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View Full Version : How do you know when you should replace the torque converter?


graedin
06-18-2003, 09:43 PM
I am having 727 problems again. My question is, how do you know when the torque converter needs replacing? And what do "stall speeds" mean? And is there a way of testing a tranny prior to installation? I have a spare 727 that hasn't been run in at least 5 years, and it came with a parts Scout II I purchased. It would be a shame to swap it in to find out it didn't work.

Thanks for the tech help.

Jay Tabor
06-18-2003, 11:02 PM
Stall test means- the speed at which engine stalls,[wont go any faster] full power is transmitted to trans from engine.
have to stall test a t/converter. or send to a trans shop to get tested. in car - one foot on brake, other on gas pedal, mash gas pedal, watch tach, engine should get to about 1700 rpm[on scouts] much faster = clutches spinning or brakes aint working,or no fluid. much slower= sprague clutch failed.
trans shops might be able to test trans out of car.

ALEE@CSIUSA.WS
06-19-2003, 06:24 AM
Can't explain it as technically as John did; But i knew mine was bad when i could not pull up my driveway. Ran great going down the road at 60 and 70 but taking off from a light took forever. And i had to get a running start to make it up my driveway! Replaced the torque converter and then i could spin the tires!

Hooper
06-19-2003, 10:15 AM
Originally posted by ALEE@CSIUSA.WS
Can't explain it as technically as John did; But i knew mine was bad when i could not pull up my driveway. Ran great going down the road at 60 and 70 but taking off from a light took forever. And i had to get a running start to make it up my driveway! Replaced the torque converter and then i could spin the tires!

All you replaced was your torque converter? Usually, if a torque converter goes out, you overheat badly. Trying to go 60 down the freeway the torque converter will slip and shear and generate a lot of heat.

Also, I have burned up many trannies, but have yet to burn up a torque converter, although I replace mine every time I toast a tranny anyway.

rick W.
06-19-2003, 05:56 PM
A reman converter is only like 50 bucks. If in doubt just replace it.:)

David Van Vorous
06-19-2003, 11:18 PM
Replacing a torque converter and getting back performance sounds more like the converter ballooned. Ballooning changes the stall and allows more fluid past the blades (slippage). A good quality converter has a thick enough wall, heavy enough blades that are fully brazed to the shell to prevent this or at least reduce the probability that this will occur except under some real high output conditions like racing.

If youve ever cut one open youll find that the low buck or remanufactured converters tend to not braze the fins to the shell completely which allows ballooning at lower pressures...

Bottm line iffen its a well made converter, the only real good reason for changing it out is because the seal area is defective, it has a leak or one wants to change the stall speed.

D.

WesV
06-20-2003, 07:22 AM
I am about to put a 727 and TC that I have never seen run before behind a good 304. The previous owner didn't know the condition of the tranny when I got it so I was wondering if I should go ahead and look at replacing the TC before I put it all together. I know I am either gonna put a shift improver kit or an MVB on it before it gets hooked to the engine and put in my scout, but that shouldn't be a real worry. I know to completely drain and refill the tranny and check for shards of metal and that type of thing, but is there anything else I am missing before I put it all together?

Mike Moore
06-20-2003, 08:50 AM
Wes, it ran fine. It would spin in the gravel easy, but we never had it moving fast enough to shift into second, though. Reverse and first...park, neutral, etc all seemed to be fine. The guy I got it from said a D.J. in Staunton owned it, and drove it every day until it rusted out too bad to drive, but the drivetrain was still goin' strong. I'd slap it in there as is...but that's just me.:)

graedin
06-20-2003, 07:33 PM
Thanks for the information so far. The trans problems I was has having started when I first put it into gear. It would delay for a second and then jerk into gear, chirping the tires. Not being a rich man, I kept driving it. Then, the other day, I was going up an inclined road, and the rig lost all momentum, stopping in the middle of the hill. No amount of accelorator pressure made a difference. I managed to roll it down the road backwards a bit into the parking lot, and I noticed my radiator was blown as well. Coolant was everywhere. What an expensive lesson. I think I will replace the radiator, trans, and converter now.

Keep Scoutin'
Nate

1972 Scout II
304/727

rick W.
06-20-2003, 07:48 PM
Foreward clutches went in the trans. Same exact thing happened to me. Putting the trans back in tomorrow.:)

graedin
06-20-2003, 07:57 PM
Did you swap a different trans in or repair it? If so was it expensive? Did you replace your torque converter?

rick W.
06-20-2003, 09:11 PM
Had the trans rebuilt by a shop. $600 with a rebuilt converter. Most shops will require a new converter in order for them to give you a warranty.:)