Re: Towing Question - Lets talk RPM\'s, Tire sizes and gear ratios
One thing no one has mentioned is how stout is your engine? Do you feel like it has the guts to tow something around 2200 rpm? (I'm assuming yes)
Contrary to popular belief, you can tow with a 700R4 in OD. Your main enemy will be heat, generated from slippage of the torque convertor as well as gear-hunting, downshifting from OD to 3rd and back up again.
Since I'm too lazy to figure out how to do the link thingie, this is shamelessly copied from an earlier post. You can search for the thread called 700R4 verses 4L60E
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If I understand correctly the problem with towing in OD is twofold: First the locking and unlocking of the torque convertor creating excess heat in the fluid as it hunts for the right gear under load, on hills, etc, and secondly, the transmission pump also running 30% slower wgile in 4th, also contributing to cooling problems.
I bought my 700 from a guy who used to use it to pull his sleds out to Vailmont every weekend. He worked in a 4wd shop in Edmonton and rebuilt it yearly himself with the good stuff, including a brazed torque convertor. He finally went to a NV4500 when he started towing a 5th wheel, so I got the 700.
Now here's the question part:
The way my trans is wired/plumbed is that the torque convertor only locks up in 4th and doesn't unlock (constant power). It's switched, so if I want to unlock it on a short hill, I can unlock the convertor for a minute or two to keep the revs a little higher to the top of the hill and then lock it back up. With 4.56 gears and 35's highway revs seem high enough to keep the pump happy enough and it has a motorhome-sized tranny cooler on it and a temp sensor in the pan to keep an eye on it.
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and in reply from CanmoreK5:
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First of all, your explanation of why the 700 builds up heat is bang on. It looks like you've done your research, and that's half the battle.
Your setup is a little different than mine. My converter locks up in D and not in OD. I assume your rig has an aftermarket lockup kit....
I NEVER tow in OD because the tranny shop that rebuilt my 700 7 years ago told me not to do it. I've also seen many older company trucks blow their trannies(700s as well) because green guys would tow in OD. I run a huge cooler but I don't have a tranny gauge so I can't really tell what my temps are. Let's just say that my 700 has survived many a pull up some of the worst passes in North America- I guess I'm doing something right!!!!
Since your truck is equipped with an ATF temp gauge, I would recommend trying towing in OD and keeping a close eye on your gauge. You'll be able to tell right away if the tranny likes it or not. I agree that 35s and 4.56s will probably help you out a bit.
Just out of curiousity, how much weight are you planning on pulling behind the K5? The general concensus around here is no more than 5500 lbs, and that's if you are using a weight distribution/anti-sway hitch setup, along with a good quality brake controller. If you need any info on any of those, feel free to PM me, brother.
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Clicky?
700R4 verses 4L60E
I would tow with my 700 in OD as long as you can monitor trans temp, prevent the up and downshifting and keep the convertor locked. I should have mine in town early next week if you want to take a look.
CT
