first 60', shifted second gear.... BOOM!! Had my friend rebuild the tranny for the last race weekend and another crack at the 150 shot, only to end up with the same results!

So I now know the 700R4's weakpoint... a stroker motor and a 150 shot!

BTW, both times I broke the same parts, the input shaft, output shaft, and sprage. However on the second attempt I managed to mangle the parts better than the first time!

 

Glad to hear that these can hold up stock if built correctly, I will throw a shift kit in that does not require the tranny to be rebuilt since it was JUST rebuilt. This will save me money till i do the T56 swap.

 

No problem. Hope it works for you as well as it did for me.

 

Change the fluid and the filter at the same time you put in the shift-kit and hope for the best. Remember you're dealing with stock parts that have only had to last behind a stock 305. Now you're putting a higher output 350 in front of it and asking it to hold the extra power. It might last, it might not. Depends on your luck. There really is no magic number that every tranny and rear end will hold, and above that number they fail.

 

I have all the hard parts you can get for the 700r4 and mine just went 11.14 at 128 last nite on a 150 shot. Left it in drive. Having a problem shifting above 6500 rpm into 3rd gear though, but the governer should fix that.

If they are built correctly and by the right person they can hold up at the track.

 

Hey gang.. I'm new to the forum.. Just wanted to say thanks for the tremendous contribution you guys make to 'not-so-savy' guys such as myself.. just bought my T/A, nice paint, body good, great power and driveline but floorpan and interior finished.. what can i say... I bet you guys have all ben there right..

 

I would agree that it'll "probably" hold up to that new motor with the transgo kit. I've beat worse and had it last, but I've also beat better and broke it. - Being an 87, it should be on the better side of model years......

The 4th gen rears do seem to be slightly tougher than our OE units. Casting and material quality have just gotten better through the years.