torque converter fundamentals ( need to understand)

[tim f.]

I am building an 1969 800A full frame off and ground up build. I have been studying axle gear science, tranfer case science, full motor science. my question is after building a d60 w/lockers and doing the tranfer case no one ever talks about the torque converter. I have a 727 auto I think I'm going to keep it it's just been rebuilt. but that torque converter bolts on with 4 little bolts and it seems could be the weak link in getting the torque to the wheels. I live next to johnson valley ca,(king of the hammers) and will be in the rocks. so I must ask
1. is it not preferable to use an automatic trans?
2. if it doesn't matter then is there modifications to the torque converter Im missing?
3. do they (torque converter) ever break from all the gearing?

I would like to hear multiple opinions thank you !!

[guidolyons]

Lots of guys run slushboxes in the rocks, point and shoot. I prefer rowing my own gears, but to each their own.

Make sure you have a good cooler, heat is the death of autos.

Those 4 bolts are plenty, torque converters actually multiple torque (about 2x), and is a fluid coupler (much like the clutch in a manual) at idle there's not enough pressure to move the vehicle, and RPM increase, up to the stall speed of the torque converter, then the vehicle begins to move. High stall speed converters create more heat.

These guys can explain mo' better than me:

http://www.tciauto.com/tc/torque-converters-explained
http://www.tciauto.com/tc/auto-trans-faq
http://www.cpgnation.com/forum/tci-product-tech.html

[tim f.]

thank you Guido you are truly a master of your craft. you have helped me several times always appreciated.

[Carl Wiese]

Originally Posted by tim f.

I am building an 1969 800A full frame off and ground up build. I have been studying axle gear science, tranfer case science, full motor science. my question is after building a d60 w/lockers and doing the tranfer case no one ever talks about the torque converter. I have a 727 auto I think I'm going to keep it it's just been rebuilt. but that torque converter bolts on with 4 little bolts and it seems could be the weak link in getting the torque to the wheels. I live next to johnson valley ca,(king of the hammers) and will be in the rocks. so I must ask
1. is it not preferable to use an automatic trans?
2. if it doesn't matter then is there modifications to the torque converter Im missing?
3. do they (torque converter) ever break from all the gearing?

I would like to hear multiple opinions thank you !!

Those 4 little bolts are all you need, in my truck I ran ARP studs for the job, these actually ARP Converter bolts. Even stock 5/16 - 24 bolts will be fine.

If you are going to crawl, and that is what the truck is built for, an automatic is the transmission you want to use, but it has to be built for the work. Good quality parts, and a large cooler will help greatly. There is a reason that all the professions in both rock crawling and rock racing use auto, and since that is what you have, don't change it now.

When I had a competition truck, I ran a stock 727 converter, nothing special and it worked great. We never had any problems with the converter, but we did break an output shaft on a Dana 300, countless drive shaft u-joints and tore up a few sets of springs. Also, one Dana 44 axle shaft. The entire time the converter and those four bolts were fine.

[tim f.]

thank you carl what can be done to a 727 to make it stronger or do you think it's good enough "as is" I'm not doing the hammers but I need good capability. I will be running 37's if I can squeeze them in there.

[jauringer]

There are all kinds of fun upgrades for the 727..

4 pinion planetary sets, low gear sets, Rear bearing supports, bolt in sprag,...the list goes on. Considering it's just been rebuilt I'm not sure how likely it would be for you to tear back into it.

As mentioned, keeping it cool is the main goal. I think installing a temp gauge would be a good idea as well.

Jason

[Carl Wiese]

Originally Posted by jauringer

There are all kinds of fun upgrades for the 727..

4 pinion planetary sets, low gear sets, Rear bearing supports, bolt in sprag,...the list goes on. Considering it's just been rebuilt I'm not sure how likely it would be for you to tear back into it.

As mentioned, keeping it cool is the main goal. I think installing a temp gauge would be a good idea as well.

Jason

I agree if it just been rebuilt leave it as is. Find a nice aftermarket cooler and call it good. If/when you break it is totally defendant on how you wheel. And once its broken you'll know what needs to upgraded.

EDIT:

We use something like this on the comp rig, but it was dual circuit. We ran transmission fluid through one side and power steering through the other.

[tim f.]

carl, my radiator runs tranny fluid through it, it's a stock radiator from a 79' scoutII. do you think that it would handle the cooling? I live in the desert of so cal. at this point I can do anything

[Carl Wiese]

Originally Posted by tim f.

carl, my radiator runs tranny fluid through it, it's a stock radiator from a 79' scoutII. do you think that it would handle the cooling? I live in the desert of so cal. at this point I can do anything

I think you need to add something, maybe not a unit with it's own fan, but something inline to supplement your stock cooler. Figure you're going to be basically not moving for long periods of time in desert heat. Getting a bit of extra cooling won't hurt anything.

[Tucker H]

When i had my auto rebuilt the local guy was so happy, i dropped the tranny and was going to put it back in myself, he use to work on these things and said now in his older age he cant lift or drop this lead sled trannys anymore without serious injury/ payment for the job. So for the work i saved him he threw in one of the above tranny coolers he orders for older trucks he does work on. So i got one for free..... yeah free minus the 800 buck rebuild. But it works just fine, and the trans runs and shifts so smooth.