Captain bob

winter is here so i am making the transmission conversion from turbo 400 to 700R4. the transmission is complete and i have to purchase convertor.1971 corvette with engine dyno. (10 pulls) 520 HP from 408".roller cam from 2000rpm to 6500,air gap intake 1500 up and gears are 3.55 . not a track car used for street and spirited driving 0 to 100mph. Nitto extreme drag radials 275/60/15 and suspension work. nobody on this forum ever mentions the rpm convertor they used with O/D trans with no lock up .love to have a consensus of opinions.

76strokervette

Call pct converters. They will custom build a unit specifically for your car. As an fyi modern quality stall converters will have a pretty efficient fluid coupling.

fishslayer143

I run a 2500 Stall with my 700r4 525HP Stroker, 3.73 gears. Why would you not want a Convertor lock-up? You can always install a manual over-ride for your "spirited" driving days ..and still lock up at cruising speeds.. I highly recommend an auxiliary cooler with any high stall T/C ..... Slip = Heat

johnt365

I think you meant http://www.ptcrace.com/ .

I have had a great experience with these guys also. Give Lane a call or really any of them.


Check this out, I ordered a 2600 converter for my TH400. Then, I swapped out to a 2004R. Turns out they have a policy for this. You can send your old unit in and they rebuild it for $175 (i think). So they swapped me to a 2004r converter for the price of a rebuild. THAT is the kind of guys they are.

Captain bob

i really wanted to know the rpm every body was using and why. i have a friend with transmission shop and i use his special high performance convertor builder just wanted pros and conns of actual driving different between 2500 rpm and 2800 plus rpm or whatever you have encountered . rule number one Never build with lock-up i could care less about 180 rpm as compare to having murphy`s law (clutch) in the convertor.

fishslayer143

You understand that clutch is not engaged under WOT ,right? It has no effect on performance but it will save your transmission from boiling going down the hiway with a loose converter .. Its not the 180 rpm, its the slip causing friction, building heat that's the issue.. Heat will destroy a transmission quickly. If you just Track Race the car, sure , no lock-up, but if you intend it to be a driver, reconsider... Lets say you are driving 55 mph at 2000rpm, and your T/C stalls to 4000... that's a lot of heat . You need to consider your cam profile as well.. a T/C that stalls to 4500 rpm on a cam that pulls at 2500 is pointless ... Just my opinion tho, you make the call. I do suggest you call a few Tech Lines at High Performance T/C manufacturers and get their input on a loose converter without lock-up for a street car.

diehrd

I run a bit more power then your running , I use a 4L80e 10" 3600 stall with lock up.

Lug location changed to work with old school V8's ..


PTC build kick a$$ converters.

7T1vette

Your most important call will be to a quality performance converter manufacturer. Search the web for list of manufacturers; ask around (here and elsewhere) for which of them is GOOD (design, quality, performance, reliability, warranty); and make your selection. THEN, call them and ask for their technical group. They will ask you questions about your car/engine/drivetrain and how you will be using the car. With that info, they will offer you 2 or 3 possibilities which will best serve your needs and you can make the final choice.

One glaring issue is whether you want the converter to have a lockup function in it (or not). My understanding is that if you get that feature and it is NOT turned 'on', the transmission will operate just like one without L/U and it will still be just as reliable and durable as one which does not have the L/U feature. Check this out thoroughly with the manufacturer so that you have all the info needed to make a good decision on this. If the L/U feature will cause no loss of tranny strength/reliability when you put mega-power thru the trans, then you should get the L/U feature and use it when you drive on the street. If so, you will need a L/U controller to make it operate properly. (A simple switch is NOT the way to hook it up.)

76strokervette

. Thanks for the correction. As for the lock up function you can add a valve to eliminate the lock up.

7T1vette

You don't have to do anything to 'eliminate' the L/U function. It is activated electrically. If you don't send power to it, the L/U feature won't engage.

76strokervette

http://www.nastyz28.com/forum/showthread.php?t=256628 Some reading if you are interested.

gkull

behind my two solid rollers I used the precision industries Vigilante 9.5 inch 3500 and 3800 stall with 700R4

don't take advice from someone who has never used a 9.5 inch. Mine was also multi disk

76strokervette

George is correct about the multi disk lockup converter if you go that route. Most people will suggest a 3000 to 3500 stall for your build. I would talk to the builder of your transmission and get his input also.

TedH

Bow-Tie Stage 2 700R4 with 2000rpm stall. I could have gone a bit higher to improve holeshot... I tend to smoke the tires with the near stock stall converter so a little higher rpm stall could have been better (2400rpm). But, I didn't want to deal with trans heat. I also went with 3.54 gears and warmed up the engine so the 700R4 was more for launch (low 1st gear) and OD if I exceed 45mph. I am not racing the car so I'm not really concerned about how well it hooks. Fresh set of rubber helps with that

gkull

highly efficient 9.5's have very little slip when cruising down the freeway. At some power level up in the 600's even multi disk lockups fail from excessive load like WOT at high speeds.

When my multi disk failed it was no big deal I drove it without lockup for about two years before pulling it out and getting a 5 speed

Alwyn678