Me and LottaBalls are thinking about putting a new 700-R4 into the IROC once we build our engine. Do yall think that it will be able to handle about 475hp & 500ft/lb of torque? I will also be running a 100 shot of nitrous occasionally.

 

Get a well built one and no problem.

 

it wont last long

 

Probuilt or Transfixleo could build you one that would.

 

You will need to get a custom built box. A stock 4L60(700-R4) is only good to about a maximum of 320-350 ft.lbs engine torque. Even the newer 4L80-E is rated at 440 ft.lbs. and that is the one GM uses for the diesels and heavy towing packages. I am running a zz-4 and I had similiar concerns about my trans. We have a local guy who specializes in GM boxes for high horse/torque applications and I got info for increasing the transmissions power handling. Budget about $2500 if you go the custom route. They completely disassemble the trans, add welds to structural stress points in the case and go from there. Don't overlook frame reinforcement either, with that kind of power generation these cars will twist like a pretzel. You will probably need a better rear also. Good luck with the project.

 

I have a buddy with a Fourth Gen Firebird making 550 ftlbs at the wheels. He went thru 3 4L60E's in a year. T-56 conversion and all is well

 

Any trans dude that knows what he is really doing can build that.

 

I'm replacing the entire suspension, and hopefully putting sfc's on it if the don't interfere with the custom exhaust that we're building.

Also, do you think my 9-bolt will be able to handle that kind of power?

 

Won't hold up for too many hole shots. That kind of HP you are in a totally new arena. GM performance parts marketed a rear for the TG's when engine horse was increased. Don't know if it is still available.

 

first thing I would do is the SFC THEN build you exhaust. you don't want to tear your car to ****. :0)

 

I have seen a tubo 350 that holds up to 900 horse and the 700R4 is derived from it so I see no problem. Get ahold of Pro-Built and he can fix you up. My car has a Vortech 383 and makes power in that range without any trouble from my tranny yet. The most important thing is a good converter that won't explode.

 

If you're gonna spend the money anyway, why not just go for the 4L80E, the successor to the TH400. You get overdrive and the capacity for monster torque without all the build up expenses. Besides, the gearing the 4L80E will be more in line with the torque you're putting through it. And you won't need big gears in the rear either. Probably not more than 3.08's for the street and an occasional drag race. Any bigger and you'll be spinning the length of the track...that's a monster engine!

 

Aloha, while the 4L80E is a good box it too will need to be strenthened to support an engine output of that level. You can check www.gmpowertrain.com for specs on all current production transmissions.

 

Plus a 4L80E weighs almost twice what a 700 does and sucks at least 15% more power which will greatly hinder your acceleration with that engine. A 700 will be fine as long as it is built right and you check your pressures at install time like the instructions say.

 

TH350s are MUCH stronger than TH700s.

 

They might be slightly stronger, but unless you have actually built and abused one of each in the same vehicle then I don't see your proof. I have as a matter of fact done this and they both lasted about the same(a long d@#$ time). There are 700's in 9 second cars, but I don't believe many of us make enough power to push 9's so whats the problem?

 

For 500ftlbs, you can run a slightly modified T400 and a Gear Vendors over/under drive unit. I run a T400, but not a GV unit as I am only running a 3.73 gear in my 9 bolt.

Yes the 9 bolt will hold up. I've been running mine for 4 years now behind my big block with 1.72-1.75 60fts. (500hp/520lbft).

Miles
Diff Solutions
www.9bolt.com

 

The car is already heavy enough so I dont want to weigh it down with a TH400 and then a GV unit on top of that, the car wont see slicks very often or drag radials for that matter so I think a probuilt trans wil last. Does anyone know what they rate there trans for?

 

What they are rated at depends on how they build it for you. Mine that I built is almost identical to one of theirs and is rated to 500 ft./lbs. Trust me if you get a well built 700 and don't have cable adjustment problems or heat problems, they will last as well as any T350.

 

The 4L80E does not have that killer first gear like the 700r4, either. The 700r4 has a 3.06 first gear while the 4L80E has something like a 2.48.

 

yes, with the correct parts it will hold up without too much problem. in one of the projects i recently completed for a friend which has a 4l60 with kevlar band, alto red race clutches, upgraded servo, and transgo kit has had no problem handling the 355 with 7 psi blower. it's all in using the right parts and driving it right. a big help is to use a deep pan. the axillary cooler isn't really needed if you use a big pan and it helps in more ways than that. for the strongest (that i know of) contact rossler transmission if you plan to just purchase a new unit.

 

Thanks for the help! It's looking like my rear end is having problems right now, so I might have to replace that too, once I figure out what's wrong with it.

 

700R4 = Heavy, overheating piece of crap.

Get a built TH350, you'll be a lot happier.

 

 

i agree with Nate2. i think the th350 would be a better choice. btw,jamesbern, how long does a 700r4 last in a car turning 9's? i'm curious.

 

Show me your 9 second car and I will tell you! If you want all out drag race, then yes go with a turbo 400, but until you can build a sub 10 second car keep the overdrive.

 

Just an afterthought, but how many 9 second cars only have 500 ft/lbs. of torque? They must weigh in at about 1800lbs.

 

so, are you going to answer my question or not?

 

What question? How long will anything last in a 9 second car? Everything is dependant on how the car is built, what it weighs, use of supercharger, nitrous. Basically your question is ridiculous, but if you can show me your 9 second car then I will gladly build you a 700 and we shall find out. Really if you have a 9 second car it probably isn't streetable and therefore you would be rather dumb to spend the extra money on a 700 anyway because it weighs more and overdrive usually isn't used at the track.

 

"There are 700's in 9 second cars and I don't believe many of us make enough power to push 9's so whats the problem?"

ok. so how many 9 second cars running 700r4's have you actually seen?

 

So I miswrote and instead of but does that pain you? If you have never been inside of any tranny then you have no business telling anybody anything about them. I on the other hand have built quite a few trannies and 700's are my specialty. I build them for big blocks and small blocks and have yet to have a problem. As for this conversation, I'm done, you show no knowledge of the subject and I doubt you have any. Thanks

 

making assumptions is a mistake.

 

Goto CarPros web site, they have a few 9 second cars running 700s. If you cant dissipate the heat on an allison tranny (which makeds the 80 look like a chicken wing) then it wont last long, its all about heat management and treating the thing nice. If you drag race everytime you step into your car then no your tranny no matter what it is will last only so long (it does have wearable parts in it). The 200 is also very simular to the 700 (anything you do to a 200 can be dont to a 700) and those suckers are in some helacious GNs running rediculous #s. Give PMAC down in Texas a call as well , if you want a turnkey killer tranny these two guys will do it (but it costs). Also who wants to cruise at 70 @ 3000 rpm?
Perry

 

There you go Rancid, now do the researching for yourself and try to learn before you speak. I am currently building a tranny for the guy with the last post. He also had trouble with his 700 and I have helped him fix it. Making assumptions based on facts is not a mistake it is the way a mechanic thinks. I have been doing this quite awhile and try to help people on this site and elsewhere to forget the myths(700's are weak junk) and present the facts. You are in no way helping by trying to refute my knowledge with your lack thereof.

 

your mistake is assuming i have no knowledge of the subject at hand.

 

I remember when I was much younger (I dont want to show my age here) but everyone thought that if it had a TH350 in it that it wouldnt hold up to a 250 inline 6s abuse much less a 250 hp 350 in a new Camaro (at the time). But as most HOTRODERS they adapt and overcome they figure things out and never say it cant be done, for instance look at the latest Hotrod magazine , there is a guy in there with an 88 or 89 Formula that is running 10.70s on the stock shortblock using Nitrous (hes also using a 700). Eli Nahed (who has an 85 Trans Am 406 EFI) is running consistant nines with a 700, Hes been around with this car in this state of tune for about 6 years now. The newer 4L60 Es have so many new beefed up parts that can be trickled down to our non-electric units that its amazing, also GM is now offering hardened drums from them. A guy here locally has a 3rd gen RS Camaro that runs 10s with a 502 crate motor and the 700 R4 that was behind the TBI motor that the car originally came with (of course worked over). And again I like being able to drive doen the freeway at 70 to 80 and not have to wear earplugs or keep my eye on the temp gauge.