# Torque converter



## drifter79 (Oct 18, 2003)

I am almost sure I have to replace my trans th350 and I do tow a old tri-hull Heavy sucker and a heavy old trailer to. I want to replace the converter with a new good towing converter but I do not under stand the (stall speed ratings) and what I would need. I want one for low end towing Torque. Thanks for any help....


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## Big Nate's Plowing (Nov 26, 2000)

the big factor is the HP & Torque that your motor puts out, more power = more of an ability to overcome the stall of the converter hence a lower stall speed would be needed

the stall speed is essentially the max rpm difference between the motor and the input shaft of the transmission under a load, like when powerbraking or pulling a large boat up the ramp.
example 
a 4.3 v6 would stall out @2200 rpm
whereas a built (350 hp) smallblock would probably stall out @ 3000 rpm

the only reason to run anything looser then stock 2500+ is if you have a radical cam and need it to idle high and/or you are racing.


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## drifter79 (Oct 18, 2003)

Hey thanks for the fast reply so the lower the stall speed the better is what I need right and in a 12in. converter. I am running a 350 motor rebuilt it awhile back motor runs great factory heads, cam, thorley headers and single 3in. exhaust k&n filter.


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## derekbroerse (Mar 6, 2004)

I had a torque convertor from a diesel for a while in my 700R4.... stalled lower than any other convertor I ever had....


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## drifter79 (Oct 18, 2003)

Question I found a converter 1,900-2,100 12in. that should work right B&M. How can you tell if your old one is bad trans works great in 1,2 in drive it works good till it shifts in to high gear and it does sutter on take off alittle sometimes. Fluid is not burnt looks and smells like new mobil syn. Thanks.....


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## ratlover (May 5, 2003)

b&m stuff kinda sucks IMO.....actually I realy dont like thier stuff. Thier converters seem like they slip more than the should and their shift kits genneraly seem more cosmetic than anything. I could go more into it if you would like.....

What does it do in high gear? Like when it trys to lock up or does it not have a lock up? What is it in?

Lock up converters are GOOD!!!

Big honking coolers are GOOD!!!

Transgo shift kits are VERY GOOD!!!

ati, tci, precision, I dont know if suncoast makes stuff for this application but they are good. anything but b&m


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## drifter79 (Oct 18, 2003)

It has a 350 motor headers,jacob`s ignition,k&n filter 3in. single exhaust. The trans TH350. In drive it sutters alittle on take off the first shift works and when it go`s to up shift I have to let up on the gas to let it shift and if I hit the gas a little hard it starts to slip. I checked the modulator vac. and it is good all other gears work good. The converter is a non-lockup I do not have to use b&m so I will check the others out so why don`t you like b&m anyway just wondering.


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## Big Nate's Plowing (Nov 26, 2000)

sounds like the clutches are wearing in the transmission causing slippage


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## ratlover (May 5, 2003)

Thier shift kits are junk IMO. They are just built to give a hard shift, they are thus harder on internals. I'm pretty shure they jack with the accumulators(its been awhile so dont quote me), that gives em the hard shift and also make em hard on parts. 

Also they have a higher slip than a comprable stall converter it seems. A car may flash or stall at a specific rpm, with a b&m and other cheaper built converters it may flash or stall at the same rpm but as you are close to the end of the 1/4 or you are cruising down the road they are slipping a bit more than others.

How long have you had the mobil 1 in there? I dont think its related since I have run it and am running it with success but???


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## drifter79 (Oct 18, 2003)

Been running the mobil 1 a couple years the fluid still looks and smells brand new it is not burnt. Looks like I have to get a trans and converter I think I just tow and haul to much for the truck.:crying:


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## derekbroerse (Mar 6, 2004)

Setting up a lockup torque convertor TH350C might be a good way to go for your purposes.... eliminate the slippage of the convertor in high gear.


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## drifter79 (Oct 18, 2003)

How would I do that do I have to change the trans rear shaft or do they make a th350 that is set up for a lock converter. It is going on a 79 4x4 203 transfer case since I need a tranny anyway that might be the way to go Thanks.


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## derekbroerse (Mar 6, 2004)

Look for a TH350 from the early 80's that has an electrical plug on the left hand side (four prong square usually). This is a TH350C. As far as I know they are dimensionally the same as the older version (Maybe Ratlover can confirm this?) and should bolt in in place of your existing unit. I'm assuming that your replacement unit is from a 4x4 as well, I honestly don't know anything about converting a 2wd unit to a 4wd.... ie: if your older rear shaft will fit the 350C....

Electrically, its pretty simple too. Some people like to do it the "Quickie" method, with a toggle switch, but that is just butchery. GM's method is very simple to duplicate for about $5 worth of parts from your local wrecker. I have done the exact same exercise swapping a 700R4 into my '68 Beaumont and '72 Chevelle.

The components you will need are easily obtainable from early 80's GM RWD cars.... think Caprice, Malibu, Monte Carlo, etc. I like to take as much of the wiring along with the parts as possible so you get the proper connectors... but the main two pieces you will need are a vaccuum switch (cone-shaped, usually on the inner fender or firewall) which has one vaccuum port and two wires... the other is the brake pedal switch which will have the two wires for the brake lights like normal, but another two as well for use with this lockup or cruise control to disengage the circuit when you step on the brakes.

When and if you are ready to put this all together I would be more than happy to take a few photo's of the parts you need and give wiring instructions.

Note that I usually tell everyone that ELECTRICITY IS NOT MY FRIEND, but this is extremely simple once you see it all. Heck, I did it!

Also note that the proceedure is exactly the same for a 700R4 installation, so if you happen to come across a good working 700R4/NP208 combo put some thought into upgrading right to that. It will require a little bit of modification to the linkage, mounts, and driveshaft (unless you happen to find a donor 4x4 pickup to rob from!) but you will really love the overdrive for regular driving (no towing in OD they say though...) and you would be gaining the benefit of a part-time transfercase.


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## derekbroerse (Mar 6, 2004)

Like I said, I'd be happy to help you through your swap to the best of my ability, so ask anything you need! If I can't answer it, hopefully some of the others can.


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