im going to be building a 350 with numbers just south of 400 hp and 450 lb ft of torque, and im going to improve my drivetrain. my 700r4 was rebuilt about 20,000 miles ago and is in good working order with a shift improver kit installed already. im looking to get either a b&m or transcat shift kit for snappier shifts. im wondering what else i should do inside while im at it to improve performance, strength, and reliability. i dont want to do an entire rebuild at this time because im going to be budgeted to under $6000. and for the rear, i know the 7.5 10 bolt probably wont handle it and i was looking at the bolt in 12 bolt rear from strange, but $2500 is a little steep for it. does anyone else make a bolt in, assembled rear? i know currie has the 9", but it doesnt have any of the internals. should i upgrade my driveshaft as well, or can the stock steel one handle my demands?

 

ive been asking around at local shops here about making a 9" from a completely different car work in mine. such as taking the mounts off the current 10bolt POS thats in it and putting them on the 9". might be a route for you to take if you can find a cheap one on craigslist or something. i find a full 9" here third member and all for anywhere from 100 to 200 bucks all the time.

as for the trany. as long as your not constantly beating on it, you should be alright with all that. maybe a higher stall, but not too dramatic.

the drive shaft will be fine, but replace the u-joints while your doin all that. they are cheap and a easily overlooked problem area with any car.

 

Transmission: A stock rebuilt 700R4 isn't going to like that power running through it. I had mine built up because I knew it would be a problem down the line. I had my transmission guy install a billet input shaft, aftermarket pump, 2300 stall converter, kevlar bands, Z pack clutches, performance valve body, shift kit, corvette servos, TCI OD kit, and a few other things. At the minimum, I would upgrade the clutches, bands, add a shift kit, and you will need a converter with a stall that matches the cam you choose.

Rear end: Is yours a stock LSD unit? If not, I would throw it to the side no matter what. A good upgrade that would most likely handle the power (for awhile anyways) would be a Borg Warner 9 bolt from a 3rd gen. Go through it and replace the axle seals, and regear to at least 4:10's, and if this isn't going to be your DD, go with 4:56's. This should take quite a load off of you drivetrain and you should be able to stay within your budget.

Driveshaft: Should be fine, I don't think I've seen one snap on a 3rd gen before.

If I were you, I would also be looking into upgrading the rest of the suspension. You will def. want sub frame connectors. A set of control arms would be a good idea, along with an adjustable panhard bar. Prothane suspension bushings all around, and upgrades sway bars would make it handle GREAT.

 

the rebuild included the forward and reverse sprags, all the bands, the case itself (guy dropped it into reverse at 4000 rpm while doing 20 mph). i was looking into the corvette servo to go into it. i dont want to totally disassemble the trans, and im not paying someone else to do it. i plan on a 2200 stall converter, and im going to get a derale cooling pan. it holds 2 more quarts and has the air tubes to assist in cooling. the rear is a stock 2.73 lsd 10 bolt, and i plan on running 3.73's to keep highway rpms down and keep high speed potential up. the suspension is all going to get reworked including tubular panhard rod, adjustable torque arm, boxed or round drag links, subframe connectors, tubular front k memeber. its not going to be drag only but all around performance.

 

Eh I think you're pushing the limits on the transmission and rear end. 450 ft/lbs is quite a bit on a stock transmission, then the numerically lower gears you have, the harder launches will be on the rest of the components.

 

alright, well i found out my trans should be ok with just an upgraded cooler for the high stall converter. i just took my auto trans class, and based on the specs from gm, they can handle right around 500 lb ft before slipping. its the same as the 4l60 and 4l60e, which are used in the trucks that are capable of towing something like 8000lbs and are also in the vette that make a lot of power. if i blow it up, i know how to rebuild it now anyway. i just may upgrade the servos and shift circuits for more apply pressure and firmer shifts.