heavy_chevy29

i finally finished everything that i needed to finish my manual to auto swap. i took it for a ride and i really think vigilantie sent me the wrong stall converter. i bought everything from dana at probuilt so ill call him on monday. when i come to a stop, it seems as if it wants to keep going. i have to fight the car with the brake pedal to keep it stopped. dana set me up with a 3300-3400 stall converter. i tryed power braking the car and it seemed to really start pulling at about 2000rpm. after that it would just spin the tires. let me know what you think. thanks alot

88IROC350TPI

I'm confused... with the car stopped and your foot planted on the brake you can bring the RPM's up to 2000RPM before the tires spin? Sounds pretty normal for a convertor like that.

Fighting with the brake pedal to keep the car stopped - sounds more like your idle is too high. Whats it set at?

327_TPI_77_Maro

iTrader: (8)

If you can only footbrake to 2000 rpms, you have a 2000 rpm converter. Sounds like something is wrong. You should be able to get a LOT more rpms against the brake than that. Flash/footbrake stall are 2 different things, but even if that converter is 3200-3400 flash stall rated, you should still be able to get more than 2000 footbrake out of it. Heck, you can get 2000 rpms footbrake out of the S10 converter...

performabuilt

Brake stall depends on many factors and should never beused as a guide for a converter. A 3200 stall will typically brake stall with good rear brakes between 2000 and 2400 RPM has been my experince, This number however may be much less with poor brakes or very low gear ratios 4:10 4:56 etc.

327_TPI_77_Maro

iTrader: (8)

I know for 727 Mopar stuff I run, when I bought an off the shelf TCI converter that said 2500 stall, it really did honestly footbrake to 2500+ before the tires broke loose. I do not build converters though so listen to the pro.

88IROC350TPI

a good way to tell what the actual stall of your converter is would be to drive the car around at a low MPH in a high gear (like 3rd gear @ 25-30mph). Smash the pedal to the floor and watch where the tach jumps to before the car starts accelerating.

performabuilt

Off the shelf converters tend to stall in a wide range so that is possible, Vig,PerformaBuilt ETC are built per application custom. The rated stall is generally equal to the flash stall or close. Brake stall is affected also by STR stall torque ratio.

heavy_chevy29

sorry for the delay. thanks alot for all the info. my brakes are in very good shape and stop very well. i have corvette c4 brakes up front( 13in rotor dual piston calipers) and i have the explorer rear brakes(i had to switch to them when i put in the 9inch rear) which are 11in rotor and single piston calipers. as for gears, im running 4:11s. ill give some specs on the motor if that helps. it is a 434ci small block wich was engine dynoed at 576hp and 582 ft-lbs of torque. the cam is .595 intake and .595 exhaust (thats lift). the duration is 252 intake and 256 exhaust (thats at .050). and i think the compression ratio is 10:1 or 10.5:1. i dont really know much about converters but i just have a feeling that this one may be wrong. i always thought that if the converter was rated at 3400 stall , i would be able to get about 3000rpm before the car started really fighting me during a powerbrake.

RacerX13

Torque converters are one of the most complex and misunderstood things on a car. The TC sits right between the force (engine) and the resistance (weight,traction,& gearing). What the TC does is a result of the load placed on it, and there are a lot of variables that determine the load. That is why if you take one TC and put it in ten different cars it will do ten different things. If you change the power you change the load and the stall will change. If you change the weight,gearing,or traction the load will change and the stall will change.

What RPM the converter stalls at against the foot brake generally means nothing since the car will at some point either spin the rear tires or slide the fronts before you can actually fully load the TC. The important thing to pay attention to is what RPM does the TC "flash" up to when you launch the car. You must have a tach that both reacts quickly and is very accurate to get good data on this. Data logging might be very useful for this. At your power level you will not be able to learn anything useful with street tires on the car-you will have to have slicks,and probably be at the track to place enough load on the TC to learn if it is properly matched to your combination. You have already taken the right step in getting a converter custom made for your combination. Off the shelf converters are often "close enough" for lower power levels like 13 seconds and slower but when you start going faster than that having the TC built for the car is very crucial.

Brakes-Disc brakes are great for hauling the car down from speed but they aren't as effective as drums for placing a load against the drivetrain from a stop. Drum brakes are self energizing and place a large amount force against the friction surface from a small amount of hydraulic pressure. Disc brakes are not-the force against the friction surface is only from the hydraulic pressure. It's pretty much a thing of the past now, but back in the olden days when you built a foot brake only drag car you would put the biggest drum brake setup you could on the back of the car(and the smallest on the front). With the cam timing that is in your car it is also possible that there is not enough vacumn at idle to properly operate the power brake booster. This could be part of the reason you have to stand on the brakes so hard.

How do you know that your converter is right for your car? If your tuning is right-timing and fuel map or carb-and the car bogs down anywhere in the 60' the TC is probably too tight. This is a very big IF-it's real easy to blame an engine tuning deficiency on the torque converter. This is a very general rule, there are combinations where the car can pull smooth and hard in the 60' and still be faster with a looser converter. If the TC is too loose for your combination you will loose speed and ET. Ideally there should only be about 300-400 RPM of slippage going thru the traps. Again you must have a tach that you know to be dead accurate to get good data. This is assuming that the car is geared to go thru the traps at or very near it's maximum engine RPM. Street cars are often geared higher and go thru the traps nearer the torque peak which increases the load and the slippage. Calculate your rollout to find what your RPM should be thru the traps based on the trap speed from your time slip. If your observed RPM thru the traps is significantly greater then the TC is too loose and not transferring all the engine's power to the drivetrain. The extra power is being converted into heat in the trans fluid. If the car is spinning the tires in the 60' you have a traction problem and you won't know if your TC is right or not until you correct the traction problem. At your power level you will probably have a big traction problem!

Good luck-hope this helps.