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stall converter in an offroad rig??

Discussion in 'The Garage' started by oneofthefewbmx, Jul 7, 2006.

  1. oneofthefewbmx

    oneofthefewbmx 1/2 ton status

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    ok guys...i kninda know what a stall converter does and why it is good for a drag car, but how would work in an off road rig...what are the disadvantages?? thanks....im just kinda curious...
     
  2. Hossbaby50

    Hossbaby50 3/4 ton status

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    It is a very dependent subject on what your setup is. It depends on gearing, horsepower, terrain, etc.

    My truck has some good lowend grunt, somewhat low gears, and is rockcrawled. My converter stall speed is 1000 RPM. It works great for my setup. I have enough gear and lowend torque to be able to spin the tires offroad on any obsticle that I need to.

    If I did not have enough torque or gearing though and I wanted to rockcrawl I would want a higher stall converter. You need to be able to spin the tires when you get in the hard spots not just get bogged down. So if you don't have enough gearing and you want to rockcrawl then you need to get into a higher stall converter so the engine can get into a higher RPM for more power before the converter stalls out.

    I have seen several trucks with lack of gearing and converters that are to low of stall. You get them on a hard flexed out climb or something and they truck literally will not move no matter how hard you hit the gas because the converter has stalled out before the engine can make enough power to move the truck.

    For stuff like mud though you want a higher stall so that you get into a good power band for the motor and let the motor stay in is power band easier (like drag racing).

    It is all dependent on what you drive, where you drive, how much gear you have, and how much power you have.

    Harley
     
  3. oneofthefewbmx

    oneofthefewbmx 1/2 ton status

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    hey, thanks for the quick reply...see my problem is that i should have a lot of power, but its all top end (built the motor for a drag car)...i do have 5.13 gears though...and my truck boggs down quite often unitl the rpms reach about 3000, then it takes off like a damn rocket....but i was always skeptical of getting a stall becuase i dint know how it would act offroad, mainly rock crawling...do you think a stall would be ok for crawling and slow offroading? thanks again
     
  4. Hossbaby50

    Hossbaby50 3/4 ton status

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    What is your complete setup? What tranny gears and tcase gears do you have? What stall converter do you have currently?

    If your motor is making alot of high end HP and you want to crawl with it it sounds like a cam swap would be a good idea to drop the powerband back into the more useable area.

    My truck has 37" tires, 3.06 trans gear, 2.61 tcase gear, and 4.56 axle gears along with the 1000 RPM stall. My motor is a mild 350 with TPI fuel injection and my truck is 5500lbs-6000lbs.

    My gears are not ultra low but with the lowend from the fuel injected motor, the decent gearing, and a 1000 RPM stall I can crawl pretty well. If I am on an obsticle and I hit 1000-1200 RPM I am either climbing whatever it is or my tires are spinning because they have overcome the available traction.

    Harley
     
  5. mrk5

    mrk5 The Sticker Guy Moderator Vendor GMOTM Winner Author

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    I don't know how much of a perspective I have because I don't know how much stall you want to do.

    Mine is a few hundred above stock, and I don't really notice any problems. I'm thinking that a couple hundred R's probably isn't enough that it should matter.

    I wish I had a lower stall for heat reasons. I think the higher stall converter is adding heat to the tranny.
     
  6. oneofthefewbmx

    oneofthefewbmx 1/2 ton status

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    well....i have a th400 right now, np208, and 5.13s w/ my 38s....but im fixin to put a 700r4 and 205 in...that is why i thought about the stall because the tranny would already be out...i dont want to have to deal w/ a cam swap rite now (though i have thought about it heavily)....and heat issues were another thing i dint think about....does the higher stall create excessive heat in the tranny? thanks for the info...and i was considering a decently higher stall like 2000 or more 2200 or so mabey, is that too much, this is my Daily driver also....thanks again
     
  7. gm500hprat

    gm500hprat 1/2 ton status

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    I have a 500 hp 468/th400/np205 and 4.11's. My engine is also built for upper rpm's and with 38.5's and 4.11's even with 500 ponies I would dog down in the sand taking off, until I put in a 2800 stall b&m on my truck. I have not had any tranni heat problems. Although I run a cooller along with the radiator. Even in stop and go orange county traffic my tranni has never heated up.
     
  8. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

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    A higher stall converter will make more heat than a lower stall converter. No big deal, just install a trans temp gauge (they're a lot cheaper than a tranny rebuild), and upgrade your cooler if your temp gets too hot (coolers are pretty cheap too).

    Mine is in a similar range (~2,300), but the heat hasn't been a problem for me on 95-100 degree days doing lots of stop and go driving, with my heavy right foot, and the occasional stoplight gran prix. This is just a personal experience thing, but I don't think 2,200 stall is too high for a DD (unless you drive a diesel, of course). If you do low speed crawling (which I do not), you might want something a little lower.

    Speaking of temp, here is a pic of my aux gauge panel (trans oil temp is #3), and about 200F is where it runs after a lot of in-town stop-and-go. By the way, the sending unit is placed to measure fluid temp as it exits the trans and heads to the cooler, not temp in the pan.

    gauge_cluster.jpg
     
  9. oneofthefewbmx

    oneofthefewbmx 1/2 ton status

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    cool, thanks guys....sounds like a stall is what i may need to go with..i would still like to hear about anyone's experiences crawling w/ a stall before i go get one tho....thanks again....
     
  10. Hossbaby50

    Hossbaby50 3/4 ton status

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    If you are putting a 700R4 in you must keep it cool or you will be paying alot of money for rebuilds. Heat is the biggest enemy of the 700R4 followed by horsepower. Put a gauge and cooler on the tranny to keep it alive.

    Where does your motor start producing power? If it was me I think that I would probably be looking at a converter in the 1800-2200 RPM stall range to help your motor get some RPM up for power but to help keep heat from slippage in check somewhat.

    Also remember when you are picking a stall converter for a truck you should make sure that the converter has reached stall speed when you are at your highway cruising RPM. So figure out with the gear calculators what the cruise RPM will be and pick a converter that is below that number.

    Harley
     
  11. oneofthefewbmx

    oneofthefewbmx 1/2 ton status

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    wow that was somthing else i dindnt think about, cruising at a lower rpm than the stall...wow thanks...but still kinda worried about crawling...
     

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