I've looked thru the forum, but havent found quite exactly the info i seek. I've got a 1990 Camaro RS that im building up for road racing in the NASA American Iron series. My motor will be a somewhat built 350, im expecting between 300 to 400 hp at the flywheel. The car has its stock 700r4 in it and supposedly in good working order, but should i keep it or go with something else? Mind you, i will be road racing this car only, and im working on a TIGHT budget. Really Tight. So, any suggestions would be greatly appreciated! Thanks in advance.

 

You will definiely need a tranny cooler.......critical for prolonged high temperature abuse road racing gives. This trans will not likely survive in stock trim for all that long. Consider a few upgrades to help it shift harder, road racing will quickly kill a slow shifting trans (burning clutches and band). Also, consider a manual switch to lockup your torque converter for long straightaways....you would be surprised how much this improves your top speed on the straights. This will affect the longevity of the torque converter, but racing is hard on it anyway. Don't forget, this trans will not **** into 4th (OD) at WOT in stock trim either. I do not know if there are any tracks you would be reaching a speed high enough for this to affect you though.

 

check the gear ratios used in the 700r4 vs other transmissions you may be considering......you will find the 3.06 first gear will get you off the line well, but the large drop to the 1.63 second gear can be a killer and drop your rpms out of the powerband, so make sure you consider the powerband of your engine before choosing the right trans to keep it there. Just as a comparison and th-350 trans has a 2.52 first gear and a 1.52 second I believe...going by memory here.

 

To make your 700r4 work for road racing,you'll need the kit that makes it shift into 4th at WOT, a shift kit most likely, and even though you're on a tight budget, id upgrade the clutchs and go through it, because thats alot of heat over a long period of time. And get a decently big tranny cooler.

The lockup switch was a great idea too

Or just swap in a 6 speed hehe, kinda pricy tho.

If you're REALLY looking for budget, you could get, build up, and put in a th350 for under 750 no problem. And i'm talking build to handle 600-700 hp easy.

A friend of mine at Certified transmission said 700r4's cant take much more than 280hp and last.

 

Tranny cooler, not a problem. Shift kit, shouldnt be a problem. I'm shooting for a power band in the 1500 to 6000 range. Might look into a th350, but then i would need a custom driveshaft right? I will look into it more, but by all means, keep up the suggestions!

 

Your powerband is too large to make power all through it. Expect that a well designed (matched) engine that will make peak horsepower at or slightly below 6000 rpm will likely really start to pull around 3500-4000rpm. Below that you will be out of your powerband. Many people define the powerband as the range of rpm between peak torque and peak horsepower. Someone will argue I'm sure. I myself believe powerband to be somewhat larger than this sometimes. Depends on whether the engine falls on its face after peak power, and it depends if it comes on really strong all of a sudden at a certain rpm.....anyway....
the stock trim 700r4 will handle 300hp, just make sure its healthy. clutches and band are a good idea for road racing...a shift kit, a 0.500 boost valve, a good servo ("corvette" servo or other aftermarket servo), upgraded planetaries, sprag, a 10 vane pump (your 90 should have this stock), are all good modifications for your purposes. I'd even consider a reverse manual valvebody with holdback in all gears if you want to get serious. For drag racing the valvebody without holdback in anygear would be much more recommended.....I could go on. Hard racing requires alot of good parts, no matter what you build.

Just as a note, the top gear in the th-350 is 1:1, which is the same as third in the 700r4......so if you NEED to run WOT into fourth gear to achieve the speeds you want, the th-350 will not get you there. You could change you rear gears to allow the three speed to get you the top speed you want, but then you just opened the overall gear spread for your engine to deal with. Alternately, I have seen people put crazy rear gears behind the 700r4 and run up to overdrive while racing, this gives very quick acceleration but can hinder straightaway top speed due to the fact that you are running in a less efficient gear (1:1 is always most efficient). The lockup converter does alot to reduce power loss through the trans when locked in any gear. Also, if you consider running hard in fourth gear for any significant lenghts of time, then you should really look at upgrading the planetary and sprag assembly......

 

I found this: http://www.700r4l60e.com/store/custo...&cat=19&page=1
Possibly buy the kit and have a local shop "rebuild" the trans with that kit, and just go to town? I'm looking at 3.42 rear gears, maybe 3.73, depending on what i can find in budget. I may have overshot my rpm range, but what i am looking for is an engine that will pull from lower rpm coming out of a corner, but be able to keep pulling for a good distance for straightaways.

 

forgot to add, the th-350 trans is a different length, which in itself is enough to make a driveshaft modification/replacement necessary. Not too sure if you can get the 700r4's crossmember to work with it either. Also, don;t forget the tailshaft casing on the 700r4 has a bracket that supports your torque arm leading to the rear axle. The th-350 has no provisions for this.....it may not be a bad idea to relocate this mount point for the torque arm off the 700r4 and mount it to the body. The torque arm put large stresses on the tailshaft housing of the trans and can (and has) actually broken the tailshaft casing on many high powered cars. The stock flexible torque arm does absorb some power, but putting in a stiff aftermarket torque arm also increases the shockloading on the tailshaft casing....which really increases the need to take the mount point off the trans .......food for thought.

 

that looks like a very good kit to get you going.....that would be my purchase.

also, if you want pull down lower in the speed range in first gear, say for tight corners, you could go with a higher stall converter (you want a lockup converter though for those straightaways!)to get the engine higher in the rpms and avoid the problem of less torque down there.......of course less power down there may be a good thing.....real good thing actually. Tight corner+slow speed+aggressive throttle+lots of torque=guaranteed spinout

A little less torque down there could really help you keep it straight coming out of a low speed corner and the higher powerband will really help on the straights. Besides, a higher stall converter will generate more heat, the enemy of any transmission. If you are at 3000rpm or less and you want more omph, gear down, if you are in first, then alot of power down there will definitely be hard to keep straight.

Keep in mind that a very hard shifting trans will likely result in a spinout on the 1-2 shift if you are in a corner at the time. If if shifts a little slower then you can maintain better car control since it will not jerk the car while under full throttle and you are exiting the corner. It's all about balance between hard enough shifting to prevent burning clutches and bands, and soft enough shifting to not jar the tires into breaking loose while accelerating out of a corner......the dynamics of a good working system (drivetrain+car) are astounding.

 

Hi guys, I'm just gonna throw my question in the pot: I am building a cruiser with low 12s quarter mile abilities. My engine is going to be a well worked over 350 and I want to hook it up to my 700R4. now I found this:

http://www.700r4l60e.com/store/custo...&cat=28&page=1

Will this kit hold up the power? Is it even the right thing to do to my tranny in order to build this street/strip car? I'd really like to keep my 700R4. As usually I'm on a tight budget too and even worse - I am livin in Germany, so there is like no way I am going to find a junkyard with just the right parts for 3rd gens, therefore I'll have to buy almost anything new...